1
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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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2
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Choi JH, Kim MS. Homeostatic Regulation of Glucose Metabolism by the Central Nervous System. Endocrinol Metab (Seoul) 2022; 37:9-25. [PMID: 35255598 PMCID: PMC8901968 DOI: 10.3803/enm.2021.1364] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 02/07/2022] [Indexed: 12/04/2022] Open
Abstract
Evidence for involvement of the central nervous system (CNS) in the regulation of glucose metabolism dates back to the 19th century, although the majority of the research on glucose metabolism has focused on the peripheral metabolic organs. Due to recent advances in neuroscience, it has now become clear that the CNS is indeed vital for maintaining glucose homeostasis. To achieve normoglycemia, specific populations of neurons and glia in the hypothalamus sense changes in the blood concentrations of glucose and of glucoregulatory hormones such as insulin, leptin, glucagon-like peptide 1, and glucagon. This information is integrated and transmitted to other areas of the brain where it eventually modulates various processes in glucose metabolism (i.e., hepatic glucose production, glucose uptake in the brown adipose tissue and skeletal muscle, pancreatic insulin and glucagon secretion, renal glucose reabsorption, etc.). Errors in these processes lead to hyper- or hypoglycemia. We here review the current understanding of the brain regulation of glucose metabolism.
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Affiliation(s)
- Jong Han Choi
- Division of Endocrinology and Metabolism, Konkuk University Medical Center, Seoul,
Korea
| | - Min-Seon Kim
- Division of Endocrinology and Metabolism, Asan Medical Center, University of Ulsan College of Medicine, Seoul,
Korea
- Appeptite Regulation Laboratory, Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul,
Korea
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3
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Ahmed S, Soliman A, De Sanctis V, Alyafie F, Alaaraj N, Hamed N, Ali HA, Kamal A. Defective Cortisol Secretion in Response to Spontaneous Hypoglycemia but Normal Cortisol Response to ACTH stimulation in neonates with Hyperinsulinemic Hypoglycemia (HH). ACTA BIO-MEDICA : ATENEI PARMENSIS 2021; 92:e2021182. [PMID: 33988135 PMCID: PMC8182578 DOI: 10.23750/abm.v92i2.11396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 02/28/2021] [Indexed: 12/04/2022]
Abstract
Introduction: Hyperinsulinemic Hypoglycaemia (HH) is the most common cause of recurrent and persistent hypoglycemia in the neonatal period. Cortisol and GH play an important role as a counterregulatory hormone during hypoglycemia. Both antagonize the peripheral effects of insulin and directly influence glucose metabolism Patients and Methods: We studied cortisol and GH secretion in newborn infants with HH during spontaneous hypoglycemia. In addition, their basal ACTH level was measured and cortisol response to a standard dose ACTH test was performed. Results: Nine newborns with HH were studied during the first 2 weeks of life. During HH, their mean glucose concentration was 1.42 ± 0.7 mmol/L, mean beta hydroxybutyrate level was 0.08 ± 0.04 mmol/L, and mean serum insulin level was 17.78 ± 9.7 μU/mL. Their cortisol and GH levels at the time of spontaneous hypoglycemia were 94.7 ± 83.1 nmol/L and 82.4 ± 29 m IU/L respectively. They had relatively low level of ACTH (range: 14 :72 pg/ml, mean: 39.4 ± 20 pg/mL) during hypoglycemia. All infants had GH concentration > 20 mIU/L at the time of hypoglycemia. All infants underwent ACTH test. Their basal serum cortisol levels did not differ compared to cortisol levels during hypoglycemia, and all had a normal peak cortisol response (> 500 nmol/L) in response to i.v. ACTH stimulation test. Conclusion: Infants with HH have low cortisol response to spontaneous hypoglycemia with normal response to exogenous standard-dose ACTH. Checking hypothalamic-pituitary axis (HPA) axis later in infancy using low dose ACTH may be useful to diagnose persistent HPA abnormalities in these infants. All HH infants had appropriate elevation of GH during hypoglycemia. (www.actabiomedica.it)
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Affiliation(s)
- Shayma Ahmed
- Departments of Pediatrics, Hamad General Hospital, Doha, Qatar.
| | - Ashraf Soliman
- Departments of Pediatrics, Hamad General Hospital, Doha, Qatar.
| | | | - Fawzia Alyafie
- Departments of Pediatrics, Hamad General Hospital, Doha, Qatar.
| | - Nada Alaaraj
- Departments of Pediatrics, Hamad General Hospital, Doha, Qatar.
| | - Noor Hamed
- Departments of Pediatrics, Hamad General Hospital, Doha, Qatar.
| | - Hamdy A Ali
- Departments of Neonatology, Hamad General Hospital, Doha, Qatar.
| | - Abdulla Kamal
- Departments of Pharmacology, Hamad General Hospital, Doha, Qatar.
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4
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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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5
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Kundu S, Islam MM, Mandal S, Sahoo P. Fluorescence ‘off–on–off’ signaling with zinc ensemble: a new array of investigating prevalence of ATP in liver cancer cells. NEW J CHEM 2021. [DOI: 10.1039/d1nj00051a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
2-Hydroxy naphthaldehyde–picolylamine conjugate (NPAC) ensemble with Zn2+ (NPAC–Zn2+) has been synthesized for the selective recognition and estimation of ATP in human liver cancer cells.
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Affiliation(s)
- Shampa Kundu
- Department of Chemistry
- Visva-Bharati University
- Santiniketan-731235
- India
| | | | - Sukhendu Mandal
- Department of Microbiology
- University of Calcutta
- Kolkata-700073
- India
| | - Prithidipa Sahoo
- Department of Chemistry
- Visva-Bharati University
- Santiniketan-731235
- India
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Nwokolo M, Amiel SA, O'Daly O, Byrne ML, Wilson BM, Pernet A, Cordon SM, Macdonald IA, Zelaya FO, Choudhary P. Hypoglycemic thalamic activation in type 1 diabetes is associated with preserved symptoms despite reduced epinephrine. J Cereb Blood Flow Metab 2020; 40:787-798. [PMID: 31006309 PMCID: PMC7168783 DOI: 10.1177/0271678x19842680] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Brain responses to low plasma glucose may be key to understanding the behaviors that prevent severe hypoglycemia in type 1 diabetes. This study investigated the impact of long duration, hypoglycemia aware type 1 diabetes on cerebral blood flow responses to hypoglycemia. Three-dimensional pseudo-continuous arterial spin labeling magnetic resonance imaging was performed in 15 individuals with type 1 diabetes and 15 non-diabetic controls during a two-step hyperinsulinemic glucose clamp. Symptom, hormone, global cerebral blood flow and regional cerebral blood flow responses to hypoglycemia were measured. Epinephrine release during hypoglycemia was attenuated in type 1 diabetes, but symptom score rose comparably in both groups. A rise in global cerebral blood flow did not differ between groups. Regional cerebral blood flow increased in the thalamus and fell in the hippocampus and temporal cortex in both groups. Type 1 diabetes demonstrated lesser anterior cingulate cortex activation; however, this difference did not survive correction for multiple comparisons. Thalamic cerebral blood flow change correlated with autonomic symptoms, and anterior cingulate cortex cerebral blood flow change correlated with epinephrine response across groups. The thalamus may thus be involved in symptom responses to hypoglycemia, independent of epinephrine action, while anterior cingulate cortex activation may be linked to counterregulation. Activation of these regions may have a role in hypoglycemia awareness and avoidance of problematic hypoglycemia.
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Affiliation(s)
- Munachiso Nwokolo
- Department of Diabetes, School of Life Course Sciences, King's College London, London, UK.,King's College Hospital, NHS Foundation Trust, London, UK
| | - Stephanie A Amiel
- Department of Diabetes, School of Life Course Sciences, King's College London, London, UK.,King's College Hospital, NHS Foundation Trust, London, UK
| | - Owen O'Daly
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Megan L Byrne
- Department of Diabetes, School of Life Course Sciences, King's College London, London, UK
| | - Bula M Wilson
- Department of Diabetes, School of Life Course Sciences, King's College London, London, UK
| | - Andrew Pernet
- Department of Diabetes, School of Life Course Sciences, King's College London, London, UK
| | - Sally M Cordon
- School of Life Sciences, MRC-ARUK Centre of Excellence in Musculoskeletal Ageing, Nottingham University Medical School, Queen's Medical Centre, Nottingham, UK
| | - Ian A Macdonald
- School of Life Sciences, MRC-ARUK Centre of Excellence in Musculoskeletal Ageing, Nottingham University Medical School, Queen's Medical Centre, Nottingham, UK
| | - Fernando O Zelaya
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Pratik Choudhary
- Department of Diabetes, School of Life Course Sciences, King's College London, London, UK.,King's College Hospital, NHS Foundation Trust, London, UK
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7
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Naderi F, Míguez JM, Soengas JL, López-Patiño MA. SIRT1 mediates the effect of stress on hypothalamic clock genes and food intake regulators in rainbow trout, Oncorhynchus mykiss. Comp Biochem Physiol A Mol Integr Physiol 2019; 235:102-111. [PMID: 31152913 DOI: 10.1016/j.cbpa.2019.05.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 05/14/2019] [Accepted: 05/20/2019] [Indexed: 11/24/2022]
Abstract
Stress negatively affects a wide range of physiological and behavioural functions (circadian physiology and food intake, among others), thus compromising animal welfare. Cortisol mediates the effect of stress on food intake, but other mediators (such as sirtuins) may participate in that related to circadian physiology. We evaluated 1) the effect of stress on the day-night variation of hypothalamic clock genes and food intake regulators, 2) changes of mRNA abundance in cortisol biosynthesis at the head kidney, and 3) changes of glucocorticoid receptors in both tissues of rainbow trout, together with the involvement of SIRT1 in such effect. Trout receiving or not SIRT1 inhibitor (EX527) and subjected or not to stress by high stocking density (72 h), were sampled at day- (ZT10) and night-time (ZT18). Our results indicate that SIRT1 mediates the effect of stress on mRNA abundance of clock genes in trout hypothalamus, but it also influences those changes occurring on food intake-related peptides. High stocking density inhibits clock genes expression, but enhances that of food intake-related peptides. EX527 treatment prevents stress-related changes observed in clock genes, thus evidencing a key role played by SIRT1 in mediating this effect on trout circadian oscillators. On the other hand, EX527 treatment partially prevents changes of food intake-related peptides, indicating that an interaction between SIRT1 and other mediators (such as cortisol) exists during response to stress. In support of that, our results reveal that SIRT1 influences cortisol biosynthesis during stress. Whatever the case is, further research will help understanding the underlying mechanisms involved.
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Affiliation(s)
- Fatemeh Naderi
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro Singular de Investigación Mariña-ECIMAT, Universidade de Vigo, Spain
| | - Jesús M Míguez
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro Singular de Investigación Mariña-ECIMAT, Universidade de Vigo, Spain
| | - José L Soengas
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro Singular de Investigación Mariña-ECIMAT, Universidade de Vigo, Spain
| | - Marcos A López-Patiño
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro Singular de Investigación Mariña-ECIMAT, Universidade de Vigo, Spain.
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8
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Bowman P, McDonald TJ, Knight BA, Flanagan SE, Leveridge M, Spaull SR, Shields BM, Hammersley S, Shepherd MH, Andrews RC, Patel KA, Hattersley AT. Patterns of postmeal insulin secretion in individuals with sulfonylurea-treated KCNJ11 neonatal diabetes show predominance of non-K ATP-channel pathways. BMJ Open Diabetes Res Care 2019; 7:e000721. [PMID: 31908791 PMCID: PMC6936449 DOI: 10.1136/bmjdrc-2019-000721] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 09/06/2019] [Accepted: 11/11/2019] [Indexed: 11/03/2022] Open
Abstract
OBJECTIVE Insulin secretion in sulfonylurea-treated KCNJ11 permanent neonatal diabetes mellitus (PNDM) is thought to be mediated predominantly through amplifying non-KATP-channel pathways such as incretins. Affected individuals report symptoms of postprandial hypoglycemia after eating protein/fat-rich foods. We aimed to assess the physiological response to carbohydrate and protein/fat in people with sulfonylurea-treated KCNJ11 PNDM. RESEARCH DESIGN AND METHODS 5 adults with sulfonylurea-treated KCNJ11 PNDM and five age, sex and body mass index-matched controls without diabetes had a high-carbohydrate and high-protein/fat meal on two separate mornings. Insulin(i) and glucose(g) were measured at baseline then regularly over 4 hours after the meal. Total area under the curve (tAUC) for insulin and glucose was calculated over 4 hours and compared between meals in controls and KCNJ11 cases. RESULTS In controls, glucose values after carbohydrate and protein/fat were similar (median glucose tAUC0-4h21.4 vs 19.7 mmol/L, p=0.08). In KCNJ11 cases glucose levels were higher after carbohydrate than after protein/fat (median glucose tAUC0-4h58.1 vs 31.3 mmol/L, p=0.04). These different glycemic responses reflected different patterns of insulin secretion: in controls, insulin secretion was greatly increased after carbohydrate versus protein/fat (median insulin tAUC0-4h727 vs 335 pmol/L, p=0.04), but in KCNJ11 cases insulin secretion was similar after carbohydrate and protein/fat (median insulin tAUC0-4h327 vs 378 pmol/L, p=0.50). CONCLUSIONS Individuals with sulfonylurea-treated KCNJ11 PNDM produce similar levels of insulin in response to both carbohydrate and protein/fat meals despite carbohydrate resulting in much higher glucose levels and protein/fat resulting in relatively low glucose levels. This suggests in an inability to modulate insulin secretion in response to glucose levels, consistent with a dependence on non-KATP pathways for insulin secretion. TRIAL REGISTRATION NUMBER NCT02921906.
