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Rønnestad I, Akiba Y, Kaji I, Kaunitz JD. Duodenal luminal nutrient sensing. Curr Opin Pharmacol 2014; 19:67-75. [PMID: 25113991 DOI: 10.1016/j.coph.2014.07.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 07/11/2014] [Accepted: 07/18/2014] [Indexed: 12/12/2022]
Abstract
The gastrointestinal mucosa is exposed to numerous chemical substances and microorganisms, including macronutrients, micronutrients, bacteria, endogenous ions, and proteins. The regulation of mucosal protection, digestion, absorption and motility is signaled in part by luminal solutes. Therefore, luminal chemosensing is an important mechanism enabling the mucosa to monitor luminal conditions, such as pH, ion concentrations, nutrient quantity, and microflora. The duodenal mucosa shares luminal nutrient receptors with lingual taste receptors in order to detect the five basic tastes, in addition to essential nutrients, and unwanted chemicals. The recent 'de-orphanization' of nutrient sensing G protein-coupled receptors provides an essential component of the mechanism by which the mucosa senses luminal nutrients. In this review, we will update the mechanisms of and underlying physiological and pathological roles in luminal nutrient sensing, with a main focus on the duodenal mucosa.
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Affiliation(s)
- Ivar Rønnestad
- Department of Medicine, School of Medicine, University of California, Los Angeles, USA; Department of Biology, University of Bergen, N5020 Bergen, Norway
| | - Yasutada Akiba
- Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, USA; Department of Medicine, School of Medicine, University of California, Los Angeles, USA; Brentwood Biomedical Research Institute, Los Angeles, CA 90073, USA
| | - Izumi Kaji
- Department of Medicine, School of Medicine, University of California, Los Angeles, USA; Brentwood Biomedical Research Institute, Los Angeles, CA 90073, USA
| | - Jonathan D Kaunitz
- Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, USA; Department of Medicine, School of Medicine, University of California, Los Angeles, USA; Department of Surgery, School of Medicine, University of California, Los Angeles, USA; Brentwood Biomedical Research Institute, Los Angeles, CA 90073, USA.
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Hayes MR, Mietlicki-Baase EG, Kanoski SE, De Jonghe BC. Incretins and amylin: neuroendocrine communication between the gut, pancreas, and brain in control of food intake and blood glucose. Annu Rev Nutr 2014; 34:237-60. [PMID: 24819325 DOI: 10.1146/annurev-nutr-071812-161201] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Arguably the most fundamental physiological systems for all eukaryotic life are those governing energy balance. Without sufficient energy, an individual is unable to survive and reproduce. Thus, an ever-growing appreciation is that mammalian physiology developed a redundant set of neuroendocrine signals that regulate energy intake and expenditure, which maintains sufficient circulating energy, predominantly in the form of glucose, to ensure that energy needs are met throughout the body. This orchestrated control requires cross talk between the gastrointestinal tract, which senses the incoming meal; the pancreas, which produces glycemic counterregulatory hormones; and the brain, which controls autonomic and behavioral processes regulating energy balance. Therefore, this review highlights the physiological, pharmacological, and pathophysiological effects of the incretin hormones glucagon-like peptide-1 and gastric inhibitory polypeptide, as well as the pancreatic hormone amylin, on energy balance and glycemic control.
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Affiliation(s)
- Matthew R Hayes
- Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104;
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53
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Abstract
Glucagon-like peptide (GLP)-1 is an incretin hormone with several antidiabetic functions including stimulation of glucose-dependent insulin secretion, increase in insulin gene expression and beta-cell survival. Despite the initial technical difficulties and profound inefficiency of direct gene transfer into the pancreas that seriously restricted in vivo gene transfer experiments with GLP-1, recent exploitation of various routes of gene delivery and alternative means of gene transfer has permitted the detailed assessment of the therapeutic efficacy of GLP-1 in animal models of type 2 diabetes (T2DM). As a result, many clinical benefits of GLP-1 peptide/analogues observed in clinical trials involving induction of glucose tolerance, reduction of hyperglycaemia, suppression of appetite and food intake linked to weight loss have been replicated in animal models using gene therapy. Furthermore, GLP-1-centered gene therapy not only improved insulin sensitivity, but also reduced abdominal and/or hepatic fat associated with obesity-induced T2DM with drastic alterations in adipokine profiles in treated subjects. Thus, a comprehensive assessment of recent GLP-1-mediated gene therapy approaches with detailed analysis of current hurdles and resolutions, is discussed.
