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Jin FX, Wang Y, Li MN, Li RJ, Guo JT. Intestinal glucagon-like peptide-1: A new player associated with impaired counterregulatory responses to hypoglycaemia in type 1 diabetic mice. World J Diabetes 2024; 15:1764-1777. [PMID: 39192849 PMCID: PMC11346100 DOI: 10.4239/wjd.v15.i8.1764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 06/03/2024] [Accepted: 07/05/2024] [Indexed: 07/25/2024] Open
Abstract
BACKGROUND Impaired hypoglycaemic counterregulation has emerged as a critical concern for diabetic patients who may be hesitant to medically lower their blood glucose levels due to the fear of potential hypoglycaemic reactions. However, the patho-genesis of hypoglycaemic counterregulation is still unclear. Glucagon-like peptide-1 (GLP-1) and its analogues have been used as adjunctive therapies for type 1 diabetes mellitus (T1DM). The role of GLP-1 in counterregulatory dys-function during hypoglycaemia in patients with T1DM has not been reported. AIM To explore the impact of intestinal GLP-1 on impaired hypoglycaemic counterregulation in type 1 diabetic mice. METHODS T1DM was induced in C57BL/6J mice using streptozotocin, followed by intraperitoneal insulin injections to create T1DM models with either a single episode of hypoglycaemia or recurrent episodes of hypoglycaemia (DH5). Immunofluorescence, Western blot, and enzyme-linked immunosorbent assay were employed to evaluate the influence of intestinal GLP-1 on the sympathetic-adrenal reflex and glucagon (GCG) secretion. The GLP-1 receptor agonist GLP-1(7-36) or the antagonist exendin (9-39) were infused into the terminal ileum or injected intraperitoneally to further investigate the role of intestinal GLP-1 in hypoglycaemic counterregulation in the model mice. RESULTS The expression levels of intestinal GLP-1 and its receptor (GLP-1R) were significantly increased in DH5 mice. Consecutive instances of excess of intestinal GLP-1 weakens the sympathetic-adrenal reflex, leading to dysfunction of adrenal counterregulation during hypoglycaemia. DH5 mice showed increased pancreatic δ-cell mass, cAMP levels in δ cells, and plasma somatostatin concentrations, while cAMP levels in pancreatic α cells and plasma GCG levels decreased. Furthermore, GLP-1R expression in islet cells and plasma active GLP-1 levels were significantly increased in the DH5 group. Further experiments involving terminal ileal infusion and intraperitoneal injection in the model mice demonstrated that intestinal GLP-1 during recurrent hypoglycaemia hindered the secretion of the counterregulatory hormone GCG via the endocrine pathway. CONCLUSION Excessive intestinal GLP-1 is strongly associated with impaired counterregulatory responses to hypoglycaemia, leading to reduced appetite and compromised secretion of adrenaline, noradrenaline, and GCG during hypo-glycaemia.
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Affiliation(s)
- Fang-Xin Jin
- Department of Histology and Embryology, Key Laboratory of Universities in Shandong Province, Shandong Second Medical University, Weifang 261053, Shandong Province, China
| | - Yan Wang
- Department of Histology and Embryology, Key Laboratory of Universities in Shandong Province, Shandong Second Medical University, Weifang 261053, Shandong Province, China
| | - Min-Ne Li
- Department of Histology and Embryology, Key Laboratory of Universities in Shandong Province, Shandong Second Medical University, Weifang 261053, Shandong Province, China
| | - Ru-Jiang Li
- Department of Histology and Embryology, Key Laboratory of Universities in Shandong Province, Shandong Second Medical University, Weifang 261053, Shandong Province, China
| | - Jun-Tang Guo
- Department of Pathological Physiology, Shandong Second Medical University, Weifang 261053, Shandong Province, China
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Castro G, Mendes NF, Weissmann L, Quaresma PGF, Saad MJA, Prada PO. Multiple metabolic signals in the CeA regulate feeding: The role of AMPK. Mol Cell Endocrinol 2024; 589:112232. [PMID: 38604549 DOI: 10.1016/j.mce.2024.112232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 03/30/2024] [Accepted: 04/01/2024] [Indexed: 04/13/2024]
Abstract
BACKGROUND The central nucleus of the amygdala (CeA) is part of the dopaminergic reward system and controls energy balance. Recently, a cluster of neurons was identified as responsive to the orexigenic effect of ghrelin and fasting. However, the signaling pathway by which ghrelin and fasting induce feeding is unknown. AMP-activated protein kinase (AMPK) is a cellular energy sensor, and its Thr172 phosphorylation (AMPKThr172) in the mediobasal hypothalamus regulates food intake. However, whether the expression and activation of AMPK in CeA could be one of the intracellular signaling activated in response to ghrelin and fasting eliciting food intake is unknown. AIM To evaluate the activation of AMPK into CeA in response to ghrelin, fasting, and 2-deoxy-D-glucose (2DG) and whether feeding accompanied these changes. In addition, to investigate whether the inhibition of AMPK into CeA could decrease food intake. METHODS On a chow diet, eight-week-old Wistar male rats were stereotaxically implanted with a cannula in the CeA to inject several modulators of AMPKα1/2Thr172 phosphorylation, and we performed physiological and molecular assays. KEY FINDINGS Fasting increased, and refeeding reduced AMPKThr172 in the CeA. Intra-CeA glucose injection decreased feeding, whereas injection of 2DG, a glucoprivation inductor, in the CeA, increased food intake and blood glucose, despite faint increases in AMPKThr172. Intra-CeA ghrelin injection increased food intake and AMPKThr172. To further confirm the role of AMPK in the CeA, chronic injection of Melanotan II (MTII) in CeA reduced body mass and food intake over seven days together with a slight decrease in AMPKThr172. SIGNIFICANCE Our findings identified that AMPK might be part of the signaling machinery in the CeA, which responds to nutrients and hormones contributing to feeding control. The results can contribute to understanding the pathophysiological mechanisms of altered feeding behavior/consumption, such as binge eating of caloric-dense, palatable food.
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Affiliation(s)
- Gisele Castro
- Department of Internal Medicine, School of Medical Science, State University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Natália Ferreira Mendes
- Department of Translational Medicine (Section of Pharmacology), School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Laís Weissmann
- Department of Internal Medicine, School of Medical Science, State University of Campinas (UNICAMP), Campinas, SP, Brazil
| | | | - Mario Jose Abdalla Saad
- Department of Internal Medicine, School of Medical Science, State University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Patricia Oliveira Prada
- Department of Internal Medicine, School of Medical Science, State University of Campinas (UNICAMP), Campinas, SP, Brazil; School of Applied Sciences, State University of Campinas (UNICAMP), Limeira, SP, Brazil; Biology Institute, State University of Campinas (UNICAMP), Campinas, SP, Brazil.
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Farrell CM, McNeilly AD, Hapca S, Fournier PA, Jones TW, Facchinetti A, Cappon G, West DJ, McCrimmon RJ. High intensity interval training as a novel treatment for impaired awareness of hypoglycaemia in people with type 1 diabetes (HIT4HYPOS): a randomised parallel-group study. Diabetologia 2024; 67:392-402. [PMID: 38010533 PMCID: PMC10789679 DOI: 10.1007/s00125-023-06051-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 10/23/2023] [Indexed: 11/29/2023]
Abstract
AIMS/HYPOTHESIS Impaired awareness of hypoglycaemia (IAH) in type 1 diabetes may develop through a process referred to as habituation. Consistent with this, a single bout of high intensity interval exercise as a novel stress stimulus improves counterregulatory responses (CRR) to next-day hypoglycaemia, referred to as dishabituation. This longitudinal pilot study investigated whether 4 weeks of high intensity interval training (HIIT) has sustained effects on counterregulatory and symptom responses to hypoglycaemia in adults with type 1 diabetes and IAH. METHODS HIT4HYPOS was a single-centre, randomised, parallel-group study. Participants were identified using the Scottish Diabetes Research Network (SDRN) and from diabetes outpatient clinics in NHS Tayside, UK. The study took place at the Clinical Research Centre, Ninewells Hospital and Medical School, Dundee, UK. Participants were aged 18-55 years with type 1 diabetes of at least 5 years' duration and HbA1c levels <75 mmol/mol (<9%). They had IAH confirmed by a Gold score ≥4, modified Clarke score ≥4 or Dose Adjustment For Normal Eating [DAFNE] hypoglycaemia awareness rating of 2 or 3, and/or evidence of recurrent hypoglycaemia on flash glucose monitoring. Participants were randomly allocated using a web-based system to either 4 weeks of real-time continuous glucose monitoring (RT-CGM) or RT-CGM+HIIT. Participants and investigators were not masked to group assignment. The HIIT programme was performed for 20 min on a stationary exercise bike three times a week. Hyperinsulinaemic-hypoglycaemic (2.5 mmol/l) clamp studies with assessment of symptoms, hormones and cognitive function were performed at baseline and after 4 weeks of the study intervention. The predefined primary outcome was the difference in hypoglycaemia-induced adrenaline (epinephrine) responses from baseline following RT-CGM or RT-CGM+HIIT. RESULTS Eighteen participants (nine men and nine women) with type 1 diabetes (median [IQR] duration 27 [18.75-32] years) and IAH were included, with nine participants randomised to each group. Data from all study participants were included in the analysis. During the 4 week intervention there were no significant mean (SEM) differences between RT-CGM and RT-CGM+HIIT in exposure to level 1 (28 [7] vs 22 [4] episodes, p=0.45) or level 2 (9 [3] vs 4 [1] episodes, p=0.29) hypoglycaemia. The CGM-derived mean glucose level, SD of glucose and glucose management indicator (GMI) did not differ between groups. During the hyperinsulinaemic-hypoglycaemic clamp studies, mean (SEM) change from baseline was greater for the noradrenergic responses (RT-CGM vs RT-CGM+HIIT: -988 [447] vs 514 [732] pmol/l, p=0.02) but not the adrenergic responses (-298 [687] vs 1130 [747] pmol/l, p=0.11) in those participants who had undergone RT-CGM+HIIT. There was a benefit of RT-CGM+HIIT for mean (SEM) change from baseline in the glucagon CRR to hypoglycaemia (RT-CGM vs RT-CGM+HIIT: 1 [4] vs 16 [6] ng/l, p=0.01). Consistent with the hormone response, the mean (SEM) symptomatic response to hypoglycaemia (adjusted for baseline) was greater following RT-CGM+HIIT (RT-CGM vs RT-CGM+HIIT: -4 [2] vs 0 [2], p<0.05). CONCLUSIONS/INTERPRETATION In this pilot clinical trial in people with type 1 diabetes and IAH, we found continuing benefits of HIIT for overall hormonal and symptomatic CRR to subsequent hypoglycaemia. Our findings also suggest that HIIT may improve the glucagon response to insulin-induced hypoglycaemia. TRIAL REGISTRATION ISRCTN15373978. FUNDING Sir George Alberti Fellowship from Diabetes UK (CMF) and the Juvenile Diabetes Research Foundation.
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Affiliation(s)
- Catriona M Farrell
- Division of Systems Medicine, School of Medicine, University of Dundee, Dundee, UK
| | - Alison D McNeilly
- Division of Systems Medicine, School of Medicine, University of Dundee, Dundee, UK
| | - Simona Hapca
- Computing Science and Mathematics, Faculty of Natural Sciences, University of Stirling, Stirling, UK
| | | | | | - Andrea Facchinetti
- Department of Information Engineering, University of Padova, Padova, Italy
| | - Giacomo Cappon
- Department of Information Engineering, University of Padova, Padova, Italy
| | - Daniel J West
- Population Health Sciences Institute, Faculty of Medical Science, Newcastle University, Newcastle upon Tyne, UK
| | - Rory J McCrimmon
- Division of Systems Medicine, School of Medicine, University of Dundee, Dundee, UK.
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Hashmi HZ, Khowaja A, Moheet A. Experimental pharmacological approaches to reverse impaired awareness of hypoglycemia-a review. Front Pharmacol 2024; 15:1349004. [PMID: 38323079 PMCID: PMC10844401 DOI: 10.3389/fphar.2024.1349004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Accepted: 01/04/2024] [Indexed: 02/08/2024] Open
Abstract
The colossal global burden of diabetes management is compounded by the serious complication of hypoglycemia. Protective physiologic hormonal and neurogenic counterregulatory responses to hypoglycemia are essential to preserve glucose homeostasis and avert serious morbidity. With recurrent exposure to hypoglycemic episodes over time, these counterregulatory responses to hypoglycemia can diminish, resulting in an impaired awareness of hypoglycemia (IAH). IAH is characterized by sudden neuroglycopenia rather than preceding cautionary autonomic symptoms. IAH increases the risk of subsequent sudden and severe hypoglycemic episodes in patients with diabetes. The postulated causative mechanisms behind IAH are complex and varied. It is therefore challenging to identify a single effective therapeutic strategy. In this review, we closely examine the efficacy and feasibility of a myriad of pharmaceutical interventions in preventing and treating IAH as described in clinical and preclinical studies. Pharmaceutical agents outlined include N-acetyl cysteine, GABA A receptor blockers, opioid receptor antagonists, AMP activated protein kinase agonists, potassium channel openers, dehydroepiandrosterone, metoclopramide, antiadrenergic agents, antidiabetic agents and glucagon.
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Affiliation(s)
- Hiba Z. Hashmi
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, MN, United States
| | - Ameer Khowaja
- Northeast Endocrinology Associates, San Antonio, TX, United States
| | - Amir Moheet
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, MN, United States
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Townsend LK, Steinberg GR. AMPK and the Endocrine Control of Metabolism. Endocr Rev 2023; 44:910-933. [PMID: 37115289 DOI: 10.1210/endrev/bnad012] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 03/10/2023] [Accepted: 04/24/2023] [Indexed: 04/29/2023]
Abstract
Complex multicellular organisms require a coordinated response from multiple tissues to maintain whole-body homeostasis in the face of energetic stressors such as fasting, cold, and exercise. It is also essential that energy is stored efficiently with feeding and the chronic nutrient surplus that occurs with obesity. Mammals have adapted several endocrine signals that regulate metabolism in response to changes in nutrient availability and energy demand. These include hormones altered by fasting and refeeding including insulin, glucagon, glucagon-like peptide-1, catecholamines, ghrelin, and fibroblast growth factor 21; adipokines such as leptin and adiponectin; cell stress-induced cytokines like tumor necrosis factor alpha and growth differentiating factor 15, and lastly exerkines such as interleukin-6 and irisin. Over the last 2 decades, it has become apparent that many of these endocrine factors control metabolism by regulating the activity of the AMPK (adenosine monophosphate-activated protein kinase). AMPK is a master regulator of nutrient homeostasis, phosphorylating over 100 distinct substrates that are critical for controlling autophagy, carbohydrate, fatty acid, cholesterol, and protein metabolism. In this review, we discuss how AMPK integrates endocrine signals to maintain energy balance in response to diverse homeostatic challenges. We also present some considerations with respect to experimental design which should enhance reproducibility and the fidelity of the conclusions.
