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Jafarkhani S, Khakbiz M, Amoabediny G, Mohammadi J, Tahmasebipour M, Rabbani H, Salimi A, Lee KB. A novel co-culture assay to evaluate the effects of sympathetic innervation on vascular smooth muscle differentiation. Bioorg Chem 2023; 133:106233. [PMID: 36731293 DOI: 10.1016/j.bioorg.2022.106233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 10/24/2022] [Accepted: 10/27/2022] [Indexed: 11/22/2022]
Abstract
Dedifferentiation of vascular smooth muscle cells (VSMCs) from a functional phenotype to an inverse synthetic phenotype is a symptom of cardiovascular disorders, such as atherosclerosis and hypertension. The sympathetic nervous system (SNS) is an essential regulator of the differentiation of vascular smooth muscle cells (VSMCs). In addition, numerous studies suggest that SNS also stimulates VSMCs to retain their contractile phenotype. However, the molecular mechanisms for this stimulation have not been thoroughly studied. In this study, we used a novel in vitro co-culture method to evaluate the effective cellular interactions and stimulatory effects of sympathetic neurons on the differentiation of VSMCs. We co-cultured rat neural-like pheochromocytoma cells (PC12) and rat aortic VSMCs with this method. Expression of VSMCs contractile genes, including smooth muscle actin (acta2), myosin heavy chain (myh11), elastin (eln), and smoothelin (smtn), were determined by quantitative real-time-PCR analysis as an indicator of VSMCs differentiation. Fold changes for specific contractile genes in VSMCs grown in vitro for seven days in the presence (innervated) and absence (non-innervated) of sympathetic neurons were 3.5 for acta2, 6.5 for myh11, 4.19 for eln, and 4 for smtn (normalized to Tata Binding Protein (TBP)). As a result, these data suggest that sympathetic innervation promotes VSMCs' contractile gene expression and also maintains VSMCs' functional phenotype.
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Affiliation(s)
- Saeed Jafarkhani
- Division of Biomedical Engineering, Faculty of New Sciences and Technologies, University of Tehran, North Karegar Ave., PO Box 14395-1561, Tehran, Iran
| | - Mehrdad Khakbiz
- Division of Biomedical Engineering, Faculty of New Sciences and Technologies, University of Tehran, North Karegar Ave., PO Box 14395-1561, Tehran, Iran; Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA.
| | - Ghasem Amoabediny
- Research Center for New Technologies in Life Science Engineering, University of Tehran, Tehran, Iran; Faculty of Chemical Engineering, College of Engineering, University of Tehran, Iran
| | - Javad Mohammadi
- Division of Biomedical Engineering, Faculty of New Sciences and Technologies, University of Tehran, North Karegar Ave., PO Box 14395-1561, Tehran, Iran
| | - Mohammad Tahmasebipour
- Department of Interdisciplinary Technology, Faculty of New Sciences and Technologies, University of Tehran, North Karegar Ave., PO Box 14395-1561, Tehran, Iran
| | - Hodjattallah Rabbani
- Monoclonal Antibody Research Center, Avicenna Research Institute, ACECR, Tehran, Iran
| | - Ali Salimi
- Monoclonal Antibody Research Center, Avicenna Research Institute, ACECR, Tehran, Iran
| | - Ki-Bum Lee
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
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Farhat R, de Santana‐Van Vliet E, Su G, Neely L, Benally T, Chan O. Carvedilol prevents impairment of the counterregulatory response in recurrently hypoglycaemic diabetic rats. Endocrinol Diabetes Metab 2021; 4:e00226. [PMID: 33855225 PMCID: PMC8029566 DOI: 10.1002/edm2.226] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 12/22/2020] [Accepted: 12/26/2020] [Indexed: 02/05/2023] Open
Abstract
Aim It has been suggested that repeated activation of the adrenergic system during antecedent episodes of hypoglycaemia contributes to the development of counterregulatory failure. We previously reported that treatment with carvedilol, a non-specific β-blocker, prevented the development of counterregulatory failure and improved hypoglycaemia awareness in recurrently hypoglycaemic non-diabetic rats. The current study investigated whether carvedilol has similar benefits in diabetic rats. Methods Recurrently hypoglycaemic streptozotocin-diabetic rats (STZ+RH) were treated with carvedilol for one week prior to undergoing a hypoglycaemic clamp. Hypoglycaemia awareness was evaluated in streptozotocin-diabetic rats made hypoglycaemia unaware using repeated injections of 2-deoxyglucose. Results Compared to hypoglycaemia-naïve STZ-diabetic controls, exogenous glucose requirements were more than doubled in the STZ+RH animals and this was associated with a 49% reduction in the epinephrine response to hypoglycaemia. Treating STZ+RH animals with carvedilol improved the epinephrine response to hypoglycaemia. Of note, neither recurrent hypoglycaemia nor carvedilol treatment affected the glucagon response in diabetic animals. Additionally, carvedilol treatment improved the feeding response to insulin-induced hypoglycaemia in diabetic animals made 'hypoglycaemia unaware' using repeated injections of 2-deoxyglucose, suggesting the treatment improved awareness of hypoglycaemia as well. Conclusion Our data suggest that carvedilol may be useful in preventing impairments of the sympathoadrenal response and the development of hypoglycaemia unawareness during recurring episodes of hypoglycaemia in diabetic animals.
