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Woodward ORM, Gribble FM, Reimann F, Lewis JE. Gut peptide regulation of food intake - evidence for the modulation of hedonic feeding. J Physiol 2022; 600:1053-1078. [PMID: 34152020 DOI: 10.1113/jp280581] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 05/17/2021] [Indexed: 12/13/2022] Open
Abstract
The number of people living with obesity has tripled worldwide since 1975 with serious implications for public health, as obesity is linked to a significantly higher chance of early death from associated comorbidities (metabolic syndrome, type 2 diabetes, cardiovascular disease and cancer). As obesity is a consequence of food intake exceeding the demands of energy expenditure, efforts are being made to better understand the homeostatic and hedonic mechanisms governing food intake. Gastrointestinal peptides are secreted from enteroendocrine cells in response to nutrient and energy intake, and modulate food intake either via afferent nerves, including the vagus nerve, or directly within the central nervous system, predominantly gaining access at circumventricular organs. Enteroendocrine hormones modulate homeostatic control centres at hypothalamic nuclei and the dorso-vagal complex. Additional roles of these peptides in modulating hedonic food intake and/or preference via the neural systems of reward are starting to be elucidated, with both peripheral and central peptide sources potentially contributing to central receptor activation. Pharmacological interventions and gastric bypass surgery for the treatment of type 2 diabetes and obesity elevate enteroendocrine hormone levels and also alter food preference. Hence, understanding of the hedonic mechanisms mediated by gut peptide action could advance development of potential therapeutic strategies for the treatment of obesity and its comorbidities.
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Affiliation(s)
- Orla R M Woodward
- Wellcome Trust - MRC Institute of Metabolic Science Metabolic Research Laboratories, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
| | - Fiona M Gribble
- Wellcome Trust - MRC Institute of Metabolic Science Metabolic Research Laboratories, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
| | - Frank Reimann
- Wellcome Trust - MRC Institute of Metabolic Science Metabolic Research Laboratories, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
| | - Jo E Lewis
- Wellcome Trust - MRC Institute of Metabolic Science Metabolic Research Laboratories, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
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2
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Laurila S, Rebelos E, Honka MJ, Nuutila P. Pleiotropic Effects of Secretin: A Potential Drug Candidate in the Treatment of Obesity? Front Endocrinol (Lausanne) 2021; 12:737686. [PMID: 34671320 PMCID: PMC8522834 DOI: 10.3389/fendo.2021.737686] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 09/15/2021] [Indexed: 12/18/2022] Open
Abstract
Secretin is the first hormone that has been discovered, inaugurating the era and the field of endocrinology. Despite the initial focus, the interest in its actions faded away over the decades. However, there is mounting evidence regarding the pleiotropic beneficial effects of secretin on whole-body homeostasis. In this review, we discuss the evidence from preclinical and clinical studies based on which secretin may have a role in the treatment of obesity.
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Affiliation(s)
- Sanna Laurila
- Turku PET Centre, University of Turku, Turku, Finland
- Heart Center, Turku University Hospital, Turku, Finland
- Department of Cardiology, Satakunta Central Hospital, Pori, Finland
| | - Eleni Rebelos
- Turku PET Centre, University of Turku, Turku, Finland
| | | | - Pirjo Nuutila
- Turku PET Centre, University of Turku, Turku, Finland
- Department of Endocrinology, Turku University Hospital, Turku, Finland
- *Correspondence: Pirjo Nuutila,
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3
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Wang L, Zhang L. Involvement of Secretin in the Control of Cell Survival and Synaptic Plasticity in the Central Nervous System. Front Neurosci 2020; 14:387. [PMID: 32435180 PMCID: PMC7218122 DOI: 10.3389/fnins.2020.00387] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 03/30/2020] [Indexed: 01/30/2023] Open
Abstract
With emerging evidence showing a wide distribution of secretin (SCT) and its receptor (SCTR) in the central nervous system (CNS), the putative neuropeptide role of SCT has become more appreciated since the disruption of SCT/SCTR axis affects various neural functions. This mini review thus focuses on the effects of SCT on cell survival and synaptic plasticity, both of which play critical roles in constructing and maintaining neural circuits with optimal output of behavioral phenotypes. Specifically, SCT-dependent cellular and molecular mechanisms that may regulate these two aspects will be discussed. The potential complementary or synergistical mechanisms between SCT and other peptides of the SCT superfamily will also be discussed for bridging their actions in the brain. A full understanding of functional SCT/SCTR in the brain may lead to future perspectives regarding therapeutic implications of SCT in relieving neural symptoms.
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Affiliation(s)
- Lei Wang
- School of Life Sciences, Guangzhou University, Guangzhou, China
| | - Li Zhang
- GHM Institute of CNS Regeneration, Jinan University, Guangzhou, China
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4
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Kokkinos A, Tsilingiris D, le Roux CW, Rubino F, Mantzoros CS. Will medications that mimic gut hormones or target their receptors eventually replace bariatric surgery? Metabolism 2019; 100:153960. [PMID: 31412266 DOI: 10.1016/j.metabol.2019.153960] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 07/31/2019] [Accepted: 08/05/2019] [Indexed: 02/07/2023]
Abstract
Bariatric surgery is currently the most effective therapeutic modality through which sustained beneficial effects on weight loss and metabolic improvement are achieved. During recent years, indications for bariatric surgery have been expanded to include cases of poorly controlled type 2 (T2DM) diabetes mellitus in lesser extremes of body weight. A spectrum of the beneficial effects of surgery is attributed to robust changes of postprandial gut peptide responses that are observed post operatively. Consolidated knowledge regarding gut peptide physiology as well as emerging new evidence shedding light on the mode of action of previously overlooked gut hormones provide appealing potential obesity and T2DM therapeutic perspectives. The accumulation of evidence from the effect of exogenous administration of native gut peptides alone or in combinations to humans as well as the development of mimetic agents exerting agonistic effects on combinations of gut hormone receptors pave the way for future integrated gut peptide-based treatments, which may mimic the effects of bariatric surgery.