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Affiliation(s)
- Logan K Townsend
- Centre for Metabolism Obesity and Diabetes Research, Hamilton, ON L8S 4L8, Canada
- Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Gregory R Steinberg
- Centre for Metabolism Obesity and Diabetes Research, Hamilton, ON L8S 4L8, Canada
- Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, Hamilton, ON L8S 4L8, Canada
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada
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Su G, Farhat R, Laxman AK, Chapman-Natewa K, Nelson IE, Chan O. Astrocyte Glycogen Is a Major Source of Hypothalamic Lactate in Rats With Recurrent Hypoglycemia. Diabetes 2023; 72:1154-1160. [PMID: 37216640 PMCID: PMC10382650 DOI: 10.2337/db22-0902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 05/13/2023] [Indexed: 05/24/2023]
Abstract
Lactate is an important metabolic substrate for sustaining brain energy requirements when glucose supplies are limited. Recurring exposure to hypoglycemia (RH) raises lactate levels in the ventromedial hypothalamus (VMH), which contributes to counterregulatory failure. However, the source of this lactate remains unclear. The current study investigates whether astrocytic glycogen serves as the major source of lactate in the VMH of RH rats. By decreasing the expression of a key lactate transporter in VMH astrocytes of RH rats, we reduced extracellular lactate concentrations, suggesting excess lactate was locally produced from astrocytes. To determine whether astrocytic glycogen serves as the major source of lactate, we chronically delivered either artificial extracellular fluid or 1,4-dideoxy-1,4-imino-d-arabinitol to inhibit glycogen turnover in the VMH of RH animals. Inhibiting glycogen turnover in RH animals prevented the rise in VMH lactate and the development of counterregulatory failure. Lastly, we noted that RH led to an increase in glycogen shunt activity in response to hypoglycemia and elevated glycogen phosphorylase activity in the hours following a bout of hypoglycemia. Our data suggest that dysregulation of astrocytic glycogen metabolism following RH may be responsible, at least in part, for the rise in VMH lactate levels. ARTICLE HIGHLIGHTS Astrocytic glycogen serves as the major source of elevated lactate levels in the ventromedial hypothalamus (VMH) of animals exposed to recurring episodes of hypoglycemia. Antecedent hypoglycemia alters VMH glycogen turnover. Antecedent exposure to hypoglycemia enhances glycogen shunt activity in the VMH during subsequent bouts of hypoglycemia. In the immediate hours following a bout of hypoglycemia, sustained elevations in glycogen phosphorylase activity in the VMH of recurrently hypoglycemic animals contribute to sustained elevations in local lactate levels.
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Affiliation(s)
- Gong Su
- Cardiac Department, Aerospace Center Hospital, Peking University Aerospace School of Clinical Medicine, Beijing, China
| | - Rawad Farhat
- Department of Internal Medicine, Division of Endocrinology, Metabolism and Diabetes, University of Utah, Salt Lake City, UT
| | - Anil K. Laxman
- University of Utah Health Sciences Metabolic Phenotyping Core, University of Utah, Salt Lake City, UT
| | | | - Irvane E. Nelson
- Department of Internal Medicine, Division of Endocrinology, Metabolism and Diabetes, University of Utah, Salt Lake City, UT
| | - Owen Chan
- Department of Internal Medicine, Division of Endocrinology, Metabolism and Diabetes, University of Utah, Salt Lake City, UT
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Sun H, Lin W, Tang Y, Tu H, Chen T, Zhou J, Wang D, Xu Q, Niu J, Dong W, Liu S, Ni X, Yang W, Zhao Y, Ying L, Zhang J, Li X, Mohammadi M, Shen WL, Huang Z. Sustained remission of type 2 diabetes in rodents by centrally administered fibroblast growth factor 4. Cell Metab 2023:S1550-4131(23)00172-9. [PMID: 37167965 DOI: 10.1016/j.cmet.2023.04.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 09/30/2022] [Accepted: 04/21/2023] [Indexed: 05/13/2023]
Abstract
Type 2 diabetes (T2D) is a major health and economic burden worldwide. Despite the availability of multiple drugs for short-term management, sustained remission of T2D is currently not achievable pharmacologically. Intracerebroventricular administration of fibroblast growth factor 1 (icvFGF1) induces sustained remission in T2D rodents, propelling intense research efforts to understand its mechanism of action. Whether other FGFs possess similar therapeutic benefits is currently unknown. Here, we show that icvFGF4 also elicits a sustained antidiabetic effect in both male db/db mice and diet-induced obese mice by activating FGF receptor 1 (FGFR1) expressed in glucose-sensing neurons within the mediobasal hypothalamus. Specifically, FGF4 excites glucose-excited (GE) neurons while inhibiting glucose-inhibited (GI) neurons. Moreover, icvFGF4 restores the percentage of GI neurons in db/db mice. Importantly, intranasal delivery of FGF4 alleviates hyperglycemia in db/db mice, paving the way for non-invasive therapy. We conclude that icvFGF4 holds significant therapeutic potential for achieving sustained remission of T2D.
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Affiliation(s)
- Hongbin Sun
- School of Life Science and Technology & Shanghai Clinical Research and Trial Center, ShanghaiTech University, Shanghai 201210, China
| | - Wei Lin
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision, and Brain Health) & School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Yu Tang
- Key Laboratory of Thermoregulation and Inflammation of Sichuan Higher Education Institutes, Department of Physiology, Chengdu Medical College, Chengdu, Sichuan 610500, China
| | - Hongqing Tu
- School of Life Science and Technology & Shanghai Clinical Research and Trial Center, ShanghaiTech University, Shanghai 201210, China
| | - Ting Chen
- School of Life Science and Technology & Shanghai Clinical Research and Trial Center, ShanghaiTech University, Shanghai 201210, China
| | - Jie Zhou
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision, and Brain Health) & School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Dezhong Wang
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision, and Brain Health) & School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Qingqing Xu
- Biology Science Institutes, Chongqing Medical University, Chongqing 400016, China
| | - Jianlou Niu
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision, and Brain Health) & School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Wenliya Dong
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision, and Brain Health) & School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Sidan Liu
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision, and Brain Health) & School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Xinyan Ni
- School of Life Science and Technology & Shanghai Clinical Research and Trial Center, ShanghaiTech University, Shanghai 201210, China
| | - Wen Yang
- School of Life Science and Technology & Shanghai Clinical Research and Trial Center, ShanghaiTech University, Shanghai 201210, China
| | - Yingzheng Zhao
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision, and Brain Health) & School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Lei Ying
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision, and Brain Health) & School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Jie Zhang
- Key Laboratory of Thermoregulation and Inflammation of Sichuan Higher Education Institutes, Department of Physiology, Chengdu Medical College, Chengdu, Sichuan 610500, China
| | - Xiaokun Li
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision, and Brain Health) & School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Moosa Mohammadi
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision, and Brain Health) & School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Wei L Shen
- School of Life Science and Technology & Shanghai Clinical Research and Trial Center, ShanghaiTech University, Shanghai 201210, China.
| | - Zhifeng Huang
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision, and Brain Health) & School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China.
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McCrimmon RJ. Remembrance of things past: The consequences of recurrent hypoglycaemia in diabetes. Diabet Med 2022; 39:e14973. [PMID: 36251572 PMCID: PMC10015985 DOI: 10.1111/dme.14973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 10/03/2022] [Accepted: 10/13/2022] [Indexed: 01/18/2023]
Abstract
AIMS People with type 1 and type 2 diabetes still frequently experience hypoglycaemia, which can be severe, leading to loss of consciousness. This review will examine the cellular consequences of recurrent hypoglycaemia. METHODS This review, based on the Dorothy Hodgkin Lecture given at the Diabetes UK 2022 annual symposium by the author, will discuss our current understanding of the mechanisms by which hypoglycaemia is detected and the consequences of recurrent exposure to hypoglycaemia. RESULTS Glucose-responsive cells found in the periphery as well as multiple areas of the brain are organised in a classical sensori-motor integrative network encompassing peripheral, hindbrain and hypothalamic components. The mechanism used by glucose-responsive neurons to detect hypoglycaemia parallel those of the classical glucose sensor the pancreatic ß-cell, namely in their use of glucokinase, KATP channels and AMP-activated protein kinase. Recurrent exposure to hypoglycaemia results in a series of cellular adaptations that may be designed to increase the resilience of cells to future hypoglycaemia. This review also highlights how hypoglycaemia, as an oxidative stressor, may also exacerbate chronic hyperglycaemia-induced increases in oxidative stress and inflammation, leading to damage to vulnerable brain regions. CONCLUSIONS Impaired awareness of hypoglycaemia follows the adaptation of central glucose-responsive neurons to repeated hypoglycaemia and may represent a form of memory called habituation. In diabetes, recurrent hypoglycaemia may have tissue consequences as a result of a profound disruption in the cellular response to a hypoglycaemic challenge that increases vulnerability to oxidative damage.
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Affiliation(s)
- Rory J. McCrimmon
- Systems Medicine, School of MedicineUniversity of Dundee, Ninewells Hospital and Medical SchoolDundeeUK
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Liu Z, Zhang L, Qian C, Zhou Y, Yu Q, Yuan J, Lv Y, Zhang L, Chang X, Li Y, Liu Y. Recurrent hypoglycemia increases hepatic gluconeogenesis without affecting glycogen metabolism or systemic lipolysis in rat. Metabolism 2022; 136:155310. [PMID: 36063868 DOI: 10.1016/j.metabol.2022.155310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 08/29/2022] [Accepted: 08/31/2022] [Indexed: 11/26/2022]
Abstract
INTRODUCTION Recurrent hypoglycemia (RH) impairs secretion of counterregulatory hormones. Whether and how RH affects responses within metabolically important peripheral organs to counterregulatory hormones are poorly understood. OBJECTIVE To study the effects of RH on metabolic pathways associated with glucose counterregulation within liver, white adipose tissue and skeletal muscle. METHODS Using a widely adopted rodent model of 3-day recurrent hypoglycemia, we first checked expression of counterregulatory hormone G-protein coupled receptors (GPCRs), their inhibitory regulators and downstream enzymes catalyzing glycogen metabolism, gluconeogenesis and lipolysis by qPCR and western blot. Then, we examined epinephrine-induced phosphorylation of PKA substrates to validate adrenergic sensitivity in each organ. Next, we measured hepatic and skeletal glycogen content, degree of breakdown by epinephrine and abundance of phosphorylated glycogen phosphorylase under hypoglycemia and that of phosphorylated glycogen synthase during recovery to evaluate glycogen turnover. Further, we performed pyruvate and lactate tolerance tests to assess gluconeogenesis. Additionally, we measured circulating FFA and glycerol to check lipolysis. The abovementioned studies were repeated in streptozotocin-induced diabetic rat model. Finally, we conducted epinephrine tolerance test to investigate systemic glycemic excursions to counterregulatory hormones. Saline-injected rats served as controls. RESULTS RH increased counterregulatory hormone GPCR signaling in liver and epidydimal white adipose tissue (eWAT), but not in skeletal muscle. For glycogen metabolism, RH did not affect total content or epinephrine-stimulated breakdown in liver and skeletal muscle. Although RH decreased expression of phosphorylated glycogen synthase 2, it did not affect hepatic glycogen biosynthesis during recovery from hypoglycemia or after fasting-refeeding. For gluconeogenesis, RH upregulated fructose 1,6-bisphosphatase 1 and monocarboxylic acid transporter 1 that imports lactate as precursor, resulting in a lower blood lactate profile during hypoglycemia. In agreement, RH elevated fasting blood glucose and caused higher glycemic excursions during pyruvate tolerance test. For lipolysis, RH did not affect circulating levels of FFA and glycerol after overnight fasting or upon epinephrine stimulation. Interestingly, RH upregulated the trophic fatty acid transporter FATP1 and glucose transporter GLUT4 to increase lipogenesis in eWAT. These aforementioned changes of gluconeogenesis, lipolysis and lipogenesis were validated in streptozotocin-diabetic rats. Finally, RH increased insulin sensitivity to accelerate glucose disposal, which was attributable to upregulated visceral adipose GLUT4. CONCLUSIONS RH caused metabolic adaptations related to counterregulation within peripheral organs. Specifically, adrenergic signaling was enhanced in liver and visceral fat, but not in skeletal muscle. Glycogen metabolism remained unchanged. Hepatic gluconeogenesis was augmented. Systemic lipolysis was unaffected, but visceral lipogenesis was enhanced. Insulin sensitivity was increased. These findings provided insights into mechanisms underlying clinical problems associated with intensive insulin therapy, such as high gluconeogenic flux and body weight gain.
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Affiliation(s)
- Zejian Liu
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Lingyu Zhang
- Department of Endocrinology, Sir Run Run Hospital, Nanjing Medical University, Nanjing, Jiangsu 211100, China
| | - Chen Qian
- Department of Endocrinology, Zhangjiagang Hospital Affiliated to Soochow University, Zhangjiagang, Suzhou, Jiangsu 215699, China
| | - Ying Zhou
- Department of Endocrinology, Sir Run Run Hospital, Nanjing Medical University, Nanjing, Jiangsu 211100, China
| | - Qiuyu Yu
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Jiaqi Yuan
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Yunfan Lv
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Leheng Zhang
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Xiaoai Chang
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Yangyang Li
- Department of Endocrinology, Sir Run Run Hospital, Nanjing Medical University, Nanjing, Jiangsu 211100, China.
| | - Yu Liu
- Department of Endocrinology, Sir Run Run Hospital, Nanjing Medical University, Nanjing, Jiangsu 211100, China.
