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Schwartz MW, Krinsley JS, Faber CL, Hirsch IB, Brownlee M. Brain Glucose Sensing and the Problem of Relative Hypoglycemia. Diabetes Care 2023; 46:237-244. [PMID: 36701597 PMCID: PMC9887623 DOI: 10.2337/dc22-1445] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Accepted: 11/22/2022] [Indexed: 01/27/2023]
Abstract
"Relative hypoglycemia" is an often-overlooked complication of diabetes characterized by an increase in the glycemic threshold for detecting and responding to hypoglycemia. The clinical relevance of this problem is linked to growing evidence that among patients with critical illness, higher blood glucose in the intensive care unit is associated with higher mortality among patients without diabetes but lower mortality in patients with preexisting diabetes and an elevated prehospitalization HbA1c. Although additional studies are needed, the cardiovascular stress associated with hypoglycemia perception, which can occur at normal or even elevated glucose levels in patients with diabetes, offers a plausible explanation for this difference in outcomes. Little is known, however, regarding how hypoglycemia is normally detected by the brain, much less how relative hypoglycemia develops in patients with diabetes. In this article, we explore the role in hypoglycemia detection played by glucose-responsive sensory neurons supplying peripheral vascular beds and/or circumventricular organs. These observations support a model wherein relative hypoglycemia results from diabetes-associated impairment of this neuronal glucose-sensing process. By raising the glycemic threshold for hypoglycemia perception, this impairment may contribute to the increased mortality risk associated with standard glycemic management of critically ill patients with diabetes.
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Affiliation(s)
- Michael W. Schwartz
- Department of Medicine, University of Washington Medicine Diabetes Institute, Seattle, WA
| | - James S. Krinsley
- Stamford Hospital, Stamford, CT
- Columbia Vagelos College of Physicians and Surgeons, New York, NY
| | - Chelsea L. Faber
- Ivy Brain Tumor Center, Department of Neurosurgery, Barrow Neurological Institute, Phoenix, AZ
| | - Irl B. Hirsch
- Department of Medicine, University of Washington Medicine Diabetes Institute, Seattle, WA
| | - Michael Brownlee
- Einstein Diabetes Research Center, Albert Einstein College of Medicine, Bronx, NY
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2
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The impact of glycaemic load on cognitive performance: A meta-analysis and guiding principles for future research. Neurosci Biobehav Rev 2022; 141:104824. [PMID: 35963545 DOI: 10.1016/j.neubiorev.2022.104824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 08/08/2022] [Accepted: 08/09/2022] [Indexed: 11/23/2022]
Abstract
The effect of breakfast glycaemic load (GL) on cognition was systematically examined. Randomised and non-randomised controlled trials were identified using PubMed, Scopus, and Cochrane Library (up to May 2022). 15 studies involving adults (aged 20 - 80 years) were included. Studies had a low risk, or some concerns, of bias. A random-effects meta-analysis model revealed no effect of GL on cognition up to 119 min post-consumption. However, after 120 min, immediate episodic memory scores were better following a low-GL compared to a high-GL (SMD = 0.16, 95% confidence interval [CI] = -0.00 to 0.32, p = 0.05, I2 = 5%). Subgroup analyses indicated that the benefit was greater in younger adults (<35 years) and those with better GT. A qualitative synthesis of 16 studies involving children and adolescents (aged 5 - 17 years) suggested that a low-GL breakfast may also benefit episodic memory and attention after 120 min. Methodological practises were identified which could explain a failure to detect benefits in some studies. Consequently, guiding principles were developed to optimise future study design.
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Toward the Decipherment of Molecular Interactions in the Diabetic Brain. Biomedicines 2022; 10:biomedicines10010115. [PMID: 35052794 PMCID: PMC8773210 DOI: 10.3390/biomedicines10010115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 01/01/2022] [Accepted: 01/04/2022] [Indexed: 12/14/2022] Open
Abstract
Diabetes mellitus (DM) has been associated with cognitive complications in the brain resulting from acute and chronic metabolic disturbances happening peripherally and centrally. Numerous studies have reported on the morphological, electrophysiological, biochemical, and cognitive changes in the brains of diabetic individuals. The detailed pathophysiological mechanisms implicated in the development of the diabetic cognitive phenotype remain unclear due to intricate molecular changes evolving over time and space. This review provides an insight into recent advances in understanding molecular events in the diabetic brain, focusing on cerebral glucose and insulin uptake, insulin action in the brain, and the role of the brain in the regulation of glucose homeostasis. Fully competent mitochondria are essential for energy metabolism and proper brain function; hence, the potential contribution of mitochondria to the DM-induced impairment of the brain is also discussed.
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Yang SY, Sencadas V, You SS, Jia NZX, Srinivasan SS, Huang HW, Ahmed AE, Liang JY, Traverso G. Powering Implantable and Ingestible Electronics. ADVANCED FUNCTIONAL MATERIALS 2021; 31:2009289. [PMID: 34720792 PMCID: PMC8553224 DOI: 10.1002/adfm.202009289] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Indexed: 05/28/2023]
Abstract
Implantable and ingestible biomedical electronic devices can be useful tools for detecting physiological and pathophysiological signals, and providing treatments that cannot be done externally. However, one major challenge in the development of these devices is the limited lifetime of their power sources. The state-of-the-art of powering technologies for implantable and ingestible electronics is reviewed here. The structure and power requirements of implantable and ingestible biomedical electronics are described to guide the development of powering technologies. These powering technologies include novel batteries that can be used as both power sources and for energy storage, devices that can harvest energy from the human body, and devices that can receive and operate with energy transferred from exogenous sources. Furthermore, potential sources of mechanical, chemical, and electromagnetic energy present around common target locations of implantable and ingestible electronics are thoroughly analyzed; energy harvesting and transfer methods befitting each energy source are also discussed. Developing power sources that are safe, compact, and have high volumetric energy densities is essential for realizing long-term in-body biomedical electronics and for enabling a new era of personalized healthcare.
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Affiliation(s)
- So-Yoon Yang
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Vitor Sencadas
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; School of Mechanical, Materials & Mechatronics Engineering, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Siheng Sean You
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Division of Gastroenterology, Hepatology and Endoscopy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Neil Zi-Xun Jia
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Shriya Sruthi Srinivasan
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Division of Gastroenterology, Hepatology and Endoscopy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Hen-Wei Huang
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Division of Gastroenterology, Hepatology and Endoscopy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Abdelsalam Elrefaey Ahmed
- Division of Gastroenterology, Hepatology and Endoscopy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Jia Ying Liang
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Division of Gastroenterology, Hepatology and Endoscopy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Giovanni Traverso
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Division of Gastroenterology, Hepatology and Endoscopy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
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5
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Craig CM, McLaughlin TL. Defining clinically important hypoglycemia in patients with postbariatric hypoglycemia. Surg Obes Relat Dis 2021; 17:1865-1872. [PMID: 34275761 DOI: 10.1016/j.soard.2021.06.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 05/16/2021] [Accepted: 06/18/2021] [Indexed: 11/25/2022]
Abstract
BACKGROUND Postbariatric hypoglycemia (PBH) is a rare but growing complication of bariatric surgery. Many aspects have yet to be established, including the blood glucose threshold which represents clinically important hypoglycemia in affected patients. OBJECTIVE To confirm the glucose threshold below which neuroglycopenic (NG) symptoms arise in patients with PBH during provoked and real-world hypoglycemia as an indicator of clinically important hypoglycemia. SETTING Stanford University School of Medicine. METHODS Forty patients with PBH were enrolled. Thirty-two patients underwent hypoglycemia provocation in the clinical research unit (CRU) during which symptoms and blood glucose concentrations were assessed. A sensitivity analysis and stepwise linear regression were conducted evaluating relationships between symptoms and glucose levels. To validate CRU findings in the real-world setting, 8 sex-, age-, body mass index (BMI)-, and disease severity-matched patients underwent 20 days of at-home continuous glucose monitoring (CGM), self-monitoring of blood glucose (SMBG), and symptom assessment by electronic diary (eDiary). RESULTS In response to hypoglycemia provocation 19%, 59%, and 22% of patients developed a postprandial glucose nadir <70-54 mg/dL , <54-40 mg/dL, and <40 mg/dL, respectively. Number of NG symptoms was highest when glucose was in the <54-40 mg/dL range, although 23% of those with NG symptoms in this range, and 37% with NG symptoms below this range lacked autonomic symptoms, indicating substantial hypoglycemia unawareness. Sensitivity of symptoms to detect hypoglycemia was poor other than for drowsiness, while specificity was high for all NG symptoms. Confusion, sweating, drowsiness, and incoordination were significant independent predictors of hypoglycemia. Events captured during real-world monitoring mirrored CRU data, showing a spike in NG symptoms in the <54-40 mg/dL range. CGM captured up to 10-fold more events than were patient-perceived and captured by SMBG/eDiary. CONCLUSION Due to the peak in NG symptoms at glucose <54-40 mg/dL during provoked and real-world hypoglycemia, the low sensitivity/high specificity of NG symptoms to detect hypoglycemia, and high prevalence of hypoglycemia unawareness at glucose values <54 mg/dL, we propose that blood glucose <54 mg/dL should be taken to signify clinically important hypoglycemia in patients with established PBH.