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Affiliation(s)
- Alexander Kokkinos
- First Department of Propaedeutic Internal Medicine, Medical School, National and Kapodistrian University of Athens, Laiko General Hospital, Athens, Greece.
| | - Dimitrios Tsilingiris
- First Department of Propaedeutic Internal Medicine, Medical School, National and Kapodistrian University of Athens, Laiko General Hospital, Athens, Greece
| | - Carel W le Roux
- Diabetes Complications Research Centre, University College Dublin, Dublin, Ireland
| | - Francesco Rubino
- Department of Metabolic and Bariatric Surgery, Diabetes and Nutritional Science Division, King's College Hospital, London, United Kingdom
| | - Christos S Mantzoros
- Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, USA
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5
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Abstract
The regulation of energy and glucose balance contributes to whole-body metabolic homeostasis, and such metabolic regulation is disrupted in obesity and diabetes. Metabolic homeostasis is orchestrated partly in response to nutrient and vagal-dependent gut-initiated functions. Specifically, the sensory and motor fibres of the vagus nerve transmit intestinal signals to the central nervous system and exert biological and physiological responses. In the past decade, the understanding of the regulation of vagal afferent signals and of the associated metabolic effect on whole-body energy and glucose balance has progressed. This Review highlights the contributions made to the understanding of the vagal afferent system and examines the integrative role of the vagal afferent in gastrointestinal regulation of appetite and glucose homeostasis. Investigating the integrative and metabolic role of vagal afferent signalling represents a potential strategy to discover novel therapeutic targets to restore energy and glucose balance in diabetes and obesity.
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6
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Wang R, Chow BKC, Zhang L. Distribution and Functional Implication of Secretin in Multiple Brain Regions. J Mol Neurosci 2018; 68:485-493. [PMID: 29882022 DOI: 10.1007/s12031-018-1089-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Accepted: 05/11/2018] [Indexed: 12/15/2022]
Abstract
Secretin is a polypeptide hormone initially identified for its gastrointestinal functions. However, emerging evidences show wide distribution of secretin and secretin receptor across various brain regions from cerebral cortex, hippocampus, hypothalamus to cerebellum. In this mini review, we will firstly describe the region-specific expression pattern of secretin and secretin receptor in the brain, followed by a summary of central physiological and neurological functions mediated by secretin. Using genetic manipulation and pharmaceutical approaches, one can elucidate the role of secretin in mediating various neurological functions from simple behaviors, such as water and food intake, to more complex functions including emotion, motor, and learning or memory. At last, current weakness and future perspectives of secretin in the central nervous system will be discussed, aiming to provide the potency of using secretin or its analog for treating various neurological disorders.
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Affiliation(s)
- Ruanna Wang
- Joint International Research Laboratory of CNS Regeneration, GHM Institute of CNS Regeneration, Jinan University, Guangzhou, China
| | - Billy K C Chow
- School of Biological Sciences, University of Hong Kong, Hong Kong SAR, China.
| | - Li Zhang
- Joint International Research Laboratory of CNS Regeneration, GHM Institute of CNS Regeneration, Jinan University, Guangzhou, China.
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Jaglin M, Rhimi M, Philippe C, Pons N, Bruneau A, Goustard B, Daugé V, Maguin E, Naudon L, Rabot S. Indole, a Signaling Molecule Produced by the Gut Microbiota, Negatively Impacts Emotional Behaviors in Rats. Front Neurosci 2018; 12:216. [PMID: 29686603 PMCID: PMC5900047 DOI: 10.3389/fnins.2018.00216] [Citation(s) in RCA: 142] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 03/19/2018] [Indexed: 12/22/2022] Open
Abstract
Gut microbiota produces a wide and diverse array of metabolites that are an integral part of the host metabolome. The emergence of the gut microbiome-brain axis concept has prompted investigations on the role of gut microbiota dysbioses in the pathophysiology of brain diseases. Specifically, the search for microbe-related metabolomic signatures in human patients and animal models of psychiatric disorders has pointed out the importance of the microbial metabolism of aromatic amino acids. Here, we investigated the effect of indole on brain and behavior in rats. Indole is produced by gut microbiota from tryptophan, through the tryptophanase enzyme encoded by the tnaA gene. First, we mimicked an acute and high overproduction of indole by injecting this compound in the cecum of conventional rats. This treatment led to a dramatic decrease of motor activity. The neurodepressant oxidized derivatives of indole, oxindole and isatin, accumulated in the brain. In addition, increase in eye blinking frequency and in c-Fos protein expression in the dorsal vagal complex denoted a vagus nerve activation. Second, we mimicked a chronic and moderate overproduction of indole by colonizing germ-free rats with the indole-producing bacterial species Escherichia coli. We compared emotional behaviors of these rats with those of germ-free rats colonized with a genetically-engineered counterpart strain unable to produce indole. Rats overproducing indole displayed higher helplessness in the tail suspension test, and enhanced anxiety-like behavior in the novelty, elevated plus maze and open-field tests. Vagus nerve activation was suggested by an increase in eye blinking frequency. However, unlike the conventional rats dosed with a high amount of indole, the motor activity was not altered and neither oxindole nor isatin could be detected in the brain. Further studies are required for a comprehensive understanding of the mechanisms supporting indole effects on emotional behaviors. As our findings suggest that people whose gut microbiota is highly prone to produce indole could be more likely to develop anxiety and mood disorders, we addressed the issue of the inter-individual variability of indole producing potential in humans. An in silico investigation of metagenomic data focused on the tnaA gene products definitively proved this inter-individual variability.