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10
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Magnan C, Le Stunff H. Role of hypothalamic de novo ceramides synthesis in obesity and associated metabolic disorders. Mol Metab 2021; 53:101298. [PMID: 34273578 PMCID: PMC8353504 DOI: 10.1016/j.molmet.2021.101298] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 06/28/2021] [Accepted: 07/09/2021] [Indexed: 12/31/2022] Open
Abstract
Background Sphingolipid-mediated signalling pathways are described as important players in the normal functioning of neurons and nonneuronal cells in the central nervous system (CNS). Scope of review This review aims to show role of de novo ceramide synthesis in the CNS in controling key physiological processes, including food intake, energy expenditure, and thermogenesis. The corollary is a condition that leads to a dysfunction in ceramide metabolism in these central regions that can have major consequences on the physiological regulation of energy balance. Major conclusions Excessive hypothalamic de novo ceramide synthesis has been shown to result in the establishment of central insulin resistance, endoplasmic reticulum stress, and inflammation. Additionally, excessive hypothalamic de novo ceramide synthesis has also been associated with changes in the activity of the autonomic nervous system. Such dysregulation of hypothalamic de novo ceramide synthesis forms the key starting point for the initiation of pathophysiological conditions such as obesity – which may or may not be associated with type 2 diabetes.
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Affiliation(s)
| | - Hervé Le Stunff
- CNRS UMR 9198 Institut des Neurosciences Paris Saclay (Neuro-PSI), Université Paris-Saclay, Saclay, France.
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11
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Synergetic Action of Forskolin and Mevastatin Induce Normalization of Lipids Profile in Dyslipidemic Rats through Adenosine Monophosphate Kinase Upregulation. BIOMED RESEARCH INTERNATIONAL 2021; 2021:6687551. [PMID: 34104650 PMCID: PMC8159628 DOI: 10.1155/2021/6687551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 03/02/2021] [Accepted: 05/13/2021] [Indexed: 11/17/2022]
Abstract
In the present study, we examined the synergetic effect of forskolin and mevastatin administration on lipid profile and lipid metabolism in omental adipose tissue in dyslipidemic rats. The study was conducted on forty male albino rats. The rats were randomly classified into four main groups of ten animals in each group as follows: group A, served as control nontreated; group B, rats that received Triton WR 1339 (500 mg/kg); group C, rats that received Triton WR 1339 with forskolin (100% FSK extract 0.5 mg/kg/day) for four weeks; and group D, dyslipidemic rats received both mevastatin and forskolin. At the end of the experimental period, blood and omental adipose tissue samples were collected, preserved, and used for biochemical determination of lipid profile and mRNA expression profile of adenylate cyclase (AC), hormone-sensitive lipase, respectively (HSL), and adenosine monophosphate-activated protein kinase (AMPK). The results showed a significant decline in the serum concentration of total cholesterol, LDL-cholesterol, and triglycerides, although there was a significant increase in serum levels of HDL-cholesterol and glycerol in rats received forskolin alone or with mevastatin when compared with control and dyslipidemic groups. The mRNA expression levels of AC, HSL, and AMPK were significantly increased in omental adipose tissue of rats received forskolin when compared with other groups. In conclusion, forskolin acts synergistically with mevastatin to lower lipid profile and improve lipid metabolism in dyslipidemic rats through upregulation of AMPK expression.
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12
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Abstract
Chronic metabolic diseases, including diabetes and obesity, have become a major global health threat of the twenty-first century. Maintaining glucose homeostasis is essential for survival in mammals. Complex and highly coordinated interactions between glucose-sensing mechanisms and multiple effector systems are essential for controlling glucose levels in the blood. The central nervous system (CNS) plays a crucial role in regulating glucose homeostasis. Growing evidence indicates that disruption of glucose sensing in selective CNS areas, such as the hypothalamus, is closely interlinked with the pathogenesis of obesity and type 2 diabetes mellitus. However, the underlying intracellular mechanisms of glucose sensing in the hypothalamus remain elusive. Here, we review the current literature on hypothalamic glucose-sensing mechanisms and discuss the impact of alterations of these mechanisms on the pathogenesis of diabetes.
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Affiliation(s)
- Nal Ae Yoon
- Institute of Human Nutrition, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY, USA
- Department of Molecular Pharmacology and Therapeutics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY, USA
| | - Sabrina Diano
- Institute of Human Nutrition, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY, USA.
- Department of Molecular Pharmacology and Therapeutics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY, USA.
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13
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Garcia SM, Hirschberg PR, Sarkar P, Siegel DM, Teegala SB, Vail GM, Routh VH. Insulin actions on hypothalamic glucose-sensing neurones. J Neuroendocrinol 2021; 33:e12937. [PMID: 33507001 PMCID: PMC10561189 DOI: 10.1111/jne.12937] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 12/22/2020] [Accepted: 12/29/2020] [Indexed: 12/13/2022]
Abstract
Subsequent to the discovery of insulin 100 years ago, great strides have been made in understanding its function, especially in the brain. It is now clear that insulin is a critical regulator of the neuronal circuitry controlling energy balance and glucose homeostasis. This review focuses on the effects of insulin and diabetes on the activity and glucose sensitivity of hypothalamic glucose-sensing neurones. We highlight the role of electrophysiological data in understanding how insulin regulates glucose-sensing neurones. A brief introduction describing the benefits and limitations of the major electrophysiological techniques used to investigate glucose-sensing neurones is provided. The mechanisms by which hypothalamic neurones sense glucose are discussed with an emphasis on those glucose-sensing neurones already shown to be modulated by insulin. Next, the literature pertaining to how insulin alters the activity and glucose sensitivity of these hypothalamic glucose-sensing neurones is described. In addition, the effects of impaired insulin signalling during diabetes and the ramifications of insulin-induced hypoglycaemia on hypothalamic glucose-sensing neurones are covered. To the extent that it is known, we present hypotheses concerning the mechanisms underlying the effects of these insulin-related pathologies. To conclude, electrophysiological data from the hippocampus are evaluated aiming to provide clues regarding how insulin might influence neuronal plasticity in glucose-sensing neurones. Although much has been accomplished subsequent to the discovery of insulin, the work described in our review suggests that the regulation of central glucose sensing by this hormone is both important and understudied.
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Affiliation(s)
- Stephanie M Garcia
- Department of Pharmacology, Physiology and Neuroscience, Rutgers, New Jersey Medical School, The State University of New Jersey, Newark, NJ, USA
| | - Pamela R Hirschberg
- Department of Pharmacology, Physiology and Neuroscience, Rutgers, New Jersey Medical School, The State University of New Jersey, Newark, NJ, USA
| | - Pallabi Sarkar
- Department of Pharmacology, Physiology and Neuroscience, Rutgers, New Jersey Medical School, The State University of New Jersey, Newark, NJ, USA
| | - Dashiel M Siegel
- Department of Pharmacology, Physiology and Neuroscience, Rutgers, New Jersey Medical School, The State University of New Jersey, Newark, NJ, USA
| | - Suraj B Teegala
- Department of Pharmacology, Physiology and Neuroscience, Rutgers, New Jersey Medical School, The State University of New Jersey, Newark, NJ, USA
| | - Gwyndolin M Vail
- Department of Pharmacology, Physiology and Neuroscience, Rutgers, New Jersey Medical School, The State University of New Jersey, Newark, NJ, USA
| | - Vanessa H Routh
- Department of Pharmacology, Physiology and Neuroscience, Rutgers, New Jersey Medical School, The State University of New Jersey, Newark, NJ, USA
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14
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Sankar A, Khodai T, McNeilly AD, McCrimmon RJ, Luckman SM. Experimental Models of Impaired Hypoglycaemia-Associated Counter-Regulation. Trends Endocrinol Metab 2020; 31:691-703. [PMID: 32563715 DOI: 10.1016/j.tem.2020.05.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 05/14/2020] [Accepted: 05/26/2020] [Indexed: 01/24/2023]
Abstract
Impaired awareness of hypoglycaemia (IAH) affects around a quarter of patients with diabetes who receive insulin treatment. This condition is characterised by a progressive reduction in symptomatic and behavioural responses to hypoglycaemia, increasing risk of deeper drops in blood glucose, unconsciousness, and collapse. Thus, patients with IAH experience severe hypoglycaemic episodes more frequently, resulting in significant morbidity and mortality. IAH is thought to develop as a consequence of whole-body adaptations to repeated insulin-induced hypoglycaemia (RH), with widespread deficits in the hypoglycaemia counter-regulatory response (CRR). Despite this important insight, the precise pathophysiology by which RH leads to an attenuated CRR is unknown. Studies into the underlying mechanisms of IAH have employed a variety of protocols in humans and experimental species. The use of animal models has many investigational benefits, including the unprecedented increase in the availability of transgenic strains. However, modelling impaired hypoglycaemia-associated counter-regulation remains challenging and appropriate interpretation of findings across species and protocols even more so. Here, we review the experimental modelling of IAH and impaired hypoglycaemia-associated counter-regulation, with a focus on understanding species-specific variation in glucose homeostasis. This review will aid investigators in interpreting outputs from different studies in IAH and aid progress in the field.
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Affiliation(s)
- Adhithya Sankar
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Tansi Khodai
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Alison D McNeilly
- Division of Systems Medicine, School of Medicine, University of Dundee, Dundee, UK
| | - Rory J McCrimmon
- Division of Systems Medicine, School of Medicine, University of Dundee, Dundee, UK
| | - Simon M Luckman
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.
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15
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Liu H, Xu Y, Hu F. AMPK in the Ventromedial Nucleus of the Hypothalamus: A Key Regulator for Thermogenesis. Front Endocrinol (Lausanne) 2020; 11:578830. [PMID: 33071984 PMCID: PMC7538541 DOI: 10.3389/fendo.2020.578830] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 08/24/2020] [Indexed: 12/19/2022] Open
Abstract
Obesity has become a global health issue, but effective therapies remain very limited. Adaptive thermogenesis promotes weight loss by dissipating energy in the form of heat, thereby representing a promising target to counteract obesity. Notably, the regulation of thermogenesis is tightly orchestrated by complex neuronal networks, especially those in the hypothalamus. Recent evidence highlights the importance of adenosine monophosphate-activated protein kinase (AMPK) within the ventromedial nucleus of the hypothalamus (VMH) in modulating thermogenesis. Various molecules, such as GLP-1, leptin, estradiol, and thyroid hormones, have been reported to act on the VMH to inhibit AMPK, which subsequently increases thermogenesis through the activation of the sympathetic nervous system (SNS). In this review, we summarize the critical role of AMPK within the VMH in the control of energy balance, focusing on its contribution to thermogenesis and the associated mechanisms.
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Affiliation(s)
- Hailan Liu
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital of Central South University, Changsha, China
- Department of Pediatrics, Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX, United States
| | - Yong Xu
- Department of Pediatrics, Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX, United States
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, United States
| | - Fang Hu
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital of Central South University, Changsha, China
- *Correspondence: Fang Hu
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16
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Hirschberg PR, Sarkar P, Teegala SB, Routh VH. Ventromedial hypothalamus glucose-inhibited neurones: A role in glucose and energy homeostasis? J Neuroendocrinol 2020; 32:e12773. [PMID: 31329314 PMCID: PMC7074896 DOI: 10.1111/jne.12773] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 06/18/2019] [Accepted: 07/14/2019] [Indexed: 12/20/2022]
Abstract
The ventromedial hypothalamus (VMH) plays a complex role in glucose and energy homeostasis. The VMH is necessary for the counter-regulatory response to hypoglycaemia (CRR) that increases hepatic gluconeogenesis to restore euglycaemia. On the other hand, the VMH also restrains hepatic glucose production during euglycaemia and stimulates peripheral glucose uptake. The VMH is also important for the ability of oestrogen to increase energy expenditure. This latter function is mediated by VMH modulation of the lateral/perifornical hypothalamic area (lateral/perifornical hypothalamus) orexin neurones. Activation of VMH AMP-activated protein kinase (AMPK) is necessary for the CRR. By contrast, VMH AMPK inhibition favours decreased basal glucose levels and is required for oestrogen to increase energy expenditure. Specialised VMH glucose-sensing neurones confer the ability to sense and respond to changes in blood glucose levels. Glucose-excited (GE) neurones increase and glucose-inhibited (GI) neurones decrease their activity as glucose levels rise. VMH GI neurones, in particular, appear to be important in the CRR, although a role for GE neurones cannot be discounted. AMPK mediates glucose sensing in VMH GI neurones suggesting that, although activation of these neurones is important for the CRR, it is necessary to silence them to lower basal glucose levels and enable oestrogen to increase energy expenditure. In support of this, we found that oestrogen reduces activation of VMH GI neurones in low glucose by inhibiting AMPK. In this review, we present the evidence underlying the role of the VMH in glucose and energy homeostasis. We then discuss the role of VMH glucose-sensing neurones in mediating these effects, with a strong emphasis on oestrogenic regulation of glucose sensing and how this may affect glucose and energy homeostasis.