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Affiliation(s)
- Colleen M Craig
- Department of Medicine, Division of Endocrinology, Stanford University School of Medicine, Stanford, California.
| | - Tracey L McLaughlin
- Department of Medicine, Division of Endocrinology, Stanford University School of Medicine, Stanford, California
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Abstract
Chronic metabolic diseases, including diabetes and obesity, have become a major global health threat of the twenty-first century. Maintaining glucose homeostasis is essential for survival in mammals. Complex and highly coordinated interactions between glucose-sensing mechanisms and multiple effector systems are essential for controlling glucose levels in the blood. The central nervous system (CNS) plays a crucial role in regulating glucose homeostasis. Growing evidence indicates that disruption of glucose sensing in selective CNS areas, such as the hypothalamus, is closely interlinked with the pathogenesis of obesity and type 2 diabetes mellitus. However, the underlying intracellular mechanisms of glucose sensing in the hypothalamus remain elusive. Here, we review the current literature on hypothalamic glucose-sensing mechanisms and discuss the impact of alterations of these mechanisms on the pathogenesis of diabetes.
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Affiliation(s)
- Nal Ae Yoon
- Institute of Human Nutrition, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY, USA
- Department of Molecular Pharmacology and Therapeutics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY, USA
| | - Sabrina Diano
- Institute of Human Nutrition, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY, USA.
- Department of Molecular Pharmacology and Therapeutics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY, USA.
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7
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Joosten L, Boss M, Jansen T, Brom M, Buitinga M, Aarntzen E, Eriksson O, Johansson L, de Galan B, Gotthardt M. Molecular Imaging of Diabetes. Mol Imaging 2021. [DOI: 10.1016/b978-0-12-816386-3.00041-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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8
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Glucose transporters in brain in health and disease. Pflugers Arch 2020; 472:1299-1343. [PMID: 32789766 PMCID: PMC7462931 DOI: 10.1007/s00424-020-02441-x] [Citation(s) in RCA: 219] [Impact Index Per Article: 54.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 07/20/2020] [Accepted: 07/24/2020] [Indexed: 12/15/2022]
Abstract
Energy demand of neurons in brain that is covered by glucose supply from the blood is ensured by glucose transporters in capillaries and brain cells. In brain, the facilitative diffusion glucose transporters GLUT1-6 and GLUT8, and the Na+-d-glucose cotransporters SGLT1 are expressed. The glucose transporters mediate uptake of d-glucose across the blood-brain barrier and delivery of d-glucose to astrocytes and neurons. They are critically involved in regulatory adaptations to varying energy demands in response to differing neuronal activities and glucose supply. In this review, a comprehensive overview about verified and proposed roles of cerebral glucose transporters during health and diseases is presented. Our current knowledge is mainly based on experiments performed in rodents. First, the functional properties of human glucose transporters expressed in brain and their cerebral locations are described. Thereafter, proposed physiological functions of GLUT1, GLUT2, GLUT3, GLUT4, and SGLT1 for energy supply to neurons, glucose sensing, central regulation of glucohomeostasis, and feeding behavior are compiled, and their roles in learning and memory formation are discussed. In addition, diseases are described in which functional changes of cerebral glucose transporters are relevant. These are GLUT1 deficiency syndrome (GLUT1-SD), diabetes mellitus, Alzheimer’s disease (AD), stroke, and traumatic brain injury (TBI). GLUT1-SD is caused by defect mutations in GLUT1. Diabetes and AD are associated with changed expression of glucose transporters in brain, and transporter-related energy deficiency of neurons may contribute to pathogenesis of AD. Stroke and TBI are associated with changes of glucose transporter expression that influence clinical outcome.
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9
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Xu X, Sehgal AA, Yadav NN, Laterra J, Blair L, Blakeley J, Seidemo A, Coughlin JM, Pomper MG, Knutsson L, van Zijl PCM. d-glucose weighted chemical exchange saturation transfer (glucoCEST)-based dynamic glucose enhanced (DGE) MRI at 3T: early experience in healthy volunteers and brain tumor patients. Magn Reson Med 2020; 84:247-262. [PMID: 31872916 PMCID: PMC7083699 DOI: 10.1002/mrm.28124] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 10/30/2019] [Accepted: 11/19/2019] [Indexed: 12/11/2022]
Abstract
PURPOSE Dynamic glucose enhanced (DGE) MRI has shown potential for imaging glucose delivery and blood-brain barrier permeability at fields of 7T and higher. Here, we evaluated issues involved with translating d-glucose weighted chemical exchange saturation transfer (glucoCEST) experiments to the clinical field strength of 3T. METHODS Exchange rates of the different hydroxyl proton pools and the field-dependent T2 relaxivity of water in d-glucose solution were used to simulate the water saturation spectra (Z-spectra) and DGE signal differences as a function of static field strength B0 , radiofrequency field strength B1 , and saturation time tsat . Multislice DGE experiments were performed at 3T on 5 healthy volunteers and 3 glioma patients. RESULTS Simulations showed that DGE signal decreases with B0 , because of decreased contributions of glucoCEST and transverse relaxivity, as well as coalescence of the hydroxyl and water proton signals in the Z-spectrum. At 3T, because of this coalescence and increased interference of direct water saturation and magnetization transfer contrast, the DGE effect can be assessed over a broad range of saturation frequencies. Multislice DGE experiments were performed in vivo using a B1 of 1.6 µT and a tsat of 1 second, leading to a small glucoCEST DGE effect at an offset frequency of 2 ppm from the water resonance. Motion correction was essential to detect DGE effects reliably. CONCLUSION Multislice glucoCEST-based DGE experiments can be performed at 3T with sufficient temporal resolution. However, the effects are small and prone to motion influence. Therefore, motion correction should be used when performing DGE experiments at clinical field strengths.
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Affiliation(s)
- Xiang Xu
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, MD, USA
| | - Akansha Ashvani Sehgal
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, MD, USA
| | - Nirbhay N. Yadav
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, MD, USA
| | - John Laterra
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Lindsay Blair
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jaishri Blakeley
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Anina Seidemo
- Department of Medical Radiation Physics, Lund University, Lund, Sweden
| | - Jennifer M. Coughlin
- Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Martin G. Pomper
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Linda Knutsson
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Medical Radiation Physics, Lund University, Lund, Sweden
| | - Peter C. M. van Zijl
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, MD, USA
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10
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Abstract
The effect on cognitive test scores of generating differences in postprandial glycaemia using test foods or beverages has been inconsistent. Methodological issues may account for some of the variable results requiring further investigation using strong study designs into the relationship between glycaemia and cognitive functioning. The objective of this study was to determine the effects of postprandial glycaemia on cognitive function by examining cognition after consumption of foods that differ only by the rate of digestion of available carbohydrate in a population of young adults. In a double-blind, randomised, crossover trial, sixty-five participants received trifle sweetened either with a higher-glycaemic index (GI) sugar (sucrose; GI 65) or a lower-GI sugar (isomaltulose; GI 34). Cognitive tests were completed prior to trifle consumption, and 60 and 120 min after. There was no between-trifle difference at 60 min in performance on free word recall (0·0 (95 % CI -0·6, 0·5)), short delay word recall (0·0 (95 % CI -0·5, 0·5)), long delay word recall (0·0 (95 % CI -0·6, 0·6)), letter-number sequence recall (0·3 (95 % CI - 0·2, 0·7)) and visuo-spatial recall (-0·2 (95 % CI -0·6, 0·2)) tests. At 120 min, no difference was detected in any of these tests. The participants performed 7·7 (95 % CI 0·5,14·9) s faster in Reitan's trail-making test B 60 min after the higher-GI trifle than the lower-GI trifle (P = 0·037). Our findings of a null effect on memory are generally consistent with other works in which blinding and robust control for confounding have been used.
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11
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Banks WA. The Blood-Brain Barrier Interface in Diabetes Mellitus: Dysfunctions, Mechanisms and Approaches to Treatment. Curr Pharm Des 2020; 26:1438-1447. [DOI: 10.2174/1381612826666200325110014] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 02/27/2020] [Indexed: 12/24/2022]
Abstract
Diabetes mellitus (DM) is one of the most common diseases in the world. Among its effects are an increase in the risk of cognitive impairment, including Alzheimer’s disease, and blood-brain barrier (BBB) dysfunction. DM is characterized by high blood glucose levels that are caused by either lack of insulin (Type I) or resistance to the actions of insulin (Type II). The phenotypes of these two types are dramatically different, with Type I animals being thin, with low levels of leptin as well as insulin, whereas Type II animals are often obese with high levels of both leptin and insulin. The best characterized change in BBB dysfunction is that of disruption. The brain regions that are disrupted, however, vary between Type I vs Type II DM, suggesting that factors other than hyperglycemia, perhaps hormonal factors such as leptin and insulin, play a regionally diverse role in BBB vulnerability or protection. Some BBB transporters are also altered in DM, including P-glycoprotein, lowdensity lipoprotein receptor-related protein 1, and the insulin transporter as other functions of the BBB, such as brain endothelial cell (BEC) expression of matrix metalloproteinases (MMPs) and immune cell trafficking. Pericyte loss secondary to the increased oxidative stress of processing excess glucose through the Krebs cycle is one mechanism that has shown to result in BBB disruption. Vascular endothelial growth factor (VEGF) induced by advanced glycation endproducts can increase the production of matrix metalloproteinases, which in turn affects tight junction proteins, providing another mechanism for BBB disruption as well as effects on P-glycoprotein. Through the enhanced expression of the redox-related mitochondrial transporter ABCB10, redox-sensitive transcription factor NF-E2 related factor-2 (Nrf2) inhibits BEC-monocyte adhesion. Several potential therapies, in addition to those of restoring euglycemia, can prevent some aspects of BBB dysfunction. Carbonic anhydrase inhibition decreases glucose metabolism and so reduces oxidative stress, preserving pericytes and blocking or reversing BBB disruption. Statins or N-acetylcysteine can reverse the BBB opening in some models of DM, fibroblast growth factor-21 improves BBB permeability through an Nrf2-dependent pathway, and nifedipine or VEGF improves memory in DM models. In summary, DM alters various aspects of BBB function through a number of mechanisms. A variety of treatments based on those mechanisms, as well as restoration of euglycemia, may be able to restore BBB functions., including reversal of BBB disruption.
