1
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Ramakrishnan RK, Srivastava A, Rajan R, Abusnana S, Mussa BM. Investigating the role of an immediate early gene FOS as a potential regulator of autophagic response to hypoglycemia in embryonic hypothalamic neurons. Clin Transl Sci 2024; 17:e13749. [PMID: 38488430 PMCID: PMC10941580 DOI: 10.1111/cts.13749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 01/31/2024] [Accepted: 02/07/2024] [Indexed: 03/18/2024] Open
Abstract
Hypoglycemia-associated autonomic failure (HAAF) is a well-established complication of diabetes. Although HAAF has serious outcomes such as recurrent morbidity, coma, and death, the mechanisms of HAAF and its pathological components are largely unknown. Our previous studies have revealed that hypoglycemia is associated with the upregulation of an immediate early gene - FOS. In addition, it is documented that glucose deprivation activates neuronal autophagic activities. Therefore, the present study aimed to identify the role of FOS and one of the core components of the autophagy pathway, Beclin-1 (encoded by the BECN1 gene), in the regulation of autophagic mechanisms in embryonic hypothalamic neurons in response to hypoglycemic conditions. Embryonic Mouse Hypothalamic Cell Line N39 (mHypoE-N39 or N39) was cultured in reduced concentrations of glucose (2000, 900, 500, and 200 mg/L). Gene and protein expression, as well as immunofluorescence studies on autophagy were conducted under different reduced glucose concentrations in N39 hypothalamic neurons with and without FOS and BECN1 gene knockdowns (KD). The outcomes of the present study have demonstrated a significant increase in autophagosome formation and subsequent lysosomal degradation in the hypothalamic neurons in response to reduced glucose concentrations. This hypoglycemic response appears to be lowered to a similar extent in the FOS KD and BECN1 KD cells, albeit insignificantly from the negative control, is indicative of the involvement of FOS in the autophagic response of hypothalamic neurons to hypoglycemia. Moreover, the KD cells exhibited a change in morphology and reduced cell viability compared with the control cells. Our findings suggest that reduced FOS expression could potentially be associated with impaired autophagic activities that are dependent on BECN1, which could lead to decreased or blunted hypothalamic activation in response to hypoglycemia, and this, in turn, may contribute to the development of HAAF.
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Affiliation(s)
- Rakhee K. Ramakrishnan
- Research Institute for Medical and Health Sciences, College of Medicine, University of SharjahSharjahUnited Arab Emirates
| | - Ankita Srivastava
- Research Institute for Medical and Health Sciences, College of Medicine, University of SharjahSharjahUnited Arab Emirates
| | - Reeja Rajan
- Research Institute for Medical and Health Sciences, College of Medicine, University of SharjahSharjahUnited Arab Emirates
| | - Salah Abusnana
- Diabetes and Endocrinology DepartmentUniversity Hospital SharjahSharjahUnited Arab Emirates
- Clinical Science DepartmentCollege of Medicine, University of SharjahSharjahUnited Arab Emirates
| | - Bashair M. Mussa
- Basic Medical Science DepartmentCollege of Medicine, University of SharjahSharjahUnited Arab Emirates
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2
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Mu Z, Sun M, Wen L, Li P, Gao J, Liu M, Bian H, Wang Z. Effect of hypoglycemia on cognitive performance in older patients with diabetes: A meta-analysis. ANNALES D'ENDOCRINOLOGIE 2024; 85:56-62. [PMID: 37884125 DOI: 10.1016/j.ando.2023.10.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 10/10/2023] [Accepted: 10/16/2023] [Indexed: 10/28/2023]
Abstract
GOALS The goal of this study was to use meta-analysis to compile information from various studies to investigate the existence and severity of cognitive impairment in elderly diabetes patients who have hypoglycemic episodes. MATERIALS AND TECHNIQUES For research studies on the relationship between hypoglycemia and cognitive decline or dementia in persons older than 45 years, we searched the PubMed, EMBASE, Cochrane Library, CNKI, WanFang, CBM and VIP databases for the period 1989 to 2022. We conducted random effects inverse variance on the meta-analysis and used the I2 statistic to assess heterogeneity. RESULT We selected 44 of the 518 studies we retrieved, 7 being appropriate for meta-analysis. Six thousand and forty-five individuals were involved in total. Both types of older diabetic patients with hypoglycemia performed considerably worse on tests of general intelligence than control participants (standardized mean difference, 0.58; 95% CI, 0.88-0.28). Also, elderly type-2 diabetes patients with hypoglycemic episodes had significantly worse memory performance (standardized mean difference, 0.19; 95% CI, 0.29-0.09). Additionally, we found that older type-2 diabetes patients with hypoglycemia had significantly poorer psychomotor function than those without hypoglycemia (standardized mean difference, 0.51; 95% CI, 0.38-0.63).
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Affiliation(s)
- Zhenzhen Mu
- Medical College of Yan'an University, Yan'an City, 716000, Shanxi Province, China
| | - Mimi Sun
- Shaanxi Provincial People's Hospital, Xi'an City, Shanxi Province, China
| | - Lian Wen
- Medical College of Yan'an University, Yan'an City, 716000, Shanxi Province, China
| | - Peipei Li
- Medical College of Yan'an University, Yan'an City, 716000, Shanxi Province, China
| | - Jiangmei Gao
- Yan'an University Affiliated Hospital, Xi'an City, Shanxi Province, China
| | - Minli Liu
- Medical College of Yan'an University, Yan'an City, 716000, Shanxi Province, China
| | - Hongyan Bian
- Medical College of Yan'an University, Yan'an City, 716000, Shanxi Province, China.
| | - Zhiguo Wang
- Yan'an University Affiliated Hospital, Xi'an City, Shanxi Province, China
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3
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Simon JJ, Lang PM, Rommerskirchen L, Bendszus M, Friederich HC. Hypothalamic Reactivity and Connectivity following Intravenous Glucose Administration. Int J Mol Sci 2023; 24:ijms24087370. [PMID: 37108533 PMCID: PMC10139105 DOI: 10.3390/ijms24087370] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 04/12/2023] [Accepted: 04/14/2023] [Indexed: 04/29/2023] Open
Abstract
Dysfunctional glucose sensing in homeostatic brain regions such as the hypothalamus is interlinked with the pathogenesis of obesity and type 2 diabetes mellitus. However, the physiology and pathophysiology of glucose sensing and neuronal homeostatic regulation remain insufficiently understood. To provide a better understanding of glucose signaling to the brain, we assessed the responsivity of the hypothalamus (i.e., the core region of homeostatic control) and its interaction with mesocorticolimbic brain regions in 31 normal-weight, healthy participants. We employed a single-blind, randomized, crossover design of the intravenous infusion of glucose and saline during fMRI. This approach allows to investigate glucose signaling independent of digestive processes. Hypothalamic reactivity and connectivity were assessed using a pseudo-pharmacological design and a glycemia-dependent functional connectivity analysis, respectively. In line with previous studies, we observed a hypothalamic response to glucose infusion which was negatively related to fasting insulin levels. The observed effect size was smaller than in previous studies employing oral or intragastric administration of glucose, demonstrating the important role of the digestive process in homeostatic signaling. Finally, we were able to observe hypothalamic connectivity with reward-related brain regions. Given the small amount of glucose employed, this points toward a high responsiveness of these regions to even a small energy stimulus in healthy individuals. Our study highlights the intricate relationship between homeostatic and reward-related systems and their pronounced sensitivity to subtle changes in glycemia.
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Affiliation(s)
- Joe J Simon
- Department of General Internal Medicine and Psychosomatics, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Pia M Lang
- Department of General Internal Medicine and Psychosomatics, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Lena Rommerskirchen
- Department of General Internal Medicine and Psychosomatics, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Martin Bendszus
- Department of Neuroradiology, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Hans-Christoph Friederich
- Department of General Internal Medicine and Psychosomatics, University Hospital Heidelberg, 69120 Heidelberg, Germany
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4
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Sanchez-Rangel E, Deajon-Jackson J, Hwang JJ. Pathophysiology and management of hypoglycemia in diabetes. Ann N Y Acad Sci 2022; 1518:25-46. [PMID: 36202764 DOI: 10.1111/nyas.14904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In the century since the discovery of insulin, diabetes has changed from an early death sentence to a manageable chronic disease. This change in longevity and duration of diabetes coupled with significant advances in therapeutic options for patients has fundamentally changed the landscape of diabetes management, particularly in patients with type 1 diabetes mellitus. However, hypoglycemia remains a major barrier to achieving optimal glycemic control. Current understanding of the mechanisms of hypoglycemia has expanded to include not only counter-regulatory hormonal responses but also direct changes in brain glucose, fuel sensing, and utilization, as well as changes in neural networks that modulate behavior, mood, and cognition. Different strategies to prevent and treat hypoglycemia have been developed, including educational strategies, new insulin formulations, delivery devices, novel technologies, and pharmacologic targets. This review article will discuss current literature contributing to our understanding of the myriad of factors that lead to the development of clinically meaningful hypoglycemia and review established and novel therapies for the prevention and treatment of hypoglycemia.
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Affiliation(s)
- Elizabeth Sanchez-Rangel
- Department of Internal Medicine, Section of Endocrinology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Jelani Deajon-Jackson
- Department of Internal Medicine, Section of Endocrinology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Janice Jin Hwang
- Department of Internal Medicine, Section of Endocrinology, Yale University School of Medicine, New Haven, Connecticut, USA.,Division of Endocrinology, Department of Internal Medicine, University of North Carolina - Chapel Hill, Chapel Hill, North Carolina, USA
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5
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Lee K, Horien C, O’Connor D, Garand-Sheridan B, Tokoglu F, Scheinost D, Lake EM, Constable RT. Arousal impacts distributed hubs modulating the integration of brain functional connectivity. Neuroimage 2022; 258:119364. [PMID: 35690257 PMCID: PMC9341222 DOI: 10.1016/j.neuroimage.2022.119364] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 06/02/2022] [Accepted: 06/07/2022] [Indexed: 12/12/2022] Open
Abstract
Even when subjects are at rest, it is thought that brain activity is organized into distinct brain states during which reproducible patterns are observable. Yet, it is unclear how to define or distinguish different brain states. A potential source of brain state variation is arousal, which may play a role in modulating functional interactions between brain regions. Here, we use simultaneous resting state functional magnetic resonance imaging (fMRI) and pupillometry to study the impact of arousal levels indexed by pupil area on the integration of large-scale brain networks. We employ a novel sparse dictionary learning-based method to identify hub regions participating in between-network integration stratified by arousal, by measuring k-hubness, the number (k) of functionally overlapping networks in each brain region. We show evidence of a brain-wide decrease in between-network integration and inter-subject variability at low relative to high arousal, with differences emerging across regions of the frontoparietal, default mode, motor, limbic, and cerebellum networks. State-dependent changes in k-hubness relate to the actual patterns of network integration within these hubs, suggesting a brain state transition from high to low arousal characterized by global synchronization and reduced network overlaps. We demonstrate that arousal is not limited to specific brain areas known to be directly associated with arousal regulation, but instead has a brain-wide impact that involves high-level between-network communications. Lastly, we show a systematic change in pairwise fMRI signal correlation structures in the arousal state-stratified data, and demonstrate that the choice of global signal regression could result in different conclusions in conventional graph theoretical analysis and in the analysis of k-hubness when studying arousal modulations. Together, our results suggest the presence of global and local effects of pupil-linked arousal modulations on resting state brain functional connectivity.
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Affiliation(s)
- Kangjoo Lee
- Department of Radiology and Bioimaging Sciences, Yale University School of Medicine, New Haven, CT 06520, United States.
| | - Corey Horien
- Interdepartmental Neuroscience Program, Yale University
School of Medicine, New Haven, CT 06520, United States
| | - David O’Connor
- Department of Biomedical Engineering, Yale University, New
Haven, CT 06520, United States
| | | | - Fuyuze Tokoglu
- Department of Radiology and Bioimaging Sciences, Yale
University School of Medicine, New Haven, CT 06520, United States
| | - Dustin Scheinost
- Department of Radiology and Bioimaging Sciences, Yale
University School of Medicine, New Haven, CT 06520, United States,Department of Biomedical Engineering, Yale University, New
Haven, CT 06520, United States,The Child Study Center, Yale University School of Medicine,
New Haven, CT 06520, United States,Department of Statistics and Data Science, Yale University,
New Haven, CT 06511, United States
| | - Evelyn M.R. Lake
- Department of Radiology and Bioimaging Sciences, Yale
University School of Medicine, New Haven, CT 06520, United States
| | - R. Todd Constable
- Department of Radiology and Bioimaging Sciences, Yale
University School of Medicine, New Haven, CT 06520, United States,Department of Biomedical Engineering, Yale University, New
Haven, CT 06520, United States,Department of Neurosurgery, Yale University School of
Medicine, New Haven, CT 06520, United States
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6
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Jacob P, Nwokolo M, Cordon SM, Macdonald IA, Zelaya FO, Amiel SA, O'Daly O, Choudhary P. Altered functional connectivity during hypoglycaemia in type 1 diabetes. J Cereb Blood Flow Metab 2022; 42:1451-1462. [PMID: 35209745 PMCID: PMC9274862 DOI: 10.1177/0271678x221082911] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Behavioural responses to hypoglycaemia require coordinated recruitment of broadly distributed networks of interacting brain regions. We investigated hypoglycaemia-related changes in brain connectivity in people without diabetes (ND) and with type 1 diabetes with normal (NAH) or impaired (IAH) hypoglycaemia awareness. Two-step hyperinsulinaemic hypoglycaemic clamps were performed in 14 ND, 15 NAH and 22 IAH participants. BOLD timeseries were acquired at euglycaemia (5.0 mmol/L) and hypoglycaemia (2.6 mmol/L), with symptom and counter-regulatory hormone measurements. We investigated hypoglycaemia-related connectivity changes using established seed regions for the default mode (DMN), salience (SN) and central executive (CEN) networks and regions whose activity is modulated by hypoglycaemia: the thalamus and right inferior frontal gyrus (RIFG). Hypoglycaemia-induced changes in the DMN, SN and CEN were evident in NAH (all p < 0.05), with no changes in ND or IAH. However, in IAH there was a reduction in connectivity between regions within the RIFG (p = 0.001), not evident in the ND or NAH groups. We conclude that hypoglycaemia induces coordinated recruitment of the DMN and SN in diabetes with preserved hypoglycaemia awareness which is absent in IAH and ND. Changes in connectivity in the RIFG, a region associated with attentional modulation, may be key in impaired hypoglycaemia awareness.