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Affiliation(s)
- Mathilde Jaglin
- Micalis Institute, Institut National de la Recherche Agronomique, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Moez Rhimi
- Micalis Institute, Institut National de la Recherche Agronomique, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Catherine Philippe
- Micalis Institute, Institut National de la Recherche Agronomique, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Nicolas Pons
- MetaGenoPolis, Institut National de la Recherche Agronomique, Université Paris-Saclay, Jouy-en-Josas, France
| | - Aurélia Bruneau
- Micalis Institute, Institut National de la Recherche Agronomique, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Bénédicte Goustard
- Micalis Institute, Institut National de la Recherche Agronomique, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Valérie Daugé
- Micalis Institute, Institut National de la Recherche Agronomique, AgroParisTech, Centre National de la Recherche Scientifique, Université Paris-Saclay, Jouy-en-Josas, France
| | - Emmanuelle Maguin
- Micalis Institute, Institut National de la Recherche Agronomique, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Laurent Naudon
- Micalis Institute, Institut National de la Recherche Agronomique, AgroParisTech, Centre National de la Recherche Scientifique, Université Paris-Saclay, Jouy-en-Josas, France
| | - Sylvie Rabot
- Micalis Institute, Institut National de la Recherche Agronomique, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
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8
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Zafra MA, Agüera AD, Molina F, Puerto A. Disruption of re-intake after partial withdrawal of gastric food contents in rats lesioned in the gelatinous part of the nucleus of the solitary tract. Appetite 2017; 113:231-238. [PMID: 28259536 DOI: 10.1016/j.appet.2017.02.040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 02/21/2017] [Accepted: 02/27/2017] [Indexed: 02/06/2023]
Abstract
Sensory information from the upper gastrointestinal tract is critical in food intake regulation. Signals from different levels of the digestive system are processed to the brain, among other systems, via the vagus nerve, which mainly projects towards the nucleus of the solitary tract (NST). The objective of this study was to analyze the participation of the gelatinous part (SolG) of the NST in short-term food intake. One-third of the stomach food content was withdrawn at 5 min after the end of a meal, and food was then available ad libitum for different time periods. SolG-lesioned and control animals ingested a similar amount of the initial liquid meal, but the former consumed significantly smaller amounts and failed to compensate for the food deficit, whereas the controls re-ingested virtually the same amount as extracted. These data suggest that the SolG, as in the case of related anatomical structures such as the vagus nerve or external lateral parabrachial subnucleus, may be relevant in particular circumstances that require the rapid processing of vagal-related food intake adjustment associated to the upper gastrointestinal tract.
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Affiliation(s)
- María A Zafra
- Department of Psychobiology, University of Granada, Campus de Cartuja, Granada 18071, Spain; Mind, Brain, and Behavior Research Center (CIMCYC), University of Granada, Campus de Cartuja, Granada 18071, Spain.
| | - Antonio D Agüera
- Department of Psychobiology, University of Granada, Campus de Cartuja, Granada 18071, Spain
| | - Filomena Molina
- Department of Psychobiology, University of Granada, Campus de Cartuja, Granada 18071, Spain; Mind, Brain, and Behavior Research Center (CIMCYC), University of Granada, Campus de Cartuja, Granada 18071, Spain
| | - Amadeo Puerto
- Department of Psychobiology, University of Granada, Campus de Cartuja, Granada 18071, Spain; Mind, Brain, and Behavior Research Center (CIMCYC), University of Granada, Campus de Cartuja, Granada 18071, Spain
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9
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Sekar R, Wang L, Chow BKC. Central Control of Feeding Behavior by the Secretin, PACAP, and Glucagon Family of Peptides. Front Endocrinol (Lausanne) 2017; 8:18. [PMID: 28223965 PMCID: PMC5293785 DOI: 10.3389/fendo.2017.00018] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 01/18/2017] [Indexed: 12/25/2022] Open
Abstract
Constituting a group of structurally related brain-gut peptides, secretin (SCT), pituitary adenylate cyclase-activating peptide (PACAP), and glucagon (GCG) family of peptide hormones exert their functions via interactions with the class B1 G protein-coupled receptors. In recent years, the roles of these peptides in neuroendocrine control of feeding behavior have been a specific area of research focus for development of potential therapeutic drug targets to combat obesity and metabolic disorders. As a result, some members in the family and their analogs have already been utilized as therapeutic agents in clinical application. This review aims to provide an overview of the current understanding on the important role of SCT, PACAP, and GCG family of peptides in central control of feeding behavior.
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Affiliation(s)
- Revathi Sekar
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China
| | - Lei Wang
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China
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10
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Satiation and re-intake after partial withdrawal of gastric food contents: A dissociation effect in external lateral parabrachial lesioned rats. Brain Res Bull 2016; 127:126-133. [DOI: 10.1016/j.brainresbull.2016.09.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 09/06/2016] [Accepted: 09/09/2016] [Indexed: 11/19/2022]
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11
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Motojima Y, Kawasaki M, Matsuura T, Saito R, Yoshimura M, Hashimoto H, Ueno H, Maruyama T, Suzuki H, Ohnishi H, Sakai A, Ueta Y. Effects of peripherally administered cholecystokinin-8 and secretin on feeding/drinking and oxytocin-mRFP1 fluorescence in transgenic rats. Neurosci Res 2016; 109:63-9. [PMID: 26919961 DOI: 10.1016/j.neures.2016.02.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 02/17/2016] [Accepted: 02/18/2016] [Indexed: 12/27/2022]
Abstract
Peripheral administration of cholecystokinin (CCK)-8 or secretin activates oxytocin (OXT)-secreting neurons in the hypothalamus. Although OXT is involved in the regulation of feeding behavior, detailed mechanism remains unclear. In the present study, we examined the central OXTergic pathways after intraperitoneally (i.p.) administration of CCK-8 and secretin using male OXT-monomeric red fluorescent protein 1 (mRFP1) transgenic rats and male Wistar rats. I.p. administration of CCK-8 (50μg/kg) and secretin (100μg/kg) decreased food intake in these rats. While i.p. administration of CCK-8 decreased water intake, i.p. administration of secretin increased water intake. Immunohistochemical study revealed that Fos-Like-Immunoreactive cells were observed abundantly in the brainstem and in the OXT neurons in the dorsal division of the parvocellular paraventricular nucleus (dpPVN). We could observe marked increase of mRFP1 fluorescence, as an indicator for OXT, in the dpPVN and mRFP1-positive granules in axon terminals of the dpPVN OXT neurons in the nucleus tractus solitarius (NTS) after i.p. administration of CCK-8 and secretin. These results provide us the evidence that, at least in part, i.p. administration of CCK-8 or secretin might be involved in the regulation of feeding/drinking via a OXTergic pathway from the dpPVN to the NTS.
