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Bruce K, Garrido AN, Zhang SY, Lam TKT. Regulation of Energy and Glucose Homeostasis by the Nucleus of the Solitary Tract and the Area Postrema. Endocrinol Metab (Seoul) 2024; 39:559-568. [PMID: 39086274 PMCID: PMC11377841 DOI: 10.3803/enm.2024.2025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Accepted: 06/07/2024] [Indexed: 08/02/2024] Open
Abstract
The central nervous system regulates feeding, weight and glucose homeostasis in rodents and humans, but the site-specific mechanisms remain unclear. The dorsal vagal complex in the brainstem that contains the nucleus of the solitary tract (NTS) and area postrema (AP) emerges as a regulatory center that impacts energy and glucose balance by monitoring hormonal and nutrient changes. However, the specific mechanistic metabolic roles of the NTS and AP remain elusive. This mini-review highlights methods to study their distinct roles and recent findings on their metabolic differences and similarities of growth differentiation factor 15 (GDF15) action and glucose sensing in the NTS and AP. In summary, future research aims to characterize hormonal and glucose sensing mechanisms in the AP and/or NTS carries potential to unveil novel targets that lower weight and glucose levels in obesity and diabetes.
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Affiliation(s)
- Kyla Bruce
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
- Toronto General Hospital Research Institute, University Health Network (UHN), Toronto, ON, Canada
| | - Ameth N Garrido
- Toronto General Hospital Research Institute, University Health Network (UHN), Toronto, ON, Canada
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Song-Yang Zhang
- Toronto General Hospital Research Institute, University Health Network (UHN), Toronto, ON, Canada
| | - Tony K T Lam
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
- Toronto General Hospital Research Institute, University Health Network (UHN), Toronto, ON, Canada
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Department of Medicine, Medicine, University of Toronto, Toronto, ON, Canada
- Banting and Best Diabetes Center, University of Toronto, Toronto, ON, Canada
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2
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Yue JTY, Garrido AN, Lam TKT. A metabolic balance of GLP-1 and NMDA receptors in the brain. Cell 2024; 187:3854-3856. [PMID: 39059361 DOI: 10.1016/j.cell.2024.06.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2024] [Revised: 06/24/2024] [Accepted: 06/24/2024] [Indexed: 07/28/2024]
Abstract
Glucagon-like peptide-1 (GLP-1) and N-methyl-D-aspartate (NMDA) receptors in the brain regulate metabolic homeostasis. In a paper published in Nature, Petersen et al. describe a bimodal molecule that conjugates a GLP-1 analog with MK-801 (NMDA receptor antagonist), which lowers feeding and body weight to a greater extent than the GLP-1R agonist alone.
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Affiliation(s)
- Jessica T Y Yue
- Department of Physiology, Alberta Diabetes Institute, Neuroscience and Mental Health Institute, and Group on Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, AB, Canada
| | - Ameth N Garrido
- Toronto General Hospital Research Institute, UHN, Toronto, ON, Canada; Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Tony K T Lam
- Toronto General Hospital Research Institute, UHN, Toronto, ON, Canada; Department of Physiology, University of Toronto, Toronto, ON, Canada; Department of Medicine, University of Toronto, Toronto, ON, Canada; Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada.
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3
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Zhang SY, Danaei Z, Bruce K, Chiu JFM, Lam TKT. Acute Activation of GFRAL in the Area Postrema Contributes to Glucose Regulation Independent of Weight. Diabetes 2024; 73:426-433. [PMID: 38064571 DOI: 10.2337/db23-0705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 12/03/2023] [Indexed: 02/22/2024]
Abstract
GDF15 regulates energy balance and glucose homeostasis in rodents by activating its receptor GFRAL, expressed in the area postrema of the brain. However, whether GDF15-GFRAL signaling in the area postrema regulates glucose tolerance independent of changes in food intake and weight and contributes to the glucose-lowering effect of metformin remain unknown. Herein, we report that direct, acute GDF15 infusion into the area postrema of rats fed a high-fat diet increased intravenous glucose tolerance and insulin sensitivity to lower hepatic glucose production independent of changes in food intake, weight, and plasma insulin levels under conscious, unrestrained, and nonstressed conditions. In parallel, metformin infusion concurrently increased plasma GDF15 levels and glucose tolerance. Finally, a knockdown of GFRAL expression in the area postrema negated administration of GDF15, as well as metformin, to increase glucose tolerance independent of changes in food intake, weight, and plasma insulin levels. In summary, activation of GFRAL in the area postrema contributes to glucose regulation of GDF15 and metformin in vivo. ARTICLE HIGHLIGHTS
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Affiliation(s)
- Song-Yang Zhang
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Zahra Danaei
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Kyla Bruce
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Jennifer F M Chiu
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Tony K T Lam
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Department of Medicine, University of Toronto, Toronto, Ontario, Canada
- Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
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4
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Hahn MK, Giacca A, Pereira S. In vivo techniques for assessment of insulin sensitivity and glucose metabolism. J Endocrinol 2024; 260:e230308. [PMID: 38198372 PMCID: PMC10895285 DOI: 10.1530/joe-23-0308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Accepted: 01/10/2024] [Indexed: 01/12/2024]
Abstract
Metabolic tests are vital to determine in vivo insulin sensitivity and glucose metabolism in preclinical models, usually rodents. Such tests include glucose tolerance tests, insulin tolerance tests, and glucose clamps. Although these tests are not standardized, there are general guidelines for their completion and analysis that are constantly being refined. In this review, we describe metabolic tests in rodents as well as factors to consider when designing and performing these tests.