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Affiliation(s)
- Peter Jacob
- Diabetes Research Group (Denmark Hill), Faculty of Life Sciences and Medicine, King's College London, London, UK
| | - Munachiso Nwokolo
- Diabetes Research Group (Denmark Hill), Faculty of Life Sciences and Medicine, 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
- Centre for Neuroimaging Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Stephanie A Amiel
- Diabetes Research Group (Denmark Hill), Faculty of Life Sciences and Medicine, King's College London, London, UK
| | - Owen O'Daly
- Centre for Neuroimaging Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Pratik Choudhary
- Diabetes Research Group (Denmark Hill), Faculty of Life Sciences and Medicine, King's College London, London, UK
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7
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Althubeati S, Avery A, Tench CR, Lobo DN, Salter A, Eldeghaidy S. Mapping brain activity of gut-brain signaling to appetite and satiety in healthy adults: A systematic review and functional neuroimaging meta-analysis. Neurosci Biobehav Rev 2022; 136:104603. [PMID: 35276299 PMCID: PMC9096878 DOI: 10.1016/j.neubiorev.2022.104603] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 02/20/2022] [Accepted: 03/06/2022] [Indexed: 12/19/2022]
Abstract
Understanding how neurohormonal gut-brain signaling regulates appetite and satiety is vital for the development of therapies for obesity and altered eating behavior. However, reported brain areas associated with appetite or satiety regulators show inconsistency across functional neuroimaging studies. The aim of this study was to systematically assess the convergence of brain regions modulated by appetite and satiety regulators. Twenty-five studies were considered for qualitative synthesis, and 14 independent studies (20-experiments) found eligible for coordinate-based neuroimaging meta-analyses across 212 participants and 123 foci. We employed two different meta-analysis approaches. The results from the systematic review revealed the modulation of insula, amygdala, hippocampus, and orbitofrontal cortex (OFC) with appetite regulators, where satiety regulators were more associated with caudate nucleus, hypothalamus, thalamus, putamen, anterior cingulate cortex in addition to the insula and OFC. The two neuroimaging meta-analyses methods identified the caudate nucleus as a key area associated with satiety regulators. Our results provide quantitative brain activation maps of neurohormonal gut-brain signaling in heathy-weight adults that can be used to define alterations with eating behavior.
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Affiliation(s)
- Sarah Althubeati
- Division of Food, Nutrition & Dietetics, School of Biosciences, University of Nottingham, Loughborough LE12 5RD, UK; Faculty of Applied Medical Sciences, Department of Clinical Nutrition, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Amanda Avery
- Division of Food, Nutrition & Dietetics, School of Biosciences, University of Nottingham, Loughborough LE12 5RD, UK
| | - Christopher R Tench
- Division of Clinical Neurosciences, Clinical Neurology, University of Nottingham, Queen's Medical Centre, Nottingham, UK; NIHR Nottingham Biomedical Research Centre, Queen's Medical Centre, University of Nottingham, Nottingham, UK
| | - Dileep N Lobo
- Nottingham Digestive Diseases Centre, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK; MRC Versus Arthritis Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Andrew Salter
- Division of Food, Nutrition & Dietetics and Future Food Beacon, School of Biosciences, University of Nottingham, Loughborough LE12 5RD, UK
| | - Sally Eldeghaidy
- Division of Food, Nutrition & Dietetics and Future Food Beacon, School of Biosciences, University of Nottingham, Loughborough LE12 5RD, UK; Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK.
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8
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Hwang JJ. Food for Thought. J Nutr 2021; 151:2089-2091. [PMID: 34195820 DOI: 10.1093/jn/nxab210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Janice J Hwang
- Section of Endocrinology, Yale School of Medicine, New Haven, CT, USA
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9
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Affiliation(s)
- Leticia E Sewaybricker
- Department of Medicine, UW Medicine Diabetes Institute, University of Washington, Seattle, WA
| | - Ellen A Schur
- Department of Medicine, UW Medicine Diabetes Institute, University of Washington, Seattle, WA
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10
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Abstract
Energy balance is centrally regulated by the brain through several interacting neuronal systems involving external, peripheral, and central factors within the brain. The hypothalamus integrates these factors and is the key brain area in the regulation of energy balance. In this review, we will explain the structure of the hypothalamus and its role in the regulation of energy balance. An important part of energy balance regulation is the sensing of nutrient status and availability. This review will focus on the sensing of the two main sources of energy by the hypothalamus: glucose and fat. As many common health problems and chronic diseases can be traced back to a disrupted hypothalamic function, we will also discuss hypothalamic sensing of glucose and fats in these pathologies. Finally, we will summarize the current knowledge and discuss how this may be applied clinically and for future research perspectives.
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11
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Differential Expression of Inflammatory Markers in Hypoglycemia Unawareness Associated with Type 1 Diabetes: A Case Report. Brain Sci 2020; 11:brainsci11010017. [PMID: 33375551 PMCID: PMC7823509 DOI: 10.3390/brainsci11010017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 12/17/2020] [Accepted: 12/18/2020] [Indexed: 02/06/2023] Open
Abstract
The recurrence of hypoglycemic episodes leads to attenuation of the normal counter-regulatory mechanisms that are controlled by the hypothalamus, which results in hypoglycemia unawareness (HU). In this case report, we described for the first time the differential expression of TNF-α, IL-1β, IL-6, and IFN-γ in a blood sample that was taken from a 27-year-old patient with type 1 diabetes mellitus (T1DM) who was diagnosed with HU. The anti-diabetic regimen is currently based on insulin injection, but the patient is planning to start the use of an insulin pump to have better control of glucose levels. Our results showed a trend toward an increase in the expression of IL-1β, IL-6, and IFN-γ in T1DM patient with HU. However, the mRNA level of TNF-α showed a significant decrease. These observations suggest that systemic inflammation could be an underlying cause of HU.
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12
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McManus R, Ioussoufovitch S, Froats E, St Lawrence K, Van Uum S, Diop M. Dynamic response of cerebral blood flow to insulin-induced hypoglycemia. Sci Rep 2020; 10:21300. [PMID: 33277531 PMCID: PMC7718270 DOI: 10.1038/s41598-020-77626-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 11/11/2020] [Indexed: 11/25/2022] Open
Abstract
The dynamics of cerebral blood flow (CBF) at the onset of hypoglycemia may play a key role in hypoglycemia unawareness; however, there is currently a paucity of techniques that can monitor adult CBF with high temporal resolution. Herein, we investigated the use of diffuse correlation spectroscopy (DCS) to monitor the dynamics of CBF during insulin-induced hypoglycemia in adults. Plasma glucose concentrations, cortisol levels, and changes in CBF were measured before and during hypoglycemia in 8 healthy subjects. Cerebral blood flow increased by 42% following insulin injection with a delay of 17 ± 10 min, while the onset of hypoglycemia symptoms was delayed by 24 ± 11 min. The findings suggest that the onset of CBF increments precedes the appearance of hypoglycemia symptoms in nondiabetic subjects with normal awareness to hypoglycemia, and DCS could be a valuable tool for investigating the role of CBF in hypoglycemia unawareness.
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Affiliation(s)
- Ruth McManus
- St. Joseph's Health Care, London, ON, N6A 4V2, Canada
| | - Seva Ioussoufovitch
- Department of Biomedical Engineering, Western University, London, ON, N6A 5C1, Canada
| | | | - Keith St Lawrence
- St. Joseph's Health Care, London, ON, N6A 4V2, Canada
- Department of Medical Biophysics, Western University, London, ON, N6A 5C1, Canada
| | - Stan Van Uum
- St. Joseph's Health Care, London, ON, N6A 4V2, Canada
| | - Mamadou Diop
- St. Joseph's Health Care, London, ON, N6A 4V2, Canada.
- Department of Biomedical Engineering, Western University, London, ON, N6A 5C1, Canada.
- Department of Medical Biophysics, Western University, London, ON, N6A 5C1, Canada.
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13
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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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14
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Mussa BM, Taneera J, Mohammed AK, Srivastava A, Mukhopadhyay D, Sulaiman N. Potential role of hypothalamic microRNAs in regulation of FOS and FTO expression in response to hypoglycemia. J Physiol Sci 2019; 69:981-991. [PMID: 31728912 PMCID: PMC10717546 DOI: 10.1007/s12576-019-00718-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 10/06/2019] [Indexed: 01/05/2023]
Abstract
Hypoglycemia-associated autonomic failure (HAAF) is a serious complication of diabetes which is associated with the absence of physiological homeostatic counter-regulatory mechanisms that are controlled by the hypothalamus and sympathetic nervous system. Identification of biomarkers for early detection of HAAF requires an advanced understanding of molecular signature of hypoglycemia which is yet to be identified. The outcomes of the present study have shown that the viability and the apoptotic rate of the hypothalamic neurons (mHypoE-N39) were decreased significantly due to hypoglycemia in a dose-dependent fashion (p < 0.05). Although there are more than 1000 miRNAs differentially expressed in hypothalamus, only twelve miRNAs (miR-7a, miR-7b, miR-9, miR-29b, miR-29c, miR-30a, miR-30b, miR-30c, miR-101b-3p, miR-181a-5p, miR-378-3p and miR-873-5p) were correlated to two main hypothalamic regulatory proteins, FOS and FTO. Expression of these proteins was very sensitive to hypoglycemia. We demonstrated that hypoglycemia modulates the expression of hypothalamic miRNAs that are related to FOS and FTO.
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Affiliation(s)
- Bashair M Mussa
- Basic Medical Science Department, College of Medicine, University of Sharjah, P.O. Box: 27272, Sharjah, United Arab Emirates.
| | - Jalal Taneera
- Basic Medical Science Department, College of Medicine, Sharjah Institute for Medical Research, University of Sharjah, P.O. Box: 27272, Sharjah, United Arab Emirates
| | - Abdul Khader Mohammed
- Sharjah Institute for Medical Research, University of Sharjah, P.O. Box: 27272, Sharjah, United Arab Emirates
| | - Ankita Srivastava
- Sharjah Institute for Medical Research, University of Sharjah, P.O. Box: 27272, Sharjah, United Arab Emirates
| | - Debasmita Mukhopadhyay
- Sharjah Institute for Medical Research, University of Sharjah, P.O. Box: 27272, Sharjah, United Arab Emirates
| | - Nabil Sulaiman
- Family Medicine and Behavioral Science, College of Medicine, University of Sharjah, P.O. Box: 27272, Sharjah, United Arab Emirates
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15
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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. Impaired Awareness of Hypoglycemia Disrupts Blood Flow to Brain Regions Involved in Arousal and Decision Making in Type 1 Diabetes. Diabetes Care 2019; 42:2127-2135. [PMID: 31455689 DOI: 10.2337/dc19-0337] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 08/07/2019] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Impaired awareness of hypoglycemia (IAH) affects one-quarter of adults with type 1 diabetes and significantly increases the risk of severe hypoglycemia. Differences in regional brain responses to hypoglycemia may contribute to the susceptibility of this group to problematic hypoglycemia. This study investigated brain responses to hypoglycemia in hypoglycemia aware (HA) and IAH adults with type 1 diabetes, using three-dimensional pseudo-continuous arterial spin labeling (3D pCASL) functional MRI to measure changes in regional cerebral blood flow (CBF). RESEARCH DESIGN AND METHODS Fifteen HA and 19 IAH individuals underwent 3D pCASL functional MRI during a two-step hyperinsulinemic glucose clamp. Symptom, hormone, global, and regional CBF responses to hypoglycemia (47 mg/dL [2.6 mmol/L]) were measured. RESULTS In response to hypoglycemia, total symptom score did not change in those with IAH (P = 0.25) but rose in HA participants (P < 0.001). Epinephrine, cortisol, and growth hormone responses to hypoglycemia were lower in the IAH group (P < 0.05). Hypoglycemia induced a rise in global CBF (HA P = 0.01, IAH P = 0.04) but was not different between groups (P = 0.99). IAH participants showed reduced regional CBF responses within the thalamus (P = 0.002), right lateral orbitofrontal cortex (OFC) (P = 0.002), and right dorsolateral prefrontal cortex (P = 0.036) and a lesser decrease of CBF in the left hippocampus (P = 0.023) compared with the HA group. Thalamic and right lateral OFC differences survived Bonferroni correction. CONCLUSIONS Responses to hypoglycemia of brain regions involved in arousal, decision making, and reward are altered in IAH. Changes in these pathways may disrupt IAH individuals' ability to recognize hypoglycemia, impairing their capacity to manage hypoglycemia effectively and benefit fully from conventional therapeutic pathways to restore awareness.