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Affiliation(s)
- William A. Banks
- Geriatric Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108, United States
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12
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Bednařík P, Henry PG, Khowaja A, Rubin N, Kumar A, Deelchand D, Eberly LE, Seaquist E, Öz G, Moheet A. Hippocampal Neurochemical Profile and Glucose Transport Kinetics in Patients With Type 1 Diabetes. J Clin Endocrinol Metab 2020; 105:5601935. [PMID: 31637440 PMCID: PMC7046023 DOI: 10.1210/clinem/dgz062] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 09/27/2019] [Indexed: 01/28/2023]
Abstract
CONTEXT Longstanding type 1 diabetes (T1D) may lead to alterations in hippocampal neurochemical profile. Upregulation of hippocampal glucose transport as a result of recurrent exposure to hypoglycemia may preserve cognitive function during future hypoglycemia in subjects with T1D and impaired awareness of hypoglycemia (IAH). The effect of T1D on hippocampal neurochemical profile and glucose transport is unknown. OBJECTIVE To test the hypothesis that hippocampal neurochemical composition is altered in T1D and glucose transport is upregulated in T1D with IAH. DESIGN AND PARTICIPANTS Hippocampal neurochemical profile was measured with single-voxel magnetic resonance spectroscopy at 3T during euglycemia in 18 healthy controls (HC), 10 T1D with IAH, and 12 T1D with normal awareness to hypoglycemia (NAH). Additionally, 12 HC, 8 T1D-IAH, and 6 T1D-NAH were scanned during hyperglycemia to assess hippocampal glucose transport with metabolic modeling. SETTING University medical center. MAIN OUTCOME MEASURES Concentrations of hippocampal neurochemicals measured during euglycemia and ratios of maximal transport rate to cerebral metabolic rate of glucose (Tmax/CMRGlc), derived from magnetic resonance spectroscopy-measured hippocampal glucose as a function of plasma glucose. RESULTS Comparison of hippocampal neurochemical profile revealed no group differences (HC, T1D, T1D-IAH, and T1D-NAH). The ratio Tmax/CMRGlc was not significantly different between the groups, T1D-IAH (1.58 ± 0.09) and HC (1.65 ± 0.07, P = 0.54), between T1D-NAH (1.50 ± 0.09) and HC (P = 0.19), and between T1D-IAH and T1D-NAH (P = 0.53). CONCLUSIONS Subjects with T1D with sufficient exposure to recurrent hypoglycemia to create IAH did not have alteration of Tmax/CMRglc or neurochemical profile compared with participants with T1D-NAH or HC.
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Affiliation(s)
- Petr Bednařík
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, Minnesota
- High Field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
- Department of Imaging Methods, Faculty of Medicine, University of Ostrava, Ostrava, Czech Republic
| | - Pierre-Gilles Henry
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota
| | - Amir Khowaja
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Nathan Rubin
- Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, Minnesota
| | - Anjali Kumar
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Dinesh Deelchand
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota
| | - Lynn E Eberly
- Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, Minnesota
| | - Elizabeth Seaquist
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Gülin Öz
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota
| | - Amir Moheet
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, Minnesota
- Correspondence and Reprint Requests: Amir Moheet, MBBS, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, MMC 101, 420 Delaware St. SE, Minneapolis, MN 55455. E-mail:
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13
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Rothman DL, de Graaf RA, Hyder F, Mason GF, Behar KL, De Feyter HM. In vivo 13 C and 1 H-[ 13 C] MRS studies of neuroenergetics and neurotransmitter cycling, applications to neurological and psychiatric disease and brain cancer. NMR IN BIOMEDICINE 2019; 32:e4172. [PMID: 31478594 DOI: 10.1002/nbm.4172] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 04/30/2019] [Accepted: 05/07/2019] [Indexed: 06/10/2023]
Abstract
In the last 25 years 13 C MRS has been established as the only noninvasive method for measuring glutamate neurotransmission and cell specific neuroenergetics. Although technically and experimentally challenging 13 C MRS has already provided important new information on the relationship between neuroenergetics and neuronal function, the high energy cost of brain function in the resting state and the role of altered neuroenergetics and neurotransmitter cycling in disease. In this paper we review the metabolic and neurotransmitter pathways that can be measured by 13 C MRS and key findings on the linkage between neuroenergetics, neurotransmitter cycling, and brain function. Applications of 13 C MRS to neurological and psychiatric disease as well as brain cancer are reviewed. Recent technological developments that may help to overcome spatial resolution and brain coverage limitations of 13 C MRS are discussed.
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Affiliation(s)
- Douglas L Rothman
- Departments of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
- Department of Biomedical Engineering, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
- Departments of Radiology and Biomedical Imaging, and Biomedical Engineering, Magnetic Resonance Research Center, Yale University School of Medicine, 300 Cedar Street, P.O. Box 208043, New Haven, CT, USA
| | - Robin A de Graaf
- Departments of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
- Department of Biomedical Engineering, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Fahmeed Hyder
- Departments of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
- Department of Biomedical Engineering, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Graeme F Mason
- Departments of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Kevin L Behar
- Department of Psychiatry, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Henk M De Feyter
- Departments of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
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14
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Liao HW, Saver J, Yeh HC, Chen CHS, Wu YL, Lee M, Ovbiagele B. Low fasting glucose and future risks of major adverse outcomes in people without baseline diabetes or cardiovascular disease: a systematic review and meta-analysis. BMJ Open 2019; 9:e026010. [PMID: 31266835 PMCID: PMC6609056 DOI: 10.1136/bmjopen-2018-026010] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
OBJECTIVE To investigate the link between low fasting blood glucose levels and all-cause mortality and cardiovascular outcomes among people without baseline diabetes or cardiovascular disease. DESIGN Systematic review and meta-analysis. DATA SOURCES PubMed and Embase (1966-February 2019). SELECTION CRITERIA Prospective cohort studies were included for meta-analysis if they reported adjusted HRs with 95% CIs for associations between risk of all-cause mortality, stroke, major cardiovascular events, coronary heart disease and low fasting glucose levels (<4.6 mmol/L and/or 4.0 mmol/L, respectively) versus normal fasting glucose levels. DATA EXTRACTION AND STATISTICAL ANALYSIS Two independent reviewers extracted data from eligible studies. Heterogeneity was assessed by p value of χ2 tests and I2. We assessed four characteristics for each included study based on items developed by the US Preventive Task Force, as well as the modified checklist used in previous studies. RESULTS Eleven articles (consisting of 129 prospective cohort studies) with 2 674 882 participants without diabetes and cardiovascular disease at baseline were included in this meta-analysis. Pooled results from the random effects model showed increased risks of all-cause mortality (HR: 1.56; 95% CI 1.09 to 2.23), total stroke (HR: 1.08, 95% CI 1.03 to 1.13) and ischaemic stroke (HR: 1.06, 95% CI 1.01 to 1.10), and major cardiovascular events (HR: 1.05, 95% CI 1.03 to 1.07) among people with a fasting glucose <4.0 mmol/L, as compared with people with normal fasting glucose. The less stringent low fasting glucose level, <4.6 mmol/L, was not associated with increased risk of any endpoints. DISCUSSION AND CONCLUSIONS Among people without baseline diabetes or cardiovascular disease, a fasting blood glucose level of <4.0 mmol/L is associated with increased risk of all-cause mortality, major cardiovascular events and stroke.
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Affiliation(s)
- Hung-Wei Liao
- Department of Nephrology, Chinru Clinic, Taipei, Taiwan
| | - Jeffrey Saver
- Department of Neurology, University of California System, Los Angeles, California, USA
| | - Hsin-Chieh Yeh
- School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA
| | | | - Yi-Ling Wu
- Institute of Population Health Sciences, National Health Research Institutes, Zhunan, Taiwan
| | - Meng Lee
- Department of Neurology, Chang Gung University, Kwei-Shan, Taoyuan, Taiwan
| | - Bruce Ovbiagele
- Department of Neurology, University of California System, San Francisco, California, USA
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15
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Hwang JJ, Jiang L, Sanchez Rangel E, Fan X, Ding Y, Lam W, Leventhal J, Dai F, Rothman DL, Mason GF, Sherwin RS. Glycemic Variability and Brain Glucose Levels in Type 1 Diabetes. Diabetes 2019; 68:163-171. [PMID: 30327383 PMCID: PMC6302539 DOI: 10.2337/db18-0722] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 10/09/2018] [Indexed: 02/06/2023]
Abstract
The impact of glycemic variability on brain glucose transport kinetics among individuals with type 1 diabetes mellitus (T1DM) remains unclear. Fourteen individuals with T1DM (age 35 ± 4 years; BMI 26.0 ± 1.4 kg/m2; HbA1c 7.6 ± 0.3) and nine healthy control participants (age 32 ± 4; BMI 23.1 ± 0.8; HbA1c 5.0 ± 0.1) wore a continuous glucose monitor (Dexcom) to measure hypoglycemia, hyperglycemia, and glycemic variability for 5 days followed by 1H MRS scanning in the occipital lobe to measure the change in intracerebral glucose levels during a 2-h glucose clamp (target glucose concentration 220 mg/dL). Hyperglycemic clamps were also performed in a rat model of T1DM to assess regional differences in brain glucose transport and metabolism. Despite a similar change in plasma glucose levels during the hyperglycemic clamp, individuals with T1DM had significantly smaller increments in intracerebral glucose levels (P = 0.0002). Moreover, among individuals with T1DM, the change in brain glucose correlated positively with the lability index (r = 0.67, P = 0.006). Consistent with findings in humans, streptozotocin-treated rats had lower brain glucose levels in the cortex, hippocampus, and striatum compared with control rats. These findings that glycemic variability is associated with brain glucose levels highlight the need for future studies to investigate the impact of glycemic variability on brain glucose kinetics.