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Affiliation(s)
- Margaret K Hahn
- Centre for Addiction and Mental Health, Toronto, Ontario, Canada
- Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada
- Department of Pharmacology, University of Toronto, Toronto, Ontario, Canada
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
- Banting & Best Diabetes Centre, Toronto, Ontario, Canada
| | - Adria Giacca
- Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada
- Banting & Best Diabetes Centre, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Sandra Pereira
- Centre for Addiction and Mental Health, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
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5
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Benedet PO, Safikhan NS, Pereira MJ, Lum BM, Botezelli JD, Kuo CH, Wu HL, Craddock BP, Miller WT, Eriksson JW, Yue JTY, Conway EM. CD248 promotes insulin resistance by binding to the insulin receptor and dampening its insulin-induced autophosphorylation. EBioMedicine 2024; 99:104906. [PMID: 38061240 PMCID: PMC10750038 DOI: 10.1016/j.ebiom.2023.104906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Revised: 11/24/2023] [Accepted: 11/25/2023] [Indexed: 12/29/2023] Open
Abstract
BACKGROUND In spite of new treatments, the incidence of type 2 diabetes (T2D) and its morbidities continue to rise. The key feature of T2D is resistance of adipose tissue and other organs to insulin. Approaches to overcome insulin resistance are limited due to a poor understanding of the mechanisms and inaccessibility of drugs to relevant intracellular targets. We previously showed in mice and humans that CD248, a pre/adipocyte cell surface glycoprotein, acts as an adipose tissue sensor that mediates the transition from healthy to unhealthy adipose, thus promoting insulin resistance. METHODS Molecular mechanisms by which CD248 regulates insulin signaling were explored using in vivo insulin clamp studies and biochemical analyses of cells/tissues from CD248 knockout (KO) and wild-type (WT) mice with diet-induced insulin resistance. Findings were validated with human adipose tissue specimens. FINDINGS Genetic deletion of CD248 in mice, overcame diet-induced insulin resistance with improvements in glucose uptake and lipolysis in white adipose tissue depots, effects paralleled by increased adipose/adipocyte GLUT4, phosphorylated AKT and GSK3β, and reduced ATGL. The insulin resistance of the WT mice could be attributed to direct interaction of the extracellular domains of CD248 and the insulin receptor (IR), with CD248 acting to block insulin binding to the IR. This resulted in dampened insulin-mediated autophosphorylation of the IR, with reduced downstream signaling/activation of intracellular events necessary for glucose and lipid homeostasis. INTERPRETATION Our discovery of a cell-surface CD248-IR complex that is accessible to pharmacologic intervention, opens research avenues toward development of new agents to prevent/reverse insulin resistance. FUNDING Funded by Canadian Institutes of Health Research (CIHR), Natural Sciences and Engineering Research Council of Canada (NSERC), Canada Foundations for Innovation (CFI), the Swedish Diabetes Foundation, Family Ernfors Foundation and Novo Nordisk Foundation.
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Affiliation(s)
- Patricia O Benedet
- Centre for Blood Research, Life Sciences Institute, Faculty of Medicine, University of British Columbia, Vancouver, Canada; Departments of Medicine and Pathology and Laboratory Medicine, Life Sciences Institute, Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - Nooshin S Safikhan
- Centre for Blood Research, Life Sciences Institute, Faculty of Medicine, University of British Columbia, Vancouver, Canada; Departments of Medicine and Pathology and Laboratory Medicine, Life Sciences Institute, Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - Maria J Pereira
- Department of Medical Sciences, Clinical Diabetology & Metabolism, Uppsala University, Sweden
| | - Bryan M Lum
- Department of Physiology, Alberta Diabetes Institute and Group on Molecular and Cell Biology of Lipids, University of Alberta, Canada
| | - José Diego Botezelli
- Centre for Blood Research, Life Sciences Institute, Faculty of Medicine, University of British Columbia, Vancouver, Canada; Departments of Medicine and Pathology and Laboratory Medicine, Life Sciences Institute, Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - Cheng-Hsiang Kuo
- International Center for Wound Repair and Regeneration, National Cheng Kung University, Tainan, Taiwan
| | - Hua-Lin Wu
- Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Barbara P Craddock
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY, USA
| | - W Todd Miller
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY, USA; Veterans Affairs Medical Center, Northport, NY, USA
| | - Jan W Eriksson
- Department of Medical Sciences, Clinical Diabetology & Metabolism, Uppsala University, Sweden
| | - Jessica T Y Yue
- Department of Physiology, Alberta Diabetes Institute and Group on Molecular and Cell Biology of Lipids, University of Alberta, Canada
| | - Edward M Conway
- Centre for Blood Research, Life Sciences Institute, Faculty of Medicine, University of British Columbia, Vancouver, Canada; Departments of Medicine and Pathology and Laboratory Medicine, Life Sciences Institute, Faculty of Medicine, University of British Columbia, Vancouver, Canada.
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6
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Zhang SY, Bruce K, Danaei Z, Li RJW, Barros DR, Kuah R, Lim YM, Mariani LH, Cherney DZ, Chiu JFM, Reich HN, Lam TKT. Metformin triggers a kidney GDF15-dependent area postrema axis to regulate food intake and body weight. Cell Metab 2023; 35:875-886.e5. [PMID: 37060902 DOI: 10.1016/j.cmet.2023.03.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 12/29/2022] [Accepted: 03/20/2023] [Indexed: 04/17/2023]
Abstract
Metformin, the most widely prescribed medication for obesity-associated type 2 diabetes (T2D), lowers plasma glucose levels, food intake, and body weight in rodents and humans, but the mechanistic site(s) of action remain elusive. Metformin increases plasma growth/differentiation factor 15 (GDF15) levels to regulate energy balance, while GDF15 administration activates GDNF family receptor α-like (GFRAL) that is highly expressed in the area postrema (AP) and the nucleus of the solitary tract (NTS) of the hindbrain to lower food intake and body weight. However, the tissue-specific contribution of plasma GDF15 levels after metformin treatment is still under debate. Here, we found that metformin increased plasma GDF15 levels in high-fat (HF) fed male rats through the upregulation of GDF15 synthesis in the kidney. Importantly, the kidney-specific knockdown of GDF15 expression as well as the AP-specific knockdown of GFRAL expression negated the ability of metformin to lower food intake and body weight gain. Taken together, we unveil the kidney as a target of metformin to regulate energy homeostasis through a kidney GDF15-dependent AP axis.
