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Norberto S, Assalin HB, Guadagnini D, Tobar N, Boer PA, Kang MC, Saad MJA, Kim YB, Prada PO. CLK2 in GABAergic neurons is critical in regulating energy balance and anxiety-like behavior in a gender-specific fashion. Front Endocrinol (Lausanne) 2023; 14:1172835. [PMID: 37635967 PMCID: PMC10449579 DOI: 10.3389/fendo.2023.1172835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 07/24/2023] [Indexed: 08/29/2023] Open
Abstract
Introduction Cdc2-like kinase (CLK2) is a member of CLK kinases expressed in hypothalamic neurons and is activated in response to refeeding, leptin, or insulin. Diet-induced obesity and leptin receptor-deficient db/db mice lack CLK2 signal in the hypothalamic neurons. The neurotransmiter gamma-aminobutyric acid (GABA) is among the most prevalent in the central nervous system (CNS), particularly in the hypothalamus. Given the abundance of GABA-expressing neurons and their potential influence on regulating energy and behavioral homeostasis, we aimed to explore whether the deletion of CLK2 in GABAergic neurons alters energy homeostasis and behavioral and cognitive functions in both genders of mice lacking CLK2 in Vgat-expressing neurons (Vgat-Cre; Clk2loxP/loxP) on chow diet. Methods We generated mice lacking Clk2 in Vgat-expressing neurons (Vgat-Cre; Clk2loxP/loxP) by mating Clk2loxP/loxP mice with Vgat-IRES-Cre transgenic mice and employed behavior, and physiological tests, and molecular approaches to investigate energy metabolism and behavior phenotype of both genders. Results and discussion We showed that deletion of CLK2 in GABAergic neurons increased adiposity and food intake in females. The mechanisms behind these effects were likely due, at least in part, to hypothalamic insulin resistance and upregulation of hypothalamic Npy and Agrp expression. Besides normal insulin and pyruvate sensitivity, Vgat-Cre; Clk2loxP/loxP females were glucose intolerant. Male Vgat-Cre; Clk2loxP/loxP mice showed an increased energy expenditure (EE). Risen EE may account for avoiding weight and fat mass gain in male Vgat-Cre; Clk2loxP/loxP mice. Vgat-Cre; Clk2loxP/loxP mice had no alteration in cognition or memory functions in both genders. Interestingly, deleting CLK2 in GABAergic neurons changed anxiety-like behavior only in females, not males. These findings suggest that CLK2 in GABAergic neurons is critical in regulating energy balance and anxiety-like behavior in a gender-specific fashion and could be a molecular therapeutic target for combating obesity associated with psychological disorders in females.
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Affiliation(s)
- Sónia Norberto
- Department of Internal Medicine, School of Medical Science, University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Heloisa Balan Assalin
- Department of Internal Medicine, School of Medical Science, University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Dioze Guadagnini
- Department of Internal Medicine, School of Medical Science, University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Natália Tobar
- Department of Radiology, University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Patrícia Aline Boer
- Department of Internal Medicine, Fetal Programming Laboratory, School of Medical Science, University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Min-Cheol Kang
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States
- Research Group of Food Processing, Korea Food Research Instute, Jeollabuk-do, Wanju, Republic of Korea
| | - Mario Jose Abdalla Saad
- Department of Internal Medicine, School of Medical Science, University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Young-Bum Kim
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States
| | - Patricia Oliveira Prada