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Affiliation(s)
- Pamela R Hirschberg
- Department of Pharmacology, Physiology and Neurosciences, Rutgers New Jersey Medical School, The State University of New Jersey, Newark, NJ, USA
| | - Pallabi Sarkar
- Department of Pharmacology, Physiology and Neurosciences, Rutgers New Jersey Medical School, The State University of New Jersey, Newark, NJ, USA
| | - Suraj B Teegala
- Department of Pharmacology, Physiology and Neurosciences, Rutgers New Jersey Medical School, The State University of New Jersey, Newark, NJ, USA
| | - Vanessa H Routh
- Department of Pharmacology, Physiology and Neurosciences, Rutgers New Jersey Medical School, The State University of New Jersey, Newark, NJ, USA
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17
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Conde-Sieira M, Capelli V, Álvarez-Otero R, Díaz-Rúa A, Velasco C, Comesaña S, López M, Soengas JL. Hypothalamic AMPKα2 regulates liver energy metabolism in rainbow trout through vagal innervation. Am J Physiol Regul Integr Comp Physiol 2019; 318:R122-R134. [PMID: 31692367 DOI: 10.1152/ajpregu.00264.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Hypothalamic AMPK plays a major role in the regulation of whole body metabolism and energy balance. Present evidence has demonstrated that this canonical mechanism is evolutionarily conserved. Thus, recent data demonstrated that inhibition of AMPKα2 in fish hypothalamus led to decreased food intake and liver capacity to use and synthesize glucose, lipids, and amino acids. We hypothesize that a signal of abundance of nutrients from the hypothalamus controls hepatic metabolism. The vagus nerve is the most important link between the brain and the liver. We therefore examined in the present study whether surgical transection of the vagus nerve in rainbow trout is sufficient to alter the effect in liver of central inhibition of AMPKα2. Thus, we vagotomized (VGX) or not (Sham) rainbow trout and then intracerebroventricularly administered adenoviral vectors tagged with green fluorescent protein alone or linked to a dominant negative isoform of AMPKα2. The inhibition of AMPKα2 led to reduced food intake in parallel with changes in the mRNA abundance of hypothalamic neuropeptides [neuropeptide Y (npy), agouti-related protein 1 (agrp1), and cocaine- and amphetamine-related transcript (cartpt)] involved in food intake regulation. Central inhibition of AMPKα2 resulted in the liver having decreased capacity to use and synthesize glucose, lipids, and amino acids. Notably, these effects mostly disappeared in VGX fish. These results support the idea that autonomic nervous system actions mediate the actions of hypothalamic AMPKα2 on liver metabolism. Importantly, this evidence indicates that the well-established role of hypothalamic AMPK in energy balance is a canonical evolutionarily preserved mechanism that is also present in the fish lineage.
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Affiliation(s)
- Marta Conde-Sieira
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro de Investigación Mariña, Universidade de Vigo, Vigo, Spain
| | - Valentina Capelli
- Departamento de Fisiología, Grupo NeurObesity, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas, Universidade de Santiago de Compostela-Instituto de Investigación Sanitaria and Centro de Investigación Biomédica en Red-Fisiopatología de la Obesidad y Nutrición, Santiago de Compostela, Spain.,Unit of Internal Medicine and Endocrinology, Istituti Clinici Scientifici Maugeri, Department of Internal Medicine and Therapeutics, University of Pavia, Pavia, Italy
| | - Rosa Álvarez-Otero
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro de Investigación Mariña, Universidade de Vigo, Vigo, Spain
| | - Adrián Díaz-Rúa
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro de Investigación Mariña, Universidade de Vigo, Vigo, Spain
| | - Cristina Velasco
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro de Investigación Mariña, Universidade de Vigo, Vigo, Spain
| | - Sara Comesaña
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro de Investigación Mariña, Universidade de Vigo, Vigo, Spain
| | - Miguel López
- Departamento de Fisiología, Grupo NeurObesity, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas, Universidade de Santiago de Compostela-Instituto de Investigación Sanitaria and Centro de Investigación Biomédica en Red-Fisiopatología de la Obesidad y Nutrición, Santiago de Compostela, Spain
| | - José L Soengas
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro de Investigación Mariña, Universidade de Vigo, Vigo, Spain
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18
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Furigo IC, de Souza GO, Teixeira PDS, Guadagnini D, Frazão R, List EO, Kopchick JJ, Prada PO, Donato J. Growth hormone enhances the recovery of hypoglycemia via ventromedial hypothalamic neurons. FASEB J 2019; 33:11909-11924. [PMID: 31366244 DOI: 10.1096/fj.201901315r] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Growth hormone (GH) is secreted during hypoglycemia, and GH-responsive neurons are found in brain areas containing glucose-sensing neurons that regulate the counter-regulatory response (CRR). However, whether GH modulates the CRR to hypoglycemia via specific neuronal populations is currently unknown. Mice carrying ablation of GH receptor (GHR) either in leptin receptor (LepR)- or steroidogenic factor-1 (SF1)-expressing cells were studied. We also investigated the importance of signal transducer and activator of transcription 5 (STAT5) signaling in SF1 cells for the CRR. GHR ablation in LepR cells led to impaired capacity to recover from insulin-induced hypoglycemia and to a blunted CRR caused by 2-deoxy-d-glucose (2DG) administration. GHR inactivation in SF1 cells, which include ventromedial hypothalamic neurons, also attenuated the CRR. The reduced CRR was prevented by parasympathetic blockers. Additionally, infusion of 2DG produced an abnormal hyperactivity of parasympathetic preganglionic neurons, whereas the 2DG-induced activation of anterior bed nucleus of the stria terminalis neurons was reduced in mice without GHR in SF1 cells. Mice carrying ablation of Stat5a/b genes in SF1 cells showed no defects in the CRR. In summary, GHR expression in SF1 cells is required for a normal CRR, and these effects are largely independent of STAT5 pathway.-Furigo, I. C., de Souza, G. O., Teixeira, P. D. S., Guadagnini, D., Frazão, R., List, E. O., Kopchick, J. J., Prada, P. O., Donato, J., Jr. Growth hormone enhances the recovery of hypoglycemia via ventromedial hypothalamic neurons.
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Affiliation(s)
- Isadora C Furigo
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Gabriel O de Souza
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Pryscila D S Teixeira
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Dioze Guadagnini
- School of Applied Sciences, State University of Campinas, Limeira, Brazil
| | - Renata Frazão
- Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Edward O List
- Edison Biotechnology Institute and Heritage College of Osteopathic Medicine, Ohio University, Athens, Ohio, USA
| | - John J Kopchick
- Edison Biotechnology Institute and Heritage College of Osteopathic Medicine, Ohio University, Athens, Ohio, USA
| | - Patricia O Prada
- School of Applied Sciences, State University of Campinas, Limeira, Brazil
| | - Jose Donato
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
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Stanley S, Moheet A, Seaquist ER. Central Mechanisms of Glucose Sensing and Counterregulation in Defense of Hypoglycemia. Endocr Rev 2019; 40:768-788. [PMID: 30689785 PMCID: PMC6505456 DOI: 10.1210/er.2018-00226] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 01/17/2019] [Indexed: 12/12/2022]
Abstract
Glucose homeostasis requires an organism to rapidly respond to changes in plasma glucose concentrations. Iatrogenic hypoglycemia as a result of treatment with insulin or sulfonylureas is the most common cause of hypoglycemia in humans and is generally only seen in patients with diabetes who take these medications. The first response to a fall in glucose is the detection of impending hypoglycemia by hypoglycemia-detecting sensors, including glucose-sensing neurons in the hypothalamus and other regions. This detection is then linked to a series of neural and hormonal responses that serve to prevent the fall in blood glucose and restore euglycemia. In this review, we discuss the current state of knowledge about central glucose sensing and how detection of a fall in glucose leads to the stimulation of counterregulatory hormone and behavior responses. We also review how diabetes and recurrent hypoglycemia impact glucose sensing and counterregulation, leading to development of impaired awareness of hypoglycemia in diabetes.
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Affiliation(s)
- Sarah Stanley
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Amir Moheet
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Elizabeth R Seaquist
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, Minnesota
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20
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Differential Role of Hypothalamic AMPKα Isoforms in Fish: an Evolutive Perspective. Mol Neurobiol 2018; 56:5051-5066. [PMID: 30460617 DOI: 10.1007/s12035-018-1434-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 11/15/2018] [Indexed: 12/11/2022]
Abstract
In mammals, hypothalamic AMP-activated protein kinase (AMPK) α1 and α2 isoforms mainly relate to regulation of thermogenesis/liver metabolism and food intake, respectively. Since both isoforms are present in fish, which do not thermoregulate, we assessed their role(s) in hypothalamus regarding control of food intake and energy homeostasis. Since many fish species are carnivorous and mostly mammals are omnivorous, assessing if the role of hypothalamic AMPK is different is also an open question. Using the rainbow trout as a fish model, we first observed that food deprivation for 5 days did not significantly increase phosphorylation status of AMPKα in hypothalamus. Then, we administered adenoviral vectors that express dominant negative (DN) AMPKα1 or AMPKα2 isoforms. The inhibition of AMPKα2 (but not AMPKα1) led to decreased food intake. The central inhibition of AMPKα2 resulted in liver with decreased capacity of use and synthesis of glucose, lipids, and amino acids suggesting that a signal of nutrient abundance flows from hypothalamus to the liver, thus suggesting a role for central AMPKα2 in the regulation of peripheral metabolism in fishes. The central inhibition of AMPKα1 induced comparable changes in liver metabolism though at a lower extent. From an evolutionary point of view, it is of interest that the function of central AMPKα2 remained similar throughout the vertebrate lineage. In contrast, the function of central AMPKα1 in fish relates to modulation of liver metabolism whereas in mammals modulates not only liver metabolism but also brown adipose tissue and thermogenesis.
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21
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Seoane-Collazo P, Roa J, Rial-Pensado E, Liñares-Pose L, Beiroa D, Ruíz-Pino F, López-González T, Morgan DA, Pardavila JÁ, Sánchez-Tapia MJ, Martínez-Sánchez N, Contreras C, Fidalgo M, Diéguez C, Coppari R, Rahmouni K, Nogueiras R, Tena-Sempere M, López M. SF1-Specific AMPKα1 Deletion Protects Against Diet-Induced Obesity. Diabetes 2018; 67:2213-2226. [PMID: 30104247 PMCID: PMC6198345 DOI: 10.2337/db17-1538] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Accepted: 07/27/2018] [Indexed: 01/09/2023]
Abstract
AMPK is a cellular gauge that is activated under conditions of low energy, increasing energy production and reducing energy waste. Current evidence links hypothalamic AMPK with the central regulation of energy balance. However, it is unclear whether targeting hypothalamic AMPK has beneficial effects in obesity. Here, we show that genetic inhibition of AMPK in the ventromedial nucleus of the hypothalamus (VMH) protects against high-fat diet (HFD)-induced obesity by increasing brown adipose tissue (BAT) thermogenesis and subsequently energy expenditure. Notably, this effect depends upon the AMPKα1 isoform in steroidogenic factor 1 (SF1) neurons of the VMH, since mice bearing selective ablation of AMPKα1 in SF1 neurons display resistance to diet-induced obesity, increased BAT thermogenesis, browning of white adipose tissue, and improved glucose and lipid homeostasis. Overall, our findings point to hypothalamic AMPK in specific neuronal populations as a potential druggable target for the treatment of obesity and associated metabolic disorders.
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Affiliation(s)
- Patricia Seoane-Collazo
- Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, Spain
| | - Juan Roa
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, Spain
- Department of Cell Biology, Physiology and Immunology, University of Córdoba, Instituto Maimónides de Investigación Biomédica (IMIBIC)/Hospital Universitario Reina Sofía, Córdoba, Spain
| | - Eva Rial-Pensado
- Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, Spain
| | - Laura Liñares-Pose
- Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, Spain
| | - Daniel Beiroa
- Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, Spain
| | - Francisco Ruíz-Pino
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, Spain
- Department of Cell Biology, Physiology and Immunology, University of Córdoba, Instituto Maimónides de Investigación Biomédica (IMIBIC)/Hospital Universitario Reina Sofía, Córdoba, Spain
| | - Tania López-González
- Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, Spain
| | - Donald A Morgan
- Department of Pharmacology, University of Iowa, Iowa City, IA
| | - José Ángel Pardavila
- Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
| | - María Jesús Sánchez-Tapia
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, Spain
- Department of Cell Biology, Physiology and Immunology, University of Córdoba, Instituto Maimónides de Investigación Biomédica (IMIBIC)/Hospital Universitario Reina Sofía, Córdoba, Spain
| | - Noelia Martínez-Sánchez
- Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, Spain
| | - Cristina Contreras
- Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, Spain
| | - Miguel Fidalgo
- Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
| | - Carlos Diéguez
- Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, Spain
| | - Roberto Coppari
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
- Diabetes Center of the Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Kamal Rahmouni
- Department of Pharmacology, University of Iowa, Iowa City, IA
- Department of Internal Medicine, University of Iowa, Iowa City, IA
| | - Rubén Nogueiras
- Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, Spain
| | - Manuel Tena-Sempere
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, Spain
- Department of Cell Biology, Physiology and Immunology, University of Córdoba, Instituto Maimónides de Investigación Biomédica (IMIBIC)/Hospital Universitario Reina Sofía, Córdoba, Spain
- FiDiPro Program, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Miguel López
- Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, Spain
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22
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Pozo M, Claret M. Hypothalamic Control of Systemic Glucose Homeostasis: The Pancreas Connection. Trends Endocrinol Metab 2018; 29:581-594. [PMID: 29866501 DOI: 10.1016/j.tem.2018.05.001] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 05/10/2018] [Accepted: 05/12/2018] [Indexed: 12/22/2022]
Abstract
Maintenance of glucose homeostasis is mandatory for organismal survival. It is accomplished by complex and coordinated interplay between glucose detection mechanisms and multiple effector systems. The brain, in particular homeostatic regions such as the hypothalamus, plays a crucial role in orchestrating such a highly integral response. We review here current understanding of how the hypothalamus senses glucose availability and participates in systemic glucose homeostasis. We provide an update of the relevant signaling pathways and neuronal subsets involved, as well as of the mechanisms modulating metabolic processes in peripheral tissues such as liver, skeletal muscle, fat, and especially the pancreas. We also discuss the relevance of these networks in human biology and prevalent metabolic conditions such as diabetes and obesity.
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Affiliation(s)
- Macarena Pozo
- Neuronal Control of Metabolism (NeuCoMe) Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain
| | - Marc Claret
- Neuronal Control of Metabolism (NeuCoMe) Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain; Centro de Investigación Biomédica en Red (CIBER) de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 08036 Barcelona, Spain.