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Affiliation(s)
- Song-Yang Zhang
- Toronto General Hospital Research Institute, UHN, Toronto, ON M5G1L7, Canada
| | - Kyla Bruce
- Toronto General Hospital Research Institute, UHN, Toronto, ON M5G1L7, Canada; Institute of Medical Science, University of Toronto, Toronto, ON M5S1A8, Canada
| | - Zahra Danaei
- Toronto General Hospital Research Institute, UHN, Toronto, ON M5G1L7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S1A8, Canada
| | - Rosa J W Li
- Toronto General Hospital Research Institute, UHN, Toronto, ON M5G1L7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S1A8, Canada
| | - Daniel R Barros
- Toronto General Hospital Research Institute, UHN, Toronto, ON M5G1L7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S1A8, Canada
| | - Rachel Kuah
- Toronto General Hospital Research Institute, UHN, Toronto, ON M5G1L7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S1A8, Canada
| | - Yu-Mi Lim
- Toronto General Hospital Research Institute, UHN, Toronto, ON M5G1L7, Canada; Medical Research Institute, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul 03181, Republic of Korea
| | - Laura H Mariani
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - David Z Cherney
- Toronto General Hospital Research Institute, UHN, Toronto, ON M5G1L7, Canada; Division of Nephrology, Department of Medicine, Toronto General Hospital, UHN, Toronto, ON M5G2C4, Canada; Department of Medicine, University of Toronto, Toronto, ON M5S1A8, Canada
| | - Jennifer F M Chiu
- Toronto General Hospital Research Institute, UHN, Toronto, ON M5G1L7, Canada; Institute of Medical Science, University of Toronto, Toronto, ON M5S1A8, Canada
| | - Heather N Reich
- Toronto General Hospital Research Institute, UHN, Toronto, ON M5G1L7, Canada; Division of Nephrology, Department of Medicine, Toronto General Hospital, UHN, Toronto, ON M5G2C4, Canada; Department of Medicine, University of Toronto, Toronto, ON M5S1A8, Canada
| | - Tony K T Lam
- Toronto General Hospital Research Institute, UHN, Toronto, ON M5G1L7, Canada; Institute of Medical Science, University of Toronto, Toronto, ON M5S1A8, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S1A8, Canada; Department of Medicine, University of Toronto, Toronto, ON M5S1A8, Canada; Banting and Best Diabetes Centre, University of Toronto, Toronto, ON M5G2C4, Canada.
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7
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de Campos Zani SC, Wang R, Veida-Silva H, Clugston RD, Yue JTY, Mori MA, Wu J, Chan CB. An Egg White-Derived Peptide Enhances Systemic Insulin Sensitivity and Modulates Markers of Non-Alcoholic Fatty Liver Disease in Obese, Insulin Resistant Mice. Metabolites 2023; 13:metabo13020174. [PMID: 36837793 PMCID: PMC9965836 DOI: 10.3390/metabo13020174] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 01/16/2023] [Accepted: 01/20/2023] [Indexed: 01/26/2023] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD), the hepatic manifestation of the metabolic syndrome, is a global health problem. Currently, no pharmacological treatment is approved for NAFLD. Natural health products, including bioactive peptides, are potential candidates to aid in the management of metabolic syndrome-related conditions, including insulin resistance and obesity. In this study, we hypothesized that an egg-white-derived bioactive peptide QAMPFRVTEQE (Peptide 2) would improve systemic and local white adipose tissue insulin sensitivity, thereby preventing high-fat diet-induced exacerbation of pathological features associated with NAFLD, such as lipid droplet size and number, inflammation, and hepatocyte hypertrophy in high-fat diet-fed mice. Similar to rosiglitazone, Peptide 2 supplementation improved systemic insulin resistance during the hyperinsulinemic-euglycemic clamp and enhanced insulin signalling in white adipose tissue, modulating ex vivo lipolysis. In the liver, compared with high-fat diet fed animals, Peptide 2 supplemented animals presented decreased hepatic cholesterol accumulation (p < 0.05) and area of individual hepatic lipid droplet by around 50% (p = 0.09) and reduced hepatic inflammatory infiltration (p < 0.05) whereas rosiglitazone exacerbated steatosis. In conclusion, Peptide 2 supplementation improved insulin sensitivity and decreased hepatic steatosis, unlike the insulin-sensitizing drug rosiglitazone.
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Affiliation(s)
- Stepheny C. de Campos Zani
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada
- Alberta Diabetes Institute, University of Alberta, Edmonton, AB T6G 2E1, Canada
| | - Ren Wang
- Department of Agricultural Food & Nutritional Science, University of Alberta, Edmonton, AB T6G 1C9, Canada
| | - Hellen Veida-Silva
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada
- Alberta Diabetes Institute, University of Alberta, Edmonton, AB T6G 2E1, Canada
| | - Robin D. Clugston
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Jessica T. Y. Yue
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada
- Alberta Diabetes Institute, University of Alberta, Edmonton, AB T6G 2E1, Canada
- Molecular and Cell Biology of Lipids Group, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Marcelo A. Mori
- Department of Biochemistry and Tissue biology, University of Campinas, Campinas P.O. Box 6109, Brazil
| | - Jianping Wu
- Department of Agricultural Food & Nutritional Science, University of Alberta, Edmonton, AB T6G 1C9, Canada
| | - Catherine B. Chan
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada
- Alberta Diabetes Institute, University of Alberta, Edmonton, AB T6G 2E1, Canada
- Department of Agricultural Food & Nutritional Science, University of Alberta, Edmonton, AB T6G 1C9, Canada
- Correspondence: ; Tel.: +1-780-492-9964
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8
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Imenshahidi M, Hossenzadeh H. Effects of glycine on metabolic syndrome components: a review. J Endocrinol Invest 2022; 45:927-939. [PMID: 35013990 DOI: 10.1007/s40618-021-01720-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 12/03/2021] [Indexed: 12/27/2022]
Abstract
PURPOSE Glycine is the simplest and major amino acid in humans. It is mainly generated in the liver and kidney and is used to produce collagen, creatine, glucose and purine. It is also involved in immune function, anti-inflammatory processes and anti-oxidation reactions. Here, we reviewed the current evidence supporting the role of glycine in the development and treatment of metabolic syndrome components. METHODS We searched Scopus, PubMed and EMBASE databases for papers concerning glycine and metabolic syndrome. RESULTS Available evidence shows that the amount of glycine synthesized in vivo is insufficient to meet metabolic demands in these species. Plasma glycine levels are lower in subjects with metabolic syndrome than in healthy individuals. Interventions such as lifestyle modification, exercise, weight loss, or drugs that improve manifestations of metabolic syndrome remarkably increase circulating glycine concentrations. CONCLUSION Glycine supplementation improves various components of metabolic syndrome including diabetes, obesity, hyperlipidemia and hypertension. In the future, the use of glycine may have a significant clinical impact on the treatment of patients with metabolic syndrome.