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Affiliation(s)
- Munachiso Nwokolo
- Department of Diabetes, School of Life Course Sciences, King's College London, London, U.K. .,King's College Hospital NHS Foundation Trust, London, U.K
| | - Stephanie A Amiel
- Department of Diabetes, School of Life Course Sciences, King's College London, London, U.K.,King's College Hospital NHS Foundation Trust, London, U.K
| | - Owen O'Daly
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, U.K
| | - Megan L Byrne
- Department of Diabetes, School of Life Course Sciences, King's College London, London, U.K
| | - Bula M Wilson
- Department of Diabetes, School of Life Course Sciences, King's College London, London, U.K
| | - Andrew Pernet
- Department of Diabetes, School of Life Course Sciences, King's College London, London, U.K
| | - Sally M Cordon
- School of Life Sciences, MRC Arthritis Research UK Centre of Excellence in Musculoskeletal Ageing, University of Nottingham Medical School, Queen's Medical Centre, Nottingham, U.K
| | - Ian A Macdonald
- School of Life Sciences, MRC Arthritis Research UK Centre of Excellence in Musculoskeletal Ageing, University of Nottingham Medical School, Queen's Medical Centre, Nottingham, U.K
| | - Fernando O Zelaya
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, U.K
| | - Pratik Choudhary
- Department of Diabetes, School of Life Course Sciences, King's College London, London, U.K.,King's College Hospital NHS Foundation Trust, London, U.K
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16
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Lundqvist MH, Almby K, Abrahamsson N, Eriksson JW. Is the Brain a Key Player in Glucose Regulation and Development of Type 2 Diabetes? Front Physiol 2019; 10:457. [PMID: 31133864 PMCID: PMC6524713 DOI: 10.3389/fphys.2019.00457] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 04/01/2019] [Indexed: 01/08/2023] Open
Abstract
Ever since Claude Bernards discovery in the mid 19th-century that a lesion in the floor of the third ventricle in dogs led to altered systemic glucose levels, a role of the CNS in whole-body glucose regulation has been acknowledged. However, this finding was later overshadowed by the isolation of pancreatic hormones in the 20th century. Since then, the understanding of glucose homeostasis and pathology has primarily evolved around peripheral mechanism. Due to scientific advances over these last few decades, however, increasing attention has been given to the possibility of the brain as a key player in glucose regulation and the pathogenesis of metabolic disorders such as type 2 diabetes. Studies of animals have enabled detailed neuroanatomical mapping of CNS structures involved in glucose regulation and key neuronal circuits and intracellular pathways have been identified. Furthermore, the development of neuroimaging techniques has provided methods to measure changes of activity in specific CNS regions upon diverse metabolic challenges in humans. In this narrative review, we discuss the available evidence on the topic. We conclude that there is much evidence in favor of active CNS involvement in glucose homeostasis but the relative importance of central vs. peripheral mechanisms remains to be elucidated. An increased understanding of this field may lead to new CNS-focusing pharmacologic strategies in the treatment of type 2 diabetes.
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Affiliation(s)
| | - Kristina Almby
- Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | | | - Jan W Eriksson
- Department of Medical Sciences, Uppsala University, Uppsala, Sweden
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17
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The Evaluation and Management of the Blood Glucose for the Intracranial Disease. Neurocrit Care 2019. [DOI: 10.1007/978-981-13-7272-8_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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18
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Embury CM, Wiesman AI, McDermott TJ, Proskovec AL, Heinrichs-Graham E, Lord GH, Brau KL, Drincic AT, Desouza CV, Wilson TW. The impact of type 1 diabetes on neural activity serving attention. Hum Brain Mapp 2018; 40:1093-1100. [PMID: 30368968 DOI: 10.1002/hbm.24431] [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] [Received: 08/03/2018] [Revised: 09/24/2018] [Accepted: 10/08/2018] [Indexed: 01/19/2023] Open
Abstract
Type 1 diabetes has been associated with alterations in attentional processing and other cognitive functions, and previous studies have found alterations in both brain structure and function in affected patients. However, these previous neuroimaging studies have generally examined older patients, particularly those with major comorbidities known to affect functioning independent of diabetes. The primary aim of the current study was to examine the neural dynamics of selective attention processing in a young group of patients with type 1 diabetes who were otherwise healthy (i.e., without major comorbidities). Our hypothesis was that these patients would exhibit significant aberrations in attention circuitry relative to closely matched controls. The final sample included 69 participants age 19-35 years old, 35 with type 1 diabetes and 34 matched nondiabetic controls, who completed an Eriksen flanker task while undergoing magnetoencephalography. Significant group differences in flanker interference activity were found across a network of brain regions, including the anterior cingulate, inferior parietal cortices, paracentral lobule, and the left precentral gyrus. In addition, neural activity in the anterior cingulate and the paracentral lobule was correlated with disease duration in patients with type 1 diabetes. These findings suggest that alterations in the neural circuitry underlying selective attention emerge early in the disease process and are specifically related to type 1 diabetes and not common comorbidities. These findings highlight the need for longitudinal studies in large cohorts to clarify the clinical implications of type 1 diabetes on cognition and the brain.
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Affiliation(s)
- Christine M Embury
- Department of Neurological Sciences, University of Nebraska Medical Center (UNMC), Omaha, Nebraska.,Center for Magnetoencephalography, UNMC, Omaha, Nebraska.,Department of Psychology, University of Nebraska Omaha, Omaha, Nebraska
| | - Alex I Wiesman
- Department of Neurological Sciences, University of Nebraska Medical Center (UNMC), Omaha, Nebraska.,Center for Magnetoencephalography, UNMC, Omaha, Nebraska
| | - Timothy J McDermott
- Department of Neurological Sciences, University of Nebraska Medical Center (UNMC), Omaha, Nebraska.,Center for Magnetoencephalography, UNMC, Omaha, Nebraska
| | - Amy L Proskovec
- Department of Neurological Sciences, University of Nebraska Medical Center (UNMC), Omaha, Nebraska.,Center for Magnetoencephalography, UNMC, Omaha, Nebraska.,Department of Psychology, University of Nebraska Omaha, Omaha, Nebraska
| | - Elizabeth Heinrichs-Graham
- Department of Neurological Sciences, University of Nebraska Medical Center (UNMC), Omaha, Nebraska.,Center for Magnetoencephalography, UNMC, Omaha, Nebraska
| | - Grace H Lord
- Department of Internal Medicine, Division of Diabetes, Endocrinology, and Metabolism, UNMC, Omaha, Nebraska
| | - Kaitlin L Brau
- Department of Internal Medicine, Division of Diabetes, Endocrinology, and Metabolism, UNMC, Omaha, Nebraska
| | - Andjela T Drincic
- Department of Internal Medicine, Division of Diabetes, Endocrinology, and Metabolism, UNMC, Omaha, Nebraska
| | - Cyrus V Desouza
- Department of Internal Medicine, Division of Diabetes, Endocrinology, and Metabolism, UNMC, Omaha, Nebraska
| | - Tony W Wilson
- Department of Neurological Sciences, University of Nebraska Medical Center (UNMC), Omaha, Nebraska.,Center for Magnetoencephalography, UNMC, Omaha, Nebraska
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19
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Dunn JT, Choudhary P, Teh MM, Macdonald I, Hunt KF, Marsden PK, Amiel SA. The impact of hypoglycaemia awareness status on regional brain responses to acute hypoglycaemia in men with type 1 diabetes. Diabetologia 2018; 61:1676-1687. [PMID: 29754288 PMCID: PMC6445483 DOI: 10.1007/s00125-018-4622-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 03/05/2018] [Indexed: 12/14/2022]
Abstract
AIMS/HYPOTHESIS Impaired awareness of hypoglycaemia (IAH) in type 1 diabetes increases the risk of severe hypoglycaemia sixfold and can be resistant to intervention. We explored the impact of IAH on central responses to hypoglycaemia to investigate the mechanisms underlying barriers to therapeutic intervention. METHODS We conducted [15O]water positron emission tomography studies of regional brain perfusion during euglycaemia (target 5 mmol/l), hypoglycaemia (achieved level, 2.4 mmol/l) and recovery (target 5 mmol/l) in 17 men with type 1 diabetes: eight with IAH, and nine with intact hypoglycaemia awareness (HA). RESULTS Hypoglycaemia with HA was associated with increased activation in brain regions including the thalamus, insula, globus pallidus (GP), anterior cingulate cortex (ACC), orbital cortex, dorsolateral frontal (DLF) cortex, angular gyrus and amygdala; deactivation occurred in the temporal and parahippocampal regions. IAH was associated with reduced catecholamine and symptom responses to hypoglycaemia vs HA (incremental AUC: autonomic scores, 26.2 ± 35.5 vs 422.7 ± 237.1; neuroglycopenic scores, 34.8 ± 88.8 vs 478.9 ± 311.1; both p < 0.002). There were subtle differences (p < 0.005, k ≥ 50 voxels) in brain activation at hypoglycaemia, including early differences in the right central operculum, bilateral medial orbital (MO) cortex, and left posterior DLF cortex, with additional differences in the ACC, right GP and post- and pre-central gyri in established hypoglycaemia, and lack of deactivation in temporal regions in established hypoglycaemia. CONCLUSIONS/INTERPRETATION Differences in activation in the post- and pre-central gyri may be expected in people with reduced subjective responses to hypoglycaemia. Alterations in the activity of regions involved in the drive to eat (operculum), emotional salience (MO cortex), aversion (GP) and recall (temporal) suggest differences in the perceived importance and urgency of responses to hypoglycaemia in IAH compared with HA, which may be key to the persistence of the condition.
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Affiliation(s)
- Joel T Dunn
- Division of Imaging Sciences and Biomedical Engineering, King's College London, London, UK
| | - Pratik Choudhary
- Diabetes Research Group, King's College London, King's College Hospital Campus, Weston Education Centre, 10 Cutcombe Road, London, SE5 9RJ, UK
- Institute of Diabetes and Obesity, King's Health Partners, London, UK
| | - Ming Ming Teh
- Diabetes Research Group, King's College London, King's College Hospital Campus, Weston Education Centre, 10 Cutcombe Road, London, SE5 9RJ, UK
- Singapore General Hospital, Singapore, Republic of Singapore
| | - Ian Macdonald
- School of Life Sciences, University of Nottingham, Nottingham, UK
| | - Katharine F Hunt
- Diabetes Research Group, King's College London, King's College Hospital Campus, Weston Education Centre, 10 Cutcombe Road, London, SE5 9RJ, UK
- Institute of Diabetes and Obesity, King's Health Partners, London, UK
| | - Paul K Marsden
- Division of Imaging Sciences and Biomedical Engineering, King's College London, London, UK
| | - Stephanie A Amiel
- Diabetes Research Group, King's College London, King's College Hospital Campus, Weston Education Centre, 10 Cutcombe Road, London, SE5 9RJ, UK.
- Institute of Diabetes and Obesity, King's Health Partners, London, UK.
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20
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Belfort-DeAguiar R, Gallezot JD, Hwang JJ, Elshafie A, Yeckel CW, Chan O, Carson RE, Ding YS, Sherwin RS. Noradrenergic Activity in the Human Brain: A Mechanism Supporting the Defense Against Hypoglycemia. J Clin Endocrinol Metab 2018; 103:2244-2252. [PMID: 29590401 PMCID: PMC6456998 DOI: 10.1210/jc.2017-02717] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 03/20/2018] [Indexed: 01/12/2023]
Abstract
CONTEXT Hypoglycemia, one of the major factors limiting optimal glycemic control in insulin-treated patients with diabetes, elicits a brain response to restore normoglycemia by activating counterregulation. Animal data indicate that local release of norepinephrine (NE) in the hypothalamus is important for triggering hypoglycemia-induced counterregulatory (CR) hormonal responses. OBJECTIVE To examine the potential role of brain noradrenergic (NA) activation in humans during hypoglycemia. DESIGN A hyperinsulinemic-hypoglycemic clamp was performed in conjunction with positron emission tomographic imaging. PARTICIPANTS Nine lean healthy volunteers were studied during the hyperinsulinemic-hypoglycemic clamp. DESIGN Participants received intravenous injections of (S,S)-[11C]O-methylreboxetine ([11C]MRB), a highly selective NE transporter (NET) ligand, at baseline and during hypoglycemia. RESULTS Hypoglycemia increased plasma epinephrine, glucagon, cortisol, and growth hormone and decreased [11C]MRB binding potential (BPND) by 24% ± 12% in the raphe nucleus (P < 0.01). In contrast, changes in [11C]MRB BPND in the hypothalamus positively correlated with increments in epinephrine and glucagon levels and negatively correlated with glucose infusion rate (all P < 0.05). Furthermore, in rat hypothalamus studies, hypoglycemia induced NET translocation from the cytosol to the plasma membrane. CONCLUSIONS Insulin-induced hypoglycemia initiated a complex brain NA response in humans. Raphe nuclei, a region involved in regulating autonomic output, motor activity, and hunger, had increased NA activity, whereas the hypothalamus showed a NET-binding pattern that was associated with the individual's CR response magnitude. These findings suggest that NA output most likely is important for modulating brain responses to hypoglycemia in humans.