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23
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Abdelazim A, Khater S, Ali H, Shalaby S, Afifi M, Saddick S, Alkaladi A, Almaghrabi OA. Panax ginseng improves glucose metabolism in streptozotocin-induced diabetic rats through 5' adenosine monophosphate kinase up-regulation. Saudi J Biol Sci 2018; 26:1436-1441. [PMID: 31762606 PMCID: PMC6864146 DOI: 10.1016/j.sjbs.2018.06.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 05/09/2018] [Accepted: 06/04/2018] [Indexed: 12/12/2022] Open
Abstract
5′ AMP-activated protein kinase (AMPK), insulin receptors and transporters are distorted in diabetes mellitus. In this study, the effect of Panax ginseng was assessed on glucose manipulating enzymes activities and gene expression of AMPK, IRA and GLUT2 in streptozotocin-induced diabetic male rats. Forty male albino rats were randomly divided to four groups 10 rats of each, group I, normal control group (received saline orally); group II, normal rats received 200 mg/kg of Panax ginseng orally; group III, Streptozotocin (STZ) –induced diabetic rats and group IV, STZ-induced diabetic rats received 200 mg/kg of Panax ginseng orally. The duration of experiment was 30 days. Results showed the ability of Panax ginseng to induce a significant decrease in the blood glucose and increase in the serum insulin levels, hepatic glucokinase (GK), and glycogen synthase (GS) activities with a modulation of lipid profile besides high expression levels of AMPK, insulin receptor A (IRA), glucose transporting protein-2 (GLUT-2) in liver of diabetic rats. In conclusion, the obtained results point to the ability of Panax ginseng to improve the glucose metabolism in diabetic models.
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Affiliation(s)
- Aaser Abdelazim
- Department of Biochemistry, Faculty of Vet. Medicine, Zagazig University, Zagazig, Egypt.,Department of Basic Medical Sciences, College of Applied Medical Sciences, University of Bisha, Bisha, Saudi Arabia
| | - Safaa Khater
- Department of Biochemistry, Faculty of Vet. Medicine, Zagazig University, Zagazig, Egypt
| | - Haytham Ali
- Department of Biochemistry, Faculty of Vet. Medicine, Zagazig University, Zagazig, Egypt.,Department of Biological Sciences, Faculty of Science, University of Jeddah, Saudi Arabia
| | - Shimaa Shalaby
- Department of Physiology, Faculty of Vet. Medicine, Zagazig University, Zagazig, Egypt
| | - Mohamed Afifi
- Department of Biochemistry, Faculty of Vet. Medicine, Zagazig University, Zagazig, Egypt.,Department of Biological Sciences, Faculty of Science, University of Jeddah, Saudi Arabia.,University of Jeddah Center for Scientific and Medical Research, University of Jeddah, Saudi Arabia
| | - Salina Saddick
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia
| | - Ali Alkaladi
- Department of Biological Sciences, Faculty of Science, University of Jeddah, Saudi Arabia
| | - Omar A Almaghrabi
- Department of Biological Sciences, Faculty of Science, University of Jeddah, Saudi Arabia
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24
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Xu Y, López M. Central regulation of energy metabolism by estrogens. Mol Metab 2018; 15:104-115. [PMID: 29886181 PMCID: PMC6066788 DOI: 10.1016/j.molmet.2018.05.012] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Revised: 05/09/2018] [Accepted: 05/15/2018] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Estrogenic actions in the brain prevent obesity. Better understanding of the underlying mechanisms may facilitate development of new obesity therapies. SCOPE OF REVIEW This review focuses on the critical brain regions that mediate effects of estrogens on food intake and/or energy expenditure, the molecular signals that are involved, and the functional interactions between brain estrogens and other signals modulating metabolism. Body weight regulation by estrogens in male brains will also be discussed. MAJOR CONCLUSIONS 17β-estradiol acts in the brain to regulate energy homeostasis in both sexes. It can inhibit feeding and stimulate brown adipose tissue thermogenesis. A better understanding of the central actions of 17β-estradiol on energy balance would provide new insight for the development of therapies against obesity in both sexes.
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Affiliation(s)
- Yong Xu
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
| | - Miguel López
- NeurObesity Group, Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, 15706, Spain.
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25
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McNeilly AD, McCrimmon RJ. Impaired hypoglycaemia awareness in type 1 diabetes: lessons from the lab. Diabetologia 2018; 61:743-750. [PMID: 29417183 PMCID: PMC6448989 DOI: 10.1007/s00125-018-4548-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 10/20/2017] [Indexed: 01/28/2023]
Abstract
Hypoglycaemia remains the most common metabolic adverse effect of insulin and sulfonylurea therapy in diabetes. Repeated exposure to hypoglycaemia leads to a change in the symptom complex that characterises hypoglycaemia, culminating in a clinical phenomenon referred to as impaired awareness of hypoglycaemia (IAH). IAH effects approximately 20-25% of people with type 1 diabetes and increases the risk of severe hypoglycaemia. This review focuses on the mechanisms that are responsible for the much higher frequency of hypoglycaemia in people with diabetes compared with those without, and subsequently how repeated exposure to hypoglycaemia leads to the development of IAH. The mechanisms that result in IAH development are incompletely understood and likely to reflect changes in multiple aspects of the counterregulatory response to hypoglycaemia, from adaptations within glucose and non-glucose-sensing cells to changes in the integrative networks that govern glucose homeostasis. Finally, we propose that the general process that incorporates many of these changes and results in IAH following recurrent hypoglycaemia is a form of adaptive memory called 'habituation'.
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Affiliation(s)
- Alison D McNeilly
- Division of Molecular and Clinical Medicine, Mailbox 12, Level 5, Ninewells Hospital and Medical School, University of Dundee, Dundee, DD1 9SY, UK
| | - Rory J McCrimmon
- Division of Molecular and Clinical Medicine, Mailbox 12, Level 5, Ninewells Hospital and Medical School, University of Dundee, Dundee, DD1 9SY, UK.
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26
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Alhamami HN, Uddin MM, Mahmood ASMH, Briski KP. Lateral but not Medial Hypothalamic AMPK Activation Occurs at the Hypoglycemic Nadir in Insulin-injected Male Rats: Impact of Caudal Dorsomedial Hindbrain Catecholamine Signaling. Neuroscience 2018. [PMID: 29534973 DOI: 10.1016/j.neuroscience.2018.03.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The hypothalamic energy sensor adenosine 5'-monophosphate-activated protein kinase (AMPK), an important regulator of counter-regulatory responses to hypoglycemia, responds to pharmacological manipulation of hindbrain AMPK activity. Dorsomedial hindbrain A2 noradrenergic neurons express hypoglycemia-sensitive metabolo-sensory biomarkers, including AMPK. Here, adult male rats were pretreated by intra-caudal fourth ventricular administration of the selective neurotoxin 6-hydroxydopamine (6-OHDA) to determine if catecholamine signaling from the aforesaid site governs hypothalamic AMPK activation during insulin-induced hypoglycemia (IIH). Micropunched arcuate (ARH), ventromedial (VMH), paraventricular (PVH), dorsomedial (DMH) nuclei and lateral hypothalamic area (LHA) tissues were obtained at the neutral protamine Hagedorn insulin-induced hypoglycemic nadir, coincident with A2 AMPK activation, for Western blot analysis of AMPK, phospho-AMPK (pAMPK), and relevant metabolic neuropeptides. ARH, VMH, LHA, and DMH norepinephrine levels were altered according to insulin dose; 6-OHDA-mediated reversal of these responses was site-specific. IIH elevated LHA and reduced VMH pAMPK protein, profiles that were respectively unchanged or increased by 6-OHDA. PVH and ARH pAMPK was resistant to IIH, but augmented in ARH of neurotoxin- plus insulin-treated rats. ARH neuropeptide Y (NPY) and pro-opiomelanocortin (POMC) proteins were correspondingly increased or refractory to IIH; 6-OHDA pretreatment normalized NPY and elevated POMC expression after insulin injection. Results demonstrate site-specific bi-directional adjustments in hypothalamic AMPK reactivity to hypoglycemia. Intensification of ARH/VMH pAMPK by 6-OHDA implies dorsomedial hindbrain improvement of energy balance in those sites during IIH. Neurotoxin-mediated augmentation versus suppression of basal catabolic (ARH POMC/VMH steroidogenic factor-1) or IIH-associated anabolic (ARH NPY) neuropeptide profiles, respectively, may involve local AMPK-dependent against independent mechanisms.
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Affiliation(s)
- Hussain N Alhamami
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, College of Health and Pharmaceutical Sciences, University of Louisiana at Monroe, Monroe, LA 71201, United States
| | - Md Main Uddin
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, College of Health and Pharmaceutical Sciences, University of Louisiana at Monroe, Monroe, LA 71201, United States
| | - A S M Hasan Mahmood
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, College of Health and Pharmaceutical Sciences, University of Louisiana at Monroe, Monroe, LA 71201, United States
| | - Karen P Briski
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, College of Health and Pharmaceutical Sciences, University of Louisiana at Monroe, Monroe, LA 71201, United States.
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27
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Zhou C, Routh VH. Thioredoxin-1 Overexpression in the Ventromedial Nucleus of the Hypothalamus Preserves the Counterregulatory Response to Hypoglycemia During Type 1 Diabetes in Male Rats. Diabetes 2018; 67:120-130. [PMID: 29079703 PMCID: PMC5741147 DOI: 10.2337/db17-0930] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 10/23/2017] [Indexed: 12/21/2022]
Abstract
We previously showed that the glutathione precursor, N-acetylcysteine (NAC), prevented hypoglycemia-associated autonomic failure (HAAF) and impaired activation of ventromedial hypothalamus (VMH) glucose-inhibited (GI) neurons by low glucose after recurrent hypoglycemia (RH) in nondiabetic rats. However, NAC does not normalize glucose sensing by VMH GI neurons when RH occurs during diabetes. We hypothesized that recruiting the thioredoxin (Trx) antioxidant defense system would prevent HAAF and normalize glucose sensing after RH in diabetes. To test this hypothesis, we overexpressed Trx-1 (cytosolic form of Trx) in the VMH of rats with streptozotocin (STZ)-induced type 1 diabetes. The counterregulatory response (CRR) to hypoglycemia in vivo and the activation of VMH GI neurons in low glucose using membrane potential sensitive dye in vitro was measured before and after RH. VMH Trx-1 overexpression normalized both the CRR and glucose sensing by VMH GI neurons in STZ rats. VMH Trx-1 overexpression also lowered the insulin requirement to prevent severe hyperglycemia in STZ rats. However, like NAC, VMH Trx-1 overexpression did not prevent HAAF or normalize activation of VMH GI neurons by low glucose in STZ rats after RH. We conclude that preventing HAAF in type 1 diabetes may require the recruitment of both antioxidant systems.
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Affiliation(s)
- Chunxue Zhou
- Department of Pharmacology, Physiology and Neurosciences, New Jersey Medical School, Rutgers University, Newark, NJ
| | - Vanessa H Routh
- Department of Pharmacology, Physiology and Neurosciences, New Jersey Medical School, Rutgers University, Newark, NJ
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28
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Koekkoek LL, Mul JD, la Fleur SE. Glucose-Sensing in the Reward System. Front Neurosci 2017; 11:716. [PMID: 29311793 PMCID: PMC5742113 DOI: 10.3389/fnins.2017.00716] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 12/07/2017] [Indexed: 01/14/2023] Open
Abstract
Glucose-sensing neurons are neurons that alter their activity in response to changes in extracellular glucose. These neurons, which are an important mechanism the brain uses to monitor changes in glycaemia, are present in the hypothalamus, where they have been thoroughly investigated. Recently, glucose-sensing neurons have also been identified in brain nuclei which are part of the reward system. However, little is known about the molecular mechanisms by which they function, and their role in the reward system. We therefore aim to provide an overview of molecular mechanisms that have been studied in the hypothalamic glucose-sensing neurons, and investigate which of these transporters, enzymes and channels are present in the reward system. Furthermore, we speculate about the role of glucose-sensing neurons in the reward system.
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Affiliation(s)
- Laura L Koekkoek
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands.,Laboratory of Endocrinology, Department of Clinical Chemistry, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands.,Metabolism and Reward Group, Netherlands Institute for Neuroscience, Institute of the Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, Netherlands
| | - Joram D Mul
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands.,Laboratory of Endocrinology, Department of Clinical Chemistry, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands.,Metabolism and Reward Group, Netherlands Institute for Neuroscience, Institute of the Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, Netherlands
| | - Susanne E la Fleur
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands.,Laboratory of Endocrinology, Department of Clinical Chemistry, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands.,Metabolism and Reward Group, Netherlands Institute for Neuroscience, Institute of the Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, Netherlands
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29
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Shimazu T, Minokoshi Y. Systemic Glucoregulation by Glucose-Sensing Neurons in the Ventromedial Hypothalamic Nucleus (VMH). J Endocr Soc 2017; 1:449-459. [PMID: 29264500 PMCID: PMC5686683 DOI: 10.1210/js.2016-1104] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 04/07/2017] [Indexed: 01/31/2023] Open
Abstract
The ventromedial hypothalamic nucleus (VMH) regulates glucose production in the liver as well as glucose uptake and utilization in peripheral tissues, including skeletal muscle and brown adipose tissue, via efferent sympathetic innervation and neuroendocrine mechanisms. The action of leptin on VMH neurons also increases glucose uptake in specific peripheral tissues through the sympathetic nervous system, with improved insulin sensitivity. On the other hand, subsets of VMH neurons, such as those that express steroidogenic factor 1 (SF1), sense changes in the ambient glucose concentration and are characterized as glucose-excited (GE) and glucose-inhibited (GI) neurons whose action potential frequency increases and decreases, respectively, as glucose levels rise. However, how these glucose-sensing (GE and GI) neurons in the VMH contribute to systemic glucoregulation remains poorly understood. In this review, we provide historical background and discuss recent advances related to glucoregulation by VMH neurons. In particular, the article describes the role of GE neurons in the control of peripheral glucose utilization and insulin sensitivity, which depend on mitochondrial uncoupling protein 2 of the neurons, as well as that of GI neurons in the control of hepatic glucose production through hypoglycemia-induced counterregulatory mechanisms.
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Affiliation(s)
- Takashi Shimazu
- Department of Medical Biochemistry, Graduate School of Medicine, Ehime University, Tohon-shi, Ehime 791-0295, Japan
| | - Yasuhiko Minokoshi
- Division of Endocrinology and Metabolism, Department of Homeostatic Regulation, National Institute for Physiological Sciences, 38 Myodaiji, Okazaki, Aichi 444-8585, Japan.,Department of Physiological Sciences, School of Life Science, Sokendai (The Graduate University for Advanced Studies), 38 Myodaiji, Okazaki, Aichi 444-8585, Japan
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30
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Al Massadi O, López M, Tschöp M, Diéguez C, Nogueiras R. Current Understanding of the Hypothalamic Ghrelin Pathways Inducing Appetite and Adiposity. Trends Neurosci 2017; 40:167-180. [PMID: 28108113 DOI: 10.1016/j.tins.2016.12.003] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 12/13/2016] [Accepted: 12/15/2016] [Indexed: 12/21/2022]
Abstract
Ghrelin is a multifaceted regulator of metabolism. Ghrelin regulates energy balance in the short term via induction of appetite and in the long term via increased body weight and adiposity. Recently, several central pathways modulating the metabolic actions of ghrelin were unmasked, and it was shown to act through different hypothalamic nuclei to induce feeding. Ghrelin also modulates glucose homeostasis, but the central mechanisms responsible for this action have not been studied in detail. Although ghrelin also acts through extrahypothalamic areas to promote feeding, this review specifically dissects hypothalamic control of ghrelin's orexigenic and adipogenic actions and presents current understanding of the intracellular ghrelin orexigenic pathways, including their dependence on other relevant systems implicated in energy balance.