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Affiliation(s)
- M Imenshahidi
- Department of Pharmacodynamics and Toxicology, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran
- Pharmaceutical Research Center, Pharmaceutical Technology Institute, Mashhad University of Medical Sciences, Mashhad, Iran
| | - H Hossenzadeh
- Department of Pharmacodynamics and Toxicology, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran.
- Pharmaceutical Research Center, Pharmaceutical Technology Institute, Mashhad University of Medical Sciences, Mashhad, Iran.
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9
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Silencing gut CCK cells alters gut reaction to sugar. Nat Neurosci 2022; 25:136-138. [PMID: 35027762 DOI: 10.1038/s41593-021-00998-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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10
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Beneficial effects of metformin supplementation in hypothalamic paraventricular nucleus and arcuate nucleus of type 2 diabetic rats. Toxicol Appl Pharmacol 2022; 437:115893. [DOI: 10.1016/j.taap.2022.115893] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 01/11/2022] [Accepted: 01/19/2022] [Indexed: 12/13/2022]
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11
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Zhang SY, Li RJW, Lim YM, Batchuluun B, Liu H, Waise TMZ, Lam TKT. FXR in the dorsal vagal complex is sufficient and necessary for upper small intestinal microbiome-mediated changes of TCDCA to alter insulin action in rats. Gut 2021; 70:1675-1683. [PMID: 33087489 DOI: 10.1136/gutjnl-2020-321757] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 10/01/2020] [Accepted: 10/02/2020] [Indexed: 12/14/2022]
Abstract
OBJECTIVE Conjugated bile acids are metabolised by upper small intestinal microbiota, and serum levels of taurine-conjugated bile acids are elevated and correlated with insulin resistance in people with type 2 diabetes. However, whether changes in taurine-conjugated bile acids are necessary for small intestinal microbiome to alter insulin action remain unknown. DESIGN We evaluated circulating and specifically brain insulin action using the pancreatic-euglycaemic clamps in high-fat (HF) versus chow fed rats with or without upper small intestinal healthy microbiome transplant. Chemical and molecular gain/loss-of-function experiments targeting specific taurine-conjugated bile acid-induced changes of farnesoid X receptor (FXR) in the brain were performed in parallel. RESULTS We found that short-term HF feeding increased the levels of taurochenodeoxycholic acid (TCDCA, an FXR ligand) in the upper small intestine, ileum, plasma and dorsal vagal complex (DVC) of the brain. Transplantation of upper small intestinal healthy microbiome into the upper small intestine of HF rats not only reversed the rise of TCDCA in all reported tissues but also enhanced the ability of either circulating hyperinsulinaemia or DVC insulin action to lower glucose production. Further, DVC infusion of TCDCA or FXR agonist negated the enhancement of insulin action, while genetic knockdown or chemical inhibition of FXR in the DVC of HF rats reversed insulin resistance. CONCLUSION Our findings indicate that FXR in the DVC is sufficient and necessary for upper small intestinal microbiome-mediated changes of TCDCA to alter insulin action in rats, and highlight a previously unappreciated TCDCA-FXR axis linking gut microbiome and host insulin action.
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Affiliation(s)
- Song-Yang Zhang
- Toronto General Hospital Research Institute, UHN, Toronto, Ontario, Canada
| | - Rosa J W Li
- Toronto General Hospital Research Institute, UHN, Toronto, Ontario, Canada.,Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Yu-Mi Lim
- Toronto General Hospital Research Institute, UHN, Toronto, Ontario, Canada.,Medical Research Institute, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | | | - Huiying Liu
- Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - T M Zaved Waise
- Toronto General Hospital Research Institute, UHN, Toronto, Ontario, Canada
| | - Tony K T Lam
- Toronto General Hospital Research Institute, UHN, Toronto, Ontario, Canada .,Physiology, University of Toronto, Toronto, Ontario, Canada.,Medicine, University of Toronto, Toronto, Ontario, Canada.,Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
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12
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Li RJW, Batchuluun B, Zhang SY, Abraham MA, Wang B, Lim YM, Yue JTY, Lam TKT. Nutrient infusion in the dorsal vagal complex controls hepatic lipid and glucose metabolism in rats. iScience 2021; 24:102366. [PMID: 33870148 PMCID: PMC8044434 DOI: 10.1016/j.isci.2021.102366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 02/08/2021] [Accepted: 03/24/2021] [Indexed: 11/22/2022] Open
Abstract
Hypothalamic regulation of lipid and glucose homeostasis is emerging, but whether the dorsal vagal complex (DVC) senses nutrients and regulates hepatic nutrient metabolism remains unclear. Here, we found in rats DVC oleic acid infusion suppressed hepatic secretion of triglyceride-rich very-low-density lipoprotein (VLDL-TG), which was disrupted by inhibiting DVC long-chain fatty acyl-CoA synthetase that in parallel disturbed lipid homeostasis during intravenous lipid infusion. DVC glucose infusion elevated local glucose levels similarly as intravenous glucose infusion and suppressed hepatic glucose production. This was independent of lactate metabolism as inhibiting lactate dehydrogenase failed to disrupt glucose sensing and neither could DVC lactate infusion recapitulate glucose effect. DVC oleic acid and glucose infusion failed to lower VLDL-TG secretion and glucose production in high-fat fed rats, while inhibiting DVC farnesoid X receptor enhanced oleic acid but not glucose sensing. Thus, an impairment of DVC nutrient sensing may lead to the disruption of lipid and glucose homeostasis in metabolic syndrome. DVC oleic acid infusion lowers hepatic secretion of VLDL-TG in chow but not HF rats Inhibition of ACSL in the DVC negates lipid sensing DVC glucose infusion lowers hepatic glucose production in chow but not HF rats Inhibition of FXR in the DVC enhances oleic acid but not glucose sensing in HF rats
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Affiliation(s)
- Rosa J W Li