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Affiliation(s)
- Rawad Farhat
- Department of Internal MedicineDivision of Endocrinology, Metabolism and DiabetesUniversity of UtahSalt Lake CityUTUSA
| | - Eliane de Santana‐Van Vliet
- Department of Internal MedicineDivision of Endocrinology, Metabolism and DiabetesUniversity of UtahSalt Lake CityUTUSA
| | - Gong Su
- Department of Cardiovascular MedicineShanghai Wusong Central HospitalShanghaiChina
| | - Levi Neely
- Department of BiologyUtah Valley UniversityOremUTUSA
| | - Thea Benally
- Department of Health, Exercise and Sports SciencesUniversity of New MexicoAlbuquerqueNMUSA
| | - Owen Chan
- Department of Internal MedicineDivision of Endocrinology, Metabolism and DiabetesUniversity of UtahSalt Lake CityUTUSA
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Sejling AS, Wang P, Zhu W, Farhat R, Knight N, Appadurai D, Chan O. Repeated Activation of Noradrenergic Receptors in the Ventromedial Hypothalamus Suppresses the Response to Hypoglycemia. Endocrinology 2021; 162:6052997. [PMID: 33367607 PMCID: PMC7814298 DOI: 10.1210/endocr/bqaa241] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Indexed: 11/19/2022]
Abstract
Activation of the adrenergic system in response to hypoglycemia is important for proper recovery from low glucose levels. However, it has been suggested that repeated adrenergic stimulation may also contribute to counterregulatory failure, but the underlying mechanisms are not known. The aim of this study was to establish whether repeated activation of noradrenergic receptors in the ventromedial hypothalamus (VMH) contributes to blunting of the counterregulatory response by enhancing local lactate production. The VMH of nondiabetic rats were infused with either artificial extracellular fluid, norepinephrine (NE), or salbutamol for 3 hours/day for 3 consecutive days before they underwent a hypoglycemic clamp with microdialysis to monitor changes in VMH lactate levels. Repeated exposure to NE or salbutamol suppressed both the glucagon and epinephrine responses to hypoglycemia compared to controls. Furthermore, antecedent NE and salbutamol treatments raised extracellular lactate levels in the VMH. To determine whether the elevated lactate levels were responsible for impairing the hormone response, we pharmacologically inhibited neuronal lactate transport in a subgroup of NE-treated rats during the clamp. Blocking neuronal lactate utilization improved the counterregulatory hormone responses in NE-treated animals, suggesting that repeated activation of VMH β2-adrenergic receptors increases local lactate levels which in turn, suppresses the counterregulatory hormone response to hypoglycemia.
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Affiliation(s)
- Anne-Sophie Sejling
- Department of Endocrinology and Nephrology, Nordsjællands Hospital, Dyrehavevej, Denmark
- Current Affiliation: A.S. is currently with Novo Nordisk A/S
| | - Peili Wang
- Department of Internal Medicine-Section of Endocrinology, Yale School of Medicine, New Haven, CT, USA
| | - Wanling Zhu
- Department of Internal Medicine-Section of Endocrinology, Yale School of Medicine, New Haven, CT, USA
| | - Rawad Farhat
- Department of Internal Medicine—Division of Endocrinology, Metabolism and Diabetes, University of Utah, Salt Lake City, UT, USA
| | - Nicholas Knight
- Department of Internal Medicine—Division of Endocrinology, Metabolism and Diabetes, University of Utah, Salt Lake City, UT, USA
| | - Daniel Appadurai
- Department of Internal Medicine—Division of Endocrinology, Metabolism and Diabetes, University of Utah, Salt Lake City, UT, USA
| | - Owen Chan
- Department of Internal Medicine—Division of Endocrinology, Metabolism and Diabetes, University of Utah, Salt Lake City, UT, USA
- Correspondence: Dr. Owen Chan, PhD, University of Utah, Department of Internal Medicine, Division of Endocrinology, Metabolism and Diabetes, 15 North 2030 East, Rm 2420B, Salt Lake City, UT 84112, USA.
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Lontchi-Yimagou E, Aleksic S, Hulkower R, Gospin R, Goyal A, Kuo B, Mitchell WG, You JY, Upadhyay L, Carey M, Sandu OA, Gabriely I, Shamoon H, Hawkins M. Plasma Epinephrine Contributes to the Development of Experimental Hypoglycemia-Associated Autonomic Failure. J Clin Endocrinol Metab 2020; 105:5903847. [PMID: 32915987 PMCID: PMC7678732 DOI: 10.1210/clinem/dgaa539] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 09/04/2020] [Indexed: 12/26/2022]
Abstract
BACKGROUND Recurrent hypoglycemia blunts counter-regulatory responses to subsequent hypoglycemic episodes, a syndrome known as hypoglycemia-associated autonomic failure (HAAF). Since adrenergic receptor blockade has been reported to prevent HAAF, we investigated whether the hypoglycemia-associated rise in plasma epinephrine contributes to pathophysiology and reported interindividual differences in susceptibility to HAAF. METHODS To assess the role of hypoglycemia-associated epinephrine responses in the susceptibility to HAAF, 24 adult nondiabetic subjects underwent two 2-hour hyperinsulinemic hypoglycemic clamp studies (nadir 54 mg/dL; 0-2 hours and 4-6 hours) on Day 1, followed by a third identical clamp on Day 2. We challenged an additional 7 subjects with two 2-hour infusions of epinephrine (0.03 μg/kg/min; 0-2 hours and 4-6 hours) vs saline on Day 1 followed by a 200-minute stepped hypoglycemic clamp (90, 80, 70, and 60 mg/dL) on Day 2. RESULTS Thirteen out of 24 subjects developed HAAF, defined by ≥20% reduction in average epinephrine levels during the final 30 minutes of the third compared with the first hypoglycemic episode (P < 0.001). Average epinephrine levels during the final 30 minutes of the first hypoglycemic episode were 2.3 times higher in subjects who developed HAAF compared with those who did not (P = 0.006).Compared to saline, epinephrine infusion on Day 1 reduced the epinephrine responses by 27% at the 70 and 60 mg/dL glucose steps combined (P = 0.04), with a parallel reduction in hypoglycemic symptoms (P = 0.03) on Day 2. CONCLUSIONS Increases in plasma epinephrine reproduce key features of HAAF in nondiabetic subjects. Marked interindividual variability in epinephrine responses to hypoglycemia may explain an individual's susceptibility to developing HAAF.