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Affiliation(s)
- Pamela Bowman
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, Devon, UK
- Exeter NIHR Clinical Research Facility, Exeter, Devon, UK
- Royal Devon and Exeter NHS Foundation Trust, Exeter, Devon, UK
| | - Timothy J McDonald
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, Devon, UK
- Exeter NIHR Clinical Research Facility, Exeter, Devon, UK
- Royal Devon and Exeter NHS Foundation Trust, Exeter, Devon, UK
| | - Bridget A Knight
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, Devon, UK
- Exeter NIHR Clinical Research Facility, Exeter, Devon, UK
- Royal Devon and Exeter NHS Foundation Trust, Exeter, Devon, UK
| | - Sarah E Flanagan
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, Devon, UK
| | - Maria Leveridge
- Royal Devon and Exeter NHS Foundation Trust, Exeter, Devon, UK
| | - Steve R Spaull
- Exeter NIHR Clinical Research Facility, Exeter, Devon, UK
| | - Beverley M Shields
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, Devon, UK
| | - Suzanne Hammersley
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, Devon, UK
- Exeter NIHR Clinical Research Facility, Exeter, Devon, UK
- Royal Devon and Exeter NHS Foundation Trust, Exeter, Devon, UK
| | - Maggie H Shepherd
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, Devon, UK
- Exeter NIHR Clinical Research Facility, Exeter, Devon, UK
- Royal Devon and Exeter NHS Foundation Trust, Exeter, Devon, UK
| | - Robert C Andrews
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, Devon, UK
- Exeter NIHR Clinical Research Facility, Exeter, Devon, UK
| | - Kashyap A Patel
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, Devon, UK
- Exeter NIHR Clinical Research Facility, Exeter, Devon, UK
- Royal Devon and Exeter NHS Foundation Trust, Exeter, Devon, UK
| | - Andrew T Hattersley
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, Devon, UK
- Exeter NIHR Clinical Research Facility, Exeter, Devon, UK
- Royal Devon and Exeter NHS Foundation Trust, Exeter, Devon, UK
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9
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Farshbaf S, Anzenbacher P. Fluorimetric sensing of ATP in water by an imidazolium hydrazone based sensor. Chem Commun (Camb) 2019; 55:1770-1773. [PMID: 30666327 DOI: 10.1039/c8cc09857c] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Bisantrene, a simple anthracene derivative carrying two imidazolium hydrazone moieties, has been used as a highly selective sensor of ATP in water.
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Affiliation(s)
- Sepideh Farshbaf
- Department of Chemistry and Center for Photochemical Sciences
- Bowling Green State University, Bowling Green
- Ohio 43403
- USA
| | - Pavel Anzenbacher
- Department of Chemistry and Center for Photochemical Sciences
- Bowling Green State University, Bowling Green
- Ohio 43403
- USA
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10
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Weightman Potter PG, Vlachaki Walker JM, Robb JL, Chilton JK, Williamson R, Randall AD, Ellacott KLJ, Beall C. Basal fatty acid oxidation increases after recurrent low glucose in human primary astrocytes. Diabetologia 2019; 62:187-198. [PMID: 30293112 PMCID: PMC6290858 DOI: 10.1007/s00125-018-4744-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 08/22/2018] [Indexed: 12/20/2022]
Abstract
AIMS/HYPOTHESIS Hypoglycaemia is a major barrier to good glucose control in type 1 diabetes. Frequent hypoglycaemic episodes impair awareness of subsequent hypoglycaemic bouts. Neural changes underpinning awareness of hypoglycaemia are poorly defined and molecular mechanisms by which glial cells contribute to hypoglycaemia sensing and glucose counterregulation require further investigation. The aim of the current study was to examine whether, and by what mechanism, human primary astrocyte (HPA) function was altered by acute and recurrent low glucose (RLG). METHODS To test whether glia, specifically astrocytes, could detect changes in glucose, we utilised HPA and U373 astrocytoma cells and exposed them to RLG in vitro. This allowed measurement, with high specificity and sensitivity, of RLG-associated changes in cellular metabolism. We examined changes in protein phosphorylation/expression using western blotting. Metabolic function was assessed using a Seahorse extracellular flux analyser. Immunofluorescent imaging was used to examine cell morphology and enzymatic assays were used to measure lactate release, glycogen content, intracellular ATP and nucleotide ratios. RESULTS AMP-activated protein kinase (AMPK) was activated over a pathophysiologically relevant glucose concentration range. RLG produced an increased dependency on fatty acid oxidation for basal mitochondrial metabolism and exhibited hallmarks of mitochondrial stress, including increased proton leak and reduced coupling efficiency. Relative to glucose availability, lactate release increased during low glucose but this was not modified by RLG. Basal glucose uptake was not modified by RLG and glycogen levels were similar in control and RLG-treated cells. Mitochondrial adaptations to RLG were partially recovered by maintaining euglycaemic levels of glucose following RLG exposure. CONCLUSIONS/INTERPRETATION Taken together, these data indicate that HPA mitochondria are altered following RLG, with a metabolic switch towards increased fatty acid oxidation, suggesting glial adaptations to RLG involve altered mitochondrial metabolism that could contribute to defective glucose counterregulation to hypoglycaemia in diabetes.
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Affiliation(s)
- Paul G Weightman Potter
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, RILD Building, Barrack Road, Exeter, EX2 5DW, UK
| | - Julia M Vlachaki Walker
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, RILD Building, Barrack Road, Exeter, EX2 5DW, UK
| | - Josephine L Robb
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, RILD Building, Barrack Road, Exeter, EX2 5DW, UK
| | - John K Chilton
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, RILD Building, Barrack Road, Exeter, EX2 5DW, UK
| | - Ritchie Williamson
- School of Pharmacy and Medical Sciences, University of Bradford, Bradford, UK
| | - Andrew D Randall
- Hatherly Laboratories, Prince of Wales Road, University of Exeter, Exeter, UK
| | - Kate L J Ellacott
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, RILD Building, Barrack Road, Exeter, EX2 5DW, UK
| | - Craig Beall
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, RILD Building, Barrack Road, Exeter, EX2 5DW, UK.
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11
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Zhao L, Dong M, Ren M, Li C, Zheng H, Gao H. Metabolomic Analysis Identifies Lactate as an Important Pathogenic Factor in Diabetes-associated Cognitive Decline Rats. Mol Cell Proteomics 2018; 17:2335-2346. [PMID: 30171160 PMCID: PMC6283288 DOI: 10.1074/mcp.ra118.000690] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 08/19/2018] [Indexed: 12/23/2022] Open
Abstract
Diabetes mellitus causes brain structure changes and cognitive decline, and it has been estimated that diabetes doubles the risk for dementia. Until now, the pathogenic mechanism of diabetes-associated cognitive decline (DACD) has remained unclear. Using metabolomics, we show that lactate levels increased over time in the hippocampus of rats with streptozotocin-induced diabetes, as compared with age-matched control rats. Additionally, mRNA levels, protein levels, and enzymatic activity of lactate dehydrogenase-A (LDH-A) were significantly up-regulated, suggesting increased glycolysis activity. Importantly, by specifically blocking the glycolysis pathway through an LDH-A inhibitor, chronic diabetes-induced memory impairment was prevented. Analyzing the underlying mechanism, we show that the expression levels of cAMP-dependent protein kinase and of phosphorylated transcription factor cAMP response element-binding proteins were decreased in 12-week diabetic rats. We suggest that G protein-coupled receptor 81 mediates cognitive decline in the diabetic rat. In this study, we report that progressively increasing lactate levels is an important pathogenic factor in DACD, directly linking diabetes to cognitive dysfunction. LDH-A may be considered as a potential target for alleviating or treating DACD in the future.
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Affiliation(s)
- Liangcai Zhao
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou 325035, Zhejiang, China
| | - Minjian Dong
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou 325035, Zhejiang, China
| | - Mengqian Ren
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou 325035, Zhejiang, China
| | - Chen Li
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou 325035, Zhejiang, China
| | - Hong Zheng
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou 325035, Zhejiang, China
| | - Hongchang Gao
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou 325035, Zhejiang, China.
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12
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Chakera AJ, Hurst PS, Spyer G, Ogunnowo-Bada EO, Marsh WJ, Riches CH, Yueh CY, Markkula SP, Dalley JW, Cox RD, Macdonald IA, Amiel SA, MacLeod KM, Heisler LK, Hattersley AT, Evans ML. Molecular reductions in glucokinase activity increase counter-regulatory responses to hypoglycemia in mice and humans with diabetes. Mol Metab 2018; 17:17-27. [PMID: 30146176 PMCID: PMC6197723 DOI: 10.1016/j.molmet.2018.08.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 08/02/2018] [Indexed: 12/25/2022] Open
Abstract
OBJECTIVE Appropriate glucose levels are essential for survival; thus, the detection and correction of low blood glucose is of paramount importance. Hypoglycemia prompts an integrated response involving reduction in insulin release and secretion of key counter-regulatory hormones glucagon and epinephrine that together promote endogenous glucose production to restore normoglycemia. However, specifically how this response is orchestrated remains to be fully clarified. The low affinity hexokinase glucokinase is found in glucose-sensing cells involved in glucose homeostasis including pancreatic β-cells and in certain brain areas. Here, we aimed to examine the role of glucokinase in triggering counter-regulatory hormonal responses to hypoglycemia, hypothesizing that reduced glucokinase activity would lead to increased and/or earlier triggering of responses. METHODS Hyperinsulinemic glucose clamps were performed to examine counter-regulatory responses to controlled hypoglycemic challenges created in humans with monogenic diabetes resulting from heterozygous glucokinase mutations (GCK-MODY). To examine the relative importance of glucokinase in different sensing areas, we then examined responses to clamped hypoglycemia in mice with molecularly defined disruption of whole body and/or brain glucokinase. RESULTS GCK-MODY patients displayed increased and earlier glucagon responses during hypoglycemia compared with a group of glycemia-matched patients with type 2 diabetes. Consistent with this, glucagon responses to hypoglycemia were also increased in I366F mice with mutated glucokinase and in streptozotocin-treated β-cell ablated diabetic I366F mice. Glucagon responses were normal in conditional brain glucokinase-knockout mice, suggesting that glucagon release during hypoglycemia is controlled by glucokinase-mediated glucose sensing outside the brain but not in β-cells. For epinephrine, we found increased responses in GCK-MODY patients, in β-cell ablated diabetic I366F mice and in conditional (nestin lineage) brain glucokinase-knockout mice, supporting a role for brain glucokinase in triggering epinephrine release. CONCLUSIONS Our data suggest that glucokinase in brain and other non β-cell peripheral hypoglycemia sensors is important in glucose homeostasis, allowing the body to detect and respond to a falling blood glucose.