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada.,Toronto General Hospital Research Institute, UHN, MaRS Center, TMDT 101 College Street, 10-705, Toronto, ON M5G 1L7, Canada
| | - Battsetseg Batchuluun
- Toronto General Hospital Research Institute, UHN, MaRS Center, TMDT 101 College Street, 10-705, Toronto, ON M5G 1L7, Canada
| | - Song-Yang Zhang
- Toronto General Hospital Research Institute, UHN, MaRS Center, TMDT 101 College Street, 10-705, Toronto, ON M5G 1L7, Canada
| | - Mona A Abraham
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada.,Toronto General Hospital Research Institute, UHN, MaRS Center, TMDT 101 College Street, 10-705, Toronto, ON M5G 1L7, Canada
| | - Beini Wang
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada.,Toronto General Hospital Research Institute, UHN, MaRS Center, TMDT 101 College Street, 10-705, Toronto, ON M5G 1L7, Canada
| | - Yu-Mi Lim
- Toronto General Hospital Research Institute, UHN, MaRS Center, TMDT 101 College Street, 10-705, Toronto, ON M5G 1L7, Canada.,Medical Research Institute, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul 03181, Republic of Korea
| | - Jessica T Y Yue
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Tony K T Lam
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada.,Toronto General Hospital Research Institute, UHN, MaRS Center, TMDT 101 College Street, 10-705, Toronto, ON M5G 1L7, Canada.,Department of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada.,Banting and Best Diabetes Centre, University of Toronto, Toronto, ON M5G 2C4, Canada
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13
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Obesity and Related Type 2 Diabetes: A Failure of the Autonomic Nervous System Controlling Gastrointestinal Function? GASTROINTESTINAL DISORDERS 2020. [DOI: 10.3390/gidisord2040039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The pandemic spread of obesity and type 2 diabetes is a serious health problem that cannot be contained with common therapies. At present, the most effective therapeutic tool is metabolic surgery, which substantially modifies the gastrointestinal anatomical structure. This review reflects the state of the art research in obesity and type 2 diabetes, describing the probable reason for their spread, how the various brain sectors are involved (with particular emphasis on the role of the vagal system controlling different digestive functions), and the possible mechanisms for the effectiveness of bariatric surgery. According to the writer’s interpretation, the identification of drugs that can modulate the activity of some receptor subunits of the vagal neurons and energy-controlling structures of the central nervous system (CNS), and/or specific physical treatment of cortical areas, could reproduce, non-surgically, the positive effects of metabolic surgery.
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14
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Glycine Metabolism and Its Alterations in Obesity and Metabolic Diseases. Nutrients 2019; 11:nu11061356. [PMID: 31208147 PMCID: PMC6627940 DOI: 10.3390/nu11061356] [Citation(s) in RCA: 182] [Impact Index Per Article: 36.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 06/07/2019] [Accepted: 06/12/2019] [Indexed: 12/11/2022] Open
Abstract
Glycine is the proteinogenic amino-acid of lowest molecular weight, harboring a hydrogen atom as a side-chain. In addition to being a building-block for proteins, glycine is also required for multiple metabolic pathways, such as glutathione synthesis and regulation of one-carbon metabolism. Although generally viewed as a non-essential amino-acid, because it can be endogenously synthesized to a certain extent, glycine has also been suggested as a conditionally essential amino acid. In metabolic disorders associated with obesity, type 2 diabetes (T2DM), and non-alcoholic fatty liver disease (NAFLDs), lower circulating glycine levels have been consistently observed, and clinical studies suggest the existence of beneficial effects induced by glycine supplementation. The present review aims at synthesizing the recent advances in glycine metabolism, pinpointing its main metabolic pathways, identifying the causes leading to glycine deficiency-especially in obesity and associated metabolic disorders-and evaluating the potential benefits of increasing glycine availability to curb the progression of obesity and obesity-related metabolic disturbances. This study focuses on the importance of diet, gut microbiota, and liver metabolism in determining glycine availability in obesity and associated metabolic disorders.
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15
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Shah M, Addison A, Wang P, Zhu W, Chan O. Recurrent glucose deprivation leads to the preferential use of lactate by neurons in the ventromedial hypothalamus. Am J Physiol Endocrinol Metab 2019; 316:E948-E955. [PMID: 30888861 PMCID: PMC6580165 DOI: 10.1152/ajpendo.00468.2018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Increased GABAergic output in the ventromedial hypothalamus (VMH) contributes to counterregulatory failure in recurrently hypoglycemic (RH) rats, and lactate, an alternate fuel source in the brain, contributes to this phenomenon. The current study assessed whether recurring bouts of glucose deprivation enhanced neuronal lactate uptake and, if so, whether this influenced γ-aminobutyric acid (GABA) output and the counterregulatory responses. Glucose deprivation was induced using 5-thioglucose (5TG). Control rats received an infusion of artificial extracellular fluid. These groups were compared with RH animals. Subsequently, the rats underwent a hypoglycemic clamp with microdialysis. To test whether 5TG affected neuronal lactate utilization, a subgroup of 5TG-treated rats was microinjected with a lactate transporter inhibitor [cyano-4-hydroxycinnamate (4CIN)] just before the start of the clamp. Both RH and 5TG raised VMH GABA levels, and this was associated with impaired counterregulatory responses. 4CIN reduced VMH GABA levels and restored the hormone responses in the 5TG group. We then evaluated [14C]lactate uptake in hypothalamic neuronal cultures. Recurring exposure to low glucose increased monocarboxylate transporter-2 mRNA expression and augmented lactate uptake. Taken together, our data suggest that glucose deprivation, per se, enhances lactate utilization in hypothalamic neurons, and this may contribute to suppression of the counterregulatory responses to hypoglycemia.