- Department of Internal Medicine, School of Medical Science, University of Campinas (UNICAMP), Campinas, SP, Brazil
- School of Applied Sciences, University of Campinas (UNICAMP), Limeira, SP, Brazil
- Max-Planck Institute for Metabolism Research, Köln, Germany
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2
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de Lima JBM, Ubah C, Debarba LK, Ayyar I, Didyuk O, Sadagurski M. Hypothalamic GHR-SIRT1 Axis in Fasting. Cells 2021; 10:cells10040891. [PMID: 33919674 PMCID: PMC8069818 DOI: 10.3390/cells10040891] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 04/11/2021] [Accepted: 04/13/2021] [Indexed: 01/06/2023] Open
Abstract
Many aspects of physiological functions are controlled by the hypothalamus, a brain region that connects the neuroendocrine system to whole-body metabolism. Growth hormone (GH) and the GH receptor (GHR) are expressed in hypothalamic regions known to participate in the regulation of feeding and whole-body energy homeostasis. Sirtuin 1 (SIRT1) is the most conserved mamma-lian nicotinamide adenine dinucleotide (NAD+)-dependent protein deacetylase that plays a key role in controlling life span and sensing nutrient availability in the hypothalamus in response to caloric restriction. However, the interaction between GHR signaling and SIRT1 in the hypothal-amus is not established. In the arcuate nucleus (ARC) of the hypothalamus, the anorexigenic proopiomelanocortin (POMC)-expressing neurons and the orexigenic agouti-related protein (AgRP)-expressing neurons are the major regulators of feeding and energy expenditure. We show that in the ARC, the majority of GHR-expressing neurons also express SIRT1 and respond to fasting by upregulating SIRT1 expression. Accordingly, hypothalamic upregulation of SIRT1 in response to fasting is blunted in animals with GHR deletion in the AgRP neurons (AgRPEYFPΔGHR). Our data thus reveal a novel interaction between GH and SIRT1 in responses to fasting.
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Biglari N, Gaziano I, Schumacher J, Radermacher J, Paeger L, Klemm P, Chen W, Corneliussen S, Wunderlich CM, Sue M, Vollmar S, Klöckener T, Sotelo-Hitschfeld T, Abbasloo A, Edenhofer F, Reimann F, Gribble FM, Fenselau H, Kloppenburg P, Wunderlich FT, Brüning JC. Functionally distinct POMC-expressing neuron subpopulations in hypothalamus revealed by intersectional targeting. Nat Neurosci 2021; 24:913-929. [PMID: 34002087 PMCID: PMC8249241 DOI: 10.1038/s41593-021-00854-0] [Citation(s) in RCA: 60] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 03/31/2021] [Indexed: 02/03/2023]
Abstract
Pro-opiomelanocortin (POMC)-expressing neurons in the arcuate nucleus of the hypothalamus represent key regulators of metabolic homeostasis. Electrophysiological and single-cell sequencing experiments have revealed a remarkable degree of heterogeneity of these neurons. However, the exact molecular basis and functional consequences of this heterogeneity have not yet been addressed. Here, we have developed new mouse models in which intersectional Cre/Dre-dependent recombination allowed for successful labeling, translational profiling and functional characterization of distinct POMC neurons expressing the leptin receptor (Lepr) and glucagon like peptide 1 receptor (Glp1r). Our experiments reveal that POMCLepr+ and POMCGlp1r+ neurons represent largely nonoverlapping subpopulations with distinct basic electrophysiological properties. They exhibit a specific anatomical distribution within the arcuate nucleus and differentially express receptors for energy-state communicating hormones and neurotransmitters. Finally, we identify a differential ability of these subpopulations to suppress feeding. Collectively, we reveal a notably distinct functional microarchitecture of critical metabolism-regulatory neurons.