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Affiliation(s)
- Ali J Chakera
- Institute of Clinical and Biomedical Sciences, University of Exeter, United Kingdom
| | - Paul S Hurst
- Wellcome Trust/ MRC Institute of Metabolic Science and Department of Medicine, University of Cambridge, United Kingdom
| | - Gill Spyer
- Institute of Clinical and Biomedical Sciences, University of Exeter, United Kingdom
| | - Emmanuel O Ogunnowo-Bada
- Wellcome Trust/ MRC Institute of Metabolic Science and Department of Medicine, University of Cambridge, United Kingdom
| | - William J Marsh
- Wellcome Trust/ MRC Institute of Metabolic Science and Department of Medicine, University of Cambridge, United Kingdom
| | - Christine H Riches
- Wellcome Trust/ MRC Institute of Metabolic Science and Department of Medicine, University of Cambridge, United Kingdom
| | - Chen-Yu Yueh
- Wellcome Trust/ MRC Institute of Metabolic Science and Department of Medicine, University of Cambridge, United Kingdom
| | - S Pauliina Markkula
- Wellcome Trust/ MRC Institute of Metabolic Science and Department of Medicine, University of Cambridge, United Kingdom
| | - Jeffrey W Dalley
- Behavioural and Clinical Neuroscience Institute and Departments of Psychology and Psychiatry, University of Cambridge, United Kingdom
| | - Roger D Cox
- MRC Harwell Institute, Mammalian Genetics Unit, Harwell Oxford, United Kingdom
| | - Ian A Macdonald
- MRC-ARUK Centre for Musculoskeletal Ageing and NIHR Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust/ University of Nottingham, Nottingham, United Kingdom
| | - Stephanie A Amiel
- Division of Diabetes and Nutritional Sciences, King's College London, United Kingdom
| | - Kenneth M MacLeod
- Institute of Clinical and Biomedical Sciences, University of Exeter, United Kingdom
| | - Lora K Heisler
- Rowett Institute, University of Aberdeen, United Kingdom
| | - Andrew T Hattersley
- Institute of Clinical and Biomedical Sciences, University of Exeter, United Kingdom.
| | - Mark L Evans
- Wellcome Trust/ MRC Institute of Metabolic Science and Department of Medicine, University of Cambridge, United Kingdom.
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13
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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: 48] [Impact Index Per Article: 8.0] [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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14
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Reno CM, Bayles J, Skinner A, Fisher SJ. Glibenclamide Prevents Hypoglycemia-Induced Fatal Cardiac Arrhythmias in Rats. Endocrinology 2018; 159:2614-2620. [PMID: 29800118 PMCID: PMC6669817 DOI: 10.1210/en.2018-00419] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 05/10/2018] [Indexed: 02/02/2023]
Abstract
Sulfonylureas increase the incidence of severe hypoglycemia in people with type 2 diabetes and might increase the risk of sudden cardiac death. Sulfonylureas stimulate insulin secretion by closing pancreatic ATP-sensitive potassium ion (KATP) channels. To investigate the role of KATP channel modulators on cardiac arrhythmias and mortality in the setting of severe hypoglycemia, adult Sprague-Dawley rats underwent hyperinsulinemic (0.2 U/kg/min) severe hypoglycemic (10 to 15 mg/dL) clamps with continuous electrocardiography. The rats were randomized for treatment with intravenous vehicle (VEH), the sulfonylurea glibenclamide (GLIB; KATP channel blocker; 5 mg/kg/h), or diazoxide (DIAZ; KATP channel opener; 5 mg/kg/h). The results demonstrated that GLIB completely prevented first-degree heart block compared with VEH (0.18 ± 0.09/min) and DIAZ (0.2 ± 0.05/min). Second-degree heart block was significantly reduced with GLIB (0.12 ± 0.1/min) compared with VEH (0.6 ± 0.2/min) and DIAZ (6.9 ± 3/min). The incidence of third-degree heart block was completely prevented by GLIB compared with VEH (67%) and DIAZ (87.5%). Hypoglycemia-induced mortality was completely prevented by GLIB compared with VEH (60%) and DIAZ (82%). In conclusion, although GLIB increases the risk of hypoglycemia by increasing insulin secretion, these results have demonstrated a paradoxical protective role of GLIB against severe hypoglycemia-induced fatal cardiac arrhythmias.
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Affiliation(s)
- Candace M Reno
- Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - Justin Bayles
- Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - Allie Skinner
- Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - Simon J Fisher
- Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, Utah
- Correspondence: Simon J. Fisher, MD, PhD, Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah School of Medicine, 15 North 2030 East, EIHG Building 533, Room 2110, Salt Lake City, Utah 84112. E-mail:
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15
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Naderi F, Hernández-Pérez J, Chivite M, Soengas JL, Míguez JM, López-Patiño MA. Involvement of cortisol and sirtuin1 during the response to stress of hypothalamic circadian system and food intake-related peptides in rainbow trout, Oncorhynchus mykiss. Chronobiol Int 2018; 35:1122-1141. [PMID: 29737878 DOI: 10.1080/07420528.2018.1461110] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Stress is conditioning animal welfare by negatively affecting a wide range of physiological and behavioral functions. This may be applied to circadian physiology and food intake. Cortisol, the stress-related hormone, may mediate such effect of stress, but other indirect mediators might be considered, such as sirtuin1. Then, either the independent modulatory effect or the existence of any interaction between mediators may be responsible. The circadian system is the main modulator of several integrative mechanisms at both central and peripheral levels that are rhythmically presented, thus influencing different processes such as food intake. In this way, food intake is controlled by the circadian system, as demonstrated by the persistence of such rhythms of food intake in the absence of environmental external cues. Our study aimed to evaluate the daily profile of hypothalamic mRNA abundance of circadian clock genes (clock1a, bmal1, per1 and rev-erbβ-like), and food intake regulators (crf, pomc-a1, cart, and npy) in rainbow trout (Oncorhynchus mykiss), the impact of stress on such rhythms, and the involvement of cortisol and sirtuin1 as mediators. Four cohorts of trout were subjected to 1) normal stocking density (control group), 2) high stocking density for 72 hours (stress group), 3) normal stocking density and implanted with mifepristone, a glucocorticoid receptors antagonist, and 4) mifepristone administered and stressed for 72 hours. Fish from each group were sampled every 4-h along the 24-h LD cycle, and cortisol, glucose and lactate plasma levels were evaluated. Hypothalamic mRNA abundance of clock genes, food intake regulators, glucocorticoid receptors and sirtuin1 were qPCR assayed. Our results reveal the impact of stress on most of the genes assayed, but different mechanisms appear to be involved. The rhythm of clock genes displayed decreased amplitude and averaged levels in stressed trout, with no changes of the acrophase being observed. This effect was not prevented by mifepristone. On the contrary, the effect of stress on the daily profile of crf, pomc-a1, and npy was totally prevented by mifepristone administration. Accordingly, cortisol appears to mainly mediate the effect of stress on food intake regulators through binding to specific glucocorticoid receptors within trout hypothalamus, whereas sirtuin1 is apparently mediating such effects on the circadian system in the same brain region. Further research must be performed to clarify those mechanisms through which stress influences food intake and the circadian oscillator within the same brain region, hypothalamus, in rainbow trout, and the interaction among them all.
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Affiliation(s)
- Fatemeh Naderi
- a Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro Singular de Investigación Mariña-ECIMAT , Universidade de Vigo , Spain
| | - Juan Hernández-Pérez
- a Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro Singular de Investigación Mariña-ECIMAT , Universidade de Vigo , Spain
| | - Mauro Chivite
- a Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro Singular de Investigación Mariña-ECIMAT , Universidade de Vigo , Spain
| | - José L Soengas
- a Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro Singular de Investigación Mariña-ECIMAT , Universidade de Vigo , Spain
| | - Jesús M Míguez
- a Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro Singular de Investigación Mariña-ECIMAT , Universidade de Vigo , Spain
| | - Marcos A López-Patiño
- a Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía and Centro Singular de Investigación Mariña-ECIMAT , Universidade de Vigo , Spain
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16
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Grøndahl MF, Keating DJ, Vilsbøll T, Knop FK. Current Therapies That Modify Glucagon Secretion: What Is the Therapeutic Effect of Such Modifications? Curr Diab Rep 2017; 17:128. [PMID: 29080075 DOI: 10.1007/s11892-017-0967-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
PURPOSE OF REVIEW Hyperglucagonemia contributes significantly to hyperglycemia in type 2 diabetes and suppressed glucagon levels may increase the risk of hypoglycemia. Here, we give a brief overview of glucagon physiology and the role of glucagon in the pathophysiology of type 2 diabetes and provide insights into how antidiabetic drugs influence glucagon secretion as well as a perspective on the future of glucagon-targeting drugs. RECENT FINDINGS Several older as well as recent investigations have evaluated the effect of antidiabetic agents on glucagon secretion to understand how glucagon may be involved in the drugs' efficacy and safety profiles. Based on these findings, modulation of glucagon secretion seems to play a hitherto underestimated role in the efficacy and safety of several glucose-lowering drugs. Numerous drugs currently available to diabetologists are capable of altering glucagon secretion: metformin, sulfonylurea compounds, insulin, glucagon-like peptide-1 receptor agonists, dipeptidyl peptidase-4 inhibitors, sodium-glucose cotransporter 2 inhibitors and amylin mimetics. Their diverse effects on glucagon secretion are of importance for their individual efficacy and safety profiles. Understanding how these drugs interact with glucagon secretion may help to optimize treatment.
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Affiliation(s)
- Magnus F Grøndahl
- Center for Diabetes Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark
| | - Damien J Keating
- Discipline of Human Physiology and Centre for Neuroscience, Flinders University of South Australia, Adelaide, Australia
- Nutrition and Metabolism, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, Australia
| | - Tina Vilsbøll
- Center for Diabetes Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical sciences, University of Copenhagen, Copenhagen, Denmark
- Steno Diabetes Center Copenhagen, University of Copenhagen, Gentofte, Denmark
| | - Filip K Knop
- Center for Diabetes Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark.
- Department of Clinical Medicine, Faculty of Health and Medical sciences, University of Copenhagen, Copenhagen, Denmark.
- Novo Nordisk Foundation Center for Metabolic Research, Faculty of Health and Medical sciences, University of Copenhagen, Copenhagen, Denmark.
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17
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van den Top M, Zhao FY, Viriyapong R, Michael NJ, Munder AC, Pryor JT, Renaud LP, Spanswick D. The impact of ageing, fasting and high-fat diet on central and peripheral glucose tolerance and glucose-sensing neural networks in the arcuate nucleus. J Neuroendocrinol 2017; 29. [PMID: 28834571 DOI: 10.1111/jne.12528] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 08/01/2017] [Accepted: 08/17/2017] [Indexed: 12/14/2022]
Abstract
Obesity and ageing are risk factors for diabetes. In the present study, we investigated the effects of ageing, obesity and fasting on central and peripheral glucose tolerance and on glucose-sensing neuronal function in the arcuate nucleus of rats, with a view to providing insight into the central mechanisms regulating glucose homeostasis and how they change or are subject to dysfunction with ageing and obesity. We show that, following a glucose load, central glucose tolerance at the level of the cerebrospinal fluid (CSF) and plasma is significantly reduced in rats maintained on a high-fat diet (HFD). With ageing, up to 2 years, central glucose tolerance was impaired in an age-dependent manner, whereas peripheral glucose tolerance remained unaffected. Ageing-induced peripheral glucose intolerance was improved by a 24-hour fast, whereas central glucose tolerance was not corrected. Pre-wean, immature animals have elevated basal plasma glucose levels and a delayed increase in central glucose levels following peripheral glucose injection compared to mature animals. Electrophysiological recording techniques revealed an energy-status-dependent role for glucose-excited, inhibited and adapting neurones, along with glucose-induced changes in synaptic transmission. We conclude that ageing affects central glucose tolerance, whereas HFD profoundly affects central and peripheral glucose tolerance and, in addition, glucose-sensing neurones adapt function in an energy-status-dependent manner.