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Manning S, Batterham RL. The Role of Gut Hormone Peptide YY in Energy and Glucose Homeostasis: Twelve Years On. Annu Rev Physiol 2014; 76:585-608. [DOI: 10.1146/annurev-physiol-021113-170404] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Sean Manning
- Centre for Obesity Research, Rayne Institute, Department of Medicine, University College London, London WC1E 6JJ, United Kingdom; ,
| | - Rachel L. Batterham
- Centre for Obesity Research, Rayne Institute, Department of Medicine, University College London, London WC1E 6JJ, United Kingdom; ,
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Hayes J, Volkoff H. Characterization of the endocrine, digestive and morphological adjustments of the intestine in response to food deprivation and torpor in cunner, Tautogolabrus adspersus. Comp Biochem Physiol A Mol Integr Physiol 2014; 170:46-59. [PMID: 24487303 DOI: 10.1016/j.cbpa.2014.01.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 01/24/2014] [Accepted: 01/24/2014] [Indexed: 11/16/2022]
Abstract
The cunner, Tautogolabrus adspersus, is a marine teleost endemic to the cold waters of the Northwest Atlantic Ocean. The cunner is non-migratory and is known for its remarkable ability to endure the freezing winter months with little to no food by entering a torpid/dormant state. To evaluate the physiological strategies employed by the cunner's intestinal tract to withstand food deprivation, fish were sampled for their gut after a four-week period of acute food deprivation during their summer (active/feeding) state, as well as after 4months of overwinter fasting. Digestive capacity was evaluated by measuring digestive enzyme activity and related mRNA transcript expression for trypsin, alkaline phosphatase, alanine aminopeptidase and lipase. In order to assess how gut hormones affect/are affected by acute fasting and torpor, we examined the intestinal mRNA expression of several putative appetite regulators, i.e. CCK, apelin, orexin and mTOR. Short-term summer fasting induced a reduction in the activity, but not the transcript expression, of all digestive enzymes examined as well as a reduction in gut apelin mRNA. Torpor induced a reduction in the activity of all enzymes with the exception of alanine aminopeptidase, and a decrease in mRNA levels of alanine aminopeptidase, orexin, CCK and mTOR. Our results suggest that both acute fasting and long-term fasting induce a reduction in the intestinal function of cunner, as evidenced by an overall decrease in the activities of digestive enzymes and mRNA expression of several factors involved in feeding and digestion.
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Affiliation(s)
- James Hayes
- Department of Biology, Memorial University of Newfoundland, St. John's, NL A1B 3X9, Canada; Department of Biochemistry, Memorial University of Newfoundland, St. John's, NL A1B 3X9, Canada
| | - Hélène Volkoff
- Department of Biology, Memorial University of Newfoundland, St. John's, NL A1B 3X9, Canada; Department of Biochemistry, Memorial University of Newfoundland, St. John's, NL A1B 3X9, Canada.
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Irwin N, Flatt PR. Enteroendocrine hormone mimetics for the treatment of obesity and diabetes. Curr Opin Pharmacol 2013; 13:989-95. [DOI: 10.1016/j.coph.2013.09.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 08/21/2013] [Accepted: 09/04/2013] [Indexed: 12/13/2022]
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Abstract
Glucagon-like peptide-1 (GLP-1), an incretin hormone secreted primarily from the intestinal L-cells in response to meals, modulates nutrient homeostasis via actions exerted in multiple tissues and cell types. GLP-1 and its analogs, as well as compounds that inhibit endogenous GLP-1 breakdown, have become an effective therapeutic strategy for many subjects with type 2 diabetes. Here we review the discovery of GLP-1; its synthesis, secretion, and elimination from the circulation; and its multiple pancreatic and extrapancreatic effects. Finally, we review current options for GLP-1-based diabetes therapy, including GLP-1 receptor agonism and inhibition of GLP-1 breakdown, as well as the benefits and drawbacks of different modes of therapy and the potential for new therapeutic avenues.