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Affiliation(s)
- Nasim Biglari
- grid.418034.a0000 0004 4911 0702Max Planck Institute for Metabolism Research, Department of Neuronal Control of Metabolism, Cologne, Germany ,grid.411097.a0000 0000 8852 305XPoliclinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Cologne, Germany ,grid.6190.e0000 0000 8580 3777Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Center of Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Isabella Gaziano
- grid.418034.a0000 0004 4911 0702Max Planck Institute for Metabolism Research, Department of Neuronal Control of Metabolism, Cologne, Germany ,grid.411097.a0000 0000 8852 305XPoliclinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Cologne, Germany ,grid.6190.e0000 0000 8580 3777Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Center of Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Jonas Schumacher
- grid.418034.a0000 0004 4911 0702Max Planck Institute for Metabolism Research, Department of Neuronal Control of Metabolism, Cologne, Germany ,grid.411097.a0000 0000 8852 305XPoliclinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Cologne, Germany ,grid.6190.e0000 0000 8580 3777Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Center of Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Jan Radermacher
- grid.6190.e0000 0000 8580 3777Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Center of Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany ,grid.6190.e0000 0000 8580 3777Institute for Zoology, Biocenter, University of Cologne, Cologne, Germany
| | - Lars Paeger
- grid.6190.e0000 0000 8580 3777Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Center of Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany ,grid.6190.e0000 0000 8580 3777Institute for Zoology, Biocenter, University of Cologne, Cologne, Germany
| | - Paul Klemm
- grid.418034.a0000 0004 4911 0702Max Planck Institute for Metabolism Research, Department of Neuronal Control of Metabolism, Cologne, Germany ,grid.411097.a0000 0000 8852 305XPoliclinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Cologne, Germany ,grid.6190.e0000 0000 8580 3777Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Center of Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Weiyi Chen
- grid.418034.a0000 0004 4911 0702Max Planck Institute for Metabolism Research, Department of Neuronal Control of Metabolism, Cologne, Germany ,grid.411097.a0000 0000 8852 305XPoliclinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Cologne, Germany ,grid.6190.e0000 0000 8580 3777Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Center of Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Svenja Corneliussen
- grid.6190.e0000 0000 8580 3777Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Center of Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany ,grid.6190.e0000 0000 8580 3777Institute for Zoology, Biocenter, University of Cologne, Cologne, Germany
| | - Claudia M. Wunderlich
- grid.418034.a0000 0004 4911 0702Max Planck Institute for Metabolism Research, Department of Neuronal Control of Metabolism, Cologne, Germany ,grid.411097.a0000 0000 8852 305XPoliclinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Cologne, Germany ,grid.6190.e0000 0000 8580 3777Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Center of Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Michael Sue
- grid.418034.a0000 0004 4911 0702Max Planck Institute for Metabolism Research, Department of Neuronal Control of Metabolism, Cologne, Germany
| | - Stefan Vollmar
- grid.418034.a0000 0004 4911 0702Max Planck Institute for Metabolism Research, Department of Neuronal Control of Metabolism, Cologne, Germany
| | - Tim Klöckener
- grid.418034.a0000 0004 4911 0702Max Planck Institute for Metabolism Research, Department of Neuronal Control of Metabolism, Cologne, Germany ,grid.411097.a0000 0000 8852 305XPoliclinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Cologne, Germany ,grid.6190.e0000 0000 8580 3777Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Center of Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Tamara Sotelo-Hitschfeld
- grid.418034.a0000 0004 4911 0702Max Planck Institute for Metabolism Research, Department of Neuronal Control of Metabolism, Cologne, Germany ,grid.411097.a0000 0000 8852 305XPoliclinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Cologne, Germany ,grid.6190.e0000 0000 8580 3777Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Center of Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Amin Abbasloo
- grid.418034.a0000 0004 4911 0702Max Planck Institute for Metabolism Research, Department of Neuronal Control of Metabolism, Cologne, Germany
| | - Frank Edenhofer
- grid.5771.40000 0001 2151 8122Leopold-Franzens-Universität Innsbruck, Institute for Molecular Biology, Innsbruck, Austria
| | - Frank Reimann
- grid.120073.70000 0004 0622 5016Cambridge Institute for Medical Research and Medical Research Council Metabolic Diseases Unit, Addenbrooke’s Hospital, Cambridge, UK