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Affiliation(s)
| | - F-Y Zhao
- NeuroSolutions Ltd, Coventry, UK
| | - R Viriyapong
- Warwick Medical School, University of Warwick, Coventry, UK
- MOAC DTC, University of Warwick, Coventry, UK
| | - N J Michael
- Metabolic Disease and Obesity Program, Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
- Department of Physiology, Monash University, Clayton, VIC, Australia
| | - A C Munder
- Metabolic Disease and Obesity Program, Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
- Department of Physiology, Monash University, Clayton, VIC, Australia
| | - J T Pryor
- Warwick Medical School, University of Warwick, Coventry, UK
- Metabolic Disease and Obesity Program, Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
- Department of Physiology, Monash University, Clayton, VIC, Australia
| | - L P Renaud
- Ottawa Hospital Research Institute, Ottawa Civic Hospital, Ottawa, ON, Canada
| | - D Spanswick
- NeuroSolutions Ltd, Coventry, UK
- Warwick Medical School, University of Warwick, Coventry, UK
- Metabolic Disease and Obesity Program, Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
- Department of Physiology, Monash University, Clayton, VIC, Australia
- Neuroscience Program, Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
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18
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Kawamori D. Exploring the molecular mechanisms underlying α- and β-cell dysfunction in diabetes. Diabetol Int 2017; 8:248-256. [PMID: 30603330 PMCID: PMC6224887 DOI: 10.1007/s13340-017-0327-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 06/20/2017] [Indexed: 01/09/2023]
Abstract
Pancreatic islet dysfunction, including impaired insulin secretion in β cells and dysregulated glucagon secretion in α cells, is the chief pathology of diabetes. In β cells, oxidative stress, evoked by chronic hyperglycemia, was found to induce dysfunction of a critical transcription factor, PDX1, caused by its nucleocytoplasmic translocation via interactions with the insulin and JNK signaling pathways and another transcription factor, FOXO1. The significance of α-cell insulin signaling in the physiological and pathological regulation of α-cell biology was demonstrated in α-cell-specific insulin receptor knockout mice, which exhibited dysregulated glucagon secretion. Moreover, a high-glucose load directly induced excessive glucagon secretion in a glucagon-secreting cell line and isolated islets, together with impairment of insulin signaling. These findings indicate that disordered insulin signaling is central to the pathophysiology of islet dysfunction in both α and β cells. On the other hand, certain beneficial effects of GLP-1 on dysfunctional α and β cells indicate that it has therapeutic potential for diabetes patients who exhibit insulin resistance in islets. These studies, involving basic medical research approaches, have-at least in part-clarified the molecular mechanisms underlying α- and β-cell dysfunction in diabetes, and offer important clues that should aid the development of future therapeutic approaches to the disease.
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Affiliation(s)
- Dan Kawamori
- Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871 Japan
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19
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Delgado MJ, Cerdá-Reverter JM, Soengas JL. Hypothalamic Integration of Metabolic, Endocrine, and Circadian Signals in Fish: Involvement in the Control of Food Intake. Front Neurosci 2017; 11:354. [PMID: 28694769 PMCID: PMC5483453 DOI: 10.3389/fnins.2017.00354] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Accepted: 06/07/2017] [Indexed: 12/12/2022] Open
Abstract
The regulation of food intake in fish is a complex process carried out through several different mechanisms in the central nervous system (CNS) with hypothalamus being the main regulatory center. As in mammals, a complex hypothalamic circuit including two populations of neurons: one co-expressing neuropeptide Y (NPY) and Agouti-related peptide (AgRP) and the second one population co-expressing pro-opiomelanocortin (POMC) and cocaine- and amphetamine-regulated transcript (CART) is involved in the integration of information relating to food intake control. The production and release of these peptides control food intake, and the production results from the integration of information of different nature such as levels of nutrients and hormones as well as circadian signals. The present review summarizes the knowledge and recent findings about the presence and functioning of these mechanisms in fish and their differences vs. the known mammalian model.
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Affiliation(s)
- María J. Delgado
- Departamento de Fisiología (Fisiología Animal II), Facultad de Biología, Universidad Complutense de MadridMadrid, Spain
| | - José M. Cerdá-Reverter
- Departamento de Fisiología de Peces y Biotecnología, Instituto de Acuicultura Torre de la Sal, Consejo Superior de Investigaciones CientíficasCastellón, Spain
| | - José L. Soengas
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía, Universidade de VigoVigo, Spain
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20
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Dadak S, Beall C, Vlachaki Walker JM, Soutar MPM, McCrimmon RJ, Ashford MLJ. Oleate induces K ATP channel-dependent hyperpolarization in mouse hypothalamic glucose-excited neurons without altering cellular energy charge. Neuroscience 2017; 346:29-42. [PMID: 28087336 PMCID: PMC5346158 DOI: 10.1016/j.neuroscience.2016.12.053] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 12/29/2016] [Indexed: 11/29/2022]
Abstract
Oleate and low glucose hyperpolarize and inhibit GT1-7 and mouse GE neurons by activation of KATP. Oleate inhibition of GT1-7 neuron activity is not mediated by AMPK or fatty acid oxidation. Activation of KATP by oleate requires ATP hydrolysis but does not reduce the levels ATP or the ATP:ADP ratio. GT1-7 hyperpolarization by oleate is not dependent on UCP2. Oleate and low glucose depolarize a subpopulation of hypothalamic GI neurons.
The unsaturated fatty acid, oleate exhibits anorexigenic properties reducing food intake and hepatic glucose output. However, its mechanism of action in the hypothalamus has not been fully determined. This study investigated the effects of oleate and glucose on GT1-7 mouse hypothalamic cells (a model of glucose-excited (GE) neurons) and mouse arcuate nucleus (ARC) neurons. Whole-cell and perforated patch-clamp recordings, immunoblotting and cell energy status measures were used to investigate oleate- and glucose-sensing properties of mouse hypothalamic neurons. Oleate or lowered glucose concentration caused hyperpolarization and inhibition of firing of GT1-7 cells by the activation of ATP-sensitive K+ channels (KATP). This effect of oleate was not dependent on fatty acid oxidation or raised AMP-activated protein kinase activity or prevented by the presence of the UCP2 inhibitor genipin. Oleate did not alter intracellular calcium, indicating that CD36/fatty acid translocase may not play a role. However, oleate activation of KATP may require ATP metabolism. The short-chain fatty acid octanoate was unable to replicate the actions of oleate on GT1-7 cells. Although oleate decreased GT1-7 cell mitochondrial membrane potential there was no change in total cellular ATP or ATP/ADP ratios. Perforated patch and whole-cell recordings from mouse hypothalamic slices demonstrated that oleate hyperpolarized a subpopulation of ARC GE neurons by KATP activation. Additionally, in a separate small population of ARC neurons, oleate application or lowered glucose concentration caused membrane depolarization. In conclusion, oleate induces KATP-dependent hyperpolarization and inhibition of firing of a subgroup of GE hypothalamic neurons without altering cellular energy charge.
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Affiliation(s)
- Selma Dadak
- Division of Molecular and Clinical Medicine, School of Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK
| | - Craig Beall
- Division of Molecular and Clinical Medicine, School of Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK; Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, RILD Building, Barrack Road, Exeter EX2 5DW, UK
| | - Julia M Vlachaki Walker
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, RILD Building, Barrack Road, Exeter EX2 5DW, UK
| | - Marc P M Soutar
- Division of Molecular and Clinical Medicine, School of Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK
| | - Rory J McCrimmon
- Division of Molecular and Clinical Medicine, School of Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK
| | - Michael L J Ashford
- Division of Molecular and Clinical Medicine, School of Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK.
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21
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Conde-Sieira M, Soengas JL. Nutrient Sensing Systems in Fish: Impact on Food Intake Regulation and Energy Homeostasis. Front Neurosci 2017; 10:603. [PMID: 28111540 PMCID: PMC5216673 DOI: 10.3389/fnins.2016.00603] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 12/19/2016] [Indexed: 12/27/2022] Open
Abstract
Evidence obtained in recent years in a few species, especially rainbow trout, supports the presence in fish of nutrient sensing mechanisms. Glucosensing capacity is present in central (hypothalamus and hindbrain) and peripheral [liver, Brockmann bodies (BB, main accumulation of pancreatic endocrine cells in several fish species), and intestine] locations whereas fatty acid sensors seem to be present in hypothalamus, liver and BB. Glucose and fatty acid sensing capacities relate to food intake regulation and metabolism in fish. Hypothalamus is as a signaling integratory center in a way that detection of increased levels of nutrients result in food intake inhibition through changes in the expression of anorexigenic and orexigenic neuropeptides. Moreover, central nutrient sensing modulates functions in the periphery since they elicit changes in hepatic metabolism as well as in hormone secretion to counter-regulate changes in nutrient levels detected in the CNS. At peripheral level, the direct nutrient detection in liver has a crucial role in homeostatic control of glucose and fatty acid whereas in BB and intestine nutrient sensing is probably involved in regulation of hormone secretion from endocrine cells.
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Affiliation(s)
- Marta Conde-Sieira
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía, Universidade de Vigo Vigo, Spain
| | - José L Soengas
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía, Universidade de Vigo Vigo, Spain
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22
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Pauliina Markkula S, Lyons D, Yueh CY, Riches C, Hurst P, Fielding B, Heisler LK, Evans ML. Intracerebroventricular Catalase Reduces Hepatic Insulin Sensitivity and Increases Responses to Hypoglycemia in Rats. Endocrinology 2016; 157:4669-4676. [PMID: 27740870 PMCID: PMC5133351 DOI: 10.1210/en.2015-2054] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Specialized metabolic sensors in the hypothalamus regulate blood glucose levels by influencing hepatic glucose output and hypoglycemic counterregulatory responses. Hypothalamic reactive oxygen species (ROS) may act as a metabolic signal-mediating responses to changes in glucose, other substrates and hormones. The role of ROS in the brain's control of glucose homeostasis remains unclear. We hypothesized that hydrogen peroxide (H2O2), a relatively stable form of ROS, acts as a sensor of neuronal glucose consumption and availability and that lowering brain H2O2 with the enzyme catalase would lead to systemic responses increasing blood glucose. During hyperinsulinemic euglycemic clamps in rats, intracerebroventricular catalase infusion resulted in increased hepatic glucose output, which was associated with reduced neuronal activity in the arcuate nucleus of the hypothalamus. Electrophysiological recordings revealed a subset of arcuate nucleus neurons expressing proopiomelanocortin that were inhibited by catalase and excited by H2O2. During hypoglycemic clamps, intracerebroventricular catalase increased glucagon and epinephrine responses to hypoglycemia, consistent with perceived lower glucose levels. Our data suggest that H2O2 represents an important metabolic cue, which, through tuning the electrical activity of key neuronal populations such as proopiomelanocortin neurons, may have a role in the brain's influence of glucose homeostasis and energy balance.