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Affiliation(s)
| | | | | | | | - Akankasha Goyal
- New York University Langone Medical Center, New York, New York
| | - Bryan Kuo
- Albert Einstein College of Medicine, Bronx, New York
| | | | - Jee Young You
- Albert Einstein College of Medicine, Bronx, New York
| | | | - Michelle Carey
- Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, Maryland
| | - Oana A Sandu
- Albert Einstein College of Medicine, Bronx, New York
| | - Ilan Gabriely
- Albert Einstein College of Medicine, Bronx, New York
| | - Harry Shamoon
- Albert Einstein College of Medicine, Bronx, New York
| | - Meredith Hawkins
- Albert Einstein College of Medicine, Bronx, New York
- Correspondence and Reprint Requests: Dr. Meredith Hawkins, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA. E-mail:
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Briski KP, Mandal SK, Bheemanapally K, Ibrahim MMH. Effects of acute versus recurrent insulin-induced hypoglycemia on ventromedial hypothalamic nucleus metabolic-sensory neuron AMPK activity: Impact of alpha 1-adrenergic receptor signaling. Brain Res Bull 2020; 157:41-50. [PMID: 31981674 DOI: 10.1016/j.brainresbull.2020.01.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 12/15/2019] [Accepted: 01/17/2020] [Indexed: 12/24/2022]
Abstract
Mechanisms that underlie metabolic sensor acclimation to recurring insulin-induced hypoglycemia (RIIH) are unclear. Norepinephrine (NE) regulates ventromedial hypothalamic nucleus (VMN) gluco-stimulatory nitric oxide (NO) and gluco-inhibitory γ-aminobutryic acid (GABA) neuron signaling. Current research addressed the hypothesis that during RIIH, NE suppresses 5'-AMP-activated protein kinase (AMPK) reactivity in both populations and impedes counter-regulation. The brain is postulated to utilize non-glucose substrates, e.g. amino acids glutamine (Gln), glutamate (Glu), and aspartate (Asp), to produce energy during hypoglycemia. A correlated aim investigated whether NE controls pyruvate recycling pathway marker protein (glutaminase, GLT; malic enzyme, ME-1) expression in either metabolic-sensory cell population. Male rats were injected subcutaneously with vehicle or insulin on days 1-3, then pretreated on day 4 by intracerebroventricular delivery of the alpha1-adrenergic receptor (α1-AR) reverse-agonist prazocin (PRZ) or vehicle before final insulin therapy. PRZ prevented acute hypoglycemic augmentation of AMPK activation in each cell group. Antecedent hypoglycemic repression of sensor activity was reversed by PRZ in GABA neurons. During RIIH, nitrergic neurons exhibited α1-AR - dependent up-regulated GLT and α2-AR profiles, while GABA cells showed down-regulated α1-AR. LC-ESI-MS analysis documented a decline in VMN Glu, Gln, and Asp concentrations during acute hypoglycemia, and habituation of the former two profiles to RIIH. PRZ attenuated glucagon and corticosterone secretion during acute hypoglycemia, but reversed decrements in output of both hormones during RIIH. Results implicate adjustments in impact of α1-AR signaling in repressed VMN metabolic-sensory AMPK activation and counter-regulatory dysfunction during RIIH. Antecedent hypoglycemia may up-regulate NO neuron energy yield via α1-AR - mediated up-regulated pyruvate recycling.
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Affiliation(s)
- Karen P Briski
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana at Monroe, Monroe, LA 71201, United States.
| | - Santosh K Mandal
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana at Monroe, Monroe, LA 71201, United States
| | - Khaggeswar Bheemanapally
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana at Monroe, Monroe, LA 71201, United States
| | - Mostafa M H Ibrahim
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana at Monroe, Monroe, LA 71201, United States
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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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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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Farhat R, Su G, Sejling AS, Knight N, Fisher SJ, Chan O. Carvedilol prevents counterregulatory failure and impaired hypoglycaemia awareness in non-diabetic recurrently hypoglycaemic rats. Diabetologia 2019; 62:676-686. [PMID: 30627753 PMCID: PMC6403018 DOI: 10.1007/s00125-018-4802-0] [Citation(s) in RCA: 7] [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] [Received: 10/19/2018] [Accepted: 11/28/2018] [Indexed: 02/07/2023]
Abstract
AIMS/HYPOTHESIS This study evaluates whether the non-selective β-blocker, carvedilol, can be used to prevent counterregulatory failure and the development of impaired awareness of hypoglycaemia (IAH) in recurrently hypoglycaemic rats. METHODS Sprague Dawley rats were implanted with vascular catheters and intracranial guide cannulas targeting the ventromedial hypothalamus (VMH). These animals underwent either three bouts of insulin-induced hypoglycaemia or received three saline injections (control group) over 3 days. A subgroup of recurrently hypoglycaemic animals was treated with carvedilol. The next day, the animals underwent a hypoglycaemic clamp with microdialysis without carvedilol treatment to evaluate changes in central lactate and hormone levels. To assess whether carvedilol prevented IAH, we treated rats that had received repeated 2-deoxyglucose (2DG) injections to impair their awareness of hypoglycaemia with carvedilol and measured food intake in response to insulin-induced hypoglycaemia as a surrogate marker for hypoglycaemia awareness. RESULTS Compared with the control group, recurrently hypoglycaemic rats had a ~1.7-fold increase in VMH lactate and this was associated with a 75% reduction in the sympathoadrenal response to hypoglycaemia. Treatment with carvedilol restored VMH lactate levels and improved the adrenaline (epinephrine) responses. In 2DG-treated rats compared with control animals receiving saline, food intake was reduced in response to hypoglycaemia and increased with carvedilol treatment. CONCLUSIONS/INTERPRETATION We conclude that carvedilol may be a useful therapy to prevent counterregulatory failure and improve IAH.
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Affiliation(s)
- Rawad Farhat
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, University of Utah, Department 15 North 2030 East, EIHG Building 533, Room 2420B, Salt Lake City, UT, 84112, USA
| | - Gong Su
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, University of Utah, Department 15 North 2030 East, EIHG Building 533, Room 2420B, Salt Lake City, UT, 84112, USA
- Beijing An Zhen Hospital, Capital Medical University, Beijing, China
| | | | - Nicholas Knight
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, University of Utah, Department 15 North 2030 East, EIHG Building 533, Room 2420B, Salt Lake City, UT, 84112, USA
| | - Simon J Fisher
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, University of Utah, Department 15 North 2030 East, EIHG Building 533, Room 2420B, Salt Lake City, UT, 84112, USA
| | - Owen Chan
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, University of Utah, Department 15 North 2030 East, EIHG Building 533, Room 2420B, Salt Lake City, UT, 84112, USA.