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Affiliation(s)
- Renata Belfort-DeAguiar
- Department of Internal Medicine, Section of Endocrinology, Yale University School of Medicine, New Haven, Connecticut
- Correspondence and Reprint Requests: Renata Belfort-DeAguiar, MD, PhD, 300 Cedar Street, TAC S135, New Haven, Connecticut 06520. E-mail:
| | | | - Janice J Hwang
- Department of Internal Medicine, Section of Endocrinology, Yale University School of Medicine, New Haven, Connecticut
| | - Ahmed Elshafie
- Department of Internal Medicine, Section of Endocrinology, Yale University School of Medicine, New Haven, Connecticut
| | - Catherine W Yeckel
- Yale School of Public Health, Yale School of Medicine, New Haven, Connecticut
| | - Owen Chan
- Department of Internal Medicine, Division of Endocrinology, Metabolism and Diabetes, University of Utah, Salt Lake City, Utah
| | - Richard E Carson
- PET Center, Department of Diagnostic Radiology, Yale University, New Haven, Connecticut
| | - Yu-Shin Ding
- Department of Radiology, New York University Medical Center, New York, New York
| | - Robert S Sherwin
- Department of Internal Medicine, Section of Endocrinology, Yale University School of Medicine, New Haven, Connecticut
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21
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Hwang JJ, Parikh L, Lacadie C, Seo D, Lam W, Hamza M, Schmidt C, Dai F, Sejling AS, Belfort-DeAguiar R, Constable RT, Sinha R, Sherwin R. Hypoglycemia unawareness in type 1 diabetes suppresses brain responses to hypoglycemia. J Clin Invest 2018; 128:1485-1495. [PMID: 29381484 DOI: 10.1172/jci97696] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 01/23/2018] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Among nondiabetic individuals, mild glucose decrements alter brain activity in regions linked to reward, motivation, and executive control. Whether these effects differ in type 1 diabetes mellitus (T1DM) patients with and without hypoglycemia awareness remains unclear. METHODS Forty-two individuals (13 healthy control [HC] subjects, 16 T1DM individuals with hypoglycemia awareness [T1DM-Aware], and 13 T1DM individuals with hypoglycemia unawareness [T1DM-Unaware]) underwent blood oxygen level-dependent functional MRI brain imaging during a 2-step hyperinsulinemic euglycemic (90 mg/dl)-hypoglycemic (60 mg/dl) clamp for assessment of neural responses to mild hypoglycemia. RESULTS Mild hypoglycemia in HC subjects altered activity in the caudate, insula, prefrontal cortex, and angular gyrus, whereas T1DM-Aware subjects showed no caudate and insula changes, but showed altered activation patterns in the prefrontal cortex and angular gyrus. Most strikingly, in direct contrast to HC and T1DM-Aware subjects, T1DM-Unaware subjects failed to show any hypoglycemia-induced changes in brain activity. These findings were also associated with blunted hormonal counterregulatory responses and hypoglycemia symptom scores during mild hypoglycemia. CONCLUSION In T1DM, and in particular T1DM-Unaware patients, there is a progressive blunting of brain responses in cortico-striatal and fronto-parietal neurocircuits in response to mild-moderate hypoglycemia. These findings have implications for understanding why individuals with impaired hypoglycemia awareness fail to respond appropriately to falling blood glucose levels. FUNDING This study was supported in part by NIH grants R01DK020495, P30 DK045735, K23DK109284, K08AA023545. The Yale Center for Clinical Investigation is supported by an NIH Clinical Translational Science Award (UL1 RR024139).
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Affiliation(s)
| | | | | | - Dongju Seo
- Department of Psychiatry, Yale School of Medicine, New Haven, Connecticut, USA
| | | | | | | | - Feng Dai
- Yale Center for Analytical Sciences, Yale School of Public Health, New Haven, Connecticut, USA
| | - Anne-Sophie Sejling
- Department of Cardiology, Nephrology and Endocrinology, Nordsjællands Hospital, Hillerød, Denmark
| | | | | | - Rajita Sinha
- Department of Psychiatry, Yale School of Medicine, New Haven, Connecticut, USA
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22
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Gejl M, Gjedde A, Brock B, Møller A, van Duinkerken E, Haahr HL, Hansen CT, Chu PL, Stender-Petersen KL, Rungby J. Effects of hypoglycaemia on working memory and regional cerebral blood flow in type 1 diabetes: a randomised, crossover trial. Diabetologia 2018; 61:551-561. [PMID: 29188338 PMCID: PMC6448973 DOI: 10.1007/s00125-017-4502-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 10/03/2017] [Indexed: 01/31/2023]
Abstract
AIMS/HYPOTHESIS The aim of this randomised, crossover trial was to compare cognitive functioning and associated brain activation patterns during hypoglycaemia (plasma glucose [PG] just below 3.1 mmol/l) and euglycaemia in individuals with type 1 diabetes mellitus. METHODS In this patient-blinded, crossover study, 26 participants with type 1 diabetes mellitus attended two randomised experimental visits: one hypoglycaemic clamp (PG 2.8 ± 0.2 mmol/l, approximate duration 55 min) and one euglycaemic clamp (PG 5.5 mmol/l ± 10%). PG levels were maintained by hyperinsulinaemic glucose clamping. Cognitive functioning was assessed during hypoglycaemia and euglycaemia conditions using a modified version of the digit symbol substitution test (mDSST) and control DSST (cDSST). Simultaneously, regional cerebral blood flow (rCBF) was measured in pre-specified brain regions by six H215O-positron emission tomographies (PET) per session. RESULTS Working memory was impaired during hypoglycaemia as indicated by a statistically significantly lower mDSST score (estimated treatment difference [ETD] -0.63 [95% CI -1.13, -0.14], p = 0.014) and a statistically significantly longer response time (ETD 2.86 s [7%] [95% CI 0.67, 5.05], p = 0.013) compared with euglycaemia. During hypoglycaemia, mDSST task performance was associated with increased activity in the frontal lobe regions, superior parietal lobe and thalamus, and decreased activity in the temporal lobe regions (p < 0.05). Working memory activation (mDSST - cDSST) statistically significantly increased blood flow in the striatum during hypoglycaemia (ETD 0.0374% [95% CI 0.0157, 0.0590], p = 0.002). CONCLUSIONS/INTERPRETATION During hypoglycaemia (mean PG 2.9 mmol/l), working memory performance was impaired. Altered performance was associated with significantly increased blood flow in the striatum, a part of the basal ganglia implicated in regulating motor functions, memory, language and emotion. TRIAL REGISTRATION NCT01789593, clinicaltrials.gov FUNDING: This study was funded by Novo Nordisk.
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Affiliation(s)
- Michael Gejl
- Department of Biomedicine, Aarhus University, Bartholins Allé 6, Building 1242, 8000, Aarhus C, Denmark.
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark.
| | - Albert Gjedde
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
- Department of Clinical Medicine, University of Southern Denmark, Odense, Denmark
| | - Birgitte Brock
- Department of Clinical Biochemistry, Aarhus University Hospital, Aarhus, Denmark
- Steno Diabetes Center Copenhagen, Gentofte, Denmark
| | - Arne Møller
- Department of Biomedicine, Aarhus University, Bartholins Allé 6, Building 1242, 8000, Aarhus C, Denmark
- PET-Center, Department of Nuclear Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - Eelco van Duinkerken
- VU University Medical Centre, Amsterdam, the Netherlands
- Pontifícia Universidade Católica, Rio de Janeiro, Brazil
| | | | | | | | | | - Jørgen Rungby
- Department of Biomedicine, Aarhus University, Bartholins Allé 6, Building 1242, 8000, Aarhus C, Denmark
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
- Department of Endocrinology IC, Bispebjerg University Hospital, Bispebjerg, Copenhagen, Denmark
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23
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The impact of gut hormones on the neural circuit of appetite and satiety: A systematic review. Neurosci Biobehav Rev 2017; 80:457-475. [PMID: 28669754 DOI: 10.1016/j.neubiorev.2017.06.013] [Citation(s) in RCA: 142] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Revised: 06/08/2017] [Accepted: 06/27/2017] [Indexed: 01/01/2023]
Abstract
The brain-gut-axis is an interdependent system affecting neural functions and controlling our eating behaviour. In recent decades, neuroimaging techniques have facilitated its investigation. We systematically looked into functional and neurochemical brain imaging studies investigating how key molecules such as ghrelin, glucagon-like peptide-1 (GLP-1), peptide tyrosine-tyrosine (PYY), cholecystokinin (CCK), leptin, glucose and insulin influence the function of brain regions regulating appetite and satiety. Of the 349 studies published before July 2016 identified in the database search, 40 were included (27 on healthy and 13 on obese subjects). Our systematic review suggests that the plasma level of ghrelin, the gut hormone promoting appetite, is positively correlated with activation in the pre-frontal cortex (PFC), amygdala and insula and negatively correlated with activation in subcortical areas such as the hypothalamus. In contrast, the plasma levels of glucose, insulin, leptin, PYY, GLP-1 affect the same brain regions conversely. Our study integrates previous investigations of the gut-brain matrix during food-intake and homeostatic regulation and may be of use for future meta-analyses of brain-gut interactions.
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24
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Wiegers EC, Becker KM, Rooijackers HM, von Samson-Himmelstjerna FC, Tack CJ, Heerschap A, de Galan BE, van der Graaf M. Cerebral blood flow response to hypoglycemia is altered in patients with type 1 diabetes and impaired awareness of hypoglycemia. J Cereb Blood Flow Metab 2017; 37:1994-2001. [PMID: 27389175 PMCID: PMC5464695 DOI: 10.1177/0271678x16658914] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
It is unclear whether cerebral blood flow responses to hypoglycemia are altered in people with type 1 diabetes and impaired awareness of hypoglycemia. The aim of this study was to investigate the effect of hypoglycemia on both global and regional cerebral blood flow in type 1 diabetes patients with impaired awareness of hypoglycemia, type 1 diabetes patients with normal awareness of hypoglycemia and healthy controls ( n = 7 per group). The subjects underwent a hyperinsulinemic euglycemic-hypoglycemic glucose clamp in a 3 T MR system. Global and regional changes in cerebral blood flow were determined by arterial spin labeling magnetic resonance imaging, at the end of both glycemic phases. Hypoglycemia generated typical symptoms in patients with type 1 diabetes and normal awareness of hypoglycemia and healthy controls, but not in patients with impaired awareness of hypoglycemia. Conversely, hypoglycemia increased global cerebral blood flow in patients with impaired awareness of hypoglycemia, which was not observed in the other two groups. Regionally, hypoglycemia caused a redistribution of cerebral blood flow towards the thalamus of both patients with normal awareness of hypoglycemia and healthy controls, consistent with activation of brain regions associated with the autonomic response to hypoglycemia. No such redistribution was found in the patients with impaired awareness of hypoglycemia. An increase in global cerebral blood flow may enhance nutrient supply to the brain, hence suppressing symptomatic awareness of hypoglycemia. Altogether these results suggest that changes in cerebral blood flow during hypoglycemia contribute to impaired awareness of hypoglycemia.