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Affiliation(s)
- Janice J Hwang
- Section of Endocrinology, Yale School of Medicine, New Haven, CT
| | - Lihong Jiang
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT
| | | | - Xiaoning Fan
- Section of Endocrinology, Yale School of Medicine, New Haven, CT
| | - Yuyan Ding
- Section of Endocrinology, Yale School of Medicine, New Haven, CT
| | - Wai Lam
- Section of Endocrinology, Yale School of Medicine, New Haven, CT
| | | | - Feng Dai
- Yale Center for Analytical Sciences, Yale School of Public Health, New Haven, CT
| | - Douglas L Rothman
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT
| | - Graeme F Mason
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT
- Department of Psychiatry, Yale School of Medicine, New Haven, CT
| | - Robert S Sherwin
- Section of Endocrinology, Yale School of Medicine, New Haven, CT
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16
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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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17
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ŽOUREK M, KYSELOVÁ P, ČECHUROVÁ D, RUŠAVÝ Z. Acute Glycemic Changes in Brain and Subcutaneous Tissue Measured by Continuous Glucose Monitoring System in Hereditary Hypertriglyceridemic Rat. Physiol Res 2018; 67:127-131. [DOI: 10.33549/physiolres.933620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Parallel glucose measurements in blood and other different tissues give us knowledge about dynamics of glycemia changes, which depend on vascularization, distribution space and local utilization by tissues. Such information is important for the understanding of glucose homeostasis and regulation. The aim of our study was to determine the time-lag between blood, brain, and adipose tissue during rapid glucose changes in a male hHTG rat (n=15). The CGMS sensor Guardian RT (Minimed/Medtronic, USA) was inserted into the brain and into the abdominal subcutaneous tissue. Fixed insulin and variable rate of glucose infusion was used to maintain euglycemia during sensor calibration period. At 0 min, 0.5 g/kg of bolus of glucose was administered, and at 50 min, 5 IU/kg of bolus of insulin was administered. Further glucose and insulin infusion was stopped at this time. The experiment was finished at 130 min and animals were euthanized. The time-shift between glycemia changes in blood, brain, and subcutaneous tissue was calculated by identification of the ideal correlation function. Moreover, the time to achieve 90 % of the maximum glucose excursion after intervention (T90) was measured to compare our data with the literature. The time-lag blood vs. brain and blood vs. subcutaneous tissue was 10 (10; 15) min and 15 (15; 25) min, respectively. The difference was statistically significant (P=0.01). T90 after glucose bolus in brain and subcutaneous tissue was 10 min (8.75; 15) and 15 min (13.75; 21.25), respectively. T90 after insulin bolus in brain and subcutaneous tissue was 10 min (10; 15) and 20 min (20; 27.5), respectively. To the contrary, with literature, our results showed earlier glucose level changes in brain in comparison with subcutaneous tissue after glucose and insulin boluses. Our results suggest that glucose dynamics is different within monitored tissues under rapid changing glucose level and we can expect similar behavior in humans. Improved knowledge about glucose distribution and dynamics is important for avoiding hypoglycemia.
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Affiliation(s)
- M. ŽOUREK
- First Department of Medicine, Charles University in Prague, Medical School and Teaching Hospital in Pilsen, Pilsen, Czech Republic
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18
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Lee JJ, Khoury N, Shackleford AM, Nelson S, Herrera H, Antenor-Dorsey JA, Semenkovich K, Shimony JS, Powers WJ, Cryer PE, Arbeláez AM. Dissociation Between Hormonal Counterregulatory Responses and Cerebral Glucose Metabolism During Hypoglycemia. Diabetes 2017; 66:2964-2972. [PMID: 28970283 PMCID: PMC5697948 DOI: 10.2337/db17-0574] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 09/23/2017] [Indexed: 11/13/2022]
Abstract
Hypoglycemia is the most common complication of diabetes, causing morbidity and death. Recurrent hypoglycemia alters the cascade of physiological and behavioral responses that maintain euglycemia. The extent to which these responses are normally triggered by decreased whole-brain cerebral glucose metabolism (CMRglc) has not been resolved by previous studies. We measured plasma counterregulatory hormonal responses and whole-brain CMRglc (along with blood-to-brain glucose transport rates and brain glucose concentrations) with 1-[11C]-d-glucose positron emission tomography during hyperinsulinemic glucose clamps at nominal plasma glucose concentrations of 90, 75, 60, and 45 mg/dL (5.0, 4.2, 3.3, and 2.5 mmol/L) in 18 healthy young adults. Clear evidence of hypoglycemic physiological counterregulation was first demonstrated between 75 mg/dL (4.2 mmol/L) and 60 mg/dL (3.3 mmol/L) with increases in both plasma epinephrine (P = 0.01) and glucagon (P = 0.01). In contrast, there was no statistically significant change in CMRglc (P = 1.0) between 75 mg/dL (4.2 mmol/L) and 60 mg/dL (3.3 mmol/L), whereas CMRglc significantly decreased (P = 0.02) between 60 mg/dL (3.3 mmol/L) and 45 mg/dL (2.5 mmol/L). Therefore, the increased epinephrine and glucagon secretion with declining plasma glucose concentrations is not in response to a decrease in whole-brain CMRglc.
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Affiliation(s)
- John J Lee
- Mallinckrodt Institute of Radiology, Washington University School of Medicine in St. Louis, St. Louis, MO
| | - Nadia Khoury
- Department of Medicine, Washington University School of Medicine in St. Louis, St. Louis, MO
| | - Angela M Shackleford
- Department of Pediatrics, Washington University School of Medicine in St. Louis, St. Louis, MO
| | - Suzanne Nelson
- Division of Biostatistics, Washington University School of Medicine in St. Louis, St. Louis, MO
| | - Hector Herrera
- Division of Biostatistics, Washington University School of Medicine in St. Louis, St. Louis, MO
| | - Jo Ann Antenor-Dorsey
- Department of Psychiatry, Washington University School of Medicine in St. Louis, St. Louis, MO
| | - Katherine Semenkovich
- Department of Pediatrics, Washington University School of Medicine in St. Louis, St. Louis, MO
| | - Joshua S Shimony
- Mallinckrodt Institute of Radiology, Washington University School of Medicine in St. Louis, St. Louis, MO
| | - William J Powers
- Department of Neurology, University of North Carolina, Chapel Hill, NC
| | - Philip E Cryer
- Department of Medicine, Washington University School of Medicine in St. Louis, St. Louis, MO
| | - Ana María Arbeláez
- Department of Pediatrics, Washington University School of Medicine in St. Louis, St. Louis, MO
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19
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Seaquist ER, Moheet A, Kumar A, Deelchand DK, Terpstra M, Kubisiak K, Eberly LE, Henry PG, Joers JM, Öz G. Hypothalamic Glucose Transport in Humans During Experimentally Induced Hypoglycemia-Associated Autonomic Failure. J Clin Endocrinol Metab 2017; 102:3571-3580. [PMID: 28911152 PMCID: PMC5587056 DOI: 10.1210/jc.2017-00477] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 07/17/2017] [Indexed: 01/15/2023]
Abstract
CONTEXT Upregulated brain glucose transport in response to recurrent hypoglycemia may contribute to the development of hypoglycemia-associated autonomic failure (HAAF) and impaired awareness of hypoglycemia. Whether recurrent hypoglycemia alters glucose transport in the hypothalamus is unknown. OBJECTIVE To test the hypothesis that hypothalamic glucose transport will increase in healthy volunteers preconditioned with recurrent hypoglycemia to induce HAAF. SETTING University medical center. DESIGN AND PARTICIPANTS Thirteen healthy subjects underwent paired euglycemic and hypoglycemic preconditioning studies separated by at least 1 month. Following preconditioning, hypothalamic glucose transport was measured by magnetic resonance spectroscopy (MRS) in the afternoon on day 2 of each preconditioning protocol. OUTCOME MEASURE The ratio of maximal transport rate to cerebral metabolic rate of glucose (Tmax/CMRglc), obtained from MRS-measured glucose in the hypothalamus as a function of plasma glucose. RESULTS HAAF was successfully induced based on lower epinephrine, glucagon, and cortisol during the third vs first hypoglycemic preconditioning clamp (P ≤ 0.01). Hypothalamic glucose transport was not different following recurrent euglycemia vs hypoglycemia (Tmax/CMRglc 1.62 ± 0.09 after euglycemia preconditioning and 1.75 ± 0.14 after hypoglycemia preconditioning; P was not significant). Hypothalamic glucose concentrations measured by MRS were not different following the two preconditioning protocols. CONCLUSIONS Glucose transport kinetics in the hypothalamus of healthy humans with experimentally induced HAAF were not different from those measured without HAAF. Future studies of patients with diabetes and impaired awareness of hypoglycemia will be necessary to determine if the existence of the diabetes state is required for this adaptation to hypoglycemia to occur.