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Ibrahim MMH, Alhamami HN, Briski KP. Norepinephrine regulation of ventromedial hypothalamic nucleus metabolic transmitter biomarker and astrocyte enzyme and receptor expression: Impact of 5' AMP-activated protein kinase. Brain Res 2019; 1711:48-57. [PMID: 30629946 DOI: 10.1016/j.brainres.2019.01.012] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 09/12/2018] [Accepted: 01/07/2019] [Indexed: 11/18/2022]
Abstract
The ventromedial hypothalamic energy sensor AMP-activated protein kinase (AMPK) maintains glucostasis via neurotransmitter signals that diminish [γ-aminobutyric acid] or enhance [nitric oxide] counter-regulation. Ventromedial hypothalamic nucleus (VMN) 'fuel-inhibited' neurons are sensitive to astrocyte-generated metabolic substrate stream. Norepinephrine (NE) regulates astrocyte glycogen metabolism in vitro, and hypoglycemia intensifies VMN NE activity in vivo. Current research investigated the premise that NE elicits AMPK-dependent adjustments in VMN astrocyte glycogen metabolic enzyme [glycogen synthase (GS); glycogen phosphorylase (GP)] and gluco-regulatory neuron biomarker [glutamate decarboxylase65/67 (GAD); neuronal nitric oxide synthase (nNOS); SF-1] protein expression in male rats. We also examined whether VMN astrocytes are directly receptive to NE and if noradrenergic input regulates cellular sensitivity to the neuro-protective steroid estradiol. Intra-VMN NE correspondingly augmented or reduced VMN tissue GAD and nNOS protein despite no change in circulating glucose, data that imply that short-term exposure to NE promotes persistent improvement in VMN nerve cell energy stability. The AMPK inhibitor Compound C (Cc) normalized VMN nNOS, GS, and GP expression in NE-treated animals. NE caused AMPK-independent down-regulation of alpha2-, alongside Cc-reversible augmentation of beta1-adrenergic receptor protein profiles in laser-microdissected astrocytes. NE elicited divergent adjustments in astrocyte estrogen receptor-beta (AMPK-unrelated reduction) and GPR-30 (Cc-revocable increase) proteins. Outcomes implicate AMPK in noradrenergic diminution of VMN nitrergic metabolic-deficit signaling and astrocyte glycogen shunt activity. Differentiating NE effects on VMN astrocyte adrenergic and estrogen receptor variant expression suggest that noradrenergic regulation of glycogen metabolism may be mediated, in part, by one or more receptors characterized here by sensitivity to this catecholamine.
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Affiliation(s)
- Mostafa M H Ibrahim
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, LA 71201, United States
| | - Hussain N Alhamami
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, LA 71201, United States
| | - Karen P Briski
- School of Basic Pharmaceutical and Toxicological Sciences, College of Pharmacy, University of Louisiana Monroe, Monroe, LA 71201, United States.
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Collares EF, Vinagre AM, Collares-Buzato CB. Dipyrone in association with atropine inhibits the effect on gastric emptying induced by hypoglycemia in rats. Braz J Med Biol Res 2017; 50:e5948. [PMID: 28876363 PMCID: PMC5579963 DOI: 10.1590/1414-431x20175948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2016] [Accepted: 06/27/2017] [Indexed: 11/21/2022] Open
Abstract
Atropine (AT) and dipyrone (Dp) induce a delay of gastric emptying (GE) of liquids in rats by inhibiting muscarinic receptors and activating β2-adrenergic receptors, respectively. The objective of the present study was to determine the effects of pretreatment with AT and Dp, given alone or in combination, on the effect of hypoglycemia in the liquid GE in rats. Male Wistar adult rats (280-310 g) were pretreated intravenously with AT, Dp, AT plus Dp or their vehicle and then treated 30 min later with iv insulin or its vehicle (n=8-10 animals/group). Thirty min after treatment, GE was evaluated by determining, in awake rats, the percent gastric retention (%GR) of a saline meal labeled with phenol red administered by gavage. The results indicated that insulin induced hypoglycemia in a dose-dependent manner resulting in a significant reduction in %GR of liquid only at the highest dose tested (1 U/kg). Pretreatment with AT significantly increased %GR in the rats treated with 1 U/kg insulin. Surprisingly, after pretreatment with AT, the group treated with the lowest dose of insulin (0.25 U/kg) displayed significantly lower %GR compared to its control (vehicle-treated group), which was not seen in the non-pretreated animals. Pretreatment with Dp alone at the dose of 40 mg/kg induced an increase in %GR in both vehicle and 0.25 U/kg-treated rats. A higher dose of Dp alone (80 mg/kg) significantly reduced the effect of a marked hypoglycemia induced by 1 U/kg of insulin on GE while in combination with AT the effect was completely abolished. The results with AT suggest that moderate hypoglycemia may render the inhibitory mechanisms of GE ineffective while Dp alone and in combination with AT significantly overcame the effect of hypoglycemia on GE.