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Affiliation(s)
- Yasuhito Motojima
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan; Department of Orthopaedics, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan
| | - Makoto Kawasaki
- Department of Orthopaedics, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan
| | - Takanori Matsuura
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan; Department of Orthopaedics, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan
| | - Reiko Saito
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan
| | - Mitsuhiro Yoshimura
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan
| | - Hirofumi Hashimoto
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan
| | - Hiromichi Ueno
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan
| | - Takashi Maruyama
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan
| | - Hitoshi Suzuki
- Department of Orthopaedics, Wakamatsu Hospital for University of Occupational and Environmental Health, Kitakyushu 808-0024, Japan
| | - Hideo Ohnishi
- Department of Orthopaedics, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan
| | - Akinori Sakai
- Department of Orthopaedics, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan
| | - Yoichi Ueta
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan.
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Pang YY, Chen XY, Xue Y, Han XH, Chen L. Effects of secretin on neuronal activity and feeding behavior in central amygdala of rats. Peptides 2015; 66:1-8. [PMID: 25698232 DOI: 10.1016/j.peptides.2015.01.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 12/15/2014] [Accepted: 01/08/2015] [Indexed: 12/13/2022]
Abstract
Previous studies have shown that secretin and secretin receptors are expressed in central amygdala neurons. By using both in vivo extracellular recording as well as behavioral test, we investigated the direct electrophysiological effects of secretin in the central amygdala and its involvement in feeding behavior. Micro-pressure ejection of secretin increased the spontaneous firing rate by 104.22±26.18% in 13 out of the 27 central amygdala neurons. In other 6 out of the 27 neurons, secretin decreased the firing rate by 68.80±12.10%. Firing patter analysis showed that secretin did not change the firing pattern significantly. Further electrophysiological recordings revealed that secretin decreased the firing rate of glucose-sensitive neurons. In behavioral test, microinjection of secretin into the central amygdala significantly reduced cumulative food intake through cAMP-activated protein kinase activation. Based on the present electrophysiological and behavioral findings, we hypothesized that secretin may suppress food intake by its modulation of spontaneous firing of central amygdala neurons.
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Affiliation(s)
- Ya-Yan Pang
- Department of Physiology, Faculty of Medicine, Qingdao University, Qingdao 266071, China
| | - Xin-Yi Chen
- Department of Neurology, Provincial Hospital Affiliated to Shandong University, Jinan, Shandong 250021, China
| | - Yan Xue
- Department of Physiology, Faculty of Medicine, Qingdao University, Qingdao 266071, China
| | - Xiao-Hua Han
- Department of Physiology, Faculty of Medicine, Qingdao University, Qingdao 266071, China
| | - Lei Chen
- Department of Physiology, Faculty of Medicine, Qingdao University, Qingdao 266071, China.
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13
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Zhang L, Chow BKC. The central mechanisms of secretin in regulating multiple behaviors. Front Endocrinol (Lausanne) 2014; 5:77. [PMID: 24904528 PMCID: PMC4033102 DOI: 10.3389/fendo.2014.00077] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 05/08/2014] [Indexed: 11/13/2022] Open
Abstract
Secretin (SCT) was firstly discovered as a gut peptide hormone in stimulating pancreatic secretion, while its novel neuropeptide role has drawn substantial research interests in recent years. SCT and its receptor (SCTR) are widely expressed in different brain regions, where they exert multiple cellular functions including neurotransmission, gene expression regulation, neurogenesis, and neural protection. As all these neural functions ultimately can affect behaviors, it is hypothesized that SCT controls multiple behavioral paradigms. Current findings support this hypothesis as SCT-SCTR axis participates in modulating social interaction, spatial learning, water and food intake, motor coordination, and motor learning behaviors. This mini-review focuses on various aspects of SCT and SCTR in hippocampus, hypothalamus, and cerebellum including distribution profiles, cellular functions, and behavioral phenotypes to elucidate the link between cellular mechanisms and behavioral control.
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Affiliation(s)
- Li Zhang
- School of Biological Sciences, University of Hong Kong, Hong Kong, China
| | - Billy K. C. Chow
- School of Biological Sciences, University of Hong Kong, Hong Kong, China
- *Correspondence: Billy K. C. Chow, School of Biological Sciences, University of Hong Kong, Kardoorie Biological Science Building, Pokfulam Road 4N-12, Sai Ying Pun, Hong Kong, China e-mail:
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14
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Chu JYS, Cheng CYY, Sekar R, Chow BKC. Vagal afferent mediates the anorectic effect of peripheral secretin. PLoS One 2013; 8:e64859. [PMID: 23738005 PMCID: PMC3667839 DOI: 10.1371/journal.pone.0064859] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 04/23/2013] [Indexed: 02/02/2023] Open
Abstract
Secretin (SCT) is a classical peptide hormone that is synthesized and released from the gastrointestinal tract after a meal. We have previously shown that it acts both as a central and peripheral anorectic peptide, and that its central effect is mediated via melanocortin system. As peripheral satiety signals from the gastrointestinal tract can be sent to the brain via the vagal afferent or by crossing the blood-brain barrier (BBB), we therefore sought to investigate the pathway by which peripheral SCT reduces appetite in this study. It is found that bilateral subdiaphragmatic vagotomy and treatment of capsaicin, an excitotoxin for primary afferent neurons, could both block the anorectic effect of peripherally injected SCT. These treatments are found to be capable of blunting i.p. SCT-induced Fos activation in pro-opiomelanocortin (POMC) neurons within the hypothalamic Arcuate Nucleus (Arc). Moreover, we have also found that bilateral midbrain transaction could block feeding reduction by peripheral SCT. Taken together, we conclude that the satiety signals of peripheral SCT released from the gastrointestinal tract are sent via the vagus nerves to the brainstem and subsequently Arc, where it controls central expression of other regulatory peptides to regulate food intake.