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Affiliation(s)
- Omar Al Massadi
- Department of Physiology, School of Medicine-CiMUS, Instituto de Investigación Sanitaria (IDIS), University of Santiago de Compostela, Av de Barcelona s/n Santiago de Compostela (A Coruña), 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Spain.
| | - Miguel López
- Department of Physiology, School of Medicine-CiMUS, Instituto de Investigación Sanitaria (IDIS), University of Santiago de Compostela, Av de Barcelona s/n Santiago de Compostela (A Coruña), 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Spain
| | - Matthias Tschöp
- Helmholtz Diabetes Center, Helmholtz Zentrum München and German Center for Diabetes Research (DZD), Neuherberg, Germany; Division of Metabolic Diseases, Technische Universität München, Munich, Germany
| | - Carlos Diéguez
- Department of Physiology, School of Medicine-CiMUS, Instituto de Investigación Sanitaria (IDIS), University of Santiago de Compostela, Av de Barcelona s/n Santiago de Compostela (A Coruña), 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Spain
| | - Ruben Nogueiras
- Department of Physiology, School of Medicine-CiMUS, Instituto de Investigación Sanitaria (IDIS), University of Santiago de Compostela, Av de Barcelona s/n Santiago de Compostela (A Coruña), 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Spain.
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31
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Haythorne E, Hamilton DL, Findlay JA, Beall C, McCrimmon RJ, Ashford MLJ. Chronic exposure to K ATP channel openers results in attenuated glucose sensing in hypothalamic GT1-7 neurons. Neuropharmacology 2016; 111:212-222. [PMID: 27618741 DOI: 10.1016/j.neuropharm.2016.09.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 07/06/2016] [Accepted: 09/07/2016] [Indexed: 10/21/2022]
Abstract
Individuals with Type 1 diabetes (T1D) are often exposed to recurrent episodes of hypoglycaemia. This reduces hormonal and behavioural responses that normally counteract low glucose in order to maintain glucose homeostasis, with altered responsiveness of glucose sensing hypothalamic neurons implicated. Although the molecular mechanisms are unknown, pharmacological studies implicate hypothalamic ATP-sensitive potassium channel (KATP) activity, with KATP openers (KCOs) amplifying, through cell hyperpolarization, the response to hypoglycaemia. Although initial findings, using acute hypothalamic KCO delivery, in rats were promising, chronic exposure to the KCO NN414 worsened the responses to subsequent hypoglycaemic challenge. To investigate this further we used GT1-7 cells to explore how NN414 affected glucose-sensing behaviour, the metabolic response of cells to hypoglycaemia and KATP activity. GT1-7 cells exposed to 3 or 24 h NN414 exhibited an attenuated hyperpolarization to subsequent hypoglycaemic challenge or NN414, which correlated with diminished KATP activity. The reduced sensitivity to hypoglycaemia was apparent 24 h after NN414 removal, even though intrinsic KATP activity recovered. The NN414-modified glucose responsiveness was not associated with adaptations in glucose uptake, metabolism or oxidation. KATP inactivation by NN414 was prevented by the concurrent presence of tolbutamide, which maintains KATP closure. Single channel recordings indicate that NN414 alters KATP intrinsic gating inducing a stable closed or inactivated state. These data indicate that exposure of hypothalamic glucose sensing cells to chronic NN414 drives a sustained conformational change to KATP, probably by binding to SUR1, that results in loss of channel sensitivity to intrinsic metabolic factors such as MgADP and small molecule agonists.
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Affiliation(s)
- Elizabeth Haythorne
- Division of Molecular and Clinical Medicine, School of Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee, UK.
| | - D Lee Hamilton
- Division of Molecular and Clinical Medicine, School of Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee, UK.
| | - John A Findlay
- Division of Molecular and Clinical Medicine, School of Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee, UK.
| | - Craig Beall
- Division of Molecular and Clinical Medicine, School of Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee, UK.
| | - Rory J McCrimmon
- Division of Molecular and Clinical Medicine, School of Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee, UK.
| | - Michael L J Ashford
- Division of Molecular and Clinical Medicine, School of Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee, UK.
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De Backer I, Hussain SS, Bloom SR, Gardiner JV. Insights into the role of neuronal glucokinase. Am J Physiol Endocrinol Metab 2016; 311:E42-55. [PMID: 27189932 PMCID: PMC4967152 DOI: 10.1152/ajpendo.00034.2016] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 05/13/2016] [Indexed: 12/17/2022]
Abstract
Glucokinase is a key component of the neuronal glucose-sensing mechanism and is expressed in brain regions that control a range of homeostatic processes. In this review, we detail recently identified roles for neuronal glucokinase in glucose homeostasis and counterregulatory responses to hypoglycemia and in regulating appetite. We describe clinical implications from these advances in our knowledge, especially for developing novel treatments for diabetes and obesity. Further research required to extend our knowledge and help our efforts to tackle the diabetes and obesity epidemics is suggested.
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Affiliation(s)
- Ivan De Backer
- Section of Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, United Kingdom
| | - Sufyan S Hussain
- Section of Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, United Kingdom
| | - Stephen R Bloom
- Section of Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, United Kingdom
| | - James V Gardiner
- Section of Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, United Kingdom
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López M, Nogueiras R, Tena-Sempere M, Diéguez C. Hypothalamic AMPK: a canonical regulator of whole-body energy balance. Nat Rev Endocrinol 2016; 12:421-32. [PMID: 27199291 DOI: 10.1038/nrendo.2016.67] [Citation(s) in RCA: 211] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
AMP-activated protein kinase (AMPK) has a major role in the modulation of energy balance. AMPK is activated in conditions of low energy, increasing energy production and reducing energy consumption. The AMPK pathway is a canonical route regulating energy homeostasis by integrating peripheral signals, such as hormones and metabolites, with neuronal networks. Current evidence has implicated AMPK in the hypothalamus and hindbrain with feeding, brown adipose tissue thermogenesis and browning of white adipose tissue, through modulation of the sympathetic nervous system, as well as glucose homeostasis. Interestingly, several potential antiobesity and/or antidiabetic agents, some of which are currently in clinical use such as metformin and liraglutide, exert some of their actions by acting on AMPK. Furthermore, the orexigenic and weight-gain effects of commonly used antipsychotic drugs are also mediated by hypothalamic AMPK. Overall, this evidence suggests that hypothalamic AMPK signalling is an interesting target for drug development, but is this approach feasible? In this Review we discuss the current understanding of hypothalamic AMPK and its role in the central regulation of energy balance and metabolism.
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Affiliation(s)
- Miguel López
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, 15782, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, 15706, Spain
| | - Rubén Nogueiras
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, 15782, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, 15706, Spain
| | - Manuel Tena-Sempere
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, 15706, Spain
- Department of Cell Biology, Physiology and Immunology, University of Córdoba; Instituto Maimónides de Investigación Biomédica (IMIBIC)/Hospital Reina Sofía, 14004 Córdoba, Spain
- FiDiPro Program, Department of Physiology, University of Turku, Kiinamyllynkatu 10, FIN-20520 Turku, Finland
| | - Carlos Diéguez
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, 15782, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, 15706, Spain
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Emerging role of the brain in the homeostatic regulation of energy and glucose metabolism. Exp Mol Med 2016; 48:e216. [PMID: 26964832 PMCID: PMC4892882 DOI: 10.1038/emm.2016.4] [Citation(s) in RCA: 226] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 12/07/2015] [Accepted: 12/09/2015] [Indexed: 12/12/2022] Open
Abstract
Accumulated evidence from genetic animal models suggests that the brain, particularly the hypothalamus, has a key role in the homeostatic regulation of energy and glucose metabolism. The brain integrates multiple metabolic inputs from the periphery through nutrients, gut-derived satiety signals and adiposity-related hormones. The brain modulates various aspects of metabolism, such as food intake, energy expenditure, insulin secretion, hepatic glucose production and glucose/fatty acid metabolism in adipose tissue and skeletal muscle. Highly coordinated interactions between the brain and peripheral metabolic organs are critical for the maintenance of energy and glucose homeostasis. Defective crosstalk between the brain and peripheral organs contributes to the development of obesity and type 2 diabetes. Here we comprehensively review the above topics, discussing the main findings related to the role of the brain in the homeostatic regulation of energy and glucose metabolism.
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Kinnunen S, Mänttäri S, Herzig KH, Nieminen P, Mustonen AM, Saarela S. Effects of wintertime fasting and seasonal adaptation on AMPK and ACC in hypothalamus, adipose tissue and liver of the raccoon dog (Nyctereutes procyonoides). Comp Biochem Physiol A Mol Integr Physiol 2015; 192:44-51. [PMID: 26603554 DOI: 10.1016/j.cbpa.2015.11.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 11/11/2015] [Accepted: 11/16/2015] [Indexed: 12/25/2022]
Abstract
The raccoon dog (Nyctereutes procyonoides) is a canid with autumnal fattening and passive wintering strategy. We examined the effects of wintertime fasting and seasonality on AMP-activated protein kinase (AMPK), a regulator of metabolism, and its target, acetyl-CoA carboxylase (ACC) on the species. Twelve farmed raccoon dogs (eleven females/one male) were divided into two groups: half were fasted for ten weeks in December-March (winter fasted) and the others were fed ad libitum (winter fed). A third group (autumn fed, eight females) was fed ad libitum and sampled in December. Total AMPK, ACC and their phosphorylated forms (pAMPK, pACC) were measured from hypothalamus, liver, intra-abdominal (iWAT) and subcutaneous white adipose tissues (sWAT). The fasted animals lost 32% and the fed 20% of their body mass. Hypothalamic AMPK expression was lower and pACC levels higher in the winter groups compared to the autumn fed group. Liver pAMPK was lower in the winter fasted group, with consistently decreased ACC and pACC. AMPK and pAMPK were down-regulated in sWAT and iWAT of both winter groups, with a parallel decline in pACC in sWAT. The responses of AMPK and ACC to fasting were dissimilar to the effects observed previously in non-seasonal mammals and hibernators. Differences between the winter fed and autumn fed groups indicate that the functions of AMPK and ACC could be regulated in a season-dependent manner. Furthermore, the distinctive effects of prolonged fasting and seasonal adaptation on AMPK-ACC pathway could contribute to the wintering strategy of the raccoon dog.
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Affiliation(s)
- Sanni Kinnunen
- Department of Biology, University of Oulu, P.O. Box 3000, FI-90014, University of Oulu, Finland.
| | - Satu Mänttäri
- Finnish Institute of Occupational Health, Aapistie 1, FI-90220 Oulu, Finland
| | - Karl-Heinz Herzig
- Institute of Biomedicine, Biocenter Oulu, P.O. Box 5000, FI-90014, University of Oulu, Finland; Medical Research Center Oulu and Oulu University Hospital, Kajaanintie 50, FI-90220 Oulu, Finland
| | - Petteri Nieminen
- Institute of Biomedicine/Anatomy, School of Medicine, Faculty of Health Sciences, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland; Department of Biology, Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland
| | - Anne-Mari Mustonen
- Institute of Biomedicine/Anatomy, School of Medicine, Faculty of Health Sciences, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland; Department of Biology, Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland
| | - Seppo Saarela
- Department of Biology, University of Oulu, P.O. Box 3000, FI-90014, University of Oulu, Finland
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Seoane-Collazo P, Fernø J, Gonzalez F, Diéguez C, Leis R, Nogueiras R, López M. Hypothalamic-autonomic control of energy homeostasis. Endocrine 2015; 50:276-91. [PMID: 26089260 DOI: 10.1007/s12020-015-0658-y] [Citation(s) in RCA: 113] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 06/06/2015] [Indexed: 10/23/2022]
Abstract
Regulation of energy homeostasis is tightly controlled by the central nervous system (CNS). Several key areas such as the hypothalamus and brainstem receive and integrate signals conveying energy status from the periphery, such as leptin, thyroid hormones, and insulin, ultimately leading to modulation of food intake, energy expenditure (EE), and peripheral metabolism. The autonomic nervous system (ANS) plays a key role in the response to such signals, innervating peripheral metabolic tissues, including brown and white adipose tissue (BAT and WAT), liver, pancreas, and skeletal muscle. The ANS consists of two parts, the sympathetic and parasympathetic nervous systems (SNS and PSNS). The SNS regulates BAT thermogenesis and EE, controlled by central areas such as the preoptic area (POA) and the ventromedial, dorsomedial, and arcuate hypothalamic nuclei (VMH, DMH, and ARC). The SNS also regulates lipid metabolism in WAT, controlled by the lateral hypothalamic area (LHA), VMH, and ARC. Control of hepatic glucose production and pancreatic insulin secretion also involves the LHA, VMH, and ARC as well as the dorsal vagal complex (DVC), via splanchnic sympathetic and the vagal parasympathetic nerves. Muscle glucose uptake is also controlled by the SNS via hypothalamic nuclei such as the VMH. There is recent evidence of novel pathways connecting the CNS and ANS. These include the hypothalamic AMP-activated protein kinase-SNS-BAT axis which has been demonstrated to be a key modulator of thermogenesis. In this review, we summarize current knowledge of the role of the ANS in the modulation of energy balance.
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Affiliation(s)
- Patricia Seoane-Collazo
- NeurObesity Group, Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, 15782, Santiago de Compostela, Spain.