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Affiliation(s)
- S Pauliina Markkula
- Wellcome Trust/Medical Research Council Institute of Metabolic Science and Department of Medicine (S.P.M., C.-Y.Y., C.R., P.H., M.L.E.), University of Cambridge, Cambridge CB20QQ, United Kingdom; Rowett Institute of Nutrition and Health (D.L., L.K.H.), University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom; Department of Family Medicine (C.-Y.Y.), Chang Gung Memorial Hospital, Chiayi, Taiwan; Chang Gung University of Science and Technology (C.-Y.Y.), Taoyuan City 33303, Taiwan; Oxford Centre for Diabetes, Endocrinology and Metabolism (B.F.), University of Oxford, Oxford OX37JT, United Kingdom; and Department of Nutritional Sciences (B.F.), University of Surrey, Guildford GU27XH, United Kingdom
| | - David Lyons
- Wellcome Trust/Medical Research Council Institute of Metabolic Science and Department of Medicine (S.P.M., C.-Y.Y., C.R., P.H., M.L.E.), University of Cambridge, Cambridge CB20QQ, United Kingdom; Rowett Institute of Nutrition and Health (D.L., L.K.H.), University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom; Department of Family Medicine (C.-Y.Y.), Chang Gung Memorial Hospital, Chiayi, Taiwan; Chang Gung University of Science and Technology (C.-Y.Y.), Taoyuan City 33303, Taiwan; Oxford Centre for Diabetes, Endocrinology and Metabolism (B.F.), University of Oxford, Oxford OX37JT, United Kingdom; and Department of Nutritional Sciences (B.F.), University of Surrey, Guildford GU27XH, United Kingdom
| | - Chen-Yu Yueh
- Wellcome Trust/Medical Research Council Institute of Metabolic Science and Department of Medicine (S.P.M., C.-Y.Y., C.R., P.H., M.L.E.), University of Cambridge, Cambridge CB20QQ, United Kingdom; Rowett Institute of Nutrition and Health (D.L., L.K.H.), University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom; Department of Family Medicine (C.-Y.Y.), Chang Gung Memorial Hospital, Chiayi, Taiwan; Chang Gung University of Science and Technology (C.-Y.Y.), Taoyuan City 33303, Taiwan; Oxford Centre for Diabetes, Endocrinology and Metabolism (B.F.), University of Oxford, Oxford OX37JT, United Kingdom; and Department of Nutritional Sciences (B.F.), University of Surrey, Guildford GU27XH, United Kingdom
| | - Christine Riches
- Wellcome Trust/Medical Research Council Institute of Metabolic Science and Department of Medicine (S.P.M., C.-Y.Y., C.R., P.H., M.L.E.), University of Cambridge, Cambridge CB20QQ, United Kingdom; Rowett Institute of Nutrition and Health (D.L., L.K.H.), University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom; Department of Family Medicine (C.-Y.Y.), Chang Gung Memorial Hospital, Chiayi, Taiwan; Chang Gung University of Science and Technology (C.-Y.Y.), Taoyuan City 33303, Taiwan; Oxford Centre for Diabetes, Endocrinology and Metabolism (B.F.), University of Oxford, Oxford OX37JT, United Kingdom; and Department of Nutritional Sciences (B.F.), University of Surrey, Guildford GU27XH, United Kingdom
| | - Paul Hurst
- Wellcome Trust/Medical Research Council Institute of Metabolic Science and Department of Medicine (S.P.M., C.-Y.Y., C.R., P.H., M.L.E.), University of Cambridge, Cambridge CB20QQ, United Kingdom; Rowett Institute of Nutrition and Health (D.L., L.K.H.), University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom; Department of Family Medicine (C.-Y.Y.), Chang Gung Memorial Hospital, Chiayi, Taiwan; Chang Gung University of Science and Technology (C.-Y.Y.), Taoyuan City 33303, Taiwan; Oxford Centre for Diabetes, Endocrinology and Metabolism (B.F.), University of Oxford, Oxford OX37JT, United Kingdom; and Department of Nutritional Sciences (B.F.), University of Surrey, Guildford GU27XH, United Kingdom
| | - Barbara Fielding
- Wellcome Trust/Medical Research Council Institute of Metabolic Science and Department of Medicine (S.P.M., C.-Y.Y., C.R., P.H., M.L.E.), University of Cambridge, Cambridge CB20QQ, United Kingdom; Rowett Institute of Nutrition and Health (D.L., L.K.H.), University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom; Department of Family Medicine (C.-Y.Y.), Chang Gung Memorial Hospital, Chiayi, Taiwan; Chang Gung University of Science and Technology (C.-Y.Y.), Taoyuan City 33303, Taiwan; Oxford Centre for Diabetes, Endocrinology and Metabolism (B.F.), University of Oxford, Oxford OX37JT, United Kingdom; and Department of Nutritional Sciences (B.F.), University of Surrey, Guildford GU27XH, United Kingdom
| | - Lora K Heisler
- Wellcome Trust/Medical Research Council Institute of Metabolic Science and Department of Medicine (S.P.M., C.-Y.Y., C.R., P.H., M.L.E.), University of Cambridge, Cambridge CB20QQ, United Kingdom; Rowett Institute of Nutrition and Health (D.L., L.K.H.), University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom; Department of Family Medicine (C.-Y.Y.), Chang Gung Memorial Hospital, Chiayi, Taiwan; Chang Gung University of Science and Technology (C.-Y.Y.), Taoyuan City 33303, Taiwan; Oxford Centre for Diabetes, Endocrinology and Metabolism (B.F.), University of Oxford, Oxford OX37JT, United Kingdom; and Department of Nutritional Sciences (B.F.), University of Surrey, Guildford GU27XH, United Kingdom
| | - Mark L Evans
- Wellcome Trust/Medical Research Council Institute of Metabolic Science and Department of Medicine (S.P.M., C.-Y.Y., C.R., P.H., M.L.E.), University of Cambridge, Cambridge CB20QQ, United Kingdom; Rowett Institute of Nutrition and Health (D.L., L.K.H.), University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom; Department of Family Medicine (C.-Y.Y.), Chang Gung Memorial Hospital, Chiayi, Taiwan; Chang Gung University of Science and Technology (C.-Y.Y.), Taoyuan City 33303, Taiwan; Oxford Centre for Diabetes, Endocrinology and Metabolism (B.F.), University of Oxford, Oxford OX37JT, United Kingdom; and Department of Nutritional Sciences (B.F.), University of Surrey, Guildford GU27XH, United Kingdom
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23
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Picard A, Soyer J, Berney X, Tarussio D, Quenneville S, Jan M, Grouzmann E, Burdet F, Ibberson M, Thorens B. A Genetic Screen Identifies Hypothalamic Fgf15 as a Regulator of Glucagon Secretion. Cell Rep 2016; 17:1795-1806. [PMID: 27829151 PMCID: PMC5120348 DOI: 10.1016/j.celrep.2016.10.041] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 10/04/2016] [Accepted: 10/13/2016] [Indexed: 12/26/2022] Open
Abstract
The counterregulatory response to hypoglycemia, which restores normal blood glucose levels to ensure sufficient provision of glucose to the brain, is critical for survival. To discover underlying brain regulatory systems, we performed a genetic screen in recombinant inbred mice for quantitative trait loci (QTL) controlling glucagon secretion in response to neuroglucopenia. We identified a QTL on the distal part of chromosome 7 and combined this genetic information with transcriptomic analysis of hypothalami. This revealed Fgf15 as the strongest candidate to control the glucagon response. Fgf15 was expressed by neurons of the dorsomedial hypothalamus and the perifornical area. Intracerebroventricular injection of FGF19, the human ortholog of Fgf15, reduced activation by neuroglucopenia of dorsal vagal complex neurons, of the parasympathetic nerve, and lowered glucagon secretion. In contrast, silencing Fgf15 in the dorsomedial hypothalamus increased neuroglucopenia-induced glucagon secretion. These data identify hypothalamic Fgf15 as a regulator of glucagon secretion.
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Affiliation(s)
- Alexandre Picard
- Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland
| | - Josselin Soyer
- Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland
| | - Xavier Berney
- Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland
| | - David Tarussio
- Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland
| | - Simon Quenneville
- Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland
| | - Maxime Jan
- Vital-IT, Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - Eric Grouzmann
- Service de Biomédicine, Laboratoire des Catécholamines et Peptides, Centre Hospitalier Universitaire Vaudois CHUV, 1011 Lausanne, Switzerland
| | - Frédéric Burdet
- Vital-IT, Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - Mark Ibberson
- Vital-IT, Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - Bernard Thorens
- Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland.
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24
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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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25
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Herrera-Moro Chao D, León-Mercado L, Foppen E, Guzmán-Ruiz M, Basualdo MC, Escobar C, Buijs RM. The Suprachiasmatic Nucleus Modulates the Sensitivity of Arcuate Nucleus to Hypoglycemia in the Male Rat. Endocrinology 2016; 157:3439-51. [PMID: 27429160 DOI: 10.1210/en.2015-1751] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The suprachiasmatic nucleus (SCN) and arcuate nucleus (ARC) have reciprocal connections; catabolic metabolic information activates the ARC and inhibits SCN neuronal activity. Little is known about the influence of the SCN on the ARC. Here, we investigated whether the SCN modulated the sensitivity of the ARC to catabolic metabolic conditions. ARC neuronal activity, as determined by c-Fos immunoreactivity, was increased after a hypoglycemic stimulus by 2-deoxyglucose (2DG). The highest ARC neuronal activity after 2DG was found at the end of the light period (zeitgeber 11, ZT11) with a lower activity in the beginning of the light period (zeitgeber 2, ZT2), suggesting the involvement of the SCN. The higher activation of ARC neurons after 2DG at ZT11 was associated with higher 2DG induced blood glucose levels as compared with ZT2. Unilateral SCN-lesioned animals, gave a mainly ipsilateral activation of ARC neurons at the lesioned side, suggesting an inhibitory role of the SCN on ARC neurons. The 2DG-induced counterregulatory glucose response correlated with increased ARC neuronal activity and was significantly higher in unilateral SCN-lesioned animals. Finally, the ARC as site where 2DG may, at least partly, induce a counterregulatory response was confirmed by local microdialysis of 2DG. 2DG administration in the ARC produced a higher increase in circulating glucose compared with 2DG administration in surrounding areas such as the ventromedial nucleus of the hypothalamus (VMH). We conclude that the SCN uses neuronal pathways to the ARC to gate sensory metabolic information to the brain, regulating ARC glucose sensitivity and counterregulatory responses to hypoglycemic conditions.
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Affiliation(s)
- D Herrera-Moro Chao
- Departamento de Biología Celular y Fisiología (D.H.-M.C., L.L.-M., M.G.-R., M.C.B., R.M.B.), Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, (UNAM) PC 04510 Distrito Federal, México; Departamento de Anatomía (C.E.), Facultad de Medicina, PC 04510 UNAM, Distrito Federal, México; and Department of Endocrinology and Metabolism (E.F.), Academic Medical Center, PC 1105 AZ Amsterdam, The Netherlands
| | - L León-Mercado
- Departamento de Biología Celular y Fisiología (D.H.-M.C., L.L.-M., M.G.-R., M.C.B., R.M.B.), Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, (UNAM) PC 04510 Distrito Federal, México; Departamento de Anatomía (C.E.), Facultad de Medicina, PC 04510 UNAM, Distrito Federal, México; and Department of Endocrinology and Metabolism (E.F.), Academic Medical Center, PC 1105 AZ Amsterdam, The Netherlands
| | - E Foppen
- Departamento de Biología Celular y Fisiología (D.H.-M.C., L.L.-M., M.G.-R., M.C.B., R.M.B.), Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, (UNAM) PC 04510 Distrito Federal, México; Departamento de Anatomía (C.E.), Facultad de Medicina, PC 04510 UNAM, Distrito Federal, México; and Department of Endocrinology and Metabolism (E.F.), Academic Medical Center, PC 1105 AZ Amsterdam, The Netherlands
| | - M Guzmán-Ruiz
- Departamento de Biología Celular y Fisiología (D.H.-M.C., L.L.-M., M.G.-R., M.C.B., R.M.B.), Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, (UNAM) PC 04510 Distrito Federal, México; Departamento de Anatomía (C.E.), Facultad de Medicina, PC 04510 UNAM, Distrito Federal, México; and Department of Endocrinology and Metabolism (E.F.), Academic Medical Center, PC 1105 AZ Amsterdam, The Netherlands
| | - M C Basualdo
- Departamento de Biología Celular y Fisiología (D.H.-M.C., L.L.-M., M.G.-R., M.C.B., R.M.B.), Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, (UNAM) PC 04510 Distrito Federal, México; Departamento de Anatomía (C.E.), Facultad de Medicina, PC 04510 UNAM, Distrito Federal, México; and Department of Endocrinology and Metabolism (E.F.), Academic Medical Center, PC 1105 AZ Amsterdam, The Netherlands
| | - C Escobar
- Departamento de Biología Celular y Fisiología (D.H.-M.C., L.L.-M., M.G.-R., M.C.B., R.M.B.), Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, (UNAM) PC 04510 Distrito Federal, México; Departamento de Anatomía (C.E.), Facultad de Medicina, PC 04510 UNAM, Distrito Federal, México; and Department of Endocrinology and Metabolism (E.F.), Academic Medical Center, PC 1105 AZ Amsterdam, The Netherlands
| | - R M Buijs
- Departamento de Biología Celular y Fisiología (D.H.-M.C., L.L.-M., M.G.-R., M.C.B., R.M.B.), Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, (UNAM) PC 04510 Distrito Federal, México; Departamento de Anatomía (C.E.), Facultad de Medicina, PC 04510 UNAM, Distrito Federal, México; and Department of Endocrinology and Metabolism (E.F.), Academic Medical Center, PC 1105 AZ Amsterdam, The Netherlands
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26
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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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27
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Foster NN, Azam S, Watts AG. Rapid-onset hypoglycemia suppresses Fos expression in discrete parts of the ventromedial nucleus of the hypothalamus. Am J Physiol Regul Integr Comp Physiol 2016; 310:R1177-85. [PMID: 27030665 DOI: 10.1152/ajpregu.00042.2016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 03/23/2016] [Indexed: 01/12/2023]
Abstract
The consensus view of the ventromedial nucleus of the hypothalamus (VMH) is that it is a key node in the rodent brain network controlling sympathoadrenal counterregulatory responses to hypoglycemia. To identify the location of hypoglycemia-responsive neurons in the VMH, we performed a high spatial resolution Fos analysis in the VMH of rats made hypoglycemic with intraperitoneal injections of insulin. We examined Fos expression in the four constituent parts of VMH throughout its rostrocaudal extent and determined their relationship to blood glucose concentrations. Hypoglycemia significantly decreased Fos expression only in the dorsomedial and central parts of the VMH, but not its anterior or ventrolateral parts. Moreover, the number of Fos-expressing neurons was significantly and positively correlated in the two responsive regions with terminal blood glucose concentrations. We also measured Fos responses in the paraventricular nucleus of the hypothalamus (PVH) and in several levels of the periaqueductal gray (PAG), which receives strong projections from the VMH. We found the expected and highly significant increase in Fos in the neuroendocrine PVH, which was negatively correlated to terminal blood glucose concentrations, but no significant differences were seen in any part of the PAG. Our results show that there are distinct populations of VMH neurons whose Fos expression is suppressed by hypoglycemia, and their numbers correlate with blood glucose. These findings support a clear division of glycemic control functions within the different parts of the VMH.