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Affiliation(s)
- Jessica Y. S. Chu
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Carrie Y. Y. Cheng
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Revathi Sekar
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Billy K. C. Chow
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
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Sekar R, Chow BKC. Metabolic effects of secretin. Gen Comp Endocrinol 2013; 181:18-24. [PMID: 23246720 DOI: 10.1016/j.ygcen.2012.11.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2012] [Revised: 11/23/2012] [Accepted: 11/27/2012] [Indexed: 12/25/2022]
Abstract
Secretin (Sct), traditionally a gastrointestinal hormone backed by a century long research, is now beginning to be recognized also as a neuroactive peptide. Substantiation by recent evidence on the functional role of Sct in various regions of the brain, especially on its potential neurosecretion from the posterior pituitary, has revealed Sct's physiological actions in regulating water homeostasis. Recent advances in understanding the functional roles of central and peripheral Sct has been made possible by the development of Sct and Sct receptor (SctR) knockout animal models which have led to novel approaches in research on the physiology of this brain-gut peptide. While research on the role of Sct in appetite regulation and fatty acid metabolism has been initiated recently, its role in glucose homeostasis is unclear. This review focuses mainly on the metabolic role of Sct by discussing data from the last century and recent discoveries, with emphasis on the need for revisiting and elucidating the role of Sct in metabolism and energy homeostasis.
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Affiliation(s)
- Revathi Sekar
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong
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Hashimoto H, Uezono Y, Ueta Y. Pathophysiological function of oxytocin secreted by neuropeptides: A mini review. PATHOPHYSIOLOGY 2012; 19:283-98. [DOI: 10.1016/j.pathophys.2012.07.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2012] [Revised: 07/04/2012] [Accepted: 07/11/2012] [Indexed: 10/28/2022] Open
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Yuan Y, Lee LTO, Ng SS, Chow BKC. Extragastrointestinal functions and transcriptional regulation of secretin and secretin receptors. Ann N Y Acad Sci 2011; 1220:23-33. [DOI: 10.1111/j.1749-6632.2011.05987.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Cheng CYY, Chu JYS, Chow BKC. Central and peripheral administration of secretin inhibits food intake in mice through the activation of the melanocortin system. Neuropsychopharmacology 2011; 36:459-71. [PMID: 20927047 PMCID: PMC3055665 DOI: 10.1038/npp.2010.178] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Secretin (Sct) is released into the circulation postprandially from the duodenal S-cells. The major functions of Sct originated from the gastrointestinal system are to delay gastric emptying, stimulate fluid secretion from pancreas and liver, and hence optimize the digestion process. In recent years, Sct and its receptor (Sctr) have been identified in discrete nuclei of the hypothalamus, including the paraventricular nucleus (PVN) and the arcuate nucleus (Arc). These nuclei are the primary brain sites that are engaged in regulating body energy homeostasis, thus providing anatomical evidence to support a functional role of Sct in appetite control. In this study, the effect of Sct on feeding behavior was investigated using wild-type (wt), Sct(-/-), and secretin receptor-deficient (Sctr(-/-)) mice. We found that both central and peripheral administration of Sct could induce Fos expression in the PVN and Arc, suggesting the activation of hypothalamic feeding centers by this peptide. Consistent with this notion, Sct was found to increase thyrotropin-releasing hormone and melanocortin-4 receptor (Mc4r) transcripts in the PVN, and augment proopiomelanocortin, but reduces agouti-related protein mRNA expression in the Arc. Injection of Sct was able to suppress food intake in wt mice, but not in Sctr(-/-) mice, and that this effect was abolished upon pretreatment with SHU9119, an antagonist for Mc4r. In summary, our data suggest for the first time that Sct is an anorectic peptide, and that this function is mediated by the melanocortin system.
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Affiliation(s)
- Carrie Yuen Yee Cheng
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Jessica Yan Shuen Chu
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Billy Kwok Chong Chow
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong SAR, China,School of Biological Sciences, The University of Hong Kong, 4N01, Kadoorie Biological Sciences Building, Pokfulam, Hong Kong SAR, China, Tel: +852 22990850, Fax: 852 25599114, E-mail:
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Abstract
Body fluid homeostasis is critical for the survival of living organisms and hence is tightly controlled. From initial studies on the effects of secretin (SCT) on renal water reabsorption in the 1940s and recent investigations of its role in cardiovascular and neuroendocrine functions, it has now become increasingly clear that this peptide is an integral component of the homeostatic processes that maintain body fluid balance. This review, containing some of our recent findings of centrally expressed SCT on water intake, focuses on the actions of SCT in influencing the physiological, neuroendocrine, and cardiovascular processes that subserve body fluid homeostasis.