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706, Santiago de Compostela, Spain.
| | - Johan Fernø
- NeurObesity Group, Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, 15782, Santiago de Compostela, Spain
- Department of Clinical Science, K. G. Jebsen Center for Diabetes Research, University of Bergen, 5021, Bergen, Norway
| | - Francisco Gonzalez
- Department of Surgery, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, 15782, Santiago de Compostela, Spain
- Service of Ophthalmology, Complejo Hospitalario Universitario de Santiago de Compostela, 15706, Santiago de Compostela, Spain
| | - Carlos Diéguez
- NeurObesity Group, Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, 15782, Santiago de Compostela, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706, Santiago de Compostela, Spain
| | - Rosaura Leis
- Unit of Investigation in Nutrition, Growth and Human Development of Galicia, Pediatric Department (USC), Complexo Hospitalario Universitario de Santiago (IDIS/SERGAS), Santiago de Compostela, Spain
| | - Rubén Nogueiras
- NeurObesity Group, Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, 15782, Santiago de Compostela, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706, Santiago de Compostela, Spain
| | - Miguel López
- NeurObesity Group, Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, 15782, Santiago de Compostela, Spain.
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706, Santiago de Compostela, Spain.
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Otlivanchik O, Sanders NM, Dunn-Meynell A, Levin BE. Orexin signaling is necessary for hypoglycemia-induced prevention of conditioned place preference. Am J Physiol Regul Integr Comp Physiol 2015; 310:R66-73. [PMID: 26511522 DOI: 10.1152/ajpregu.00066.2015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 10/19/2015] [Indexed: 01/24/2023]
Abstract
While the neural control of glucoregulatory responses to insulin-induced hypoglycemia is beginning to be elucidated, brain sites responsible for behavioral responses to hypoglycemia are relatively poorly understood. To help elucidate central control mechanisms associated with hypoglycemia unawareness, we first evaluated the effect of recurrent hypoglycemia on a simple behavioral measure, the robust feeding response to hypoglycemia, in rats. First, food intake was significantly, and similarly, increased above baseline saline-induced intake (1.1 ± 0.2 g; n = 8) in rats experiencing a first (4.4 ± 0.3; n = 8) or third daily episode of recurrent insulin-induced hypoglycemia (IIH, 3.7 ± 0.3 g; n = 9; P < 0.05). Because food intake was not impaired as a result of prior IIH, we next developed an alternative animal model of hypoglycemia-induced behavioral arousal using a conditioned place preference (CPP) model. We found that hypoglycemia severely blunted previously acquired CPP in rats and that recurrent hypoglycemia prevented this blunting. Pretreatment with a brain penetrant, selective orexin receptor-1 antagonist, SB-334867A, blocked hypoglycemia-induced blunting of CPP. Recurrently hypoglycemic rats also showed decreased preproorexin expression in the perifornical hypothalamus (50%) but not in the adjacent lateral hypothalamus. Pretreatment with sertraline, previously shown to prevent hypoglycemia-associated glucoregulatory failure, did not prevent blunting of hypoglycemia-induced CPP prevention by recurrent hypoglycemia. This work describes the first behavioral model of hypoglycemia unawareness and suggests a role for orexin neurons in mediating behavioral responses to hypoglycemia.
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Affiliation(s)
- Oleg Otlivanchik
- Graduate School of Biomedical Sciences, Rutgers University, Newark, New Jersey; Department of Neurology, New Jersey Medical School, Rutgers University, Newark, New Jersey
| | | | - Ambrose Dunn-Meynell
- Graduate School of Biomedical Sciences, Rutgers University, Newark, New Jersey; Department of Neurology, New Jersey Medical School, Rutgers University, Newark, New Jersey; Neurology Service, Veterans Affairs Medical Center, East Orange, New Jersey; and
| | - Barry E Levin
- Department of Neurology, New Jersey Medical School, Rutgers University, Newark, New Jersey; Neurology Service, Veterans Affairs Medical Center, East Orange, New Jersey; and
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Steinbusch L, Labouèbe G, Thorens B. Brain glucose sensing in homeostatic and hedonic regulation. Trends Endocrinol Metab 2015; 26:455-66. [PMID: 26163755 DOI: 10.1016/j.tem.2015.06.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 06/15/2015] [Accepted: 06/16/2015] [Indexed: 11/21/2022]
Abstract
Glucose homeostasis as well as homeostatic and hedonic control of feeding is regulated by hormonal, neuronal, and nutrient-related cues. Glucose, besides its role as a source of metabolic energy, is an important signal controlling hormone secretion and neuronal activity, hence contributing to whole-body metabolic integration in coordination with feeding control. Brain glucose sensing plays a key, but insufficiently explored, role in these metabolic and behavioral controls, which when deregulated may contribute to the development of obesity and diabetes. The recent introduction of innovative transgenic, pharmacogenetic, and optogenetic techniques allows unprecedented analysis of the complexity of central glucose sensing at the molecular, cellular, and neuronal circuit levels, which will lead to a new understanding of the pathogenesis of metabolic diseases.
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Affiliation(s)
- Laura Steinbusch
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Gwenaël Labouèbe
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Bernard Thorens
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland.
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Martínez de Morentin PB, Lage R, González-García I, Ruíz-Pino F, Martins L, Fernández-Mallo D, Gallego R, Fernø J, Señarís R, Saha AK, Tovar S, Diéguez C, Nogueiras R, Tena-Sempere M, López M. Pregnancy induces resistance to the anorectic effect of hypothalamic malonyl-CoA and the thermogenic effect of hypothalamic AMPK inhibition in female rats. Endocrinology 2015; 156:947-60. [PMID: 25535827 PMCID: PMC4330316 DOI: 10.1210/en.2014-1611] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2014] [Accepted: 12/19/2014] [Indexed: 12/20/2022]
Abstract
During gestation, hyperphagia is necessary to cope with the metabolic demands of embryonic development. There were three main aims of this study: Firstly, to investigate the effect of pregnancy on hypothalamic fatty acid metabolism, a key pathway for the regulation of energy balance; secondly, to study whether pregnancy induces resistance to the anorectic effect of fatty acid synthase (FAS) inhibition and accumulation of malonyl-coenzyme A (CoA) in the hypothalamus; and, thirdly, to study whether changes in hypothalamic AMPK signaling are associated with brown adipose tissue (BAT) thermogenesis during pregnancy. Our data suggest that in pregnant rats, the hypothalamic fatty acid pathway shows an overall state that should lead to anorexia and elevated BAT thermogenesis: decreased activities of AMP-activated protein kinase (AMPK), FAS, and carnitine palmitoyltransferase 1, coupled with increased acetyl-CoA carboxylase function with subsequent elevation of malonyl-CoA levels. This profile seems dependent of estradiol levels but not prolactin or progesterone. Despite the apparent anorexic and thermogenic signaling in the hypothalamus, pregnant rats remain hyperphagic and display reduced temperature and BAT function. Actually, pregnant rats develop resistance to the anorectic effects of central FAS inhibition, which is associated with a reduction of proopiomelanocortin (POMC) expression and its transcription factors phospho-signal transducer and activator of transcription 3, and phospho-forkhead box O1. This evidence demonstrates that pregnancy induces a state of resistance to the anorectic and thermogenic actions of hypothalamic cellular signals of energy surplus, which, in parallel to the already known refractoriness to leptin effects, likely contributes to gestational hyperphagia and adiposity.
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Affiliation(s)
- Pablo B Martínez de Morentin
- Department of Physiology, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS) (P.B.M.d.M., R.L., I.G.-G., L.M., D.F.M., R.S., S.T., C.D., R.N., M.L.), University of Santiago de Compostela (USC)-Instituto de Investigación Sanitaria (IDIS), Santiago de Compostela 15782, Spain; Centro de Investigación Biomédica en Red (CIBER) Fisiopatología de la Obesidad y Nutrición (CIBERobn) (P.B.M.d.M., R.L., I.G.-G., F.R.-P., L.M., D.F.M., S.T., C.D., R.N., M.T.-S., M.L.), Santiago de Compostela 15706, Spain; Department of Cell Biology, Physiology and Immunology (F.R.-P., M.T.-S.), University of Córdoba, Córdoba 14004, Spain; Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC)/Hospital Universitario Reina Sofía (F.R.-P., M.T.-S.), Córdoba 14004, Spain; Department of Morphological Sciences (R.G.), School of Medicine, University of Santiago de Compostela, Santiago de Compostela 15782, Spain; Department of Clinical Science (J.F.), K. G. Jebsen Center for Diabetes Research, University of Bergen, Bergen, N-5021, Norway; and Diabetes Research Unit, EBRC-827 (A.K.S.), Boston Medical Center, Boston, Massachusetts 02118
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40
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Orban BO, Routh VH, Levin BE, Berlin JR. Direct effects of recurrent hypoglycaemia on adrenal catecholamine release. Diab Vasc Dis Res 2015; 12:2-12. [PMID: 25268022 PMCID: PMC8771481 DOI: 10.1177/1479164114549755] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
In Type 1 and advanced Type 2 diabetes mellitus, elevation of plasma epinephrine plays a key role in normalizing plasma glucose during hypoglycaemia. However, recurrent hypoglycaemia blunts this elevation of plasma epinephrine. To determine whether recurrent hypoglycaemia affects peripheral components of the sympatho-adrenal system responsible for epinephrine release, male rats were administered subcutaneous insulin daily for 3 days. These recurrent hypoglycaemic animals showed a smaller elevation of plasma epinephrine than saline-injected controls when subjected to insulin-induced hypoglycaemia. Electrical stimulation of an adrenal branch of the splanchnic nerve in recurrent hypoglycaemic animals elicited less release of epinephrine and norepinephrine than in controls, without a change in adrenal catecholamine content. Responsiveness of isolated, perfused adrenal glands to acetylcholine and other acetylcholine receptor agonists was also unchanged. These results indicate that recurrent hypoglycaemia compromised the efficacy with which peripheral neuronal activity stimulates adrenal catecholamine release and demonstrate that peripheral components of the sympatho-adrenal system were directly affected by recurrent hypoglycaemia.
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Affiliation(s)
- Branly O Orban
- Department of Pharmacology & Physiology, New Jersey Medical School, Rutgers University, Newark, NJ, USA Actavis LLC, Elizabeth, NJ, USA
| | - Vanessa H Routh
- Department of Pharmacology & Physiology, New Jersey Medical School, Rutgers University, Newark, NJ, USA Department of Neurology & Neurosciences, New Jersey Medical School, Rutgers University, Newark, NJ, USA
| | - Barry E Levin
- Department of Neurology & Neurosciences, New Jersey Medical School, Rutgers University, Newark, NJ, USA Neurology Service, Veterans Affairs Medical Center, East Orange, NJ, USA
| | - Joshua R Berlin
- Department of Pharmacology & Physiology, New Jersey Medical School, Rutgers University, Newark, NJ, USA
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Affiliation(s)
- Miguel López
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706, Spain.
| | - Carlos Diéguez
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706, Spain.
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Contreras C, González-García I, Martínez-Sánchez N, Seoane-Collazo P, Jacas J, Morgan DA, Serra D, Gallego R, Gonzalez F, Casals N, Nogueiras R, Rahmouni K, Diéguez C, López M. Central ceramide-induced hypothalamic lipotoxicity and ER stress regulate energy balance. Cell Rep 2014; 9:366-377. [PMID: 25284795 PMCID: PMC5157160 DOI: 10.1016/j.celrep.2014.08.057] [Citation(s) in RCA: 187] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 08/07/2014] [Accepted: 08/23/2014] [Indexed: 12/30/2022] Open
Abstract
Hypothalamic endoplasmic reticulum (ER) stress is a key mechanism leading to obesity. Here, we demonstrate that ceramides induce lipotoxicity and hypothalamic ER stress, leading to sympathetic inhibition, reduced brown adipose tissue (BAT) thermogenesis, and weight gain. Genetic overexpression of the chaperone GRP78/BiP (glucose-regulated protein 78 kDa/binding immunoglobulin protein) in the ventromedial nucleus of the hypothalamus (VMH) abolishes ceramide action by reducing hypothalamic ER stress and increasing BAT thermogenesis, which leads to weight loss and improved glucose homeostasis. The pathophysiological relevance of this mechanism is demonstrated in obese Zucker rats, which show increased hypothalamic ceramide levels and ER stress. Overexpression of GRP78 in the VMH of these animals reduced body weight by increasing BAT thermogenesis as well as decreasing leptin and insulin resistance and hepatic steatosis. Overall, these data identify a triangulated signaling network involving central ceramides, hypothalamic lipotoxicity/ER stress, and BAT thermogenesis as a pathophysiological mechanism of obesity.
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Affiliation(s)
- Cristina Contreras
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, 15782 Santiago de Compostela, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
| | - Ismael González-García
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, 15782 Santiago de Compostela, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
| | - Noelia Martínez-Sánchez
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, 15782 Santiago de Compostela, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
| | - Patricia Seoane-Collazo
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, 15782 Santiago de Compostela, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
| | - Jordi Jacas
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain; Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Sant Cugat del Vallés, 08195 Barcelona, Spain
| | - Donald A Morgan
- Department of Pharmacology, University of Iowa, Iowa City, IA 52242, USA
| | - Dolors Serra
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain; Department of Biochemistry and Molecular Biology, School of Pharmacy, Institut de Biomedicina (IBUB), Universitat de Barcelona, 08028 Barcelona, Spain
| | - Rosalía Gallego
- Department of Morphological Sciences, School of Medicine, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Francisco Gonzalez
- Department of Surgery, CIMUS, University of Santiago de Compostela-Instituto de Invesstiagacion Sanitaria, 15782 Santiago de Compostela, Spain; Service of Ophthalmology, Complejo Hospitalario Universitario de Santiago de Compostela, 15706 Santiago de Compostela, Spain
| | - Núria Casals
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain; Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Sant Cugat del Vallés, 08195 Barcelona, Spain
| | - Rubén Nogueiras
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, 15782 Santiago de Compostela, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
| | - Kamal Rahmouni
- Department of Pharmacology, University of Iowa, Iowa City, IA 52242, USA; Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Carlos Diéguez
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, 15782 Santiago de Compostela, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
| | - Miguel López
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, 15782 Santiago de Compostela, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain.