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Affiliation(s)
- Maitreyee Shah
- Section of Endocrinology, Department of Internal Medicine, Yale School of Medicine , New Haven, Connecticut
| | - Augustina Addison
- Section of Endocrinology, Department of Internal Medicine, Yale School of Medicine , New Haven, Connecticut
| | - Peili Wang
- Section of Endocrinology, Department of Internal Medicine, Yale School of Medicine , New Haven, Connecticut
| | - Wanling Zhu
- Section of Endocrinology, Department of Internal Medicine, Yale School of Medicine , New Haven, Connecticut
| | - Owen Chan
- Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, University of Utah School of Medicine , Salt Lake City, Utah
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16
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Gu Y, Liu C, Zheng N, Jia W, Zhang W, Li H. Metabolic and Gut Microbial Characterization of Obesity-Prone Mice under a High-Fat Diet. J Proteome Res 2019; 18:1703-1714. [PMID: 30793608 DOI: 10.1021/acs.jproteome.8b00945] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Obesity is characterized with high heterogeneity due to genetic abnormality, energy imbalance, gut dysbiosis, or a combination of all three. Obesity-prone (OP) and -resistant (OR) phenotypes are frequently observed in rodents, even in those given a high-fat diet (HFD). However, the underlying mechanisms are largely unknown. Male C57BL/6J mice were fed with chow or a HFD for 8 weeks. OP and OR mice were defined based on body weight gain, and integrated serum metabolic and gut microbial profiling was performed by the gas chromatography-mass spectroscopy-based metabolomic sequencing and pyrosequencing of 16S rDNA of cecum contents. A total of 60 differential metabolites were identified in comparisons among Con, OP, and OR groups, in which 27 were OP-related. These differential metabolites are mainly involved in glycolysis, lipids, and amino acids metabolism and the TCA cycle. Meanwhile, OP mice had a distinct profile in gut microbiota compared to those of OR or Con mice, which showed a reduced ratio of Firmicutes to Bacteroidetes and increased Proteobacteria. Moreover, the gut microbial alteration of OP mice was correlated with the changes of the key serum metabolites. OP-enriched Parasutterella from the Proteobacteria phylum correlated to most of metabolites, suggesting that it was essential in obesity. OP mice are distinct in metabolic and gut microbial profiles, and OP-related metabolites and bacteria are of significance for understanding obesity development.
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Affiliation(s)
- Yu Gu
- Institute of Interdisciplinary Integrative Medicine Research , Shanghai University of Traditional Chinese Medicine , Shanghai 201203 , China
| | - Can Liu
- Department of Biochemistry and Molecular Biology , Bengbu Medical College , Anhui Province 233030 , China
| | - Ningning Zheng
- Institute of Interdisciplinary Integrative Medicine Research , Shanghai University of Traditional Chinese Medicine , Shanghai 201203 , China
| | - Wei Jia
- Shanghai Key Laboratory of Diabetes Mellitus and Center for Translational Medicine , Shanghai Jiao Tong University Affiliated Sixth People's Hospital , Shanghai 200233 , China.,University of Hawaii Cancer Center , Honolulu , Hawaii 96813 , United States
| | - Weidong Zhang
- Institute of Interdisciplinary Integrative Medicine Research , Shanghai University of Traditional Chinese Medicine , Shanghai 201203 , China.,Department of Phytochemistry, College of Pharmacy , Second Military Medical University , Shanghai 200433 , China
| | - Houkai Li
- Institute of Interdisciplinary Integrative Medicine Research , Shanghai University of Traditional Chinese Medicine , Shanghai 201203 , China
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17
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ter Horst KW, Lammers NM, Trinko R, Opland DM, Figee M, Ackermans MT, Booij J, van den Munckhof P, Schuurman PR, Fliers E, Denys D, DiLeone RJ, la Fleur SE, Serlie MJ. Striatal dopamine regulates systemic glucose metabolism in humans and mice. Sci Transl Med 2018; 10:10/442/eaar3752. [DOI: 10.1126/scitranslmed.aar3752] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 05/03/2018] [Indexed: 12/12/2022]
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18
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Physiological and therapeutic regulation of glucose homeostasis by upper small intestinal PepT1-mediated protein sensing. Nat Commun 2018; 9:1118. [PMID: 29549253 PMCID: PMC5856761 DOI: 10.1038/s41467-018-03490-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 02/16/2018] [Indexed: 02/07/2023] Open
Abstract
High protein feeding improves glucose homeostasis in rodents and humans with diabetes, but the mechanisms that underlie this improvement remain elusive. Here we show that acute administration of casein hydrolysate directly into the upper small intestine increases glucose tolerance and inhibits glucose production in rats, independently of changes in plasma amino acids, insulin levels, and food intake. Inhibition of upper small intestinal peptide transporter 1 (PepT1), the primary oligopeptide transporter in the small intestine, reverses the preabsorptive ability of upper small intestinal casein infusion to increase glucose tolerance and suppress glucose production. The glucoregulatory role of PepT1 in the upper small intestine of healthy rats is further demonstrated by glucose homeostasis disruption following high protein feeding when PepT1 is inhibited. PepT1-mediated protein-sensing mechanisms also improve glucose homeostasis in models of early-onset insulin resistance and obesity. We demonstrate that preabsorptive upper small intestinal protein-sensing mechanisms mediated by PepT1 have beneficial effects on whole-body glucose homeostasis. High protein diets are known to improve metabolic parameters including adiposity and glucose homeostasis. Here the authors demonstrate that preabsorptive upper small intestinal protein-sensing mechanisms mediated by peptide transporter 1 improve glucose homeostasis by inhibiting hepatic glucose production.