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Affiliation(s)
- Elizabeth R. Seaquist
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, Minnesota 55455
| | - Amir Moheet
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, Minnesota 55455
| | - Anjali Kumar
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, Minnesota 55455
| | - Dinesh K. Deelchand
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota 55455
| | - Melissa Terpstra
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota 55455
| | - Kristine Kubisiak
- Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, Minnesota 55455
| | - Lynn E. Eberly
- Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, Minnesota 55455
| | - Pierre-Gilles Henry
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota 55455
| | - James M. Joers
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota 55455
| | - Gülin Öz
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota 55455
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20
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Seke Etet PF, Farahna M, Satti GMH, Bushara YM, El-Tahir A, Hamza MA, Osman SY, Dibia AC, Vecchio L. Garcinia kola seeds may prevent cognitive and motor dysfunctions in a type 1 diabetes mellitus rat model partly by mitigating neuroinflammation. JOURNAL OF COMPLEMENTARY & INTEGRATIVE MEDICINE 2017; 14:/j/jcim.2017.14.issue-3/jcim-2016-0167/jcim-2016-0167.xml. [PMID: 28889733 DOI: 10.1515/jcim-2016-0167] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 02/21/2017] [Indexed: 01/06/2023]
Abstract
Background We reported recently that extracts of seeds of Garcinia kola, a plant with established hypoglycemic properties, prevented the loss of inflammation-sensible neuronal populations like Purkinje cells in a rat model of type 1 diabetes mellitus (T1DM). Here, we assessed G. kola extract ability to prevent the early cognitive and motor dysfunctions observed in this model. Methods Rats made diabetic by single injection of streptozotocin were treated daily with either vehicle solution (diabetic control group), insulin, or G. kola extract from the first to the 6th week post-injection. Then, cognitive and motor functions were assessed using holeboard and vertical pole behavioral tests, and animals were sacrificed. Brains were dissected out, cut, and processed for Nissl staining and immunohistochemistry. Results Hyperglycemia (209.26 %), body weight loss (-12.37 %), and T1DM-like cognitive and motor dysfunctions revealed behavioral tests in diabetic control animals were not observed in insulin and extract-treated animals. Similar, expressions of inflammation markers tumor necrosis factor (TNF), iba1 (CD68), and Glial fibrillary acidic protein (GFAP), as well as decreases of neuronal density in regions involved in cognitive and motor functions (-49.56 % motor cortex, -33.24 % medial septal nucleus, -41.8 % /-37.34 % cerebellar Purkinje /granular cell layers) were observed in diabetic controls but not in animals treated with insulin or G. kola. Conclusions Our results indicate that T1DM-like functional alterations are mediated, at least partly, by neuroinflammation and neuronal loss in this model. The prevention of the development of such alterations by early treatment with G. kola confirms the neuroprotective properties of the plant and warrant further mechanistic studies, considering the potential for human disease.
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21
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van der Harg JM, Eggels L, Bangel FN, Ruigrok SR, Zwart R, Hoozemans JJM, la Fleur SE, Scheper W. Insulin deficiency results in reversible protein kinase A activation and tau phosphorylation. Neurobiol Dis 2017; 103:163-173. [PMID: 28400135 DOI: 10.1016/j.nbd.2017.04.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 03/13/2017] [Accepted: 04/05/2017] [Indexed: 12/25/2022] Open
Abstract
Alzheimer's disease (AD) is a highly prevalent multifactorial disease for which Diabetes Mellitus (DM) is a risk factor. Abnormal phosphorylation and aggregation of tau is a key hallmark of AD. In animal models, DM induces or exacerbates the phosphorylation of tau, suggesting that DM may influence the risk at AD by directly facilitating tau pathology. Previously we reported that tau phosphorylation induced in response to metabolic stress is reversible. Since identification and understanding of early players in tau pathology is pivotal for therapeutic intervention, we here investigated the mechanism underlying tau phosphorylation in the diabetic brain and its potential for reversibility. To model DM we used streptozotocin-treatment to induce insulin deficiency in rats. Insulin depletion leads to increased tau phosphorylation in the brain and we investigated the activation status of known tau kinases and phosphatases in this model. We identified protein kinase A (PKA) as a tau kinase activated by DM in the brain. The potential relevance of this signaling pathway to AD pathogenesis is indicated by the increased level of active PKA in temporal cortex of early stage AD patients. Our data indicate that activation of PKA and tau phosphorylation are associated with insulin deficiency per se, rather than the downstream energy deprivation. In vitro studies confirm that insulin deficiency results in PKA activation and tau phosphorylation. Strikingly, both active PKA and induced tau phosphorylation are reversed upon insulin treatment in the steptozotocin animal model. Our data identify insulin deficiency as a direct trigger that induces the activity of the tau kinase PKA and results in tau phosphorylation. The reversibility upon insulin treatment underscores the potential of insulin as an early disease-modifying intervention in AD and other tauopathies.
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Affiliation(s)
- Judith M van der Harg
- Dept. of Genome Analysis, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Dept. of Functional Genomics, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience VU University, Amsterdam, The Netherlands.
| | - Leslie Eggels
- Dept. Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
| | - Fabian N Bangel
- Dept. of Functional Genomics, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience VU University, Amsterdam, The Netherlands; Dept. of Clinical Genetics and Alzheimer Center, VU University Medical Center, Amsterdam, The Netherlands.
| | - Silvie R Ruigrok
- Dept. of Functional Genomics, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience VU University, Amsterdam, The Netherlands.
| | - Rob Zwart
- Dept. of Genome Analysis, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
| | | | - Susanne E la Fleur
- Dept. Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
| | - Wiep Scheper
- Dept. of Genome Analysis, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Dept. of Functional Genomics, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience VU University, Amsterdam, The Netherlands; Dept. of Clinical Genetics and Alzheimer Center, VU University Medical Center, Amsterdam, The Netherlands.
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22
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van Bussel FCG, Backes WH, Hofman PAM, van Oostenbrugge RJ, van Boxtel MPJ, Verhey FRJ, Steinbusch HWM, Schram MT, Stehouwer CDA, Wildberger JE, Jansen JFA. Cerebral Pathology and Cognition in Diabetes: The Merits of Multiparametric Neuroimaging. Front Neurosci 2017; 11:188. [PMID: 28424581 PMCID: PMC5380729 DOI: 10.3389/fnins.2017.00188] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 03/21/2017] [Indexed: 12/19/2022] Open
Abstract
Type 2 diabetes mellitus is associated with accelerated cognitive decline and various cerebral abnormalities visible on MRI. The exact pathophysiological mechanisms underlying cognitive decline in diabetes still remain to be elucidated. In addition to conventional images, MRI offers a versatile set of novel contrasts, including blood perfusion, neuronal function, white matter microstructure, and metabolic function. These more-advanced multiparametric MRI contrasts and the pertaining parameters are able to reveal abnormalities in type 2 diabetes, which may be related to cognitive decline. To further elucidate the nature of the link between diabetes, cognitive decline, and brain abnormalities, and changes over time thereof, biomarkers are needed which can be provided by advanced MRI techniques. This review summarizes to what extent MRI, especially advanced multiparametric techniques, can elucidate the underlying neuronal substrate that reflects the cognitive decline in type 2 diabetes.