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Ogunnowo-Bada EO, Heeley N, Brochard L, Evans ML. Brain glucose sensing, glucokinase and neural control of metabolism and islet function. Diabetes Obes Metab 2014; 16 Suppl 1:26-32. [PMID: 25200293 PMCID: PMC4405079 DOI: 10.1111/dom.12334] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2014] [Accepted: 06/05/2014] [Indexed: 11/30/2022]
Abstract
It is increasingly apparent that the brain plays a central role in metabolic homeostasis, including the maintenance of blood glucose. This is achieved by various efferent pathways from the brain to periphery, which help control hepatic glucose flux and perhaps insulin-stimulated insulin secretion. Also, critically important for the brain given its dependence on a constant supply of glucose as a fuel--emergency counter-regulatory responses are triggered by the brain if blood glucose starts to fall. To exert these control functions, the brain needs to detect rapidly and accurately changes in blood glucose. In this review, we summarize some of the mechanisms postulated to play a role in this and examine the potential role of the low-affinity hexokinase, glucokinase, in the brain as a key part of some of this sensing. We also discuss how these processes may become altered in diabetes and related metabolic diseases.
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Affiliation(s)
- E O Ogunnowo-Bada
- Wellcome Trust-MRC Institute of Metabolic Science, IMS Metabolic Research Laboratories, University of CambridgeCambridge, UK
| | - N Heeley
- Wellcome Trust-MRC Institute of Metabolic Science, IMS Metabolic Research Laboratories, University of CambridgeCambridge, UK
| | - L Brochard
- Wellcome Trust-MRC Institute of Metabolic Science, IMS Metabolic Research Laboratories, University of CambridgeCambridge, UK
| | - M L Evans
- Wellcome Trust-MRC Institute of Metabolic Science, IMS Metabolic Research Laboratories, University of CambridgeCambridge, UK
- Correspondence to: Mark Evans, Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge, IMS Metabolic Research Laboratories, Box 289 Addenbrookes Hospital, Hills Road, Cambridge CB2 0QQ, UK. E-mail:
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Hahn MK, Chintoh A, Remington G, Teo C, Mann S, Arenovich T, Fletcher P, Lam L, Nobrega J, Guenette M, Cohn T, Giacca A. Effects of intracerebroventricular (ICV) olanzapine on insulin sensitivity and secretion in vivo: an animal model. Eur Neuropsychopharmacol 2014; 24:448-58. [PMID: 24001874 DOI: 10.1016/j.euroneuro.2013.07.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2013] [Revised: 06/27/2013] [Accepted: 07/26/2013] [Indexed: 10/26/2022]
Abstract
The atypical antipsychotics (AAPs) have been associated with an increased risk of type 2 diabetes. While weight gain associated with AAPs is a risk factor for diabetes, preclinical work suggests that among these medications, olanzapine, when given peripherally in a single dose, causes pronounced effects on insulin sensitivity and secretion. Given a critical role of the hypothalamus in control of glucose metabolism, we examined the effect of central administration of olanzapine. Sprague-Dawley rats were treated with a single 75 μg intracerebroventricular (ICV) dose of olanzapine and tested using separate hyperinsulinemic-euglycemic and hyperglycemic clamps. Dosing of olanzapine was established based on inhibition of amphetamine-induced locomotion. In contrast to the single dosing peripheral paradigm, there was no effect of central olanzapine on insulin sensitivity, either with respect to hepatic glucose production or peripheral glucose uptake. Analogous to the peripheral model, a single ICV dose of olanzapine followed by the hyperglycemic clamp decreased insulin (p=0.0041) and C-peptide response (p=0.0039) to glucose challenge as compared to vehicle, mirrored also by a decrease in the steady state glucose infusion rate required to maintain hyperglycemia (p=0.002). In conclusion, we demonstrate novel findings that at least part of the effect of olanzapine on beta-cell function in vivo is central.
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Affiliation(s)
- Margaret K Hahn
- Center for Addiction and Mental Health, 250 College Street, Toronto, Ontario, Canada M5T 1R8; Institute of Medical Sciences, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8.
| | - Araba Chintoh
- Center for Addiction and Mental Health, 250 College Street, Toronto, Ontario, Canada M5T 1R8; Institute of Medical Sciences, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Gary Remington
- Center for Addiction and Mental Health, 250 College Street, Toronto, Ontario, Canada M5T 1R8; Institute of Medical Sciences, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8; Department of Psychiatry, University of Toronto, 250 College Street, Toronto, Ontario, Canada M5T 1R8
| | - Celine Teo
- Center for Addiction and Mental Health, 250 College Street, Toronto, Ontario, Canada M5T 1R8
| | - Steve Mann
- Center for Addiction and Mental Health, 250 College Street, Toronto, Ontario, Canada M5T 1R8; Institute of Medical Sciences, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Tamara Arenovich
- Center for Addiction and Mental Health, 250 College Street, Toronto, Ontario, Canada M5T 1R8
| | - Paul Fletcher
- Center for Addiction and Mental Health, 250 College Street, Toronto, Ontario, Canada M5T 1R8; Department of Psychology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Loretta Lam
- Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Jose Nobrega
- Center for Addiction and Mental Health, 250 College Street, Toronto, Ontario, Canada M5T 1R8; Department of Pharmacology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Melanie Guenette
- Center for Addiction and Mental Health, 250 College Street, Toronto, Ontario, Canada M5T 1R8; Institute of Medical Sciences, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Tony Cohn
- Center for Addiction and Mental Health, 250 College Street, Toronto, Ontario, Canada M5T 1R8; Department of Psychiatry, University of Toronto, 250 College Street, Toronto, Ontario, Canada M5T 1R8; Department of Nutritional Sciences, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Adria Giacca
- Institute of Medical Sciences, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8; Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
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45
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Chan O, Sherwin R. Influence of VMH fuel sensing on hypoglycemic responses. Trends Endocrinol Metab 2013; 24:616-24. [PMID: 24063974 PMCID: PMC3909530 DOI: 10.1016/j.tem.2013.08.005] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 08/20/2013] [Accepted: 08/27/2013] [Indexed: 12/12/2022]
Abstract
Hypoglycemia produces complex neural and hormonal responses that restore glucose levels to normal. Glucose, metabolic substrates and their transporters, neuropeptides and neurotransmitters alter the firing rate of glucose-sensing neurons in the ventromedial hypothalamus (VMH); these monitor energy status and regulate the release of neurotransmitters that instigate a suitable counter-regulatory response. Under normal physiological conditions, these mechanisms maintain blood glucose concentrations within narrow margins. However, antecedent hypoglycemia and diabetes can lead to adaptations within the brain that impair counter-regulatory responses. Clearly, the mechanisms employed to detect and regulate the response to hypoglycemia, and the pathophysiology of defective counter-regulation in diabetes, are complex and need to be elucidated to permit the development of therapies that prevent or reduce the risk of hypoglycemia.
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Affiliation(s)
- Owen Chan
- Yale University School of Medicine, Department of Internal Medicine - Section of Endocrinology, New Haven, CT, 06520 U.S.A
| | - Robert Sherwin
- Yale University School of Medicine, Department of Internal Medicine - Section of Endocrinology, New Haven, CT, 06520 U.S.A
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46
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Diepenbroek C, Serlie MJ, Fliers E, Kalsbeek A, la Fleur SE. Brain areas and pathways in the regulation of glucose metabolism. Biofactors 2013; 39:505-13. [PMID: 23913677 DOI: 10.1002/biof.1123] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Accepted: 05/28/2013] [Indexed: 11/11/2022]
Abstract
Glucose is the most important source of fuel for the brain and its concentration must be kept within strict boundaries to ensure the organism's optimal fitness. To maintain glucose homeostasis, an optimal balance between glucose uptake and glucose output is required. Besides managing acute changes in plasma glucose concentrations, the brain controls a daily rhythm in glucose concentrations. The various nuclei within the hypothalamus that are involved in the control of both these processes are well known. However, novel studies indicate an additional role for brain areas that are originally appreciated in other processes than glucose metabolism. Therefore, besides the classic hypothalamic pathways, we will review cortico-limbic brain areas and their role in glucose metabolism.
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Affiliation(s)
- Charlene Diepenbroek
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
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Ikegami M, Ikeda H, Ishikawa Y, Ohsawa M, Ohashi T, Kai M, Kamei A, Kamei J. Olanzapine induces glucose intolerance through the activation of AMPK in the mouse hypothalamus. Eur J Pharmacol 2013; 718:376-82. [PMID: 23973646 DOI: 10.1016/j.ejphar.2013.08.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 07/23/2013] [Accepted: 08/14/2013] [Indexed: 12/31/2022]
Abstract
Treatment with atypical antipsychotic drugs is known to increase the risk of glucose intolerance and diabetes. However, the mechanism of this effect is unclear. Since central adenosine 5'-monophosphate-activated protein kinase (AMPK) plays an important role in regulating nutrient homeostasis, the present study was performed to examine the involvement of central AMPK in the glucose intolerance induced by olanzapine, an atypical antipsychotic drug, in mice. Acute intraperitoneal treatment with olanzapine dose-dependently increased blood glucose levels in the glucose tolerance test. Intracerebroventricular administration of olanzapine also increased blood glucose levels in the glucose tolerance test. The glucose intolerance induced by both intraperitoneal and intracerebroventricular treatment with olanzapine was significantly attenuated by intracerebroventricular pretreatment with the AMPK inhibitor compound C. Intracerebroventricular treatment with the AMPK activator AICAR increased blood glucose levels in the glucose tolerance test, and this increase was inhibited by compound C. Moreover, the hypothalamic level of phosphorylated AMPK after glucose injection was significantly increased by intracerebroventricular pretreatment with olanzapine. Olanzapine did not affect plasma glucagon and insulin levels. Our results indicate that acute treatment with olanzapine causes glucose intolerance through the activation of hypothalamic AMPK. The present study suggests that the inhibition of central AMPK activity may have a therapeutic effect on the metabolic disturbance induced by atypical antipsychotic drugs.
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Affiliation(s)
- Megumi Ikegami
- Department of Pathophysiology and Therapeutics, Hoshi University School of Pharmacy and Pharmaceutical Sciences, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan
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48
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Hurtado-Carneiro V, Roncero I, Blazquez E, Alvarez E, Sanz C. PAS kinase as a nutrient sensor in neuroblastoma and hypothalamic cells required for the normal expression and activity of other cellular nutrient and energy sensors. Mol Neurobiol 2013; 48:904-20. [PMID: 23765195 DOI: 10.1007/s12035-013-8476-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Accepted: 05/29/2013] [Indexed: 12/16/2022]
Abstract
PAS kinase (PASK) is a nutrient sensor that is highly conserved throughout evolution. PASK-deficient mice reveal a metabolic phenotype similar to that described in S6 kinase-1 S6K1-deficient mice that are protected against obesity. Hypothalamic metabolic sensors, such as AMP-activated protein kinase (AMPK) and the mammalian target of rapamycin (mTOR), play an important role in feeding behavior, the homeostasis of body weight, and energy balance. These sensors respond to changes in nutrient levels in the hypothalamic areas involved in feeding behavior and in neuroblastoma N2A cells, and we have recently reported that those effects are modulated by the anorexigenic peptide glucagon-like peptide-1 (GLP-1). Here, we identified PASK in both N2A cells and rat VMH and LH areas and found that its expression is regulated by glucose and GLP-1. High levels of glucose decreased Pask gene expression. Furthermore, PASK-silenced N2A cells record an impaired response by the AMPK and mTOR/S6K1 pathways to changes in glucose levels. Likewise, GLP-1 effect on the activity of AMPK, S6K1, and other intermediaries of both pathways and the regulatory role at the level of gene expression were also blocked in PASK-silenced cells. The absence of response to low glucose concentrations in PASK-silenced cells correlates with increased ATP content, low expression of mRNA coding for AMPK upstream kinase LKB1, and enhanced activation of S6K1. Our findings indicate that, at least in N2A cells, PASK is a key kinase in GLP-1 actions and exerts a coordinated response with the other metabolic sensors, suggesting that PASK might play an important role in feeding behavior.
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Affiliation(s)
- Verónica Hurtado-Carneiro
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Complutense University, Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Ciudad Universitaria, sn, 28040, Madrid, Spain
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Herzog RI, Jiang L, Herman P, Zhao C, Sanganahalli BG, Mason GF, Hyder F, Rothman DL, Sherwin RS, Behar KL. Lactate preserves neuronal metabolism and function following antecedent recurrent hypoglycemia. J Clin Invest 2013; 123:1988-98. [PMID: 23543056 DOI: 10.1172/jci65105] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 01/31/2013] [Indexed: 12/30/2022] Open
Abstract
Hypoglycemia occurs frequently during intensive insulin therapy in patients with both type 1 and type 2 diabetes and remains the single most important obstacle in achieving tight glycemic control. Using a rodent model of hypoglycemia, we demonstrated that exposure to antecedent recurrent hypoglycemia leads to adaptations of brain metabolism so that modest increments in circulating lactate allow the brain to function normally under acute hypoglycemic conditions. We characterized 3 major factors underlying this effect. First, we measured enhanced transport of lactate both into as well as out of the brain that resulted in only a small increase of its contribution to total brain oxidative capacity, suggesting that it was not the major fuel. Second, we observed a doubling of the glucose contribution to brain metabolism under hypoglycemic conditions that restored metabolic activity to levels otherwise only observed at euglycemia. Third, we determined that elevated lactate is critical for maintaining glucose metabolism under hypoglycemia, which preserves neuronal function. These unexpected findings suggest that while lactate uptake was enhanced, it is insufficient to support metabolism as an alternate substrate to replace glucose. Lactate is, however, able to modulate metabolic and neuronal activity, serving as a "metabolic regulator" instead.
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Affiliation(s)
- Raimund I Herzog
- Department of Internal Medicine, Section of Endocrinology, Yale School of Medicine, New Haven, Connecticut 06520-8040, USA.
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50
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Abstract
Islet hormones, especially insulin and glucagon, are important for glucose homeostasis. Insulin is a necessity for life, and disturbed insulin release results in disordered blood glucose regulation. Although isolated islets are fully capable of detecting changes in their local environment (particularly glucose fluctuations) and altering hormone release appropriately, experimentally manipulating pancreatic innervation alters islet hormone release in the whole animal. This article describes how brain may play a role in influencing and directing secretion of insulin and glucagon as a key part of the integrated physiology of blood glucose homeostasis.
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Affiliation(s)
- Mayowa A Osundiji
- Department of Medicine, Institute of Metabolic Science, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK
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