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19
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Bauer PV, Duca FA, Waise TMZ, Dranse HJ, Rasmussen BA, Puri A, Rasti M, O'Brien CA, Lam TKT. Lactobacillus gasseri in the Upper Small Intestine Impacts an ACSL3-Dependent Fatty Acid-Sensing Pathway Regulating Whole-Body Glucose Homeostasis. Cell Metab 2018. [PMID: 29514066 DOI: 10.1016/j.cmet.2018.01.013] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Long-chain acyl-CoA synthetase (ACSL)-dependent upper small intestinal lipid metabolism activates pre-absorptive pathways to regulate metabolic homeostasis, but whether changes in the upper small intestinal microbiota alter specific fatty acid-dependent pathways to impact glucose homeostasis remains unknown. We here first find that upper small intestinal infusion of Intralipid, oleic acid, or linoleic acid pre-absorptively increases glucose tolerance and lowers glucose production in rodents. High-fat feeding impairs pre-absorptive fatty acid sensing and reduces upper small intestinal Lactobacillus gasseri levels and ACSL3 expression. Transplantation of healthy upper small intestinal microbiota to high-fat-fed rodents restores L. gasseri levels and fatty acid sensing via increased ACSL3 expression, while L. gasseri probiotic administration to non-transplanted high-fat-fed rodents is sufficient to restore upper small intestinal ACSL3 expression and fatty acid sensing. In summary, we unveil a glucoregulatory role of upper small intestinal L. gasseri that impacts an ACSL3-dependent glucoregulatory fatty acid-sensing pathway.
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Affiliation(s)
- Paige V Bauer
- Toronto General Hospital Research Institute, UHN, MaRS Centre, Toronto Medical Discovery Tower, Room 10-705, 101 College Street, Toronto, ON M5G 1L7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Frank A Duca
- Toronto General Hospital Research Institute, UHN, MaRS Centre, Toronto Medical Discovery Tower, Room 10-705, 101 College Street, Toronto, ON M5G 1L7, Canada
| | - T M Zaved Waise
- Toronto General Hospital Research Institute, UHN, MaRS Centre, Toronto Medical Discovery Tower, Room 10-705, 101 College Street, Toronto, ON M5G 1L7, Canada
| | - Helen J Dranse
- Toronto General Hospital Research Institute, UHN, MaRS Centre, Toronto Medical Discovery Tower, Room 10-705, 101 College Street, Toronto, ON M5G 1L7, Canada
| | - Brittany A Rasmussen
- Toronto General Hospital Research Institute, UHN, MaRS Centre, Toronto Medical Discovery Tower, Room 10-705, 101 College Street, Toronto, ON M5G 1L7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Akshita Puri
- Princess Margaret Cancer Centre, UHN, Toronto, ON M5G 2M9, Canada
| | - Mozhgan Rasti
- Toronto General Hospital Research Institute, UHN, MaRS Centre, Toronto Medical Discovery Tower, Room 10-705, 101 College Street, Toronto, ON M5G 1L7, Canada
| | - Catherine A O'Brien
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada; Princess Margaret Cancer Centre, UHN, Toronto, ON M5G 2M9, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Tony K T Lam
- Toronto General Hospital Research Institute, UHN, MaRS Centre, Toronto Medical Discovery Tower, Room 10-705, 101 College Street, Toronto, ON M5G 1L7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada; Banting and Best Diabetes Centre, University of Toronto, Toronto, ON M5G 2C4, Canada.
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20
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Caravaggio F, Iwata Y, Plitman E, Chavez S, Borlido C, Chung JK, Kim J, Agarwal SM, Gerretsen P, Remington G, Hahn M, Graff-Guerrero A. Reduced insulin sensitivity may be related to less striatal glutamate: An 1H-MRS study in healthy non-obese humans. Eur Neuropsychopharmacol 2018; 28:285-296. [PMID: 29269206 DOI: 10.1016/j.euroneuro.2017.12.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 11/22/2017] [Accepted: 12/02/2017] [Indexed: 10/18/2022]
Abstract
Levels of striatal dopamine (DA) may be positively correlated with levels of striatal glutamate (Glu). While reduced insulin sensitivity (%S) has been associated with reduced striatal DA levels in healthy non-obese persons, whether reduced %S is also associated with reduced striatal Glu levels has not yet been established. Using 1H-MRS, we measured levels of several neurometabolites in the striatum and dorsolateral prefrontal cortex (DLPFC) of seventeen healthy non-obese persons (9 female, mean age: 28.35 ± 9.53). Insulin sensitivity was estimated for each subject from fasting plasma glucose and insulin using the Homeostasis Model Assessment II. We hypothesized that %S would be positively related with levels of Glu and Glu + glutamine (Glx) in the striatum. Exploratory analyses were also conducted between other fasting markers of metabolic health and neurometabolites measured with 1H-MRS. In the right striatum, %S was positively correlated with levels of Glu (r(15) = .49, p = .04) and Glx (r(15) = .50, p = .04). In the left striatum, there was a trend positive correlation between %S and Glu (r(15) = .46, p = .06), but not Glx levels (r(15) = .20, p = .44). The relationships between %S and striatal Glu levels remained after controlling for age, sex, and BMI (right: r(12) = .73, β = .52, t = 2.55, p = .03; left: (r(12) = .63, β = .53, t = 2.25, p = .04) These preliminary findings suggest that %S may be related to markers of glutamatergic functioning in the striatum of healthy non-obese persons. These findings warrant replication in larger samples and extension into neuropsychiatric populations where altered striatal DA, Glu, and %S are implicated.