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Affiliation(s)
- Frank C G van Bussel
- Department of Radiology, Maastricht University Medical CenterMaastricht, Netherlands.,School for Mental Health and Neuroscience, Maastricht University Medical CenterMaastricht, Netherlands
| | - Walter H Backes
- Department of Radiology, Maastricht University Medical CenterMaastricht, Netherlands.,School for Mental Health and Neuroscience, Maastricht University Medical CenterMaastricht, Netherlands
| | - Paul A M Hofman
- Department of Radiology, Maastricht University Medical CenterMaastricht, Netherlands.,School for Mental Health and Neuroscience, Maastricht University Medical CenterMaastricht, Netherlands
| | - Robert J van Oostenbrugge
- School for Mental Health and Neuroscience, Maastricht University Medical CenterMaastricht, Netherlands.,Department of Neurology, Maastricht University Medical CenterMaastricht, Netherlands.,Cardiovascular Research Institute Maastricht, Maastricht University Medical CenterMaastricht, Netherlands
| | - Martin P J van Boxtel
- School for Mental Health and Neuroscience, Maastricht University Medical CenterMaastricht, Netherlands.,Department of Psychiatry and Neuropsychology, Maastricht University Medical CenterMaastricht, Netherlands
| | - Frans R J Verhey
- School for Mental Health and Neuroscience, Maastricht University Medical CenterMaastricht, Netherlands.,Department of Psychiatry and Neuropsychology, Maastricht University Medical CenterMaastricht, Netherlands
| | - Harry W M Steinbusch
- School for Mental Health and Neuroscience, Maastricht University Medical CenterMaastricht, Netherlands.,Department of Psychiatry and Neuropsychology, Maastricht University Medical CenterMaastricht, Netherlands
| | - Miranda T Schram
- Cardiovascular Research Institute Maastricht, Maastricht University Medical CenterMaastricht, Netherlands.,Department of Internal Medicine, Maastricht University Medical CenterMaastricht, Netherlands
| | - Coen D A Stehouwer
- Cardiovascular Research Institute Maastricht, Maastricht University Medical CenterMaastricht, Netherlands.,Department of Internal Medicine, Maastricht University Medical CenterMaastricht, Netherlands
| | - Joachim E Wildberger
- Department of Radiology, Maastricht University Medical CenterMaastricht, Netherlands.,Cardiovascular Research Institute Maastricht, Maastricht University Medical CenterMaastricht, Netherlands
| | - Jacobus F A Jansen
- Department of Radiology, Maastricht University Medical CenterMaastricht, Netherlands.,School for Mental Health and Neuroscience, Maastricht University Medical CenterMaastricht, Netherlands
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23
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Farahna M, Seke Etet PF, Osman SY, Yurt KK, Amir N, Vecchio L, Aydin I, Aldebasi YH, Sheikh A, Chijuka JC, Kaplan S, Adem A. Garcinia kola aqueous suspension prevents cerebellar neurodegeneration in long-term diabetic rat - a type 1 diabetes mellitus model. JOURNAL OF ETHNOPHARMACOLOGY 2017; 195:159-165. [PMID: 27825990 DOI: 10.1016/j.jep.2016.11.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 08/04/2016] [Accepted: 11/02/2016] [Indexed: 06/06/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE The development of compounds able to improve metabolic syndrome and mitigate complications caused by inappropriate glycemic control in type 1 diabetes mellitus is challenging. The medicinal plant with established hypoglycemic properties Garcinia kola Heckel might have the potential to mitigate diabetes mellitus metabolic syndrome and complications. AIM OF THE STUDY We have investigated the neuroprotective properties of a suspension of G. kola seeds in long-term type 1 diabetes mellitus rat model. MATERIALS AND METHODS Wistar rats, made diabetic by single injection of streptozotocin were monitored for 8 months. Then, they were administered with distilled water or G. kola oral aqueous suspension daily for 30 days. Body weight and glycemia were determined before and after treatment. After sacrifice, cerebella were dissected out and processed for stereological quantification of Purkinje cells. Histopathological and immunohistochemical analyses of markers of neuroinflammation and neurodegeneration were performed. RESULTS Purkinje cell counts were significantly increased, and histopathological signs of apoptosis and neuroinflammation decreased, in diabetic animals treated with G. kola compared to diabetic rats given distilled water. Glycemia was also markedly improved and body weight restored to non-diabetic control values, following G. kola treatment. CONCLUSIONS These results suggest that G. kola treatment improved the general condition of long-term diabetic rats and protected Purkinje cells partly by improving the systemic glycemia and mitigating neuroinflammation.
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Affiliation(s)
- Mohammed Farahna
- Department of Basic Health Sciences, College of Applied Medical Sciences, Qassim University, 51452 Buraydah, Saudi Arabia.
| | - Paul F Seke Etet
- Department of Basic Health Sciences, College of Applied Medical Sciences, Qassim University, 51452 Buraydah, Saudi Arabia
| | - Sayed Y Osman
- Department of Basic Health Sciences, College of Applied Medical Sciences, Qassim University, 51452 Buraydah, Saudi Arabia; Department of Biochemistry and Molecular Biology, Faculty of Science and Technology, Al-Neelain University, Khartoum, Sudan
| | - Kıymet K Yurt
- Department of Histology and Embryology, Medical Faculty, Ondokuz Mayis University, 55139 Samsun, Turkey
| | - Naheed Amir
- Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box 17666, Al Ain, UAE
| | - Lorella Vecchio
- Department of Basic Health Sciences, College of Applied Medical Sciences, Qassim University, 51452 Buraydah, Saudi Arabia
| | - Isınsu Aydin
- Department of Histology and Embryology, Medical Faculty, Ondokuz Mayis University, 55139 Samsun, Turkey
| | - Yousef H Aldebasi
- Department of Optometry, College of Applied Medical Sciences, Qassim University, 51452 Buraydah, Saudi Arabia
| | - Azimullah Sheikh
- Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box 17666, Al Ain, UAE
| | - John C Chijuka
- Department of Optometry, College of Applied Medical Sciences, Qassim University, 51452 Buraydah, Saudi Arabia
| | - Süleyman Kaplan
- Department of Histology and Embryology, Medical Faculty, Ondokuz Mayis University, 55139 Samsun, Turkey
| | - Abdu Adem
- Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box 17666, Al Ain, UAE.
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Angleys H, Jespersen SN, Østergaard L. The Effects of Capillary Transit Time Heterogeneity (CTH) on the Cerebral Uptake of Glucose and Glucose Analogs: Application to FDG and Comparison to Oxygen Uptake. Front Comput Neurosci 2016; 10:103. [PMID: 27790110 PMCID: PMC5062759 DOI: 10.3389/fncom.2016.00103] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 09/15/2016] [Indexed: 11/13/2022] Open
Abstract
Glucose is the brain's principal source of ATP, but the extent to which cerebral glucose consumption (CMRglc) is coupled with its oxygen consumption (CMRO2) remains unclear. Measurements of the brain's oxygen-glucose index OGI = CMRO2/CMRglc suggest that its oxygen uptake largely suffices for oxidative phosphorylation. Nevertheless, during functional activation and in some disease states, brain tissue seemingly produces lactate although cerebral blood flow (CBF) delivers sufficient oxygen, so-called aerobic glycolysis. OGI measurements, in turn, are method-dependent in that estimates based on glucose analog uptake depend on the so-called lumped constant (LC) to arrive at CMRglc. Capillary transit time heterogeneity (CTH), which is believed to change during functional activation and in some disease states, affects the extraction efficacy of oxygen from blood. We developed a three-compartment model of glucose extraction to examine whether CTH also affects glucose extraction into brain tissue. We then combined this model with our previous model of oxygen extraction to examine whether differential glucose and oxygen extraction might favor non-oxidative glucose metabolism under certain conditions. Our model predicts that glucose uptake is largely unaffected by changes in its plasma concentration, while changes in CBF and CTH affect glucose and oxygen uptake to different extents. Accordingly, functional hyperemia facilitates glucose uptake more than oxygen uptake, favoring aerobic glycolysis during enhanced energy demands. Applying our model to glucose analogs, we observe that LC depends on physiological state, with a risk of overestimating relative increases in CMRglc during functional activation by as much as 50%.
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Affiliation(s)
- Hugo Angleys
- Center of Functionally Integrative Neuroscience and MINDLab, Aarhus University Aarhus, Denmark
| | - Sune N Jespersen
- Center of Functionally Integrative Neuroscience and MINDLab, Aarhus UniversityAarhus, Denmark; Department of Physics and Astronomy, Aarhus UniversityAarhus, Denmark
| | - Leif Østergaard
- Center of Functionally Integrative Neuroscience and MINDLab, Aarhus UniversityAarhus, Denmark; Department of Neuroradiology, Aarhus University HospitalAarhus, Denmark
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Nagalski A, Kozinski K, Wisniewska MB. Metabolic pathways in the periphery and brain: Contribution to mental disorders? Int J Biochem Cell Biol 2016; 80:19-30. [PMID: 27644152 DOI: 10.1016/j.biocel.2016.09.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 09/14/2016] [Accepted: 09/15/2016] [Indexed: 12/20/2022]
Abstract
The association between mental disorders and diabetes has a long history. Recent large-scale, well-controlled epidemiological studies confirmed a link between diabetes and psychiatric illnesses. The scope of this review is to summarize our current understanding of this relationship from a molecular perspective. We first discuss the potential contribution of diabetes-associated metabolic impairments to the etiology of mental conditions. Then, we focus on possible shared molecular risk factors and mechanisms. Simple comorbidity, shared susceptibility loci, and common pathophysiological processes in diabetes and mental illnesses have changed our traditional way of thinking about mental illness. We conclude that schizophrenia and affective disorders are not limited to an imbalance in dopaminergic and serotoninergic neurotransmission in the brain. They are also systemic disorders that can be considered, to some extent, as metabolic disorders.
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Affiliation(s)
- Andrzej Nagalski
- Laboratory of Molecular Neurobiology, Centre of New Technologies, University of Warsaw, 02-097 Warsaw, Poland
| | - Kamil Kozinski
- Laboratory of Molecular Neurobiology, Centre of New Technologies, University of Warsaw, 02-097 Warsaw, Poland
| | - Marta B Wisniewska
- Laboratory of Molecular Neurobiology, Centre of New Technologies, University of Warsaw, 02-097 Warsaw, Poland.
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26
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Wiegers EC, Rooijackers HM, Tack CJ, Heerschap A, de Galan BE, van der Graaf M. Brain Lactate Concentration Falls in Response to Hypoglycemia in Patients With Type 1 Diabetes and Impaired Awareness of Hypoglycemia. Diabetes 2016; 65:1601-5. [PMID: 26993070 DOI: 10.2337/db16-0068] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 03/09/2016] [Indexed: 11/13/2022]
Abstract
Brain lactate may be involved in the development of impaired awareness of hypoglycemia (IAH), a condition that affects approximately 25% of patients with type 1 diabetes and increases the risk of severe hypoglycemia. The aim of this study was to investigate the effect of acute hypoglycemia on brain lactate concentration in patients with IAH as compared with those with normal awareness of hypoglycemia (NAH) and healthy control subjects (n = 7 per group). After an overnight fast, all subjects underwent a two-step hyperinsulinemic euglycemic (5.0 mmol/L)-hypoglycemic (2.8 mmol/L) glucose clamp. Brain lactate concentrations were measured continuously with (1)H-MRS using a specific lactate detection method. Hypoglycemia generated symptoms in patients with NAH and healthy control subjects but not in patients with IAH. Brain lactate fell significantly by ∼20% in response to hypoglycemia in patients with type 1 diabetes with IAH but remained stable in both healthy control subjects and in patients with NAH. The fall in brain lactate is compatible with increased brain lactate oxidation providing an alternative fuel source during hypoglycemia, which may contribute to the impaired detection of hypoglycemia.