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Affiliation(s)
- E F Collares
- Departamento de Pediatria, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, SP, Brasil.,Núcleo de Medicina e Cirurgia Experimental, Universidade Estadual de Campinas, Campinas, SP, Brasil
| | - A M Vinagre
- Núcleo de Medicina e Cirurgia Experimental, Universidade Estadual de Campinas, Campinas, SP, Brasil
| | - C B Collares-Buzato
- Departamento de Bioquímica e Biologia Tecidual, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP, Brasil
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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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12
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Belfort-DeAguiar RD, Naik S, Hwang J, Szepietowska B, Sherwin RS. Inhaled Formoterol Diminishes Insulin-Induced Hypoglycemia in Type 1 Diabetes. Diabetes Care 2015; 38:1736-41. [PMID: 26153273 PMCID: PMC4542274 DOI: 10.2337/dc14-2472] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 06/14/2015] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Hypoglycemia is one of the major factors limiting implementation of tight glycemic control in patients with type 1 diabetes and is associated with increased morbidity and mortality during intensive insulin treatment. β-2 Adrenergic receptor (AR) agonists have been reported to diminish nocturnal hypoglycemia; however, whether long-acting inhaled β-2 AR agonists could potentially be used to treat or prevent hypoglycemia has not been established. RESEARCH DESIGN AND METHODS Seven patients with type 1 diabetes and seven healthy control subjects received inhaled formoterol (48 μg), a highly specific β-2 AR agonist, or a placebo during a hyperinsulinemic-hypoglycemic clamp study to evaluate its capacity to antagonize the effect of insulin. In a second set of studies, five subjects with type 1 diabetes received inhaled formoterol to assess its effect as a preventive therapy for insulin-induced hypoglycemia. RESULTS During a hyperinsulinemic-hypoglycemic clamp, compared with placebo, inhaled formoterol decreased the glucose infusion rate required to maintain plasma glucose at a target level by 45-50% (P < 0.05). There was no significant effect on glucagon, epinephrine, cortisol, or growth hormone release (P = NS). Furthermore, in volunteers with type 1 diabetes 1 h after increasing basal insulin delivery twofold, glucose levels dropped to 58 ± 5 mg/dL, whereas hypoglycemia was prevented by inhaled formoterol (P < 0.001). CONCLUSIONS Inhalation of the β-2 AR-specific agonist formoterol may be useful in the prevention or treatment of acute hypoglycemia and thus may help patients with type 1 diabetes achieve optimal glucose control more safely.
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Affiliation(s)
- Renata D Belfort-DeAguiar
- Department of Internal Medicine and Endocrinology, Yale University School of Medicine, New Haven, CT
| | - Sarita Naik
- Department of Internal Medicine and Endocrinology, Yale University School of Medicine, New Haven, CT
| | - Janice Hwang
- Department of Internal Medicine and Endocrinology, Yale University School of Medicine, New Haven, CT
| | - Barbara Szepietowska
- Department of Internal Medicine and Endocrinology, Yale University School of Medicine, New Haven, CT
| | - Robert S Sherwin
- Department of Internal Medicine and Endocrinology, Yale University School of Medicine, New Haven, CT
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13
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Routh VH, Hao L, Santiago AM, Sheng Z, Zhou C. Hypothalamic glucose sensing: making ends meet. Front Syst Neurosci 2014; 8:236. [PMID: 25540613 PMCID: PMC4261699 DOI: 10.3389/fnsys.2014.00236] [Citation(s) in RCA: 122] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 11/26/2014] [Indexed: 01/12/2023] Open
Abstract
The neuroendocrine system governs essential survival and homeostatic functions. For example, growth is needed for development, thermoregulation maintains optimal core temperature in a changing environment, and reproduction ensures species survival. Stress and immune responses enable an organism to overcome external and internal threats while the circadian system regulates arousal and sleep such that vegetative and active functions do not overlap. All of these functions require a significant portion of the body's energy. As the integrator of the neuroendocrine system, the hypothalamus carefully assesses the energy status of the body in order to appropriately partition resources to provide for each system without compromising the others. While doing so the hypothalamus must ensure that adequate glucose levels are preserved for brain function since glucose is the primary fuel of the brain. To this end, the hypothalamus contains specialized glucose sensing neurons which are scattered throughout the nuclei controlling distinct neuroendocrine functions. We hypothesize that these neurons play a key role in enabling the hypothalamus to partition energy to meet these peripheral survival needs without endangering the brain's glucose supply. This review will first describe the varied mechanisms underlying glucose sensing in neurons within discrete hypothalamic nuclei. We will then evaluate the way in which peripheral energy status regulates glucose sensitivity. For example, during energy deficit such as fasting specific hypothalamic glucose sensing neurons become sensitized to decreased glucose. This increases the gain of the information relay when glucose availability is a greater concern for the brain. Finally, changes in glucose sensitivity under pathological conditions (e.g., recurrent insulin-hypoglycemia, diabetes) will be addressed. The overall goal of this review is to place glucose sensing neurons within the context of hypothalamic control of neuroendocrine function.
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Affiliation(s)
- Vanessa H Routh
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers University Newark, NJ, USA
| | - Lihong Hao
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers University Newark, NJ, USA ; Department of Pharmacology and Physiology and Graduate School of the Biomedical Sciences, New Jersey Medical School, Rutgers University Newark, NJ, USA
| | - Ammy M Santiago
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers University Newark, NJ, USA ; Department of Pharmacology and Physiology and Graduate School of the Biomedical Sciences, New Jersey Medical School, Rutgers University Newark, NJ, USA
| | - Zhenyu Sheng
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers University Newark, NJ, USA
| | - Chunxue Zhou
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers University Newark, NJ, USA ; Department of Pharmacology and Physiology and Graduate School of the Biomedical Sciences, New Jersey Medical School, Rutgers University Newark, NJ, USA
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14
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Barnes TM, Otero YF, Elliott AD, Locke AD, Malabanan CM, Coldren AG, Brissova M, Piston DW, McGuinness OP. Interleukin-6 amplifies glucagon secretion: coordinated control via the brain and pancreas. Am J Physiol Endocrinol Metab 2014; 307:E896-905. [PMID: 25205821 PMCID: PMC4233256 DOI: 10.1152/ajpendo.00343.2014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Inappropriate glucagon secretion contributes to hyperglycemia in inflammatory disease. Previous work implicates the proinflammatory cytokine interleukin-6 (IL-6) in glucagon secretion. IL-6-KO mice have a blunted glucagon response to lipopolysaccharide (LPS) that is restored by intravenous replacement of IL-6. Given that IL-6 has previously been demonstrated to have a transcriptional (i.e., slow) effect on glucagon secretion from islets, we hypothesized that the rapid increase in glucagon following LPS occurred by a faster mechanism, such as by action within the brain. Using chronically catheterized conscious mice, we have demonstrated that central IL-6 stimulates glucagon secretion uniquely in the presence of an accompanying stressor (hypoglycemia or LPS). Contrary to our hypothesis, however, we found that IL-6 amplifies glucagon secretion in two ways; IL-6 not only stimulates glucagon secretion via the brain but also by direct action on islets. Interestingly, IL-6 augments glucagon secretion from both sites only in the presence of an accompanying stressor (such as epinephrine). Given that both adrenergic tone and plasma IL-6 are elevated in multiple inflammatory diseases, the interactions of the IL-6 and catecholaminergic signaling pathways in regulating GCG secretion may contribute to our present understanding of these diseases.