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Affiliation(s)
- Evita C Wiegers
- 1 Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Kirsten M Becker
- 1 Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Hanne M Rooijackers
- 2 Department of Internal Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Federico C von Samson-Himmelstjerna
- 3 Fraunhofer MEVIS, Institute for Medical Image Computing, Bremen, Germany.,4 Faculty of Physics and Electronics, University of Bremen, Bremen, Germany
| | - Cees J Tack
- 2 Department of Internal Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Arend Heerschap
- 1 Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Bastiaan E de Galan
- 2 Department of Internal Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Marinette van der Graaf
- 1 Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, the Netherlands.,5 Department of Pediatrics, Radboud University Medical Center, Nijmegen, the Netherlands
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Kochunov P, Wey HY, Fox PT, Lancaster JL, Davis MD, Wang DJJ, Lin AL, Bastarrachea RA, Andrade MCR, Mattern V, Frost P, Higgins PB, Comuzzie AG, Voruganti VS. Changes in Cerebral Blood Flow during an Alteration in Glycemic State in a Large Non-human Primate ( Papio hamadryas sp.). Front Neurosci 2017; 11:49. [PMID: 28261040 PMCID: PMC5306336 DOI: 10.3389/fnins.2017.00049] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 01/23/2017] [Indexed: 11/24/2022] Open
Abstract
Changes in cerebral blood flow (CBF) during a hyperglycemic challenge were mapped, using perfusion-weighted MRI, in a group of non-human primates. Seven female baboons were fasted for 16 h prior to 1-h imaging experiment, performed under general anesthesia, that consisted of a 20-min baseline, followed by a bolus infusion of glucose (500 mg/kg). CBF maps were collected every 7 s and blood glucose and insulin levels were sampled at regular intervals. Blood glucose levels rose from 51.3 ± 10.9 to 203.9 ± 38.9 mg/dL and declined to 133.4 ± 22.0 mg/dL, at the end of the experiment. Regional CBF changes consisted of four clusters: cerebral cortex, thalamus, hypothalamus, and mesencephalon. Increases in the hypothalamic blood flow occurred concurrently with the regulatory response to systemic glucose change, whereas CBF declined for other clusters. The return to baseline of hypothalamic blood flow was observed while CBF was still increasing in other brain regions. The spatial pattern of extra-hypothalamic CBF changes was correlated with the patterns of several cerebral networks including the default mode network. These findings suggest that hypothalamic blood flow response to systemic glucose levels can potentially be explained by regulatory activity. The response of extra-hypothalamic clusters followed a different time course and its spatial pattern resembled that of the default-mode network.
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Affiliation(s)
- Peter Kochunov
- Maryland Psychiatric Research Center, University of Maryland School of MedicineBaltimore, MA, USA; Research Imaging Institute, University of Texas Health Science Center at San AntonioSan Antonio, TX, USA; Southwest National Primate Research CenterSan Antonio, TX, USA
| | - Hsiao-Ying Wey
- Research Imaging Institute, University of Texas Health Science Center at San AntonioSan Antonio, TX, USA; Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical SchoolCharlestown, MA, USA
| | - Peter T Fox
- Research Imaging Institute, University of Texas Health Science Center at San Antonio San Antonio, TX, USA
| | - Jack L Lancaster
- Research Imaging Institute, University of Texas Health Science Center at San Antonio San Antonio, TX, USA
| | - Michael D Davis
- Research Imaging Institute, University of Texas Health Science Center at San Antonio San Antonio, TX, USA
| | - Danny J J Wang
- Ahmanson-Lovelace Brain Mapping Center, University of California at Los AngelesLos Angeles, CA, USA; Mark and Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern CaliforniaLos Angeles, CA, USA
| | - Ai-Ling Lin
- Research Imaging Institute, University of Texas Health Science Center at San Antonio San Antonio, TX, USA
| | - Raul A Bastarrachea
- Southwest National Primate Research CenterSan Antonio, TX, USA; Department of Genetics, Texas Biomedical Research InstituteSan Antonio, TX, USA
| | - Marcia C R Andrade
- Department of Genetics, Texas Biomedical Research InstituteSan Antonio, TX, USA; Center for Laboratory Animal Breeding, Oswaldo Cruz FoundationRio de Janeiro, Brazil
| | - Vicki Mattern
- Department of Genetics, Texas Biomedical Research Institute San Antonio, TX, USA
| | - Patrice Frost
- Southwest National Primate Research Center San Antonio, TX, USA
| | - Paul B Higgins
- Department of Genetics, Texas Biomedical Research Institute San Antonio, TX, USA
| | - Anthony G Comuzzie
- Southwest National Primate Research CenterSan Antonio, TX, USA; Department of Genetics, Texas Biomedical Research InstituteSan Antonio, TX, USA
| | - Venkata S Voruganti
- Department of Nutrition and UNC Nutrition Research Institute, University of North Carolina at Chapel Hill Kannapolis, NC, USA
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Belfort-DeAguiar R, Seo D, Naik S, Hwang J, Lacadie C, Schmidt C, Constable RT, Sinha R, Sherwin R. Food image-induced brain activation is not diminished by insulin infusion. Int J Obes (Lond) 2016; 40:1679-1686. [PMID: 27569684 PMCID: PMC5101182 DOI: 10.1038/ijo.2016.152] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 07/26/2016] [Accepted: 08/07/2016] [Indexed: 12/19/2022]
Abstract
BACKGROUND/OBJECTIVES The obesity epidemic appears to be driven in large part by our modern environment inundated by food cues, which may influence our desire to eat. Although insulin decreases food intake in both animals and humans, the effect of insulin on motivation for food in the presence of food cues is not known. Therefore, the aim of this study was to evaluate the effect of an intravenous insulin infusion on the brain response to visual food cues, hunger and food craving in non-obese human subjects. SUBJECTS/METHODS Thirty-four right-handed healthy non-obese subjects (19F/15M, age: 29±8 years.; BMI: 23.1±2.1 kg m-2) were divided in two groups matched by age and BMI; the insulin group (18 subjects) underwent a hyperinsulinemic-euglycemic-clamp, and the control group (16 subjects) received an intravenous saline infusion, while viewing high and low-calorie food and non-food pictures during a functional MRI scan. Motivation for food was determined via analog scales for hunger, wanting and liking ratings. RESULTS Food images induced brain responses in the hypothalamus, striatum, amygdala, insula, ventromedial prefrontal cortex (PFC), dorsolateral PFC and occipital lobe (whole brain correction, P<0.05). Wanting (P<0.001) and liking (P<0.001) ratings were significantly higher for the food than the non-food images, but not different between insulin and saline infusion groups. Hunger ratings increased throughout the MRI scan and correlated with preference for high-calorie food pictures (r=0.70; P<0.001). However, neither brain activity nor food cravings were affected by hyperinsulinemia or hormonal status (leptin and ghrelin levels) (P=NS). CONCLUSIONS Our data demonstrate that visual food cues induce a strong response in motivation/reward and cognitive-executive control brain regions in non-obese subjects, but that these responses are not diminished by hyperinsulinemia per se. These findings suggest that our modern food cue saturated environment may be sufficient to overpower homeostatic hormonal signals, and thus contribute to the current obesity epidemic.
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Affiliation(s)
| | - Dongju Seo
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - Sarita Naik
- Section of Endocrinology, Yale University School of Medicine, New Haven, CT, USA
- University College London Hospitals NHS, London, UK
| | - Janice Hwang
- Section of Endocrinology, Yale University School of Medicine, New Haven, CT, USA
| | - Cheryl Lacadie
- Department of Radiology, Yale University School of Medicine, New Haven, CT, USA
| | - Christian Schmidt
- Section of Endocrinology, Yale University School of Medicine, New Haven, CT, USA
| | - R. Todd Constable
- Department of Radiology, Yale University School of Medicine, New Haven, CT, USA
| | - Rajita Sinha
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - Robert Sherwin
- Section of Endocrinology, Yale University School of Medicine, New Haven, CT, USA
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Kullmann S, Heni M, Hallschmid M, Fritsche A, Preissl H, Häring HU. Brain Insulin Resistance at the Crossroads of Metabolic and Cognitive Disorders in Humans. Physiol Rev 2016; 96:1169-209. [PMID: 27489306 DOI: 10.1152/physrev.00032.2015] [Citation(s) in RCA: 352] [Impact Index Per Article: 44.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Ever since the brain was identified as an insulin-sensitive organ, evidence has rapidly accumulated that insulin action in the brain produces multiple behavioral and metabolic effects, influencing eating behavior, peripheral metabolism, and cognition. Disturbances in brain insulin action can be observed in obesity and type 2 diabetes (T2D), as well as in aging and dementia. Decreases in insulin sensitivity of central nervous pathways, i.e., brain insulin resistance, may therefore constitute a joint pathological feature of metabolic and cognitive dysfunctions. Modern neuroimaging methods have provided new means of probing brain insulin action, revealing the influence of insulin on both global and regional brain function. In this review, we highlight recent findings on brain insulin action in humans and its impact on metabolism and cognition. Furthermore, we elaborate on the most prominent factors associated with brain insulin resistance, i.e., obesity, T2D, genes, maternal metabolism, normal aging, inflammation, and dementia, and on their roles regarding causes and consequences of brain insulin resistance. We also describe the beneficial effects of enhanced brain insulin signaling on human eating behavior and cognition and discuss potential applications in the treatment of metabolic and cognitive disorders.
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Affiliation(s)
- Stephanie Kullmann
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany; German Center for Diabetes Research (DZD e.V.), Tübingen, Germany; Department of Internal Medicine IV, University of Tübingen, Tübingen, Germany; Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany; and Department of Pharmacy and Biochemistry, Faculty of Science, Eberhard Karls Universität Tübingen, Tübingen, Germany
| | - Martin Heni
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany; German Center for Diabetes Research (DZD e.V.), Tübingen, Germany; Department of Internal Medicine IV, University of Tübingen, Tübingen, Germany; Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany; and Department of Pharmacy and Biochemistry, Faculty of Science, Eberhard Karls Universität Tübingen, Tübingen, Germany
| | - Manfred Hallschmid
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany; German Center for Diabetes Research (DZD e.V.), Tübingen, Germany; Department of Internal Medicine IV, University of Tübingen, Tübingen, Germany; Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany; and Department of Pharmacy and Biochemistry, Faculty of Science, Eberhard Karls Universität Tübingen, Tübingen, Germany
| | - Andreas Fritsche
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany; German Center for Diabetes Research (DZD e.V.), Tübingen, Germany; Department of Internal Medicine IV, University of Tübingen, Tübingen, Germany; Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany; and Department of Pharmacy and Biochemistry, Faculty of Science, Eberhard Karls Universität Tübingen, Tübingen, Germany
| | - Hubert Preissl
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany; German Center for Diabetes Research (DZD e.V.), Tübingen, Germany; Department of Internal Medicine IV, University of Tübingen, Tübingen, Germany; Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany; and Department of Pharmacy and Biochemistry, Faculty of Science, Eberhard Karls Universität Tübingen, Tübingen, Germany
| | - Hans-Ulrich Häring
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany; German Center for Diabetes Research (DZD e.V.), Tübingen, Germany; Department of Internal Medicine IV, University of Tübingen, Tübingen, Germany; Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany; and Department of Pharmacy and Biochemistry, Faculty of Science, Eberhard Karls Universität Tübingen, Tübingen, Germany
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Jastreboff AM, Sinha R, Arora J, Giannini C, Kubat J, Malik S, Van Name MA, Santoro N, Savoye M, Duran EJ, Pierpont B, Cline G, Constable RT, Sherwin RS, Caprio S. Altered Brain Response to Drinking Glucose and Fructose in Obese Adolescents. Diabetes 2016; 65:1929-39. [PMID: 27207544 PMCID: PMC5384636 DOI: 10.2337/db15-1216] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 03/23/2016] [Indexed: 02/06/2023]
Abstract
Increased sugar-sweetened beverage consumption has been linked to higher rates of obesity. Using functional MRI, we assessed brain perfusion responses to drinking two commonly consumed monosaccharides, glucose and fructose, in obese and lean adolescents. Marked differences were observed. In response to drinking glucose, obese adolescents exhibited decreased brain perfusion in brain regions involved in executive function (prefrontal cortex [PFC]) and increased perfusion in homeostatic appetite regions of the brain (hypothalamus). Conversely, in response to drinking glucose, lean adolescents demonstrated increased PFC brain perfusion and no change in perfusion in the hypothalamus. In addition, obese adolescents demonstrated attenuated suppression of serum acyl-ghrelin and increased circulating insulin level after glucose ingestion; furthermore, the change in acyl-ghrelin and insulin levels after both glucose and fructose ingestion was associated with increased hypothalamic, thalamic, and hippocampal blood flow in obese relative to lean adolescents. Additionally, in all subjects there was greater perfusion in the ventral striatum with fructose relative to glucose ingestion. Finally, reduced connectivity between executive, homeostatic, and hedonic brain regions was observed in obese adolescents. These data demonstrate that obese adolescents have impaired prefrontal executive control responses to drinking glucose and fructose, while their homeostatic and hedonic responses appear to be heightened. Thus, obesity-related brain adaptations to glucose and fructose consumption in obese adolescents may contribute to excessive consumption of glucose and fructose, thereby promoting further weight gain.