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Welch MG, Anwar M, Chang CY, Gross KJ, Ruggiero DA, Gershon MD, Gershon MD. Combined administration of secretin and oxytocin inhibits chronic colitis and associated activation of forebrain neurons. Neurogastroenterol Motil 2010; 22:654-e202. [PMID: 20210978 PMCID: PMC3068601 DOI: 10.1111/j.1365-2982.2010.01477.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
BACKGROUND The pathogenesis of inflammatory bowel disease is unknown; however, the disorder is aggravated by psychological stress and is itself psychologically stressful. Chronic intestinal inflammation, moreover, has been reported to activate forebrain neurons. We tested the hypotheses that the chronically inflamed bowel signals to the brain through the vagi and that administration of a combination of secretin (S) and oxytocin (OT) inhibits this signaling. METHODS Three daily enemas containing 2,4,6-trinitrobenzene sulfonic acid (TNBS), which were given to rats produced chronic colitis and ongoing activation of Fos in brain neurons. KEY RESULTS Fos was induced in neurons in the paraventricular nucleus of the hypothalamus, basolateral amygdala, central amygdala, and piriform cortex. Subdiaphragmatic vagotomy failed to inhibit this activation of Fos, suggesting that colitis activates forebrain neurons independently of the vagi. When administered intravenously, but not when given intracerebroventricularly, in doses that were individually ineffective, combined S/OT prevented colitis-associated activation of central neurons. Strikingly, S/OT decreased inflammatory infiltrates into the colon and colonic expression of tumor necrosis factor-alpha and interferon-gamma. CONCLUSIONS & INFERENCES These observations suggest that chronic colonic inflammation is ameliorated by the systemic administration of S/OT, which probably explains the parallel ability of systemic S/OT to inhibit the colitis-associated activation of forebrain neurons. It is possible that S and OT, which are endogenous to the colon, might normally combine to restrict the severity of colonic inflammatory responses and that advantage might be taken of this system to develop novel means of treating inflammation-associated intestinal disorders.
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Affiliation(s)
- Martha G. Welch
- Dept. of Psychiatry, Columbia Univ. College of P & S, 1051 Riverside Drive Unit 40, NY, NY, 10032,Dept. of Pathology & Cell Biology, Columbia U. College of P & S, 630 West 168th Street, NY, NY, 10032
| | - Muhammad Anwar
- Dept. of Psychiatry, Columbia Univ. College of P & S, 1051 Riverside Drive Unit 40, NY, NY, 10032
| | - Christine Y. Chang
- Dept. of Psychiatry, Columbia Univ. College of P & S, 1051 Riverside Drive Unit 40, NY, NY, 10032,Dept. of Pathology & Cell Biology, Columbia U. College of P & S, 630 West 168th Street, NY, NY, 10032
| | - Kara J. Gross
- Dept. of Pathology & Cell Biology, Columbia U. College of P & S, 630 West 168th Street, NY, NY, 10032
| | - David A. Ruggiero
- Dept. of Psychiatry, Columbia Univ. College of P & S, 1051 Riverside Drive Unit 40, NY, NY, 10032,Dept. of Pathology & Cell Biology, Columbia U. College of P & S, 630 West 168th Street, NY, NY, 10032
| | - Michael D. Gershon
- Dept. of Pathology & Cell Biology, Columbia U. College of P & S, 630 West 168th Street, NY, NY, 10032
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Velmurugan S, Brunton PJ, Leng G, Russell JA. Circulating secretin activates supraoptic nucleus oxytocin and vasopressin neurons via noradrenergic pathways in the rat. Endocrinology 2010; 151:2681-8. [PMID: 20332196 DOI: 10.1210/en.2009-1440] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Secretin is a 27-amino acid brain-gut peptide from duodenal S-cells. We tested the effects of systemic administration of secretin to simulate its postprandial release on neuroendocrine neurons of the supraoptic nucleus (SON) in urethane-anesthetized female rats. Secretin dose-dependently increased the firing rate of oxytocin neurons, more potently than cholecystokinin, and dose-dependently increased plasma oxytocin concentration. The effect of secretin on SON vasopressin neurons was also predominantly excitatory, in contrast to the inhibitory actions of cholecystokinin. To explore the involvement of noradrenergic inputs in secretin-induced excitation, benoxathian, an alpha1-adrenoceptor antagonist, was infused intracerebroventricularly. Benoxathian intracerebroventricular infusion blocked the excitation by secretin of both oxytocin and vasopressin neurons. To test the role of local noradrenaline release in the SON, benoxathian was microdialyzed onto the SON. The basal firing rate of oxytocin neurons was slightly reduced and the secretin-induced excitation was attenuated during benoxathian microdialysis. Hence, noradrenergic pathways mediate the excitation by systemic secretin of oxytocin neurons via alpha1-adrenoceptors in the SON. As both systemic secretin and oxytocin are involved in regulating gastrointestinal functions and natriuresis, systemically released secretin might act partly through oxytocin.
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Affiliation(s)
- Sathya Velmurugan
- Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh EH8 9XD, United Kingdom
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22
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Abstract
Metabolic pathologies such as Type 2 Diabetes have become a major health problem for worldwide populations. Unfortunately, efforts to cure and especially to prevent these significant global problems have so far been met with disappointment. Recently, the involvement of the gut-derived hormonal dysregulation in the development of obesity-related disturbances has been intensively studied. For instance, studies of gut-derived peptides such as peptide YY 3-36, glucagon-like peptide-1, oxyntomodulin and, more recently, ghrelin have significantly improved our understanding of mechanisms underlying weight and metabolic regulation. Even though early reports of the existence of secretin, the first peptide hormone to be described, date back as far as 1825, so much and yet so little is still known about its physiological role in mammals, including humans. However, recent years have provided a better understanding of how the release of secretin is regulated by enteral secretagogues. On the other hand, most basic questions about its role in the post-prandial regulation of metabolic functions in normal and pathophysiological conditions remain to be elucidated. The present work intends to review the physiology of secretin along with its central and peripheral outcomes on metabolic functions.