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Affiliation(s)
- Tammy M Barnes
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Yolanda F Otero
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Amicia D Elliott
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Alicia D Locke
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Carlo M Malabanan
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Anastasia G Coldren
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Marcela Brissova
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - David W Piston
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Owen P McGuinness
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
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15
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Jokiaho AJ, Donovan CM, Watts AG. The rate of fall of blood glucose determines the necessity of forebrain-projecting catecholaminergic neurons for male rat sympathoadrenal responses. Diabetes 2014; 63:2854-65. [PMID: 24740574 PMCID: PMC4113074 DOI: 10.2337/db13-1753] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Different onset rates of insulin-induced hypoglycemia use distinct glucosensors to activate sympathoadrenal counterregulatory responses (CRRs). Glucosensory elements in the portal-mesenteric veins are dispensable with faster rates when brain elements predominate, but are essential for responses to the slower-onset hypoglycemia that is common with insulin therapy. Whether a similar rate-associated divergence exists within more expansive brain networks is unknown. Hindbrain catecholamine neurons distribute glycemia-related information throughout the forebrain. We tested in male rats whether catecholaminergic neurons that project to the medial and ventromedial hypothalamus are required for sympathoadrenal CRRs to rapid- and slow-onset hypoglycemia and whether these neurons are differentially engaged as onset rates change. Using a catecholamine-specific neurotoxin and hyperinsulinemic-hypoglycemic clamps, we found that sympathoadrenal CRRs to slow- but not rapid-onset hypoglycemia require hypothalamus-projecting catecholaminergic neurons, the majority of which originate in the ventrolateral medulla. As determined with Fos, these neurons are differentially activated by the two onset rates. We conclude that 1) catecholaminergic projections to the hypothalamus provide essential information for activating sympathoadrenal CRRs to slow- but not rapid-onset hypoglycemia, 2) hypoglycemia onset rates have a major impact on the hypothalamic mechanisms that enable sympathoadrenal CRRs, and 3) hypoglycemia-related sensory information activates hindbrain catecholaminergic neurons in a rate-dependent manner.
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Affiliation(s)
- Anne J Jokiaho
- Center for NeuroMetabolic Interactions, The Integrated and Evolutionary Biology Graduate Program, and The Department of Biological Sciences, USC Dornsife College of Letters, Arts, and Sciences, University of Southern California, Los Angeles, CA
| | - Casey M Donovan
- Center for NeuroMetabolic Interactions, The Integrated and Evolutionary Biology Graduate Program, and The Department of Biological Sciences, USC Dornsife College of Letters, Arts, and Sciences, University of Southern California, Los Angeles, CA
| | - Alan G Watts
- Center for NeuroMetabolic Interactions, The Integrated and Evolutionary Biology Graduate Program, and The Department of Biological Sciences, USC Dornsife College of Letters, Arts, and Sciences, University of Southern California, Los Angeles, CA
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16
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Jensen VFH, Bøgh IB, Lykkesfeldt J. Effect of insulin-induced hypoglycaemia on the central nervous system: evidence from experimental studies. J Neuroendocrinol 2014; 26:123-50. [PMID: 24428753 DOI: 10.1111/jne.12133] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 12/13/2013] [Accepted: 01/08/2014] [Indexed: 12/12/2022]
Abstract
Insulin-induced hypoglycaemia (IIH) is a major acute complication in type 1 as well as in type 2 diabetes, particularly during intensive insulin therapy. The brain plays a central role in the counter-regulatory response by eliciting parasympathetic and sympathetic hormone responses to restore normoglycaemia. Brain glucose concentrations, being approximately 15-20% of the blood glucose concentration in humans, are rigorously maintained during hypoglycaemia through adaptions such as increased cerebral glucose transport, decreased cerebral glucose utilisation and, possibly, by using central nervous system glycogen as a glucose reserve. However, during sustained hypoglycaemia, the brain cannot maintain a sufficient glucose influx and, as the cerebral hypoglycaemia becomes severe, electroencephalogram changes, oxidative stress and regional neuronal death ensues. With particular focus on evidence from experimental studies on nondiabetic IIH, this review outlines the central mechanisms behind the counter-regulatory response to IIH, as well as cerebral adaption to avoid sequelae of cerebral neuroglycopaenia, including seizures and coma.
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Affiliation(s)
- V F H Jensen
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Department of Diabetes Toxicology and Safety Pharmacology, Novo Nordisk A/S, Maaloev, Denmark
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17
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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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18
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Hagiwara S, Jha JC, Cooper ME. Identifying and interpreting novel targets that address more than one diabetic complication: a strategy for optimal end organ protection in diabetes. Diabetol Int 2013. [DOI: 10.1007/s13340-013-0148-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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19
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Szepietowska B, Zhu W, Sherwin RS. β2-Adrenergic receptor agonist administration promotes counter-regulatory responses and recovery from hypoglycaemia in rats. Diabetologia 2013; 56:2517-23. [PMID: 23933834 PMCID: PMC3857969 DOI: 10.1007/s00125-013-3009-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 07/10/2013] [Indexed: 01/22/2023]
Abstract
AIMS/HYPOTHESIS We have previously reported that local activation of β2-adrenergic receptors (B2ARs) in the ventromedial hypothalamus (VMH) enhances hypoglycaemic counter-regulation. This study examines whether peripheral delivery of a selective B2AR agonist could also promote counter-regulatory responses and thereby has potential therapeutic value to limit hypoglycaemia risk. METHODS Conscious male Sprague-Dawley rats received an intra-arterial injection of the B2AR specific agonist, formoterol, or a control solution either before a hyperinsulinaemic-hypoglycaemic clamp study or immediately before recovery from insulin-induced hypoglycaemia. In addition, the capacity of a VMH-targeted microinjection of a B2AR antagonist to limit the anti-insulin effect of the B2AR agonist was assessed. RESULTS Systemic delivery of B2AR agonist markedly reduced the exogenous glucose infusion rate (GIR) required during the hypoglycaemic clamp study. This effect was mediated by blockade of insulin's inhibitory effect on endogenous glucose production. Local blockade of B2ARs within the VMH using a specific antagonist partially diminished the effect of systemic activation of B2ARs during hypoglycaemia at least in part by diminishing the adrenaline (epinephrine) response to hypoglycaemia. Peripheral B2AR agonist injection also enhanced glucose recovery from insulin-induced hypoglycaemia. CONCLUSIONS/INTERPRETATION Systemic B2AR agonist administration acts to limit insulin-induced hypoglycaemia by offsetting insulin's inhibitory effect on hepatic glucose production. This effect appears to be predominately mediated via a direct effect on liver B2ARs, but a small stimulatory effect on B2ARs within the VMH cannot be excluded. Our data suggest that formoterol may have therapeutic value to limit the risk of hypoglycaemia in patients with diabetes.