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Affiliation(s)
- Ania M Jastreboff
- Division of Endocrinology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT Division of Pediatric Endocrinology, Department of Pediatrics, Yale University School of Medicine, New Haven, CT
| | - Rajita Sinha
- Department of Psychiatry, Yale Stress Center, Yale University School of Medicine, New Haven, CT Child Study Center, Yale University School of Medicine, New Haven, CT
| | - Jagriti Arora
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT
| | - Cosimo Giannini
- Division of Pediatric Endocrinology, Department of Pediatrics, Yale University School of Medicine, New Haven, CT
| | - Jessica Kubat
- Division of Pediatric Endocrinology, Department of Pediatrics, Yale University School of Medicine, New Haven, CT
| | - Saima Malik
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT
| | - Michelle A Van Name
- Division of Pediatric Endocrinology, Department of Pediatrics, Yale University School of Medicine, New Haven, CT
| | - Nicola Santoro
- Division of Pediatric Endocrinology, Department of Pediatrics, Yale University School of Medicine, New Haven, CT
| | - Mary Savoye
- Division of Pediatric Endocrinology, Department of Pediatrics, Yale University School of Medicine, New Haven, CT
| | - Elvira J Duran
- Division of Pediatric Endocrinology, Department of Pediatrics, Yale University School of Medicine, New Haven, CT
| | - Bridget Pierpont
- Division of Pediatric Endocrinology, Department of Pediatrics, Yale University School of Medicine, New Haven, CT
| | - Gary Cline
- Division of Endocrinology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
| | - R Todd Constable
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT
| | - Robert S Sherwin
- Division of Endocrinology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
| | - Sonia Caprio
- Division of Pediatric Endocrinology, Department of Pediatrics, Yale University School of Medicine, New Haven, CT
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30
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Rooijackers HMM, Wiegers EC, Tack CJ, van der Graaf M, de Galan BE. Brain glucose metabolism during hypoglycemia in type 1 diabetes: insights from functional and metabolic neuroimaging studies. Cell Mol Life Sci 2016; 73:705-22. [PMID: 26521082 PMCID: PMC4735263 DOI: 10.1007/s00018-015-2079-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 10/16/2015] [Accepted: 10/20/2015] [Indexed: 12/30/2022]
Abstract
Hypoglycemia is the most frequent complication of insulin therapy in patients with type 1 diabetes. Since the brain is reliant on circulating glucose as its main source of energy, hypoglycemia poses a threat for normal brain function. Paradoxically, although hypoglycemia commonly induces immediate decline in cognitive function, long-lasting changes in brain structure and cognitive function are uncommon in patients with type 1 diabetes. In fact, recurrent hypoglycemia initiates a process of habituation that suppresses hormonal responses to and impairs awareness of subsequent hypoglycemia, which has been attributed to adaptations in the brain. These observations sparked great scientific interest into the brain's handling of glucose during (recurrent) hypoglycemia. Various neuroimaging techniques have been employed to study brain (glucose) metabolism, including PET, fMRI, MRS and ASL. This review discusses what is currently known about cerebral metabolism during hypoglycemia, and how findings obtained by functional and metabolic neuroimaging techniques contributed to this knowledge.
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Affiliation(s)
- Hanne M M Rooijackers
- Department of Internal Medicine 463, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
| | - Evita C Wiegers
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Cees J Tack
- Department of Internal Medicine 463, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Marinette van der Graaf
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Pediatrics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Bastiaan E de Galan
- Department of Internal Medicine 463, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
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31
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Galeffi F, Shetty PK, Sadgrove MP, Turner DA. Age-related metabolic fatigue during low glucose conditions in rat hippocampus. Neurobiol Aging 2014; 36:982-92. [PMID: 25443286 DOI: 10.1016/j.neurobiolaging.2014.09.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 09/03/2014] [Accepted: 09/17/2014] [Indexed: 12/14/2022]
Abstract
Previous reports have indicated that with aging, intrinsic brain tissue changes in cellular bioenergetics may hamper the brain's ability to cope with metabolic stress. Therefore, we analyzed the effects of age on neuronal sensitivity to glucose deprivation by monitoring changes in field excitatory postsynaptic potentials (fEPSPs), tissue Po2, and NADH fluorescence imaging in the CA1 region of hippocampal slices obtained from F344 rats (1-2, 3-6, 12-20, and >22 months). Forty minutes of moderate low glucose (2.5 mM) led to approximately 80% decrease of fEPSP amplitudes and NADH decline in all 4 ages that reversed after reintroduction of 10 mM glucose. However, tissue slices from 12 to 20 months and >22-month-old rats were more vulnerable to low glucose: fEPSPs decreased by 50% on average 8 minutes faster compared with younger slices. Tissue oxygen utilization increased after onset of 2.5 mM glucose in all ages of tissue slices, which persisted for 40 minutes in younger tissue slices. But, in older tissue slices the increased oxygen utilization slowly faded and tissue Po2 levels increased toward baseline values after approximately 25 minutes of glucose deprivation. In addition, with age the ability to regenerate NADH after oxidation was diminished. The NAD(+)/NADH ratio remained relatively oxidized after low glucose, even during recovery. In young slices, glycogen levels were stable throughout the exposure to low glucose. In contrast, with aging utilization of glycogen stores was increased during low glucose, particularly in hippocampal slices from >22 months old rats, indicating both inefficient metabolism and increased demand for glucose. Lactate addition (20 mM) improved oxidative metabolism by directly supplementing the mitochondrial NADH pool and maintained fEPSPs in young as well as aged tissue slices, indicating that inefficient metabolism in the aging tissue can be improved by directly enhancing NADH regeneration.
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Affiliation(s)
- Francesca Galeffi
- Department of Surgery (Neurosurgery), Duke University Medical Center, Durham, NC, USA; Research and Surgery Services, Durham VAMC, Durham NC, USA.
| | - Pavan K Shetty
- Department of Surgery (Neurosurgery), Duke University Medical Center, Durham, NC, USA; Research and Surgery Services, Durham VAMC, Durham NC, USA
| | - Matthew P Sadgrove
- Department of Surgery (Neurosurgery), Duke University Medical Center, Durham, NC, USA; Research and Surgery Services, Durham VAMC, Durham NC, USA
| | - Dennis A Turner
- Department of Surgery (Neurosurgery), Duke University Medical Center, Durham, NC, USA; Research and Surgery Services, Durham VAMC, Durham NC, USA; Department of Neurobiology, Duke University Medical Center, Durham, NC, USA
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Acosta A, Abu Dayyeh BK, Port JD, Camilleri M. Recent advances in clinical practice challenges and opportunities in the management of obesity. Gut 2014; 63:687-95. [PMID: 24402654 PMCID: PMC4170188 DOI: 10.1136/gutjnl-2013-306235] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Despite advances in understanding the roles of adiposity, food intake, GI and adipocyte-related hormones, inflammatory mediators, the gut-brain axis and the hypothalamic nervous system in the pathophysiology of obesity, the effects of different therapeutic interventions on those pathophysiological mechanisms are controversial. There are still no low-cost, safe, effective treatments for obesity and its complications. Currently, bariatric surgical approaches targeting the GI tract are more effective than non-surgical approaches in inducing weight reduction and resolving obesity-related comorbidities. However, current guidelines emphasise non-surgical approaches through lifestyle modification and medications to achieve slow weight loss, which is not usually sustained and may be associated with medication-related side effects. This review analyses current central, peripheral or hormonal targets to treat obesity and addresses challenges and opportunities to develop novel approaches for obesity.
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Affiliation(s)
- Andres Acosta
- Clinical Enteric Neuroscience Translational and Epidemiological Research (C.E.N.T.E.R.), Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Barham K. Abu Dayyeh
- Clinical Enteric Neuroscience Translational and Epidemiological Research (C.E.N.T.E.R.), Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - John D. Port
- Division of Neuroradiology, Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Michael Camilleri
- Clinical Enteric Neuroscience Translational and Epidemiological Research (C.E.N.T.E.R.), Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, Minnesota
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Sherr J, Xing D, Ruedy KJ, Beck RW, Kollman C, Buckingham B, White NH, Fox L, Tsalikian E, Weinzimer S, Arbelaez AM, Tamborlane WV. Lack of association between residual insulin production and glucagon response to hypoglycemia in youth with short duration of type 1 diabetes. Diabetes Care 2013; 36:1470-6. [PMID: 23288858 PMCID: PMC3661789 DOI: 10.2337/dc12-1697] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Accepted: 11/30/2012] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To examine the loss of glucagon response to hypoglycemia and its relationship with residual β-cell function early in the course of type 1 diabetes (T1D) in youth. RESEARCH DESIGN AND METHODS Twenty-one youth with T1D duration <1 year (ages 8-18 years, T1D duration 6-52 weeks) underwent mixed-meal tolerance tests (MMTTs) to assess residual β-cell function and hypoglycemic clamps to assess glucagon responses to hypoglycemia. Glucagon responses to hypoglycemia in T1D subjects were compared with those in 12 nondiabetic young adults (ages 19-25 years). RESULTS Peak MMTT-stimulated C-peptide levels (range 0.12-1.43) were ≥ 0.2 nmol/L in all but one T1D subject. As expected, the median of glucagon responses to hypoglycemia in the T1D subjects (18 pg/mL [interquartile range 7-32]) was significantly reduced compared with the responses in nondiabetic control subjects (38 pg/mL [19-66], P = 0.02). However, there was no correlation between the incremental increase in plasma glucagon during the hypoglycemic clamp and the incremental increase and peak plasma C-peptide level during the MMTT. Similarly, the seven T1D subjects who failed to achieve an increase in glucagon ≥ 12 pg/mL (i.e., 3 SD above baseline values) had C-peptide response ≥ 0.2 nmol/L (0.54-1.12), and the one T1D subject with peak stimulated <0.2 nmol/L had a 14 pg/mL increase in plasma glucagon in response to hypoglycemia. CONCLUSIONS Impaired plasma glucagon responses to hypoglycemia are evident in youth with T1D during the first year of the disease. Moreover, defective and absent glucagon responses to hypoglycemia were observed in patients who retained clinically important residual endogenous β-cell function.
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Affiliation(s)
- Jennifer Sherr
- Pediatric Endocrinology, Yale University, New Haven, Connecticut
| | | | | | - Roy W. Beck
- Jaeb Center for Health Research, Tampa, Florida
| | | | - Bruce Buckingham
- Pediatric Endocrinology, Stanford University, Stanford, California
| | - Neil H. White
- Department of Pediatrics, Washington University, St. Louis, Missouri
| | - Larry Fox
- Pediatric Endocrinology, Nemours Children’s Clinic, Jacksonville, Florida
| | - Eva Tsalikian
- Pediatric Endocrinology, University of Iowa, Iowa City, Iowa
| | - Stuart Weinzimer
- Pediatric Endocrinology, Yale University, New Haven, Connecticut
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Szepietowska B, Zhu W, Czyzyk J, Eid T, Sherwin RS. EphA5-EphrinA5 interactions within the ventromedial hypothalamus influence counterregulatory hormone release and local glutamine/glutamate balance during hypoglycemia. Diabetes 2013; 62:1282-8. [PMID: 23274893 PMCID: PMC3609598 DOI: 10.2337/db12-0982] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Activation of β-cell EphA5 receptors by its ligand ephrinA5 from adjacent β-cells has been reported to decrease insulin secretion during hypoglycemia. Given the similarities between islet and ventromedial hypothalamus (VMH) glucose sensing, we tested the hypothesis that the EphA5/ephrinA5 system might function within the VMH during hypoglycemia to stimulate counterregulatory hormone release as well. Counterregulatory responses and glutamine/glutamate concentrations in the VMH were assessed during a hyperinsulinemic-hypoglycemic glucose clamp study in chronically catheterized awake male Sprague-Dawley rats that received an acute VMH microinjection of ephrinA5-Fc, chronic VMH knockdown, or overexpression of ephrinA5 using an adenoassociated viral construct. Local stimulation of VMH EphA5 receptors by ephrinA5-Fc or ephrinA5 overexpression increased, whereas knockdown of VMH ephrinA5 reduced counterregulatory responses during hypoglycemia. Overexpression of VMH ephrinA5 transiently increased local glutamate concentrations, whereas ephrinA5 knockdown produced profound suppression of VMH interstitial fluid glutamine concentrations in the basal state and during hypoglycemia. Changes in ephrinA5/EphA5 interactions within the VMH, a key brain glucose-sensing region, act in concert with islets to restore glucose homeostasis during acute hypoglycemia, and its effect on counterregulation may be mediated by changes in glutamate/glutamine cycling.
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Affiliation(s)
- Barbara Szepietowska
- Department of Internal Medicine and Endocrinology, Yale University School of Medicine, New Haven, Connecticut
| | - Wanling Zhu
- Department of Internal Medicine and Endocrinology, Yale University School of Medicine, New Haven, Connecticut
| | - Jan Czyzyk
- Department of Pathology and Laboratory Medicine, University of Rochester, Rochester, New York
| | - Tore Eid
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Robert S. Sherwin
- Department of Internal Medicine and Endocrinology, Yale University School of Medicine, New Haven, Connecticut
- Corresponding author: Robert S. Sherwin,
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Arbeláez AM, Su Y, Thomas JB, Hauch AC, Hershey T, Ances BM. Comparison of regional cerebral blood flow responses to hypoglycemia using pulsed arterial spin labeling and positron emission tomography. PLoS One 2013; 8:e60085. [PMID: 23555895 PMCID: PMC3610825 DOI: 10.1371/journal.pone.0060085] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 02/22/2013] [Indexed: 12/30/2022] Open
Abstract
Different brain regions sense and modulate the counterregulatory responses that can occur in response to declining plasma glucose levels. The aim of this study was to determine if changes in regional cerebral blood flow (rCBF) during hypoglycemia relative to euglycemia are similar for two imaging modalities–pulsed arterial spin labeling magnetic resonance imaging (PASL-MRI) and positron emission tomography (PET). Nine healthy non-diabetic participants underwent a hyperinsulinemic euglycemic (92±3 mg/dL) – hypoglycemic (53±1 mg/dL) clamp. Counterregulatory hormone levels were collected at each of these glycemic levels and rCBF measurements within the previously described network of hypoglycemia-responsive regions (thalamus, medial prefrontal cortex and globus pallidum) were obtained using PASL-MRI and [15O] water PET. In response to hypoglycemia, rCBF was significantly increased in the thalamus, medial prefrontal cortex, and globus pallidum compared to euglycemia for both PASL-MRI and PET methodologies. Both imaging techniques found similar increases in rCBF in the thalamus, medial prefrontal cortex, and globus pallidum in response to hypoglycemia. These brain regions may be involved in the physiologic and symptom responses to hypoglycemia. Compared to PET, PASL-MRI may provide a less invasive, less expensive method for assessing changes in rCBF during hypoglycemia without radiation exposure.