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Affiliation(s)
- Nicholas N Foster
- Department of Biological Sciences, USC Dornsife College of Letters, Arts, and Sciences, University of Southern California, Los Angeles, California
| | - Sana Azam
- Department of Biological Sciences, USC Dornsife College of Letters, Arts, and Sciences, University of Southern California, Los Angeles, California
| | - Alan G Watts
- Department of Biological Sciences, USC Dornsife College of Letters, Arts, and Sciences, University of Southern California, Los Angeles, California
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28
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Bidirectional electromagnetic control of the hypothalamus regulates feeding and metabolism. Nature 2016; 531:647-50. [PMID: 27007848 DOI: 10.1038/nature17183] [Citation(s) in RCA: 154] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 01/28/2016] [Indexed: 12/16/2022]
Abstract
Targeted, temporally regulated neural modulation is invaluable in determining the physiological roles of specific neural populations or circuits. Here we describe a system for non-invasive, temporal activation or inhibition of neuronal activity in vivo and its use to study central nervous system control of glucose homeostasis and feeding in mice. We are able to induce neuronal activation remotely using radio waves or magnetic fields via Cre-dependent expression of a GFP-tagged ferritin fusion protein tethered to the cation-conducting transient receptor potential vanilloid 1 (TRPV1) by a camelid anti-GFP antibody (anti-GFP-TRPV1). Neuronal inhibition via the same stimuli is achieved by mutating the TRPV1 pore, rendering the channel chloride-permeable. These constructs were targeted to glucose-sensing neurons in the ventromedial hypothalamus in glucokinase-Cre mice, which express Cre in glucose-sensing neurons. Acute activation of glucose-sensing neurons in this region increases plasma glucose and glucagon, lowers insulin levels and stimulates feeding, while inhibition reduces blood glucose, raises insulin levels and suppresses feeding. These results suggest that pancreatic hormones function as an effector mechanism of central nervous system circuits controlling blood glucose and behaviour. The method we employ obviates the need for permanent implants and could potentially be applied to study other neural processes or used to regulate other, even dispersed, cell types.
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29
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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: 213] [Impact Index Per Article: 26.6] [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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30
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Korim WS, Llewellyn-Smith IJ, Verberne AJM. Activation of Medulla-Projecting Perifornical Neurons Modulates the Adrenal Sympathetic Response to Hypoglycemia: Involvement of Orexin Type 2 (OX2-R) Receptors. Endocrinology 2016; 157:810-9. [PMID: 26653571 DOI: 10.1210/en.2015-1712] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Iatrogenic hypoglycemia in response to insulin treatment is commonly experienced by patients with type 1 diabetes and can be life threatening. The body releases epinephrine in an attempt to counterregulate hypoglycemia, but the neural mechanisms underlying this phenomenon remain to be elucidated. Orexin neurons in the perifornical hypothalamus (PeH) project to the rostral ventrolateral medulla (RVLM) and are likely to be involved in epinephrine secretion during hypoglycemia. In anesthetized rats, we report that hypoglycemia increases the sympathetic preganglionic discharge to the adrenal gland by activating PeH orexin neurons that project to the RVLM (PeH-RVLM). Electrophysiological characterization shows that the majority of identified PeH-RVLM neurons, including a subpopulation of orexin neurons, are activated in response to hypoglycemia or glucoprivation. Furthermore, the excitatory input from the PeH is mediated by orexin type 2 receptors in the RVLM. These results suggest that activation of orexin PeH-RVLM neurons and orexin type 2 receptors in the RVLM facilitates epinephrine release by increasing sympathetic drive to adrenal chromaffin cells during hypoglycemia.
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Affiliation(s)
- Willian S Korim
- Clinical Pharmacology and Therapeutics Unit (W.S.K., A.J.M.V.), Department of Medicine Austin Health, University of Melbourne, Heidelberg, Victoria 3084, Australia; Florey Institute of Neuroscience and Mental Health (W.S.K.), University of Melbourne, Parkville, Victoria 3052, Australia; and Cardiovascular Medicine (I.J.L.-S.), Human Physiology and Centre for Neuroscience, School of Medicine, Flinders University, Bedford Park, South Australia 5042, Australia
| | - Ida J Llewellyn-Smith
- Clinical Pharmacology and Therapeutics Unit (W.S.K., A.J.M.V.), Department of Medicine Austin Health, University of Melbourne, Heidelberg, Victoria 3084, Australia; Florey Institute of Neuroscience and Mental Health (W.S.K.), University of Melbourne, Parkville, Victoria 3052, Australia; and Cardiovascular Medicine (I.J.L.-S.), Human Physiology and Centre for Neuroscience, School of Medicine, Flinders University, Bedford Park, South Australia 5042, Australia
| | - Anthony J M Verberne
- Clinical Pharmacology and Therapeutics Unit (W.S.K., A.J.M.V.), Department of Medicine Austin Health, University of Melbourne, Heidelberg, Victoria 3084, Australia; Florey Institute of Neuroscience and Mental Health (W.S.K.), University of Melbourne, Parkville, Victoria 3052, Australia; and Cardiovascular Medicine (I.J.L.-S.), Human Physiology and Centre for Neuroscience, School of Medicine, Flinders University, Bedford Park, South Australia 5042, Australia
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Reno CM, Ding Y, Sherwin R. Leptin acts in the brain to influence hypoglycemic counterregulation: disparate effects of acute and recurrent hypoglycemia on glucagon release. Am J Physiol Endocrinol Metab 2015; 309:E960-7. [PMID: 26506851 PMCID: PMC4816199 DOI: 10.1152/ajpendo.00361.2015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 10/21/2015] [Indexed: 12/24/2022]
Abstract
Leptin has been shown to diminish hyperglycemia via reduced glucagon secretion, although it can also enhance sympathoadrenal responses. However, whether leptin can also inhibit glucagon secretion during insulin-induced hypoglycemia or increase epinephrine during acute or recurrent hypoglycemia has not been examined. To test whether leptin acts in the brain to influence counterregulation, hyperinsulinemic hypoglycemic (∼45 mg/dl) clamps were performed on rats exposed to or not exposed to recurrent hypoglycemia (3 days, ∼40 mg/dl). Intracerebroventricular artificial cerebral spinal fluid or leptin was infused during the clamp. During acute hypoglycemia, leptin decreased glucagon responses by 51% but increased epinephrine and norepinephrine by 24 and 48%, respectively. After recurrent hypoglycemia, basal plasma leptin levels were undetectable. Subsequent brain leptin infusion during hypoglycemia paradoxically increased glucagon by 45% as well as epinephrine by 19%. In conclusion, leptin acts within the brain to diminish glucagon secretion during acute hypoglycemia but increases epinephrine, potentially limiting its detrimental effects during hypoglycemia. Exposure to recurrent hypoglycemia markedly suppresses plasma leptin, whereas exogenous brain leptin delivery enhances both glucagon and epinephrine release to subsequent hypoglycemia. These data suggest that recurrent hypoglycemia may diminish counterregulatory responses in part by reducing brain leptin action.
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Affiliation(s)
- Candace M Reno
- Yale University School of Medicine, Department of Internal Medicine-Section of Endocrinology, New Haven, Connecticut
| | - Yuyan Ding
- Yale University School of Medicine, Department of Internal Medicine-Section of Endocrinology, New Haven, Connecticut
| | - Robert Sherwin
- Yale University School of Medicine, Department of Internal Medicine-Section of Endocrinology, New Haven, Connecticut
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Goux E, Lespinasse Q, Guieu V, Perrier S, Ravelet C, Fiore E, Peyrin E. Fluorescence anisotropy-based structure-switching aptamer assay using a peptide nucleic acid (PNA) probe. Methods 2015; 97:69-74. [PMID: 26455538 DOI: 10.1016/j.ymeth.2015.09.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 09/04/2015] [Accepted: 09/18/2015] [Indexed: 01/04/2023] Open
Abstract
This study describes for the first time the feasibility of using peptide nucleic acids (PNAs) as an alternative to the DNA probes in structure-switching aptamer fluorescence polarisation assays. The effects of experimental parameters such as the length of the PNA strand, the nature of dye and the buffer conditions on the assay performances are first explored using two different methodologies based on the competition between the PNA/aptamer hydribridisation and the target/aptamer complexation. D-ATP can be detected from 1 to 25 μM in a linear range and a detection limit (LOD) of 3 μM can be reached. For this target, this lowers by a factor >5 the LOD reported with conventional DNA-based fluorescent structure switching aptamer-based assays and by a factor 3 the LOD observed with non-competitive fluorescent sensing platform indicating the usefulness of the PNA-based approach.
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Affiliation(s)
- Emma Goux
- Département de Pharmacochimie Moléculaire, Université Grenoble Alpes, UMR 5063 CNRS, ICMG FR 2607, Campus universitaire, Saint-Martin d'Hères, France
| | - Quentin Lespinasse
- Département de Pharmacochimie Moléculaire, Université Grenoble Alpes, UMR 5063 CNRS, ICMG FR 2607, Campus universitaire, Saint-Martin d'Hères, France
| | - Valérie Guieu
- Département de Pharmacochimie Moléculaire, Université Grenoble Alpes, UMR 5063 CNRS, ICMG FR 2607, Campus universitaire, Saint-Martin d'Hères, France.
| | - Sandrine Perrier
- Département de Pharmacochimie Moléculaire, Université Grenoble Alpes, UMR 5063 CNRS, ICMG FR 2607, Campus universitaire, Saint-Martin d'Hères, France
| | - Corinne Ravelet
- Département de Pharmacochimie Moléculaire, Université Grenoble Alpes, UMR 5063 CNRS, ICMG FR 2607, Campus universitaire, Saint-Martin d'Hères, France
| | - Emmanuelle Fiore
- Département de Pharmacochimie Moléculaire, Université Grenoble Alpes, UMR 5063 CNRS, ICMG FR 2607, Campus universitaire, Saint-Martin d'Hères, France
| | - Eric Peyrin
- Département de Pharmacochimie Moléculaire, Université Grenoble Alpes, UMR 5063 CNRS, ICMG FR 2607, Campus universitaire, Saint-Martin d'Hères, France.
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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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Sandoval DA, D'Alessio DA. Physiology of proglucagon peptides: role of glucagon and GLP-1 in health and disease. Physiol Rev 2015; 95:513-48. [PMID: 25834231 DOI: 10.1152/physrev.00013.2014] [Citation(s) in RCA: 286] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The preproglucagon gene (Gcg) is expressed by specific enteroendocrine cells (L-cells) of the intestinal mucosa, pancreatic islet α-cells, and a discrete set of neurons within the nucleus of the solitary tract. Gcg encodes multiple peptides including glucagon, glucagon-like peptide-1, glucagon-like peptide-2, oxyntomodulin, and glicentin. Of these, glucagon and GLP-1 have received the most attention because of important roles in glucose metabolism, involvement in diabetes and other disorders, and application to therapeutics. The generally accepted model is that GLP-1 improves glucose homeostasis indirectly via stimulation of nutrient-induced insulin release and by reducing glucagon secretion. Yet the body of literature surrounding GLP-1 physiology reveals an incompletely understood and complex system that includes peripheral and central GLP-1 actions to regulate energy and glucose homeostasis. On the other hand, glucagon is established principally as a counterregulatory hormone, increasing in response to physiological challenges that threaten adequate blood glucose levels and driving glucose production to restore euglycemia. However, there also exists a potential role for glucagon in regulating energy expenditure that has recently been suggested in pharmacological studies. It is also becoming apparent that there is cross-talk between the proglucagon derived-peptides, e.g., GLP-1 inhibits glucagon secretion, and some additive or synergistic pharmacological interaction between GLP-1 and glucagon, e.g., dual glucagon/GLP-1 agonists cause more weight loss than single agonists. In this review, we discuss the physiological functions of both glucagon and GLP-1 by comparing and contrasting how these peptides function, variably in concert and opposition, to regulate glucose and energy homeostasis.