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Affiliation(s)
- D H St-Pierre
- Division of Endocrinology, Diabetology and Metabolism, Department of Internal Medicine, Ospedale Molinette, University of Turin, Turin, Italy
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Lu Y, Owyang C. Secretin-induced gastric relaxation is mediated by vasoactive intestinal polypeptide and prostaglandin pathways. Neurogastroenterol Motil 2009; 21:754-e47. [PMID: 19239625 PMCID: PMC2743409 DOI: 10.1111/j.1365-2982.2009.01271.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Secretin has been shown to delay gastric emptying and inhibit gastric motility. We have demonstrated that secretin acts on the afferent vagal pathway to induce gastric relaxation in the rat. However, the efferent pathway that mediates the action of secretin on gastric motility remains unknown. We recorded the response of intragastric pressure to graded doses of secretin administered intravenously to anaesthetized rats using a balloon attached to a catheter and placed in the body of the stomach. Secretin evoked a dose-dependent decrease in intragastric pressure. The threshold dose of secretin was 1.4 pmol kg(-1) h(-1) and the effective dose, 50% was 5.6 pmol kg(-1) h(-1). Pretreatment with hexamethonium markedly reduced gastric relaxation induced by secretin (5.6 pmol kg(-1) h(-1)). Bilateral vagotomy also significantly reduced gastric motor responses to secretin. Administration of N(G)-nitro-L-arginine methyl ester (10 mg kg(-1)) did not affect gastric relaxation induced by secretin. In contrast, intravenous administration of a vasoactive intestinal polypeptide (VIP) antagonist (30 nmol kg(-1)) reduced the gastric relaxation response to secretin (5.6 pmol kg(-1) h(-1)) by 89 +/- 5%. Indomethacin (2 mg kg(-1)) reduced gastric relaxation induced by secretin (5.6 pmol kg(-1) h(-1)) by 87 +/- 5%. Administration of prostaglandin (48 mg kg(-1) h(-1)) prevented this inhibitory effect. Indomethacin also reduced gastric relaxation induced by VIP (300 pmol kg(-1)) by 90 +/- 7%. These observations indicate that secretin acts through stimulation of presynaptic cholinergic neurons in a vagally mediated pathway. Through nicotinic synapses, secretin stimulates VIP release from postganglionic neurons in the gastric myenteric plexus, which in turn induces gastric relaxation through a prostaglandin-dependent pathway.
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Affiliation(s)
- Y Lu
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109-0362, USA
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Wang QP, Guan JL, Pan W, Kastin AJ, Shioda S. A diffusion barrier between the area postrema and nucleus tractus solitarius. Neurochem Res 2008; 33:2035-43. [PMID: 18373195 DOI: 10.1007/s11064-008-9676-y] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2007] [Accepted: 03/13/2008] [Indexed: 12/19/2022]
Abstract
The blood-brain barrier (BBB) is a structural and functional barrier that prevents free exchange of circulating substances with the brain, where the endothelial cells of microvessels are joined by tight junctions. The circumventricular organs (CVOs), by contrast, lack tight junctions and exhibit more direct communication with the circulating blood and cerebrospinal fluid. Despite many outstanding morphological studies at the electron microscopic level, there remain misconceptions that the CVOs provide direct passage of blood-borne substances to the rest of the brain. This study will show the structure of the anatomical borders of the dorsal vagal complex in the brainstem. A distinct diffusion barrier between the area postrema (AP, a CVO) and the nucleus tractus solitarius (NTS) was illustrated by immunohistochemistry at both the light and electron microscopic levels. The border zone between the AP and NTS was underlined by a continuous monolayer of columnar cells that were immunopositive for both the tight junction protein zona occludin-1 and the astrocyte marker glial fibrillary acidic protein. This observation of a diffusion barrier between the AP and NTS resolves a long-standing dispute about whether the NTS is a structural extension of the AP with a leaky BBB.
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Affiliation(s)
- Qing-Ping Wang
- Department of Anatomy, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan
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Lam IPY, Siu FKY, Chu JYS, Chow BKC. Multiple actions of secretin in the human body. INTERNATIONAL REVIEW OF CYTOLOGY 2008; 265:159-90. [PMID: 18275888 DOI: 10.1016/s0074-7696(07)65004-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The discovery of secretin initiated the field of endocrinology. Over the past century, multiple gastrointestinal functions of secretin have been extensively studied, and it was discovered that the principal function of this peptide in the gastrointestinal system is to facilitate digestion and to provide protection. In view of the late identification of secretin and the secretin receptor in various tissues, including the central nervous system, the pleiotropic functions of secretin have more recently been an area of intense focus. Secretin is a classical hormone, and recent studies clearly showed secretin's involvement in neural and neuroendocrine pathways, although the neuroactivity and neural regulation of its release are yet to be elucidated. This chapter reviews our current understanding of the pleiotropic actions of secretin with a special focus on the hormonal and neural interdependent pathways that mediate these actions.
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Affiliation(s)
- Ian P Y Lam
- Department of Zoology, University of Hong Kong, Hong Kong, China
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Siu FKY, Lam IPY, Chu JYS, Chow BKC. Signaling mechanisms of secretin receptor. ACTA ACUST UNITED AC 2006; 137:95-104. [PMID: 16930743 DOI: 10.1016/j.regpep.2006.02.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2006] [Revised: 02/14/2006] [Accepted: 02/27/2006] [Indexed: 10/24/2022]
Abstract
Secretin, a 27-amino acid gastrointestinal peptide, was initially discovered based on its activities in stimulating pancreatic juice. In the past 20 years, secretin was demonstrated to exhibit pleiotropic functions in many different tissues and more importantly, its role as a neuropeptide was substantiated. To carry out its activities in the central nervous system and in peripheral organs, secretin interacts specifically with one known receptor. Secretin receptor, a member of guanine nucleotide-binding protein (G protein)-coupled receptor (GPCR) in the secretin/VIP/glucagon subfamily, possesses the characteristics of GPCR with seven conserved transmembrane domains, a relatively large amino-terminal extracellular domain and an intracellular carboxyl terminus. The structural features and signal transduction pathways of the secretin receptor in various tissues are reviewed in this article.