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Affiliation(s)
- Fernando Caravaggio
- Research Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario, Canada M5T 1R8; Department of Psychiatry, University of Toronto, 250 College Street, Toronto, Ontario, Canada M5T 1R8
| | - Yusuke Iwata
- Research Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario, Canada M5T 1R8
| | - Eric Plitman
- Research Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario, Canada M5T 1R8; Institute of Medical Science, University of Toronto, 2374 Medical Sciences Building, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Sofia Chavez
- Research Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario, Canada M5T 1R8; Department of Psychiatry, University of Toronto, 250 College Street, Toronto, Ontario, Canada M5T 1R8
| | - Carol Borlido
- Research Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario, Canada M5T 1R8
| | - Jun Ku Chung
- Research Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario, Canada M5T 1R8; Institute of Medical Science, University of Toronto, 2374 Medical Sciences Building, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Julia Kim
- Research Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario, Canada M5T 1R8; Institute of Medical Science, University of Toronto, 2374 Medical Sciences Building, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Sri Mahavir Agarwal
- Research Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario, Canada M5T 1R8
| | - Philip Gerretsen
- Research Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario, Canada M5T 1R8; Department of Psychiatry, University of Toronto, 250 College Street, Toronto, Ontario, Canada M5T 1R8; Institute of Medical Science, University of Toronto, 2374 Medical Sciences Building, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Gary Remington
- Research Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario, Canada M5T 1R8; Department of Psychiatry, University of Toronto, 250 College Street, Toronto, Ontario, Canada M5T 1R8; Institute of Medical Science, University of Toronto, 2374 Medical Sciences Building, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Margaret Hahn
- Research Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario, Canada M5T 1R8; Department of Psychiatry, University of Toronto, 250 College Street, Toronto, Ontario, Canada M5T 1R8; Institute of Medical Science, University of Toronto, 2374 Medical Sciences Building, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Ariel Graff-Guerrero
- Research Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario, Canada M5T 1R8; Department of Psychiatry, University of Toronto, 250 College Street, Toronto, Ontario, Canada M5T 1R8; Institute of Medical Science, University of Toronto, 2374 Medical Sciences Building, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8.
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21
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Abraham MA, Rasti M, Bauer PV, Lam TKT. Leptin enhances hypothalamic lactate dehydrogenase A (LDHA)-dependent glucose sensing to lower glucose production in high-fat-fed rats. J Biol Chem 2018; 293:4159-4166. [PMID: 29374061 DOI: 10.1074/jbc.ra117.000838] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 01/10/2018] [Indexed: 01/15/2023] Open
Abstract
The responsiveness of glucose sensing per se to regulate whole-body glucose homeostasis is dependent on the ability of a rise in glucose to lower hepatic glucose production and increase peripheral glucose uptake in vivo In both rodents and humans, glucose sensing is lost in diabetes and obesity, but the site(s) of impairment remains elusive. Here, we first report that short-term high-fat feeding disrupts hypothalamic glucose sensing to lower glucose production in rats. Second, leptin administration into the hypothalamus of high-fat-fed rats restored hypothalamic glucose sensing to lower glucose production during a pancreatic (basal insulin)-euglycemic clamp and increased whole-body glucose tolerance during an intravenous glucose tolerance test. Finally, both chemical inhibition of hypothalamic lactate dehydrogenase (LDH) (achieved via hypothalamic LDH inhibitor oxamate infusion) and molecular knockdown of LDHA (achieved via hypothalamic lentiviral LDHA shRNA injection) negated the ability of hypothalamic leptin infusion to enhance glucose sensing to lower glucose production in high fat-fed rats. In summary, our findings illustrate that leptin enhances LDHA-dependent glucose sensing in the hypothalamus to lower glucose production in high-fat-fed rodents in vivo.
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Affiliation(s)
- Mona A Abraham
- From the Toronto General Hospital Research Institute, University Health Network, Toronto M5G 1L7, Canada.,Departments of Physiology and
| | - Mozhgan Rasti
- From the Toronto General Hospital Research Institute, University Health Network, Toronto M5G 1L7, Canada
| | - Paige V Bauer
- From the Toronto General Hospital Research Institute, University Health Network, Toronto M5G 1L7, Canada.,Departments of Physiology and
| | - Tony K T Lam
- From the Toronto General Hospital Research Institute, University Health Network, Toronto M5G 1L7, Canada, .,Departments of Physiology and.,Medicine, University of Toronto, Toronto M5S 1A8, Canada, and.,Banting and Best Diabetes Centre, University of Toronto, Toronto M5G 2C4, Canada
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22
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Yan-Do R, MacDonald PE. Impaired "Glycine"-mia in Type 2 Diabetes and Potential Mechanisms Contributing to Glucose Homeostasis. Endocrinology 2017; 158:1064-1073. [PMID: 28323968 DOI: 10.1210/en.2017-00148] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 03/10/2017] [Indexed: 12/11/2022]
Abstract
The onset and/or progression of type 2 diabetes (T2D) can be prevented if intervention is early enough. As such, much effort has been placed on the search for indicators predictive of prediabetes and disease onset or progression. An increasing body of evidence suggests that changes in plasma glycine may be one such biomarker. Circulating glycine levels are consistently low in patients with T2D. Levels of this nonessential amino acid correlate negatively with obesity and insulin resistance. Plasma glycine correlates positively with glucose disposal, and rises with interventions such as exercise and bariatric surgery that improve glucose homeostasis. A role for glycine in the regulation of glucose, beyond being a potential biomarker, is less clear, however. Dietary glycine supplementation increases insulin, reduces systemic inflammation, and improves glucose tolerance. Emerging evidence suggests that glycine, a neurotransmitter, also acts directly on target tissues that include the endocrine pancreas and the brain via glycine receptors and as a coligand for N-methyl-d-aspartate glutamate receptors to control insulin secretion and liver glucose output, respectively. Here, we review the current evidence supporting a role for glycine in glucose homeostasis via its central and peripheral actions and changes that occur in T2D.
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Affiliation(s)
- Richard Yan-Do
- Alberta Diabetes Institute and Department of Pharmacology, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
| | - Patrick E MacDonald
- Alberta Diabetes Institute and Department of Pharmacology, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
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