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Affiliation(s)
- Darleen A Sandoval
- Division of Endocrinology and Metabolism, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - David A D'Alessio
- Division of Endocrinology and Metabolism, University of Cincinnati College of Medicine, Cincinnati, Ohio
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Joy NG, Tate DB, Davis SN. Counterregulatory responses to hypoglycemia differ between glimepiride and glyburide in non diabetic individuals. Metabolism 2015; 64:729-37. [PMID: 25765720 PMCID: PMC4408247 DOI: 10.1016/j.metabol.2015.02.006] [Citation(s) in RCA: 9] [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: 09/11/2014] [Revised: 01/09/2015] [Accepted: 02/19/2015] [Indexed: 11/19/2022]
Abstract
OBJECTIVE Reported rates of hypoglycemia in patients with type 2 diabetes mellitus are lower with glimepiride as compared to glyburide. The aim of this study was to determine whether physiologic differences in counterregulatory neuroendocrine and metabolic mechanisms during hypoglycemia provide a basis for the observed clinical differences between glimepiride and glyburide. RESEARCH DESIGN AND METHODS Non-diabetic volunteers (age 38±2years, BMI 26±1kg/m(2)) were studied in a single-blind fashion during separate 2day randomized protocols consisting of 2h hyperinsulinemic (9pmol/kg/min) euglycemic (4.9±0.1mmol) and hypoglycemic (2.9±0.1mmol/L) clamps. Individuals received biologically equivalent doses of glimepiride (4mg) or glyburide (10mg) 1h prior to each glucose clamp (n=11) as well as a control group of placebo studies. Glucose kinetics were calculated using D-Glucose-6-6d2. RESULTS Insulin and C-peptide levels were increased (p<0.05) during euglycemia in both sulfonylurea groups as compared to placebo. However, despite equivalent hypoglycemia, insulin and C-peptide levels were higher (p<0.05) only after glyburide. Glucagon responses and endogenous glucose production (EGP) were decreased (p<0.05) during hypoglycemia following glyburide administration as compared to glimepiride. Glyburide reduced (p<0.05) norepinephrine responses during euglycemic clamps. In addition combined epinephrine and norepinephrine responses during hypoglycemia were reduced (p<0.05) following glyburide as compared to placebo. Leptin levels fell by a greater amount (p<0.05) during hypoglycemia with both sulfonylureas as compared to placebo. CONCLUSIONS In summary, glimepiride and glyburide can both similarly increase insulin and C-peptide levels during hyperinsulinemic euglycemia. However, during moderate hyperinsulinemic hypoglycemia (2.9mmol/L) glyburide resulted in increased C-peptide and insulin, but blunted glucagon, sympathetic nervous system and EGP responses. We conclude that glyburide can acutely reduce key neuroendocrine and metabolic counterregulatory defenses during hypoglycemia in healthy individuals.
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Affiliation(s)
- Nino G Joy
- University of Maryland, Baltimore, Department of Medicine
| | - Donna B Tate
- University of Maryland, Baltimore, Department of Medicine
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George PS, Tavendale R, Palmer CNA, McCrimmon RJ. Diazoxide improves hormonal counterregulatory responses to acute hypoglycemia in long-standing type 1 diabetes. Diabetes 2015; 64:2234-41. [PMID: 25591873 DOI: 10.2337/db14-1539] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 01/07/2015] [Indexed: 11/13/2022]
Abstract
Individuals with long-standing type 1 diabetes (T1D) are at increased risk of severe hypoglycemia secondary to impairments in normal glucose counterregulatory responses (CRRs). Strategies to prevent hypoglycemia are often ineffective, highlighting the need for novel therapies. ATP-sensitive potassium (KATP) channels within the hypothalamus are thought to be integral to hypoglycemia detection and initiation of CRRs; however, to date this has not been confirmed in human subjects. In this study, we examined whether the KATP channel-activator diazoxide was able to amplify the CRR to hypoglycemia in T1D subjects with long-duration diabetes. A randomized, double-blind, placebo-controlled cross-over trial using a stepped hyperinsulinemic hypoglycemia clamp was performed in 12 T1D subjects with prior ingestion of diazoxide (7 mg/kg) or placebo. Diazoxide resulted in a 37% increase in plasma levels of epinephrine and a 44% increase in plasma norepinephrine during hypoglycemia compared with placebo. In addition, a subgroup analysis revealed that the response to oral diazoxide was blunted in participants with E23K polymorphism in the KATP channel. This study has therefore shown for the first time the potential utility of KATP channel activators to improve CRRs to hypoglycemia in individuals with T1D and, moreover, that it may be possible to stratify therapeutic approaches by genotype.
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Affiliation(s)
- Priya S George
- Division of Diabetes and Cardiovascular Medicine, Medical Research Institute, Ninewells Hospital and Medical School, Dundee, Scotland, U.K.
| | - Roger Tavendale
- The Pat McPherson Centre for Pharmacogenomics & Pharmacogenetics, Medical Research Institute, Ninewells Hospital and Medical School, Dundee, Scotland, U.K
| | - Colin N A Palmer
- The Pat McPherson Centre for Pharmacogenomics & Pharmacogenetics, Medical Research Institute, Ninewells Hospital and Medical School, Dundee, Scotland, U.K
| | - Rory J McCrimmon
- Division of Diabetes and Cardiovascular Medicine, Medical Research Institute, Ninewells Hospital and Medical School, Dundee, Scotland, U.K
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37
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Park JH, Byun JY, Shim WB, Kim SU, Kim MG. High-sensitivity detection of ATP using a localized surface plasmon resonance (LSPR) sensor and split aptamers. Biosens Bioelectron 2015; 73:26-31. [PMID: 26042875 DOI: 10.1016/j.bios.2015.05.043] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 05/08/2015] [Accepted: 05/19/2015] [Indexed: 01/24/2023]
Abstract
A highly sensitive localized surface plasmon resonance (LSPR) aptasensor for detection of adenosine triphosphate (ATP) has been developed. The sensor utilizes two split ATP aptamers, one (receptor fragment) being covalently attached to the surface of a gold nanorod (GNR) and the other labeled with a random DNA sequence and TAMRA dye (probe fragment). In the presence of both ATP and the probe fragment, a significant shift takes place in the wavelength of the LSPR band. This phenomenon is a consequence of the fact that the split fragments assemble into an intact folded structure in the presence of ATP, which brings about a decrease in the distance between the GNR surface and TAMRA dye and an associated LSPR wavelength. By using this sensor system, concentrations of ATP in the range of 10 pM-10 μM can be determined. In addition, by taking advantage of its denaturation properties, the LSPR aptasensor can be reused by simply subjecting it to quadruple salt-addition/2M NaCl washing steps. That the new method is applicable to biological systems was demonstrated by its use to measure ATP concentrations in E. coli and, thus to determine cell concentrations as low as 1.0×10(3) CFU.
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Affiliation(s)
- Jin-Ho Park
- Department of Chemistry, School of Physics and Chemistry, Gwangju Institute of Science and Technology (GIST), 261 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712,Republic of Korea
| | - Ju-Young Byun
- Department of Chemistry, School of Physics and Chemistry, Gwangju Institute of Science and Technology (GIST), 261 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712,Republic of Korea
| | - Won-Bo Shim
- Food Analysis Research Team, Industry Service Research Center, World Institute of Kimchi an Annex of Korea Food Research Institute, 86 Kimchi-ro, Nam-gu, Gwangju, Republic of Korea
| | - Seong U Kim
- Advanced Photonics Research Institute, Gwangju Institute of Science and Technology (GIST), 261 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712, Republic of Korea
| | - Min-Gon Kim
- Department of Chemistry, School of Physics and Chemistry, Gwangju Institute of Science and Technology (GIST), 261 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712,Republic of Korea; Advanced Photonics Research Institute, Gwangju Institute of Science and Technology (GIST), 261 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712, Republic of Korea.
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38
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Soengas JL. Contribution of glucose- and fatty acid sensing systems to the regulation of food intake in fish. A review. Gen Comp Endocrinol 2014; 205:36-48. [PMID: 24530522 DOI: 10.1016/j.ygcen.2014.01.015] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 01/13/2014] [Accepted: 01/28/2014] [Indexed: 01/01/2023]
Abstract
Food intake in fish is a complex process regulated through many different factors including abundance of energy and nutrients. In recent years, evidence have been obtained in several fishes, mainly in rainbow trout, regarding the presence and functioning in brain areas of metabolic sensors informing about changes in the levels of nutrients like glucose and fatty acids. The activity of these sensors relate to the control of food intake through changes in the expression of anorexigenic and orexigenic neuropeptides. The present review will provide a picture of the main results obtained to date in these studies, as well as perspectives for future research in the field.
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Affiliation(s)
- José L Soengas
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía, Universidade de Vigo, Spain.
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39
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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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40
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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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41
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Beall C, Haythorne E, Fan X, Du Q, Jovanovic S, Sherwin RS, Ashford MLJ, McCrimmon RJ. Continuous hypothalamic K(ATP) activation blunts glucose counter-regulation in vivo in rats and suppresses K(ATP) conductance in vitro. Diabetologia 2013; 56:2088-92. [PMID: 23793715 DOI: 10.1007/s00125-013-2970-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 05/23/2013] [Indexed: 11/28/2022]
Abstract
AIMS/HYPOTHESIS Acute systemic delivery of the sulfonylurea receptor (SUR)-1-specific ATP-sensitive K(+) channel (K(ATP)) opener, NN414, has been reported to amplify glucose counter-regulatory responses (CRRs) in rats exposed to hypoglycaemia. Thus, we determined whether continuous NN414 could prevent hypoglycaemia-induced defective counter-regulation. METHODS Chronically catheterised male Sprague-Dawley rats received a continuous infusion of NN414 into the third ventricle for 8 days after implantation of osmotic minipumps. Counter-regulation was examined by hyperinsulinaemic-hypoglycaemic clamp on day 8 after three episodes of insulin-induced hypoglycaemia (recurrent hypoglycaemia [RH]) on days 5, 6 and 7. In a subset of rats exposed to RH, NN414 infusion was terminated on day 7 to wash out NN414 before examination of counter-regulation on day 8. To determine whether continuous NN414 exposure altered K(ATP) function, we used the hypothalamic glucose-sensing GT1-7 cell line, which expresses the SUR-1-containing K(ATP) channel. RESULTS Continuous exposure to NN414 in the setting of RH increased, rather than decreased, the glucose infusion rate (GIR), as exemplified by attenuated adrenaline (epinephrine) secretion. Termination of NN414 on day 7 with subsequent washout for 24 h partially diminished the GIR. The same duration of exposure of GT1-7 cells to NN414 substantially reduced K(ATP) conductance, which was also reversed on washout of the agonist. The suppression of K(ATP) current was not associated with reduced channel subunit mRNA or protein levels. CONCLUSIONS/INTERPRETATION These data indicate that continuous K(ATP) activation results in suppressed CRRs to hypoglycaemia in vivo, which in vitro is associated with the reversible conversion of KATP into a stable inactive state.
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Affiliation(s)
- Craig Beall
- Cardiovascular and Diabetes Medicine, Medical Research Institute, Ninewells Hospital and Medical School, University of Dundee, Dundee, DD1 9SY Scotland, UK
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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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43
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Bozzo L, Puyal J, Chatton JY. Lactate modulates the activity of primary cortical neurons through a receptor-mediated pathway. PLoS One 2013; 8:e71721. [PMID: 23951229 PMCID: PMC3741165 DOI: 10.1371/journal.pone.0071721] [Citation(s) in RCA: 145] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 07/10/2013] [Indexed: 12/17/2022] Open
Abstract
Lactate is increasingly described as an energy substrate of the brain. Beside this still debated metabolic role, lactate may have other effects on brain cells. Here, we describe lactate as a neuromodulator, able to influence the activity of cortical neurons. Neuronal excitability of mouse primary neurons was monitored by calcium imaging. When applied in conjunction with glucose, lactate induced a decrease in the spontaneous calcium spiking frequency of neurons. The effect was reversible and concentration dependent (IC50 ∼4.2 mM). To test whether lactate effects are dependent on energy metabolism, we applied the closely related substrate pyruvate (5 mM) or switched to different glucose concentrations (0.5 or 10 mM). None of these conditions reproduced the effect of lactate. Recently, a Gi protein-coupled receptor for lactate called HCA1 has been introduced. To test if this receptor is implicated in the observed lactate sensitivity, we incubated cells with pertussis toxin (PTX) an inhibitor of Gi-protein. PTX prevented the decrease of neuronal activity by L-lactate. Moreover 3,5-dyhydroxybenzoic acid, a specific agonist of the HCA1 receptor, mimicked the action of lactate. This study indicates that lactate operates a negative feedback on neuronal activity by a receptor-mediated mechanism, independent from its intracellular metabolism.