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Affiliation(s)
- Young Min Cho
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul National University College of Medicine, Seoul 110-744, South Korea;
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58
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Gault VA, Bhat VK, Irwin N, Flatt PR. A novel glucagon-like peptide-1 (GLP-1)/glucagon hybrid peptide with triple-acting agonist activity at glucose-dependent insulinotropic polypeptide, GLP-1, and glucagon receptors and therapeutic potential in high fat-fed mice. J Biol Chem 2013; 288:35581-91. [PMID: 24165127 DOI: 10.1074/jbc.m113.512046] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and glucagon bind to related members of the same receptor superfamily and exert important effects on glucose homeostasis, insulin secretion, and energy regulation. The present study assessed the biological actions and therapeutic utility of novel GIP/glucagon/GLP-1 hybrid peptides. Nine novel peptides were synthesized and exhibited complete DPP-IV resistance and enhanced in vitro insulin secretion. The most promising peptide, [dA(2)]GLP-1/GcG, stimulated cAMP production in GIP, GLP-1, and glucagon receptor-transfected cells. Acute administration of [dA(2)]GLP-1/GcG in combination with glucose significantly lowered plasma glucose and increased plasma insulin in normal and obese diabetic (ob/ob) mice. Furthermore, [dA(2)]GLP-1/GcG elicited a protracted glucose-lowering and insulinotropic effect in high fat-fed mice. Twice daily administration of [dA(2)]GLP-1/GcG for 21 days decreased body weight and nonfasting plasma glucose and increased circulating plasma insulin concentrations in high fat-fed mice. Furthermore, [dA(2)]GLP-1/GcG significantly improved glucose tolerance and insulin sensitivity by day 21. Interestingly, locomotor activity was increased in [dA(2)]GLP-1/GcG mice, without appreciable changes in aspects of metabolic rate. Studies in knock-out mice confirmed the biological action of [dA(2)]GLP-1/GcG via multiple targets including GIP, GLP-1, and glucagon receptors. The data suggest significant promise for novel triple-acting hybrid peptides as therapeutic options for obesity and diabetes.
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Affiliation(s)
- Victor A Gault
- From the SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, BT52 1SA Northern Ireland, United Kingdom
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Abstract
The clinical efficacy of bariatric surgery has encouraged the scientific investigation of the gut as a major endocrine organ. Manipulation of gastrointestinal anatomy through surgery has been shown to profoundly affect the physiological and metabolic processes that control body weight and glycaemia. The most popular bariatric surgical procedures are gastric bypass, adjustable gastric banding and vertical sleeve gastrectomy. Even though these procedures were designed with the aim of causing restriction of food intake and nutrient malabsorption, evidence suggests that their contributions to weight loss are minimal. Instead, these interventions reduce body weight by decreasing hunger, increasing satiation during a meal, changing food preferences and energy expenditure. In this Review, we have explored these mechanisms as well as their mediators. The hope is that that their in-depth investigation will enable the optimization and individualization of surgical techniques, the development of equally effective but safer nonsurgical weight-loss interventions, and even the understanding of the pathophysiology of obesity itself.
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Affiliation(s)
- Alexander D Miras
- Molecular and Metabolic Imaging Group, Institute of Clinical Sciences, Imperial College London, Hammersmith Hospital, London W12 0NN, UK
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60
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Mace OJ, Marshall F. DIGESTIVE PHYSIOLOGY OF THE PIG SYMPOSIUM: Gut chemosensing and the regulation of nutrient absorption and energy supply1. J Anim Sci 2013; 91:1932-45. [DOI: 10.2527/jas.2012-5906] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Affiliation(s)
- O. J. Mace
- Heptares Therapeutics, BioPark, Broadwater Road, Welwyn Garden City, AL7 3AX, United Kingdom
| | - F. Marshall
- Heptares Therapeutics, BioPark, Broadwater Road, Welwyn Garden City, AL7 3AX, United Kingdom
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