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Affiliation(s)
- Barbara Szepietowska
- Section of Endocrinology, Yale University School of Medicine, 300 Cedar St, TAC S141, New Haven, CT, 06520, USA
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20
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Reno CM, Daphna-Iken D, Chen YS, VanderWeele J, Jethi K, Fisher SJ. Severe hypoglycemia-induced lethal cardiac arrhythmias are mediated by sympathoadrenal activation. Diabetes 2013; 62:3570-81. [PMID: 23835337 PMCID: PMC3781452 DOI: 10.2337/db13-0216] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
For people with insulin-treated diabetes, severe hypoglycemia can be lethal, though potential mechanisms involved are poorly understood. To investigate how severe hypoglycemia can be fatal, hyperinsulinemic, severe hypoglycemic (10-15 mg/dL) clamps were performed in Sprague-Dawley rats with simultaneous electrocardiogram monitoring. With goals of reducing hypoglycemia-induced mortality, the hypotheses tested were that: 1) antecedent glycemic control impacts mortality associated with severe hypoglycemia; 2) with limitation of hypokalemia, potassium supplementation could limit hypoglycemia-associated deaths; 3) with prevention of central neuroglycopenia, brain glucose infusion could prevent hypoglycemia-associated arrhythmias and deaths; and 4) with limitation of sympathoadrenal activation, adrenergic blockers could prevent hypoglycemia-induced arrhythmic deaths. Severe hypoglycemia-induced mortality was noted to be worsened by diabetes, but recurrent antecedent hypoglycemia markedly improved the ability to survive an episode of severe hypoglycemia. Potassium supplementation tended to reduce mortality. Severe hypoglycemia caused numerous cardiac arrhythmias including premature ventricular contractions, tachycardia, and high-degree heart block. Intracerebroventricular glucose infusion reduced severe hypoglycemia-induced arrhythmias and overall mortality. β-Adrenergic blockade markedly reduced cardiac arrhythmias and completely abrogated deaths due to severe hypoglycemia. Under conditions studied, sudden deaths caused by insulin-induced severe hypoglycemia were mediated by lethal cardiac arrhythmias triggered by brain neuroglycopenia and the marked sympathoadrenal response.
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Affiliation(s)
- Candace M. Reno
- Division of Endocrinology, Metabolism, & Lipid Research, Department of Medicine, Washington University, St. Louis, Missouri
| | - Dorit Daphna-Iken
- Division of Endocrinology, Metabolism, & Lipid Research, Department of Medicine, Washington University, St. Louis, Missouri
| | - Y. Stefanie Chen
- Division of Endocrinology, Metabolism, & Lipid Research, Department of Medicine, Washington University, St. Louis, Missouri
| | - Jennifer VanderWeele
- Division of Endocrinology, Metabolism, & Lipid Research, Department of Medicine, Washington University, St. Louis, Missouri
| | - Krishan Jethi
- Division of Endocrinology, Metabolism, & Lipid Research, Department of Medicine, Washington University, St. Louis, Missouri
| | - Simon J. Fisher
- Division of Endocrinology, Metabolism, & Lipid Research, Department of Medicine, Washington University, St. Louis, Missouri
- Department of Cell Biology and Physiology, Washington University, St. Louis, Missouri
- Corresponding author: Simon J. Fisher,
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21
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Awoniyi O, Rehman R, Dagogo-Jack S. Hypoglycemia in patients with type 1 diabetes: epidemiology, pathogenesis, and prevention. Curr Diab Rep 2013; 13:669-78. [PMID: 23912765 DOI: 10.1007/s11892-013-0411-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Hypoglycemia is uncommon in the general, nondiabetic population but occurs frequently in persons with diabetes treated with insulin or insulin secretagogues. Thus, iatrogenic hypoglycemia explains the majority of cases among persons with type 1 diabetes (T1DM). Since T1DM is characterized by absolute insulin dependence, the current imperfections in insulin replacement therapies often lead to a mismatch between caloric supply and circulating insulin levels, thus increasing the risk for glycemic fluctuations. Hypoglycemia is the limiting factor to excellent glycemic control in insulin-treated subjects. Intensification of glycemic control was associated with a 300 % increase in the rate of hypoglycemia in the Diabetes Control and Complications Trial. Recent measurements using continuous glucose monitoring reveal an alarming rate of daytime and nocturnal episodes of hypoglycemia in patients with T1DM. Etiological factors underlying hypoglycemia in T1DM include predictable triggers (skipped meals, exercise, insulin over dosage) as well as defective counterregulation, a component of hypoglycemia-associated autonomic failure.
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Affiliation(s)
- Omodele Awoniyi
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism & Clinical Research Center, University of Tennessee Health Science Center, 920 Madison Avenue, Suite 300A, Memphis, TN, 38163, USA
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22
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Reno CM, Litvin M, Clark AL, Fisher SJ. Defective counterregulation and hypoglycemia unawareness in diabetes: mechanisms and emerging treatments. Endocrinol Metab Clin North Am 2013; 42:15-38. [PMID: 23391237 PMCID: PMC3568263 DOI: 10.1016/j.ecl.2012.11.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
For people with diabetes, hypoglycemia remains the limiting factor in achieving glycemic control. This article reviews recent advances in how the brain senses and responds to hypoglycemia. Novel mechanisms by which individuals with insulin-treated diabetes develop hypoglycemia unawareness and impaired counterregulatory responses are outlined. Prevention strategies for reducing the incidence of hypoglycemia are discussed.