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Affiliation(s)
- Evita C Wiegers
- Department of Radiology and Nuclear Medicine, Radboud university medical center, Nijmegen, the Netherlands
| | - Hanne M Rooijackers
- Department of Internal Medicine, Radboud university medical center, Nijmegen, the Netherlands
| | - Cees J Tack
- Department of Internal Medicine, Radboud university medical center, Nijmegen, the Netherlands
| | - Arend Heerschap
- Department of Radiology and Nuclear Medicine, Radboud university medical center, Nijmegen, the Netherlands
| | - Bastiaan E de Galan
- Department of Internal Medicine, Radboud university medical center, 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
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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: 24] [Impact Index Per Article: 3.0] [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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In Vivo NMR Studies of the Brain with Hereditary or Acquired Metabolic Disorders. Neurochem Res 2015; 40:2647-85. [PMID: 26610379 DOI: 10.1007/s11064-015-1772-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2015] [Revised: 11/10/2015] [Accepted: 11/12/2015] [Indexed: 01/09/2023]
Abstract
Metabolic disorders, whether hereditary or acquired, affect the brain, and abnormalities of the brain are related to cellular integrity; particularly in regard to neurons and astrocytes as well as interactions between them. Metabolic disturbances lead to alterations in cellular function as well as microscopic and macroscopic structural changes in the brain with diabetes, the most typical example of metabolic disorders, and a number of hereditary metabolic disorders. Alternatively, cellular dysfunction and degeneration of the brain lead to metabolic disturbances in hereditary neurological disorders with neurodegeneration. Nuclear magnetic resonance (NMR) techniques allow us to assess a range of pathophysiological changes of the brain in vivo. For example, magnetic resonance spectroscopy detects alterations in brain metabolism and energetics. Physiological magnetic resonance imaging (MRI) detects accompanying changes in cerebral blood flow related to neurovascular coupling. Diffusion and T1/T2-weighted MRI detect microscopic and macroscopic changes of the brain structure. This review summarizes current NMR findings of functional, physiological and biochemical alterations within a number of hereditary and acquired metabolic disorders in both animal models and humans. The global view of the impact of these metabolic disorders on the brain may be useful in identifying the unique and/or general patterns of abnormalities in the living brain related to the pathophysiology of the diseases, and identifying future fields of inquiry.
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Changes in human brain glutamate concentration during hypoglycemia: insights into cerebral adaptations in hypoglycemia-associated autonomic failure in type 1 diabetes. J Cereb Blood Flow Metab 2014; 34:876-82. [PMID: 24549182 PMCID: PMC4013769 DOI: 10.1038/jcbfm.2014.32] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 01/09/2014] [Accepted: 01/13/2014] [Indexed: 01/27/2023]
Abstract
Hypoglycemia-associated autonomic failure (HAAF) is a condition in which patients with type 1 diabetes (T1D) who experience frequent hypoglycemia develop defective glucose counter-regulation and become unable to sense hypoglycemia. Brain glutamate may be involved in the mechanism of HAAF. The goal of this study was to follow the human brain glutamate concentration during experimentally induced hypoglycemia in subjects with and without HAAF. (1)H magnetic resonance spectroscopy was used to track the occipital cortex glutamate concentration throughout a euglycemic clamp followed immediately by a hypoglycemic clamp. T1D patients with HAAF were studied in comparison to two control groups, i.e., T1D patients without HAAF and healthy controls (n=5 per group). Human brain glutamate concentration decreased (P ≤ 0.01) after the initiation of hypoglycemia in the two control groups, but a smaller trend toward a decrease in patients with HAAF did not reach significance (P>0.05). These findings are consistent with a metabolic adaptation in HAAF to provide higher glucose and/or alternative fuel to the brain, eliminating the need to oxidize glutamate. In an exploratory analysis, we detected additional metabolite changes in response to hypoglycemia in the T1D patient without HAAF control group, namely, increased aspartate and decreased lactate.
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30
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Sinha S, Ekka M, Sharma U, P R, Pandey RM, Jagannathan NR. Assessment of changes in brain metabolites in Indian patients with type-2 diabetes mellitus using proton magnetic resonance spectroscopy. BMC Res Notes 2014; 7:41. [PMID: 24433580 PMCID: PMC3897881 DOI: 10.1186/1756-0500-7-41] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 01/10/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The brain is a target for diabetic end-organ damage, though the pathophysiology of diabetic encephalopathy is still not well understood. The aim of the present study was to investigate the effect of diabetes on the metabolic profile of brain of patients having diabetes in comparison to healthy controls, using in-vivo magnetic resonance spectroscopy to get an insight into the pathophysiology of cerebral damages caused due to diabetes. METHODS Single voxel proton magnetic resonance spectroscopy (1H-MRS) was performed at 1.5 T on right frontal, right parieto-temporal and right parieto-occipital white matter regions of the brain of 10 patients having type-2 diabetes along with 7 healthy controls. Absolute concentration of N-acetylaspartate (NAA), choline (cho), myo-inositol (mI), glutamate (Glu) and glutamine (Gln), creatine (Cr) and glucose were determined using the LC-Model and compared between the two groups. RESULTS The concentration of N-acetylaspartate was significantly lower in the right frontal [4.35 ±0.69 vs. 5.23 ±0.74; p = 0.03] and right parieto-occipital region [5.44 ±0.52 vs.6.08 ±0.25; p = 0.02] of the brain of diabetics as compared to the control group. The concentrations of glutamate and glutamine were found to be significantly higher in the right frontal region of the brain [7.98 ±2.57 vs. 5.32 ±1.43; P = 0.01] in diabetics. Glucose levels were found significantly elevated in all the three regions of the brain in diabetics as compared to the control group. However, no significant changes in levels of choline, myo-inositol and creatine were observed in the three regions of the brain examined among the two groups. CONCLUSIONS 1H-MRS analysis indicates that type-2 diabetes mellitus may cause subtle changes in the metabolic profile of the brain. Decreased concentrations of NAA might be indicative of decreased neuronal viability in diabetics while elevated concentrations of Gln and Glu might be related to the fluid imbalance resulting from disruption of glucose homeostasis.
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Affiliation(s)
- Sanjeev Sinha
- Department of Medicine, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India.
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Gulanski BI, De Feyter HM, Page KA, Belfort-DeAguiar R, Mason GF, Rothman DL, Sherwin RS. Increased brain transport and metabolism of acetate in hypoglycemia unawareness. J Clin Endocrinol Metab 2013; 98:3811-20. [PMID: 23796565 PMCID: PMC4425818 DOI: 10.1210/jc.2013-1701] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
CONTEXT Intensive insulin therapy reduces the risk for long-term complications in patients with type 1 diabetes mellitus (T1DM) but increases the risk for hypoglycemia-associated autonomic failure (HAAF), a syndrome that includes hypoglycemia unawareness and defective glucose counterregulation (reduced epinephrine and glucagon responses to hypoglycemia). OBJECTIVE The objective of the study was to address mechanisms underlying HAAF, we investigated whether nonglucose fuels such as acetate, a monocarboxylic acid (MCA), can support cerebral energetics during hypoglycemia in T1DM individuals with hypoglycemia unawareness. DESIGN Magnetic resonance spectroscopy was used to measure brain transport and metabolism of [2-(13)C]acetate under hypoglycemic conditions. SETTING The study was conducted at the Yale Center for Clinical Investigation Hospital Research Unit, Yale Magnetic Resonance Research Center. PATIENTS AND OTHER PARTICIPANTS T1DM participants with moderate to severe hypoglycemia unawareness (n = 7), T1DM controls without hypoglycemia unawareness (n = 5), and healthy nondiabetic controls (n = 10) participated in the study. MAIN OUTCOME MEASURE(S) Brain acetate concentrations, (13)C percent enrichment of glutamine and glutamate, and absolute rates of acetate metabolism were measured. RESULTS Absolute rates of acetate metabolism in the cerebral cortex were 1.5-fold higher among T1DM/unaware participants compared with both control groups during hypoglycemia (P = .001). Epinephrine levels of T1DM/unaware subjects were significantly lower than both control groups (P < .05). Epinephrine levels were inversely correlated with levels of cerebral acetate use across the entire study population (P < .01), suggesting a relationship between up-regulated brain MCA use and HAAF. CONCLUSION Increased MCA transport and metabolism among T1DM individuals with hypoglycemia unawareness may be a mechanism to supply the brain with nonglucose fuels during episodes of acute hypoglycemia and may contribute to the syndrome of hypoglycemia unawareness, independent of diabetes.