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Affiliation(s)
- Ana Maria Arbeláez
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, USA.
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Reno CM, Litvin M, Clark AL, Fisher SJ. Defective counterregulation and hypoglycemia unawareness in diabetes: mechanisms and emerging treatments. Endocrinol Metab Clin North Am 2013; 42:15-38. [PMID: 23391237 PMCID: PMC3568263 DOI: 10.1016/j.ecl.2012.11.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
For people with diabetes, hypoglycemia remains the limiting factor in achieving glycemic control. This article reviews recent advances in how the brain senses and responds to hypoglycemia. Novel mechanisms by which individuals with insulin-treated diabetes develop hypoglycemia unawareness and impaired counterregulatory responses are outlined. Prevention strategies for reducing the incidence of hypoglycemia are discussed.
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Affiliation(s)
- Candace M. Reno
- Division of Endocrinology, Metabolism, & Lipid Research, Department of Medicine, Washington University, St. Louis, MO
| | - Marina Litvin
- Division of Endocrinology, Metabolism, & Lipid Research, Department of Medicine, Washington University, St. Louis, MO
| | - Amy L. Clark
- Division of Endocrinology and Diabetes, Department of Pediatrics, Washington University, St. Louis, MO
| | - Simon J. Fisher
- Division of Endocrinology, Metabolism, & Lipid Research, Department of Medicine, Washington University, St. Louis, MO
- Department of Cell Biology and Physiology, Washington University, St. Louis, MO
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Heni M, Kullmann S, Ketterer C, Guthoff M, Bayer M, Staiger H, Machicao F, Häring HU, Preissl H, Veit R, Fritsche A. Differential effect of glucose ingestion on the neural processing of food stimuli in lean and overweight adults. Hum Brain Mapp 2013; 35:918-28. [PMID: 23307469 DOI: 10.1002/hbm.22223] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 10/16/2012] [Accepted: 10/22/2012] [Indexed: 12/19/2022] Open
Abstract
Eating behavior is crucial in the development of obesity and Type 2 diabetes. To further investigate its regulation, we studied the effects of glucose versus water ingestion on the neural processing of visual high and low caloric food cues in 12 lean and 12 overweight subjects by functional magnetic resonance imaging. We found body weight to substantially impact the brain's response to visual food cues after glucose versus water ingestion. Specifically, there was a significant interaction between body weight, condition (water versus glucose), and caloric content of food cues. Although overweight subjects showed a generalized reduced response to food objects in the fusiform gyrus and precuneus, the lean group showed a differential pattern to high versus low caloric foods depending on glucose versus water ingestion. Furthermore, we observed plasma insulin and glucose associated effects. The hypothalamic response to high caloric food cues negatively correlated with changes in blood glucose 30 min after glucose ingestion, while especially brain regions in the prefrontal cortex showed a significant negative relationship with increases in plasma insulin 120 min after glucose ingestion. We conclude that the postprandial neural processing of food cues is highly influenced by body weight especially in visual areas, potentially altering visual attention to food. Furthermore, our results underline that insulin markedly influences prefrontal activity to high caloric food cues after a meal, indicating that postprandial hormones may be potential players in modulating executive control.
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Affiliation(s)
- Martin Heni
- Division of Endocrinology, Diabetology, Angiology, Nephrology and Clinical Chemistry, Department of Internal Medicine, Eberhard Karls University Tübingen, Germany
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Page KA, Chan O, Arora J, Belfort-Deaguiar R, Dzuira J, Roehmholdt B, Cline GW, Naik S, Sinha R, Constable RT, Sherwin RS. Effects of fructose vs glucose on regional cerebral blood flow in brain regions involved with appetite and reward pathways. JAMA 2013; 309:63-70. [PMID: 23280226 PMCID: PMC4076145 DOI: 10.1001/jama.2012.116975] [Citation(s) in RCA: 239] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
IMPORTANCE Increases in fructose consumption have paralleled the increasing prevalence of obesity, and high-fructose diets are thought to promote weight gain and insulin resistance. Fructose ingestion produces smaller increases in circulating satiety hormones compared with glucose ingestion, and central administration of fructose provokes feeding in rodents, whereas centrally administered glucose promotes satiety. OBJECTIVE To study neurophysiological factors that might underlie associations between fructose consumption and weight gain. DESIGN, SETTING, AND PARTICIPANTS Twenty healthy adult volunteers underwent 2 magnetic resonance imaging sessions at Yale University in conjunction with fructose or glucose drink ingestion in a blinded, random-order, crossover design. MAIN OUTCOME MEASURES Relative changes in hypothalamic regional cerebral blood flow (CBF) after glucose or fructose ingestion. Secondary outcomes included whole-brain analyses to explore regional CBF changes, functional connectivity analysis to investigate correlations between the hypothalamus and other brain region responses, and hormone responses to fructose and glucose ingestion. RESULTS There was a significantly greater reduction in hypothalamic CBF after glucose vs fructose ingestion (-5.45 vs 2.84 mL/g per minute, respectively; mean difference, 8.3 mL/g per minute [95% CI of mean difference, 1.87-14.70]; P = .01). Glucose ingestion (compared with baseline) increased functional connectivity between the hypothalamus and the thalamus and striatum. Fructose increased connectivity between the hypothalamus and thalamus but not the striatum. Regional CBF within the hypothalamus, thalamus, insula, anterior cingulate, and striatum (appetite and reward regions) was reduced after glucose ingestion compared with baseline (P < .05 significance threshold, family-wise error [FWE] whole-brain corrected). In contrast, fructose reduced regional CBF in the thalamus, hippocampus, posterior cingulate cortex, fusiform, and visual cortex (P < .05 significance threshold, FWE whole-brain corrected). In whole-brain voxel-level analyses, there were no significant differences between direct comparisons of fructose vs glucose sessions following correction for multiple comparisons. Fructose vs glucose ingestion resulted in lower peak levels of serum glucose (mean difference, 41.0 mg/dL [95% CI, 27.7-54.5]; P < .001), insulin (mean difference, 49.6 μU/mL [95% CI, 38.2-61.1]; P < .001), and glucagon-like polypeptide 1 (mean difference, 2.1 pmol/L [95% CI, 0.9-3.2]; P = .01). CONCLUSION AND RELEVANCE In a series of exploratory analyses, consumption of fructose compared with glucose resulted in a distinct pattern of regional CBF and a smaller increase in systemic glucose, insulin, and glucagon-like polypeptide 1 levels.
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Affiliation(s)
- Kathleen A Page
- Section of Endocrinology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520-8020, USA
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Hypoglycemia-induced increases in thalamic cerebral blood flow are blunted in subjects with type 1 diabetes and hypoglycemia unawareness. J Cereb Blood Flow Metab 2012; 32:2084-90. [PMID: 22892724 PMCID: PMC3494000 DOI: 10.1038/jcbfm.2012.117] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The thalamus has been found to be activated during the early phase of moderate hypoglycemia. Here, we tested the hypothesis that this region is less activated during hypoglycemia in subjects with type 1 diabetes (T1DM) and hypoglycemia unawareness relative to controls. Twelve controls (5 F/7 M, age 40 ± 14 years, body mass index 24.2 ± 2.7 kg/m(2)) and eleven patients (7 F/4 M, age 39 ± 13 years, body mass index 26.5 ± 4.4 kg/m(2)) with well-controlled T1DM (A1c 6.8 ± 0.4%) underwent a two-step hyperinsulinemic (2.0 mU/kg per minute) clamp. Cerebral blood flow (CBF) weighted images were acquired using arterial spin labeling to monitor cerebral activation in the midbrain regions. Blood glucose was first held at 95 mg/dL and then allowed to decrease to 50 mg/dL. The CBF image acquisition during euglycemia and hypoglycemia began within a few minutes of when the target blood glucose values were reached. Hypoglycemia unaware T1DM subjects displayed blunting of the physiologic CBF increase that occurs in the thalamus of healthy individuals during the early phase of moderate hypoglycemia. A positive correlation was observed between thalamic response and epinephrine response to hypoglycemia, suggesting that this region may be involved in the coordination of the counter regulatory response to hypoglycemia.
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Abstract
Functional neuroimaging techniques can be used to study changes in regional brain activation, using changes in surrogate markers such as regional cerebral perfusion and rates of glucose uptake or metabolism. These approaches are shedding new light on two major health problems: the increasing burden of type 2 diabetes mellitus (T2DM), which is driven by the rising prevalence of insulin resistance and obesity; and recurrent intractable problematic hypoglycaemia, which is driven by the cognitive impairment that can occur in association with iatrogenic hypoglycaemic episodes. Some patients with diabetes mellitus lose awareness of being hypoglycaemic, which puts them at risk of severe hypoglycaemia as they are unlikely to take action to prevent the condition worsening. Involvement of corticolimbic brain and centres serving higher executive functions as well as the hypothalamus has been demonstrated in both situations and has implications for therapy. This Review describes the relevant principles of functional neuroimaging techniques and presents data supporting the notion that the dysregulation of central pathways involved in metabolic regulation, reward and appetite could contribute to problematic hypoglycaemia during therapy for diabetes mellitus and to insulin-resistant obesity and T2DM. Understanding these dysregulations could enable the development of novel clinical interventions.
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Affiliation(s)
- Yee-Seun Cheah
- Diabetes Research Group, Weston Education Centre, Denmark Hill Campus, King's College London, 10 Cutcombe Road, London SE5 9RJ, UK
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Abstract
Neurons whose activity is regulated by glucose are found in a number of brain regions. Glucose-excited (GE) neurons increase while glucose-inhibited (GI) neurons decrease their action potential frequency as interstitial brain glucose levels increase. We hypothesize that these neurons evolved to sense and respond to severe energy deficit (e.g., fasting) that threatens the brains glucose supply. During modern times, they are also important for the restoration of blood glucose levels following insulin-induced hypoglycemia. Our data suggest that impaired glucose sensing by hypothalamic glucose sensing neurons may contribute to the syndrome known as hypoglycemia-associated autonomic failure in which the mechanisms which restore euglycemia following hypoglycemia become impaired. On the other hand, increased responses of glucose sensing neurons to glucose deficit may play a role in the development of Type 2 Diabetes Mellitus and obesity. This review will discuss the mechanisms by which glucose sensing neurons sense changes in interstitial glucose and explore the roles of these specialized glucose sensors in glucose and energy homeostasis.
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Affiliation(s)
- Vanessa H Routh
- Department of Pharmacology & Physiology, New Jersey Medical School (UMDNJ), Newark, NJ 07101, USA.
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Page KA, Seo D, Belfort-DeAguiar R, Lacadie C, Dzuira J, Naik S, Amarnath S, Constable RT, Sherwin RS, Sinha R. Circulating glucose levels modulate neural control of desire for high-calorie foods in humans. J Clin Invest 2011; 121:4161-9. [PMID: 21926468 DOI: 10.1172/jci57873] [Citation(s) in RCA: 153] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Accepted: 07/27/2011] [Indexed: 01/01/2023] Open
Abstract
Obesity is a worldwide epidemic resulting in part from the ubiquity of high-calorie foods and food images. Whether obese and nonobese individuals regulate their desire to consume high-calorie foods differently is not clear. We set out to investigate the hypothesis that circulating levels of glucose, the primary fuel source for the brain, influence brain regions that regulate the motivation to consume high-calorie foods. Using functional MRI (fMRI) combined with a stepped hyperinsulinemic euglycemic-hypoglycemic clamp and behavioral measures of interest in food, we have shown here that mild hypoglycemia preferentially activates limbic-striatal brain regions in response to food cues to produce a greater desire for high-calorie foods. In contrast, euglycemia preferentially activated the medial prefrontal cortex and resulted in less interest in food stimuli. Indeed, higher circulating glucose levels predicted greater medial prefrontal cortex activation, and this response was absent in obese subjects. These findings demonstrate that circulating glucose modulates neural stimulatory and inhibitory control over food motivation and suggest that this glucose-linked restraining influence is lost in obesity. Strategies that temper postprandial reductions in glucose levels might reduce the risk of overeating, particularly in environments inundated with visual cues of high-calorie foods.