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Affiliation(s)
- Francis K Y Siu
- Department of Zoology, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, PR China
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27
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Zhao Q, Boismenu R, Rusche JR, Holmes GL. Lack of effect of secretin on kindling and seizures. Epilepsy Behav 2006; 9:46-50. [PMID: 16723277 DOI: 10.1016/j.yebeh.2006.04.006] [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: 02/21/2006] [Revised: 03/28/2006] [Accepted: 04/02/2006] [Indexed: 10/24/2022]
Abstract
Secretin infused into rats activates neurons located in brain areas controlling autonomic function and emotion. The brain activity of secretin is mediated, at least in part, through vagal pathways. It is known that afferent stimulation of the vagus nerve results in considerable antiepileptic effects. Whether or not secretin has an effect on seizures is unknown. In this study, we evaluated the efficacy and safety of secretin as an antiepileptogenic agent in electrical kindling and as an anticonvulsant in fully kindled seizures. To assess antiepileptogenic effects, we administered secretin (10, 30, or 100 microg/kg/dose) or normal saline intravenously 5 min before twice-daily kindling stimulation. To assess the anticonvulsant effect of secretin, we administered either normal saline or secretin (100 microg/kg/dose) 5 min before the electrical stimulation to fully kindled rats. We observed no effect on kindling rate or afterdischarge duration. In fully kindled rats, secretin administration had no effect on kindling stage or afterdischarge duration. Thus, in the dose range used in this preliminary acute treatment study, secretin had no discernible antiepileptogenic or anticonvulsant effects. Secretin was very well tolerated in this multidose protocol.
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Affiliation(s)
- Qian Zhao
- Neuroscience Center at Dartmouth, Section of Neurology, Dartmouth Medical School, Lebanon, NH, USA.
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Li Y, Wu X, Yao H, Owyang C. Secretin activates vagal primary afferent neurons in the rat: evidence from electrophysiological and immunohistochemical studies. Am J Physiol Gastrointest Liver Physiol 2005; 289:G745-52. [PMID: 15920018 DOI: 10.1152/ajpgi.00039.2005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In this study, we evaluated the vagal afferent response to secretin at physiological concentrations and localized the site of secretin's action on vagal afferent pathways in the rat. The discharge of sensory neurons supplying the gastrointestinal tract was recorded from nodose ganglia. Of 91 neurons activated by electrical vagal stimulation, 19 neurons showed an increase in firing rate in response to intestinal perfusion of 5-HT (from 1.5 +/- 0.2 to 25 +/- 4 impulses/20 s) but no response to intestinal distension. A close intra-arterial injection of secretin (2.5 and 5.0 pmol) elicited responses in 15 of these 19 neurons (from 1.5 +/- 0.2 impulses/20 s at basal to 21 +/- 4 and 43 +/- 5 impulses/20 s, respectively). Subdiaphragmatic vagotomy and perivagal application of capsaicin, but not supranodose vagotomy, completely abolished the secretin-elicited vagal nodose neuronal response. In a separate study, 9 tension receptor afferents among 91 neurons responded positively to intestinal distension but failed to respond to luminal 5-HT. These nine neurons also showed no response to administration of secretin. As expected, immunohistochemical studies showed that secretin administration significantly increased the number of Fos-positive neurons in vagal nodose ganglia. In conclusion, we demonstrated for the first time that vagal sensory neurons are activated by secretin at physiological concentrations. A subpopulation of secretin-sensitive vagal afferent fibers is located in the intestinal mucosa, many of which are responsive to luminal 5-HT.
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Affiliation(s)
- Ying Li
- Gastroenterology Research Unit, University of Michigan Health System, Ann Arbor, MI 48109, USA
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Myers KM, Goulet M, Rusche J, Boismenu R, Davis M. Partial reversal of phencyclidine-induced impairment of prepulse inhibition by secretin. Biol Psychiatry 2005; 58:67-73. [PMID: 15992525 DOI: 10.1016/j.biopsych.2005.03.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2004] [Revised: 03/09/2005] [Accepted: 03/15/2005] [Indexed: 10/25/2022]
Abstract
BACKGROUND Secretin is a "gut-brain" peptide whose neural function is as yet poorly understood. Several clinical studies have reported modestly increased social interaction in autistic children following intravenous secretin administration. Very recently secretin also was administered to schizophrenic patients and found to increase social interaction in some individuals. METHODS In light of this finding, we assessed the ability of secretin to reverse phencyclidine- (PCP) induced impairment in prepulse inhibition (PPI), a leading animal model of sensorimotor gating deficits in schizophrenia. RESULTS Similar to atypical antipsychotics, secretin (1, 3, 10, 30, and 100 microg/kg) partially and dose-dependently reversed the PCP-induced deficit in PPI without significantly affecting baseline startle when administered intraperitoneally (IP) 10 minutes following IP administration of PCP (3 mg/kg). CONCLUSIONS This finding may be relevant to observations of antipsychotic efficacy of secretin in schizophrenic patients as well as our previous report that systemically administered secretin is capable of modulating conditioned fear, even at quite low doses.
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Affiliation(s)
- Karyn M Myers
- Department of Psychiatry and Behavioral Sciences, Emory University, Atlanta, Georgia, USA
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Clement HW, Pschibul A, Schulz E. Effects of secretin on extracellular GABA and other amino acid concentrations in the rat hippocampus. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2005; 71:239-71. [PMID: 16512354 DOI: 10.1016/s0074-7742(05)71011-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
Affiliation(s)
- Hans-Willi Clement
- Department of Child and Adolescent Psychiatry, University of Freiburg, Germany
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