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De Feyter HM, Mason GF, Shulman GI, Rothman DL, Petersen KF. Increased brain lactate concentrations without increased lactate oxidation during hypoglycemia in type 1 diabetic individuals. Diabetes 2013; 62:3075-80. [PMID: 23715622 PMCID: PMC3749358 DOI: 10.2337/db13-0313] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Previous studies have reported that brain metabolism of acetate is increased more than twofold during hypoglycemia in type 1 diabetic (T1D) subjects with hypoglycemia unawareness. These data support the hypothesis that upregulation of blood-brain barrier monocarboxylic acid (MCA) transport may contribute to the maintenance of brain energetics during hypoglycemia in subjects with hypoglycemia unawareness. Plasma lactate concentrations are ∼10-fold higher than acetate concentrations, making lactate the most likely alternative MCA as brain fuel. We therefore examined transport of [3-(13)C]lactate across the blood-brain barrier and its metabolism in the brains of T1D patients and nondiabetic control subjects during a hypoglycemic clamp using (13)C magnetic resonance spectroscopy. Brain lactate concentrations were more than fivefold higher (P < 0.05) during hypoglycemia in the T1D subjects compared with the control subjects. Surprisingly, we observed no increase in the oxidation of blood-borne lactate in the T1D subjects, as reflected by similar (13)C fractional enrichments in brain glutamate and glutamine. Taken together, these data suggest that in addition to increased MCA transport at the blood-brain barrier, there may be additional metabolic adaptations that contribute to hypoglycemia unawareness in patients with T1D.
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Affiliation(s)
- Henk M. De Feyter
- Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, Connecticut
| | - Graeme F. Mason
- Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, Connecticut
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut
| | - Gerald I. Shulman
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut
| | - Douglas L. Rothman
- Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, Connecticut
- Department of Biomedical Engineering, Yale University School of Medicine, New Haven, Connecticut
| | - Kitt Falk Petersen
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
- Corresponding author: Kitt Falk Petersen,
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Affiliation(s)
- Philip E Cryer
- Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Passeleu-Le Bourdonnec C, Carrupt PA, Scherrmann JM, Martel S. Methodologies to assess drug permeation through the blood-brain barrier for pharmaceutical research. Pharm Res 2013; 30:2729-56. [PMID: 23801086 DOI: 10.1007/s11095-013-1119-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Accepted: 06/11/2013] [Indexed: 12/21/2022]
Abstract
The drug discovery process for drugs that target the central nervous system suffers from a very high rate of failure due to the presence of the blood-brain barrier, which limits the entry of xenobiotics into the brain. To minimise drug failure at different stages of the drug development process, new methodologies have been developed to understand the absorption, distribution, metabolism, excretion and toxicity (ADMET) profile of drug candidates at early stages of drug development. Additionally, understanding the permeation of drug candidates is also important, particularly for drugs that target the central nervous system. During the first stages of the drug discovery process, in vitro methods that allow for the determination of permeability using high-throughput screening methods are advantageous. For example, performing the parallel artificial membrane permeability assay followed by cell-based models with interesting hits is a useful technique for identifying potential drugs. In silico models also provide interesting information but must be confirmed by in vitro models. Finally, in vivo models, such as in situ brain perfusion, should be studied to reduce a large number of drug candidates to a few lead compounds. This article reviews the different methodologies used in the drug discovery and drug development processes to determine the permeation of drug candidates through the blood-brain barrier.
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Affiliation(s)
- Céline Passeleu-Le Bourdonnec
- School of Pharmaceutical Sciences, University of Geneva University of Lausanne, Quai Ernest Ansermet 30, 1211, Geneva, Switzerland
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Herzog RI, Jiang L, Herman P, Zhao C, Sanganahalli BG, Mason GF, Hyder F, Rothman DL, Sherwin RS, Behar KL. Lactate preserves neuronal metabolism and function following antecedent recurrent hypoglycemia. J Clin Invest 2013; 123:1988-98. [PMID: 23543056 DOI: 10.1172/jci65105] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 01/31/2013] [Indexed: 12/30/2022] Open
Abstract
Hypoglycemia occurs frequently during intensive insulin therapy in patients with both type 1 and type 2 diabetes and remains the single most important obstacle in achieving tight glycemic control. Using a rodent model of hypoglycemia, we demonstrated that exposure to antecedent recurrent hypoglycemia leads to adaptations of brain metabolism so that modest increments in circulating lactate allow the brain to function normally under acute hypoglycemic conditions. We characterized 3 major factors underlying this effect. First, we measured enhanced transport of lactate both into as well as out of the brain that resulted in only a small increase of its contribution to total brain oxidative capacity, suggesting that it was not the major fuel. Second, we observed a doubling of the glucose contribution to brain metabolism under hypoglycemic conditions that restored metabolic activity to levels otherwise only observed at euglycemia. Third, we determined that elevated lactate is critical for maintaining glucose metabolism under hypoglycemia, which preserves neuronal function. These unexpected findings suggest that while lactate uptake was enhanced, it is insufficient to support metabolism as an alternate substrate to replace glucose. Lactate is, however, able to modulate metabolic and neuronal activity, serving as a "metabolic regulator" instead.
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Affiliation(s)
- Raimund I Herzog
- Department of Internal Medicine, Section of Endocrinology, Yale School of Medicine, New Haven, Connecticut 06520-8040, USA.
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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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van de Ven KC, Tack CJ, Heerschap A, van der Graaf M, de Galan BE. Patients with type 1 diabetes exhibit altered cerebral metabolism during hypoglycemia. J Clin Invest 2013; 123:623-9. [PMID: 23298837 PMCID: PMC3561817 DOI: 10.1172/jci62742] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Accepted: 11/08/2012] [Indexed: 01/24/2023] Open
Abstract
Patients with type 1 diabetes mellitus (T1DM) experience, on average, 2 to 3 hypoglycemic episodes per week. This study investigated the effect of hypoglycemia on cerebral glucose metabolism in patients with uncomplicated T1DM. For this purpose, hyperinsulinemic euglycemic and hypoglycemic glucose clamps were performed on separate days, using [1-13C]glucose infusion to increase plasma 13C enrichment. In vivo brain 13C magnetic resonance spectroscopy was used to measure the time course of 13C label incorporation into different metabolites and to calculate the tricarboxylic acid cycle flux (VTCA) by a one-compartment metabolic model. We found that cerebral glucose metabolism, as reflected by the VTCA, was not significantly different comparing euglycemic and hypoglycemic conditions in patients with T1DM. However, the VTCA was inversely related to the HbA1C and was, under hypoglycemic conditions, approximately 45% higher than that in a previously investigated group of healthy subjects. These data suggest that the brains of patients with T1DM are better able to endure moderate hypoglycemia than those of subjects without diabetes.
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Affiliation(s)
- Kim C.C. van de Ven
- Department of Radiology,
Department of General Internal Medicine, and
Clinical Physics Laboratory, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Cees J. Tack
- Department of Radiology,
Department of General Internal Medicine, and
Clinical Physics Laboratory, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Arend Heerschap
- Department of Radiology,
Department of General Internal Medicine, and
Clinical Physics Laboratory, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Marinette van der Graaf
- Department of Radiology,
Department of General Internal Medicine, and
Clinical Physics Laboratory, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Bastiaan E. de Galan
- Department of Radiology,
Department of General Internal Medicine, and
Clinical Physics Laboratory, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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Abstract
The occurrence of altered brain glucose metabolism has long been suggested in both diabetes and Alzheimer’s diseases. However, the preceding mechanism to altered glucose metabolism has not been well understood. Glucose enters the brain via glucose transporters primarily present at the blood-brain barrier. Any changes in glucose transporter function and expression dramatically affects brain glucose homeostasis and function. In the brains of both diabetic and Alzheimer’s disease patients, changes in glucose transporter function and expression have been observed, but a possible link between the altered glucose transporter function and disease progress is missing. Future recognition of the role of new glucose transporter isoforms in the brain may provide a better understanding of brain glucose metabolism in normal and disease states. Elucidation of clinical pathological mechanisms related to glucose transport and metabolism may provide common links to the etiology of these two diseases. Considering these facts, in this review we provide a current understanding of the vital roles of a variety of glucose transporters in the normal, diabetic and Alzheimer’s disease brain.
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Affiliation(s)
- Kaushik Shah
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, 1300 S. Coulter Street, Amarillo, TX 79106, USA.
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39
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Shah K, Desilva S, Abbruscato T. The role of glucose transporters in brain disease: diabetes and Alzheimer’s Disease. Int J Mol Sci 2012. [PMID: 23202918 DOI: 10.3390/ijms13101262] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2023] Open
Abstract
The occurrence of altered brain glucose metabolism has long been suggested in both diabetes and Alzheimer’s diseases. However, the preceding mechanism to altered glucose metabolism has not been well understood. Glucose enters the brain via glucose transporters primarily present at the blood-brain barrier. Any changes in glucose transporter function and expression dramatically affects brain glucose homeostasis and function. In the brains of both diabetic and Alzheimer’s disease patients, changes in glucose transporter function and expression have been observed, but a possible link between the altered glucose transporter function and disease progress is missing. Future recognition of the role of new glucose transporter isoforms in the brain may provide a better understanding of brain glucose metabolism in normal and disease states. Elucidation of clinical pathological mechanisms related to glucose transport and metabolism may provide common links to the etiology of these two diseases. Considering these facts, in this review we provide a current understanding of the vital roles of a variety of glucose transporters in the normal, diabetic and Alzheimer’s disease brain.
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Affiliation(s)
- Kaushik Shah
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, 1300 S. Coulter Street, Amarillo, TX 79106, USA.
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40
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Affiliation(s)
- Elizabeth R Seaquist
- Division of Endocrinology and Diabetes, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, USA.
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