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Affiliation(s)
- Kathleen A Page
- Section of Endocrinology, Yale University School of Medicine, New Haven, Connecticut 06520-8020, USA
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Brabant G, Cain J, Jackson A, Kreitschmann-Andermahr I. Visualizing hormone actions in the brain. Trends Endocrinol Metab 2011; 22:153-63. [PMID: 21497512 DOI: 10.1016/j.tem.2011.01.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Revised: 01/19/2011] [Accepted: 01/20/2011] [Indexed: 01/01/2023]
Abstract
Profound and multifaceted effects of hormones on the development, maturation and function of the CNS are well documented. Recent developments in magnetic resonance imagining (MRI) and positron emission tomography (PET) permit detailed in vivo studies of cerebral structure and function in humans. Techniques to measure subtle differences in cerebral structure, regional brain activation, changes in blood flow and other physiological biomarkers allow us to translate experimental evidence of hormone effects obtained from animal models to humans. Here we review the imaging techniques available to support studies of hormone effects on the CNS, emphasizing the recent developments of MRI. In summarizing the major current studies we discuss the potential of these techniques for an emerging new field in endocrinology.
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Affiliation(s)
- Georg Brabant
- Department of Endocrinology, The Christie, Manchester Academic Health Science Centre, Wilmslow Road, Manchester M20 4BX, UK.
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Fioramonti X, Song Z, Vazirani RP, Beuve A, Routh VH. Hypothalamic nitric oxide in hypoglycemia detection and counterregulation: a two-edged sword. Antioxid Redox Signal 2011; 14:505-17. [PMID: 20518706 PMCID: PMC3025177 DOI: 10.1089/ars.2010.3331] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Hypoglycemia is the main complication for patients with type 1 diabetes mellitus receiving intensive insulin therapy. In addition to the obvious deleterious effects of acute hypoglycemia on brain function, recurrent episodes of hypoglycemia (RH) have an even more insidious effect. RH impairs the ability of the brain to detect and initiate an appropriate counterregulatory response (CRR) to restore euglycemia in response to subsequent hypoglycemia. Knowledge of mechanisms involved in hypoglycemia detection and counterregulation has significantly improved over the past 20 years. Glucose sensitive neurons (GSNs) in the ventromedial hypothalamus (VMH) may play a key role in the CRR. VMH nitric oxide (NO) production has recently been shown to be critical for both the CRR and glucose sensing by glucose-inhibited neurons. Interestingly, downstream effects of NO may also contribute to the impaired CRR after RH. In this review, we will discuss current literature regarding the molecular mechanisms by which VMH GSNs sense glucose. Putative roles of GSNs in the detection and initiation of the CRR will then be described. Finally, hypothetical mechanisms by which VMH NO production may both facilitate and subsequently impair the CRR will be discussed.
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Affiliation(s)
- Xavier Fioramonti
- Department of Pharmacology and Physiology, New Jersey Medical School, Newark, New Jersey 07101-1709, USA.
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Abstract
PURPOSE OF REVIEW To review neuroimaging findings that have been reported in samples of patients with cardiovascular disorders and their association with the onset of Alzheimer's disease, vascular dementia, depression and bipolar disorder in the elderly and to highlight the implications of these findings to the knowledge about the pathophysiology of psychiatric disorders in old age, as well as their potential clinical implications. RECENT FINDINGS Vascular risk factors, such as hypertension, diabetes, dyslipidemia, smoking habits and heart failure, have all been associated with signs of cerebrovascular dysfunction, including structural MRI findings of signal hyperintensities, lacunes and stroke and functional imaging findings of brain regional hypoperfusion and hypometabolism. Such brain abnormalities have been found to increase the risk of onset of psychiatric disorder (depression, bipolar and dementia) in old age. SUMMARY As vascular risk factors are potentially modifiable when detected in midlife, the early characterization of brain changes associated with the presence of cardiovascular diseases holds promise to afford clinical applications in psychiatry, providing new perspectives for the prevention of old age psychiatric disorders.
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Abstract
The counterregulatory response to hypoglycemia is a complex and well-coordinated process. As blood glucose concentration declines, peripheral and central glucose sensors relay this information to central integrative centers to coordinate neuroendocrine, autonomic, and behavioral responses and avert the progression of hypoglycemia. Diabetes, both type 1 and type 2, can perturb these counterregulatory responses. Moreover, defective counterregulation in the setting of diabetes can progress to hypoglycemia unawareness. While the mechanisms that underlie the development of hypoglycemia unawareness are not completely known, possible causes include altered sensing of hypoglycemia by the brain and/or impaired coordination of responses to hypoglycemia. Further study is needed to better understand the intricacies of the counterregulatory response and the mechanisms contributing to the development of hypoglycemia unawareness.
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Affiliation(s)
- Nolawit Tesfaye
- Department of Medicine, Division of Endocrinology and Diabetes, University of Minnesota, 420 Delaware St. SE, Minneapolis, MN 55455, USA
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Jordan SD, Könner AC, Brüning JC. Sensing the fuels: glucose and lipid signaling in the CNS controlling energy homeostasis. Cell Mol Life Sci 2010; 67:3255-73. [PMID: 20549539 PMCID: PMC2933848 DOI: 10.1007/s00018-010-0414-7] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Revised: 05/18/2010] [Accepted: 05/19/2010] [Indexed: 12/15/2022]
Abstract
The central nervous system (CNS) is capable of gathering information on the body's nutritional state and it implements appropriate behavioral and metabolic responses to changes in fuel availability. This feedback signaling of peripheral tissues ensures the maintenance of energy homeostasis. The hypothalamus is a primary site of convergence and integration for these nutrient-related feedback signals, which include central and peripheral neuronal inputs as well as hormonal signals. Increasing evidence indicates that glucose and lipids are detected by specialized fuel-sensing neurons that are integrated in these hypothalamic neuronal circuits. The purpose of this review is to outline the current understanding of fuel-sensing mechanisms in the hypothalamus, to integrate the recent findings in this field, and to address the potential role of dysregulation in these pathways in the development of obesity and type 2 diabetes mellitus.
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Affiliation(s)
- Sabine D. Jordan
- Department of Mouse Genetics and Metabolism, Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD), University of Cologne, Zülpicher Straße 47, 50674 Cologne, Germany
- Center of Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - A. Christine Könner
- Department of Mouse Genetics and Metabolism, Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD), University of Cologne, Zülpicher Straße 47, 50674 Cologne, Germany
- Center of Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
- 2nd Department for Internal Medicine, University Hospital Cologne, Cologne, Germany
| | - Jens C. Brüning
- Department of Mouse Genetics and Metabolism, Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD), University of Cologne, Zülpicher Straße 47, 50674 Cologne, Germany
- Center of Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
- 2nd Department for Internal Medicine, University Hospital Cologne, Cologne, Germany
- Max Planck Institute for the Biology of Aging, Cologne, Germany
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Yi CX, Sun N, Ackermans MT, Alkemade A, Foppen E, Shi J, Serlie MJ, Buijs RM, Fliers E, Kalsbeek A. Pituitary adenylate cyclase-activating polypeptide stimulates glucose production via the hepatic sympathetic innervation in rats. Diabetes 2010; 59:1591-600. [PMID: 20357362 PMCID: PMC2889757 DOI: 10.2337/db09-1398] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
OBJECTIVE The unraveling of the elaborate brain networks that control glucose metabolism presents one of the current challenges in diabetes research. Within the central nervous system, the hypothalamus is regarded as the key brain area to regulate energy homeostasis. The aim of the present study was to investigate the hypothalamic mechanism involved in the hyperglycemic effects of the neuropeptide pituitary adenylyl cyclase-activating polypeptide (PACAP). RESEARCH DESIGN AND METHODS Endogenous glucose production (EGP) was determined during intracerebroventricular infusions of PACAP-38, vasoactive intestinal peptide (VIP), or their receptor agonists. The specificity of their receptors was examined by coinfusions of receptor antagonists. The possible neuronal pathway involved was investigated by 1) local injections in hypothalamic nuclei, 2) retrograde neuronal tracing from the thoracic spinal cord to hypothalamic preautonomic neurons together with Fos immunoreactivity, and 3) specific hepatic sympathetic or parasympathetic denervation to block the autonomic neuronal input to liver. RESULTS Intracerebroventricular infusion of PACAP-38 increased EGP to a similar extent as a VIP/PACAP-2 (VPAC2) receptor agonist, and intracerebroventricular administration of VIP had significantly less influence on EGP. The PACAP-38 induced increase of EGP was significantly suppressed by preinfusion of a VPAC2 but not a PAC1 receptor antagonist, as well as by hepatic sympathetic but not parasympathetic denervation. In the hypothalamus, Fos immunoreactivity induced by PACAP-38 was colocalized within autonomic neurons in paraventricular nuclei projecting to preganglionic sympathetic neurons in the spinal cord. Local infusion of PACAP-38 directly into the PVN induced a significant increase of EGP. CONCLUSIONS This study demonstrates that PACAP-38 signaling via sympathetic preautonomic neurons located in the paraventricular nucleus is an important component in the hypothalamic control of hepatic glucose production.
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Affiliation(s)
- Chun-Xia Yi
- Hypothalamic Integration Mechanisms, Netherlands Institute for Neuroscience, Amsterdam, the Netherlands.
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Fioramonti X, Marsollier N, Song Z, Fakira KA, Patel RM, Brown S, Duparc T, Pica-Mendez A, Sanders NM, Knauf C, Valet P, McCrimmon RJ, Beuve A, Magnan C, Routh VH. Ventromedial hypothalamic nitric oxide production is necessary for hypoglycemia detection and counterregulation. Diabetes 2010; 59:519-28. [PMID: 19934009 PMCID: PMC2809968 DOI: 10.2337/db09-0421] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE The response of ventromedial hypothalamic (VMH) glucose-inhibited neurons to decreased glucose is impaired under conditions where the counterregulatory response (CRR) to hypoglycemia is impaired (e.g., recurrent hypoglycemia). This suggests a role for glucose-inhibited neurons in the CRR. We recently showed that decreased glucose increases nitric oxide (NO) production in cultured VMH glucose-inhibited neurons. These in vitro data led us to hypothesize that NO release from VMH glucose-inhibited neurons is critical for the CRR. RESEARCH DESIGN AND METHODS The CRR was evaluated in rats and mice in response to acute insulin-induced hypoglycemia and hypoglycemic clamps after modulation of brain NO signaling. The glucose sensitivity of ventromedial nucleus glucose-inhibited neurons was also assessed. RESULTS Hypoglycemia increased hypothalamic constitutive NO synthase (NOS) activity and neuronal NOS (nNOS) but not endothelial NOS (eNOS) phosphorylation in rats. Intracerebroventricular and VMH injection of the nonselective NOS inhibitor N(G)-monomethyl-l-arginine (l-NMMA) slowed the recovery to euglycemia after hypoglycemia. VMH l-NMMA injection also increased the glucose infusion rate (GIR) and decreased epinephrine secretion during hyperinsulinemic/hypoglycemic clamp in rats. The GIR required to maintain the hypoglycemic plateau was higher in nNOS knockout than wild-type or eNOS knockout mice. Finally, VMH glucose-inhibited neurons were virtually absent in nNOS knockout mice. CONCLUSIONS We conclude that VMH NO production is necessary for glucose sensing in glucose-inhibited neurons and full generation of the CRR to hypoglycemia. These data suggest that potentiating NO signaling may improve the defective CRR resulting from recurrent hypoglycemia in patients using intensive insulin therapy.
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Affiliation(s)
- Xavier Fioramonti
- Department of Pharmacology and Physiology, New Jersey Medical School, Newark, New Jersey
| | - Nicolas Marsollier
- National Center for Scientific Research, University Paris Diderot, Paris, France
| | - Zhentao Song
- Department of Pharmacology and Physiology, New Jersey Medical School, Newark, New Jersey
| | - Kurt A. Fakira
- Department of Pharmacology and Physiology, New Jersey Medical School, Newark, New Jersey
| | - Reema M. Patel
- Department of Pharmacology and Physiology, New Jersey Medical School, Newark, New Jersey
| | - Stacey Brown
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Thibaut Duparc
- INSERM U858, Institut de Medecine Moleculaire de Rangueil, IFR150, Université Paul Sabatier, Toulouse, France
| | - Arnaldo Pica-Mendez
- Department of Pharmacology and Physiology, New Jersey Medical School, Newark, New Jersey
| | - Nicole M. Sanders
- Division of Endocrinology/Metabolism, Veterans Affairs Puget Sound Health Care System, Seattle, Washington
| | - Claude Knauf
- INSERM U858, Institut de Medecine Moleculaire de Rangueil, IFR150, Université Paul Sabatier, Toulouse, France
| | - Philippe Valet
- INSERM U858, Institut de Medecine Moleculaire de Rangueil, IFR150, Université Paul Sabatier, Toulouse, France
| | - Rory J. McCrimmon
- INSERM U858, Institut de Medecine Moleculaire de Rangueil, IFR150, Université Paul Sabatier, Toulouse, France
| | - Annie Beuve
- Department of Pharmacology and Physiology, New Jersey Medical School, Newark, New Jersey
| | - Christophe Magnan
- National Center for Scientific Research, University Paris Diderot, Paris, France
| | - Vanessa H. Routh
- Department of Pharmacology and Physiology, New Jersey Medical School, Newark, New Jersey
- Corresponding author: Vanessa H. Routh,
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