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Affiliation(s)
- Candace M. Reno
- Division of Endocrinology, Metabolism, & Lipid Research, Department of Medicine, Washington University, St. Louis, MO
| | - Marina Litvin
- Division of Endocrinology, Metabolism, & Lipid Research, Department of Medicine, Washington University, St. Louis, MO
| | - Amy L. Clark
- Division of Endocrinology and Diabetes, Department of Pediatrics, Washington University, St. Louis, MO
| | - Simon J. Fisher
- Division of Endocrinology, Metabolism, & Lipid Research, Department of Medicine, Washington University, St. Louis, MO
- Department of Cell Biology and Physiology, Washington University, St. Louis, MO
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23
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Abstract
It is increasingly apparent that not only is a cure for the current worldwide diabetes epidemic required, but also for its major complications, affecting both small and large blood vessels. These complications occur in the majority of individuals with both type 1 and type 2 diabetes. Among the most prevalent microvascular complications are kidney disease, blindness, and amputations, with current therapies only slowing disease progression. Impaired kidney function, exhibited as a reduced glomerular filtration rate, is also a major risk factor for macrovascular complications, such as heart attacks and strokes. There have been a large number of new therapies tested in clinical trials for diabetic complications, with, in general, rather disappointing results. Indeed, it remains to be fully defined as to which pathways in diabetic complications are essentially protective rather than pathological, in terms of their effects on the underlying disease process. Furthermore, seemingly independent pathways are also showing significant interactions with each other to exacerbate pathology. Interestingly, some of these pathways may not only play key roles in complications but also in the development of diabetes per se. This review aims to comprehensively discuss the well validated, as well as putative mechanisms involved in the development of diabetic complications. In addition, new fields of research, which warrant further investigation as potential therapeutic targets of the future, will be highlighted.
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Affiliation(s)
- Josephine M Forbes
- Diabetes Division, Baker IDI Heart and Diabetes Institute, Melbourne, Australia
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24
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Routh VH, Donovan CM, Ritter S. 2. Hypoglycemia Detection. TRANSLATIONAL ENDOCRINOLOGY & METABOLISM 2012; 3:47-87. [PMID: 24910721 PMCID: PMC4045627 DOI: 10.1210/team.9781936704200.ch2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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25
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Li F, Ohtani A, Senzaki K, Shiga T. Receptor-dependent regulation of dendrite formation of noradrenaline and dopamine in non-GABAergic cerebral cortical neurons. Dev Neurobiol 2012; 73:370-83. [PMID: 23135899 DOI: 10.1002/dneu.22065] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 09/18/2012] [Accepted: 10/31/2012] [Indexed: 12/12/2022]
Abstract
The present study characterized the receptor-dependent regulation of dendrite formation of noradrenaline (NA) and dopamine (DA) in cultured neurons obtained from embryonic day 16 rat cerebral cortex. Morphological diversity of cortical dendrites was analyzed on various features: dendrite initiation, dendrite outgrowth, and dendrite branching. Using a combination of immunocytochemical markers of dendrites and GABAergic neurons, we focused on the dendrite morphology of non-GABAergic neurons. Our results showed that (1) NA inhibited the dendrite branching, (2) β adrenergic receptor (β-AR) agonist inhibited the dendrite initiation, while promoted the dendrite outgrowth, (3) β1-AR and β2-AR were present in all the cultured neurons, and both agonists inhibited the dendrite initiation, while only β1-AR agonist induced the dendrite branching; (4) DA inhibited the dendrite outgrowth, (5) D1 receptor agonist inhibited the dendrite initiation, while promoted the dendrite branching. In conclusion, this study compared the effects of NA, DA and their receptors and showed that NA and DA regulate different features on the dendrite formation of non-GABAergic cortical neurons, depending on the receptors.
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Affiliation(s)
- Fei Li
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, 305-8577, Ibaraki, Japan
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26
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Siafarikas A, Johnston RJ, Bulsara MK, O'Leary P, Jones TW, Davis EA. Early loss of the glucagon response to hypoglycemia in adolescents with type 1 diabetes. Diabetes Care 2012; 35:1757-62. [PMID: 22699295 PMCID: PMC3402257 DOI: 10.2337/dc11-2010] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To assess the glucagon response to hypoglycemia and identify influencing factors in patients with type 1 diabetes compared with nondiabetic control subjects. RESEARCH DESIGN AND METHODS Hyperinsulinemic hypoglycemic clamp studies were performed in all participants. The glucagon response to both hypoglycemia and arginine was measured, as well as epinephrine, cortisol, and growth hormone responses to hypoglycemia. Residual β-cell function was assessed using fasting and stimulated C-peptide. RESULTS Twenty-eight nonobese adolescents with type 1 diabetes (14 female, mean age 14.9 years [range 11.2-19.8]) and 12 healthy control subjects (6 female, 15.3 years [12.8-18.7]) participated in the study. Median duration of type 1 diabetes was 0.66 years (range 0.01-9.9). The glucagon peak to arginine stimulation was similar between groups (P = 0.27). In contrast, the glucagon peak to hypoglycemia was reduced in the group with diabetes (95% CI): 68 (62-74) vs. 96 (87-115) pg/mL (P < 0.001). This response was greater than 3 SDs from baseline for only 7% of subjects with type 1 diabetes in comparison with 83% of control subjects and was lost at a median duration of diabetes of 8 months and as early as 1 month after diagnosis (R = -0.41, P < 0.01). There was no correlation in response with height, weight, BMI, and HbA(1c). Epinephrine, cortisol, and growth hormone responses to hypoglycemia were present in both groups. CONCLUSIONS The glucagon response to hypoglycemia in adolescents with type 1 diabetes is influenced by the duration of diabetes and can be lost early in the course of the disease.
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Affiliation(s)
- Aris Siafarikas
- Department of Endocrinology and Diabetes, Princess Margaret Hospital for Children, Perth, Western Australia, Australia
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