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Affiliation(s)
- Luigi Bozzo
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Julien Puyal
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Jean-Yves Chatton
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
- Cellular Imaging Facility, University of Lausanne, Lausanne, Switzerland
- * E-mail:
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44
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Dacks PA, Moreno CL, Kim ES, Marcellino BK, Mobbs CV. Role of the hypothalamus in mediating protective effects of dietary restriction during aging. Front Neuroendocrinol 2013; 34:95-106. [PMID: 23262258 PMCID: PMC3626742 DOI: 10.1016/j.yfrne.2012.12.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Revised: 11/04/2012] [Accepted: 12/11/2012] [Indexed: 01/09/2023]
Abstract
Dietary restriction (DR) can extend lifespan and reduce disease burden across a wide range of animals and yeast but the mechanisms mediating these remarkably protective effects remain to be elucidated despite extensive efforts. Although it has generally been assumed that protective effects of DR are cell-autonomous, there is considerable evidence that many whole-body responses to nutritional state, including DR, are regulated by nutrient-sensing neurons. In this review, we explore the hypothesis that nutrient sensing neurons in the ventromedial hypothalamus hierarchically regulate the protective responses of dietary restriction. We describe multiple peripheral responses that are hierarchically regulated by the hypothalamus and we present evidence for non-cell autonomous signaling of dietary restriction gathered from a diverse range of models including invertebrates, mammalian cell culture, and rodent studies.
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Affiliation(s)
- Penny A. Dacks
- Department of Neurosciences and Friedman Brain Institute, Mount Sinai School of Medicine, New York, NY 10029
- Alzheimer's Drug Discovery Foundation, New York, NY 10019
| | - Cesar L. Moreno
- Department of Neurosciences and Friedman Brain Institute, Mount Sinai School of Medicine, New York, NY 10029
| | - Esther S. Kim
- Department of Neurosciences and Friedman Brain Institute, Mount Sinai School of Medicine, New York, NY 10029
| | - Bridget K. Marcellino
- Department of Neurosciences and Friedman Brain Institute, Mount Sinai School of Medicine, New York, NY 10029
| | - Charles V. Mobbs
- Department of Neurosciences and Friedman Brain Institute, Mount Sinai School of Medicine, New York, NY 10029
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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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46
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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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47
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Christesen HT, Brusgaard K, Hussain K. Recurrent spontaneous hypoglycaemia causes loss of neurogenic and neuroglycopaenic signs in infants with congenital hyperinsulinism. Clin Endocrinol (Oxf) 2012; 76:548-54. [PMID: 21981106 DOI: 10.1111/j.1365-2265.2011.04250.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Hypoglycaemia-associated autonomic failure (HAAF) with impaired neurogenic and neuroglycopaenic responses occurs in adults following recent, repeated hypoglycaemia. We aimed to evaluate whether HAAF also occurs in patients with infant-onset congenital hyperinsulinism (CHI). DESIGN, PATIENTS A controlled fast was performed in (i) seven CHI infants with initial symptomatic hypoglycaemia and three recent episodes of spontaneous recurrent hypoglycaemia each lasting <5 min and in (ii) seven infants with idiopathic ketotic hypoglycaemia for control. MEASUREMENTS At the time of hypoglycaemia (blood glucose <3 mmol/l or clinical signs), blood was drawn for serum insulin, cortisol, glucagon, adrenalin and nor-adrenalin. Signs of hypoglycaemia were documented. In CHI patients, the ABCC8 and KCNJ11 genes were analysed by denaturing high performance liquid chromatography (DHPLC) and/or direct bidirectional sequencing. RESULTS Two CHI patients had a paternal ABCC8 mutation, five had no mutations. When repeated hypoglycaemia was provoked, all CHI patients exhibited a complete loss of clinical signs of hypoglycaemia, along with a global blunting of the counter-regulatory hormones cortisol, glucagon, growth hormone, adrenalin and nor-adrenalin responses (median values 256 nmol/l, 23 pmol/l, 5·6 mU/l, 390 pmol/l and 2·9 nmol/l, respectively), irrespective of mutational status. In the controls, hypoglycaemia was always clinically overt with normal counter-regulatory cortisol, glucagon, adrenalin and nor-adrenalin responses (530 nmol/l, 60, 920 pmol/l and 4·0 nmol/l, respectively). CONCLUSION Recurrent hyperinsulinaemic hypoglycaemia even of short duration blunts the autonomic, neuroglycopaenic and glucose counter-regulatory hormonal responses in patients with infant-onset CHI resulting in clinically silent hypoglycaemia. Tight, or continuous, glucose monitoring is therefore recommended, especially in conservatively treated patients.
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48
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Hurst P, Garfield AS, Marrow C, Heisler LK, Evans ML. Recurrent hypoglycemia is associated with loss of activation in rat brain cingulate cortex. Endocrinology 2012; 153:1908-14. [PMID: 22396449 PMCID: PMC3328129 DOI: 10.1210/en.2011-1827] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Accepted: 01/26/2012] [Indexed: 12/30/2022]
Abstract
A subset of people with diabetes fail to mount defensive counterregulatory responses (CRR) to hypoglycemia. Although the mechanisms by which this occurs remain unclear, recurrent exposure to hypoglycemia may be an important etiological factor. We hypothesized that loss of CRR to recurrent exposure to hypoglycemia represents a type of stress desensitization, in which limbic brain circuitry involved in modulating stress responses might be implicated. Here, we compared activation of limbic brain regions associated with stress desensitization during acute hypoglycemia (AH) and recurrent hypoglycemia (RH). Healthy Sprague Dawley rats were exposed to either acute or recurrent 3-d hypoglycemia. We also examined whether changes in neuronal activation were caused directly by the CRR itself by infusing epinephrine, glucagon, and corticosterone without hypoglycemia. AH increased neuronal activity as quantified by c-fos immunoreactivity (FOS-IR) in the cingulate cortex and associated ectorhinal and perirhinal cortices but not in an adjacent control area (primary somatosensory cortex). FOS-IR was not observed after hormone infusion, suggesting that AH-associated activation was caused by hypoglycemia rather than by CRR. Importantly, AH FOS-IR activation was significantly blunted in rats exposed to RH. In conclusion, analogous with other models of stress habituation, activation in the cingulate cortex and associated brain areas is lost with exposure to RH. Our data support the hypothesis that limbic brain areas may be associated with the loss of CRR to RH in diabetes.
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Affiliation(s)
- Paul Hurst
- University of Cambridge Metabolic Research Laboratories/Department of Medicine/National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge CB2 0QQ, United Kingdom
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49
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Conde-Sieira M, Librán-Pérez M, López Patiño MA, Míguez JM, Soengas JL. CRF treatment induces a readjustment in glucosensing capacity in the hypothalamus and hindbrain of rainbow trout. ACTA ACUST UNITED AC 2012; 214:3887-94. [PMID: 22031754 DOI: 10.1242/jeb.061564] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Stress conditions induced in rainbow trout a readjustment in the glucosensing response of the hypothalamus and hindbrain such that those sensors did not respond properly to changes in glucose levels, as demonstrated in previous studies. To evaluate the hypothesis that corticotropin-releasing factor (CRF) could be involved in that response, we have incubated the hypothalamus and hindbrain of rainbow trout at different glucose concentrations in the presence of different concentrations of CRF. Under those conditions, we evaluated whether parameters related to glucosensing [the levels of glucose, glycogen and glucose 6-phosphate, the activities of glucokinase (GK), glycogen synthase (GSase) and pyruvate kinase (PK), and mRNA abundance of transcripts for GK, Glut2, Kir.6-like and sulfonylurea receptor (SUR)-like] are modified in the presence of CRF in a way comparable to that observed under stress conditions. We obtained evidence allowing us to suggest that CRF could be involved in the interaction between stress and glucosensing as CRF treatment of the hypothalamus and hindbrain in vitro induced a readjustment in glucosensing parameters similar to that previously observed under stress conditions in vivo. We had also previously demonstrated that stress elicits alterations in food intake in parallel with the readjustment of glucosensing systems. Here, we provide evidence that the mRNA abundance of several of the neuropeptides involved in the regulation of food intake, such as neuropeptide Y (NPY) or cocaine and amphetamine-regulated transcript (CART), is affected by CRF treatment, in such a way that their expression does not respond to changes in glucose levels in the same way as controls, allowing us to suggest that the food intake response that is integrated by changes in those peptides and known to be reduced by stress could be also mediated by CRF action in glucosensing areas.
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Affiliation(s)
- Marta Conde-Sieira
- Laboratorio de Fisioloxía Animal, Departamento de Bioloxía Funcional e Ciencias da Saúde, Facultade de Bioloxía, Universidade de Vigo, E-36310 Vigo, Spain
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50
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Osundiji MA, Lam DD, Shaw J, Yueh CY, Markkula SP, Hurst P, Colliva C, Roda A, Heisler LK, Evans ML. Brain glucose sensors play a significant role in the regulation of pancreatic glucose-stimulated insulin secretion. Diabetes 2012; 61:321-8. [PMID: 22210318 PMCID: PMC3266403 DOI: 10.2337/db11-1050] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 11/10/2011] [Indexed: 11/13/2022]
Abstract
As patients decline from health to type 2 diabetes, glucose-stimulated insulin secretion (GSIS) typically becomes impaired. Although GSIS is driven predominantly by direct sensing of a rise in blood glucose by pancreatic β-cells, there is growing evidence that hypothalamic neurons control other aspects of peripheral glucose metabolism. Here we investigated the role of the brain in the modulation of GSIS. To examine the effects of increasing or decreasing hypothalamic glucose sensing on glucose tolerance and insulin secretion, glucose or inhibitors of glucokinase, respectively, were infused into the third ventricle during intravenous glucose tolerance tests (IVGTTs). Glucose-infused rats displayed improved glucose handling, particularly within the first few minutes of the IVGTT, with a significantly lower area under the excursion curve within the first 10 min (AUC0-10). This was explained by increased insulin secretion. In contrast, infusion of the glucokinase inhibitors glucosamine or mannoheptulose worsened glucose tolerance and decreased GSIS in the first few minutes of IVGTT. Our data suggest a role for brain glucose sensors in the regulation of GSIS, particularly during the early phase. We propose that pharmacological agents targeting hypothalamic glucose-sensing pathways may represent novel therapeutic strategies for enhancing early phase insulin secretion in type 2 diabetes.
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Affiliation(s)
- Mayowa A. Osundiji
- Department of Medicine, University of Cambridge Metabolic Research Laboratories, and National Institute for Health Research, Cambridge Biomedical Research Centre, Cambridge, U.K
| | - Daniel D. Lam
- Department of Pharmacology, University of Cambridge, Cambridge, U.K
| | - Jill Shaw
- Department of Medicine, University of Cambridge Metabolic Research Laboratories, and National Institute for Health Research, Cambridge Biomedical Research Centre, Cambridge, U.K
- Department of Pharmacology, University of Cambridge, Cambridge, U.K
| | - Chen-Yu Yueh
- Department of Medicine, University of Cambridge Metabolic Research Laboratories, and National Institute for Health Research, Cambridge Biomedical Research Centre, Cambridge, U.K
- Department of Family Medicine, Chang Gung Memorial Hospital at Chiayi, Chang Gung Institute of Technology, Chiayi, Taiwan
| | - S. Pauliina Markkula
- Department of Medicine, University of Cambridge Metabolic Research Laboratories, and National Institute for Health Research, Cambridge Biomedical Research Centre, Cambridge, U.K
| | - Paul Hurst
- Department of Medicine, University of Cambridge Metabolic Research Laboratories, and National Institute for Health Research, Cambridge Biomedical Research Centre, Cambridge, U.K
| | - Carolina Colliva
- Department of Pharmaceutical Sciences, University of Bologna, Bologna, Italy
| | - Aldo Roda
- Department of Pharmaceutical Sciences, University of Bologna, Bologna, Italy
| | - Lora K. Heisler
- Department of Pharmacology, University of Cambridge, Cambridge, U.K
| | - Mark L. Evans
- Department of Medicine, University of Cambridge Metabolic Research Laboratories, and National Institute for Health Research, Cambridge Biomedical Research Centre, Cambridge, U.K
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