| | - Fiona M. Gribble
- grid.120073.70000 0004 0622 5016Cambridge Institute for Medical Research and Medical Research Council Metabolic Diseases Unit, Addenbrooke’s Hospital, Cambridge, UK
| | - Henning Fenselau
- grid.411097.a0000 0000 8852 305XPoliclinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Cologne, Germany ,grid.6190.e0000 0000 8580 3777Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Center of Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany ,grid.418034.a0000 0004 4911 0702Max Planck Institute for Metabolism Research, Research Group Synaptic Transmission in Energy Homeostasis, Cologne, Germany
| | - Peter Kloppenburg
- grid.6190.e0000 0000 8580 3777Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Center of Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany ,grid.6190.e0000 0000 8580 3777Institute for Zoology, Biocenter, University of Cologne, Cologne, Germany
| | - Frank T. Wunderlich
- grid.418034.a0000 0004 4911 0702Max Planck Institute for Metabolism Research, Department of Neuronal Control of Metabolism, Cologne, Germany ,grid.411097.a0000 0000 8852 305XPoliclinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Cologne, Germany ,grid.6190.e0000 0000 8580 3777Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Center of Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
| | - Jens C. Brüning
- grid.418034.a0000 0004 4911 0702Max Planck Institute for Metabolism Research, Department of Neuronal Control of Metabolism, Cologne, Germany ,grid.411097.a0000 0000 8852 305XPoliclinic for Endocrinology, Diabetes and Preventive Medicine (PEDP), University Hospital Cologne, Cologne, Germany ,grid.6190.e0000 0000 8580 3777Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD) and Center of Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany ,National Center for Diabetes Research (DZD), Ingolstädter Landstrasse 1, Neuherberg, Germany
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Zhao ZJ, Derous D, Gerrard A, Wen J, Liu X, Tan S, Hambly C, Speakman JR. Limits to sustained energy intake. XXX. Constraint or restraint? Manipulations of food supply show peak food intake in lactation is constrained. J Exp Biol 2020; 223:jeb208314. [PMID: 32139473 DOI: 10.1242/jeb.208314] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 02/27/2020] [Indexed: 11/20/2022]
Abstract
Lactating mice increase food intake 4- to 5-fold, reaching an asymptote in late lactation. A key question is whether this asymptote reflects a physiological constraint, or a maternal investment strategy (a 'restraint'). We exposed lactating mice to periods of food restriction, hypothesizing that if the limit reflected restraint, they would compensate by breaching the asymptote when refeeding. In contrast, if it was a constraint, they would by definition be unable to increase their intake on refeeding days. Using isotope methods, we found that during food restriction, the females shut down milk production, impacting offspring growth. During refeeding, food intake and milk production rose again, but not significantly above unrestricted controls. These data provide strong evidence that asymptotic intake in lactation reflects a physiological/physical constraint, rather than restraint. Because hypothalamic neuropeptide Y (Npy) was upregulated under both states of restriction, this suggests the constraint is not imposed by limits in the capacity to upregulate hunger signalling (the saturated neural capacity hypothesis). Understanding the genetic basis of the constraint will be a key future goal and will provide us additional information on the nature of the constraining factors on reproductive output, and their potential links to life history strategies.
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Affiliation(s)
- Zhi-Jun Zhao
- School of Life and Environmental Sciences, Wenzhou University, Wenzhou, Zhejiang 325035, China
| | - Davina Derous
- School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, UK
| | - Abby Gerrard
- School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, UK
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100100, China
| | - Jing Wen
- School of Life and Environmental Sciences, Wenzhou University, Wenzhou, Zhejiang 325035, China
| | - Xue Liu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100100, China
| | - Song Tan
- School of Life and Environmental Sciences, Wenzhou University, Wenzhou, Zhejiang 325035, China
| | - Catherine Hambly
- School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, UK
| | - John R Speakman
- School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, UK
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100100, China
- CAS Center of Excellence for Animal Evolution and Genetics, Kunming 650223, China
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Wahab F, Atika B, Ullah F, Shahab M, Behr R. Metabolic Impact on the Hypothalamic Kisspeptin-Kiss1r Signaling Pathway. Front Endocrinol (Lausanne) 2018; 9:123. [PMID: 29643834 PMCID: PMC5882778 DOI: 10.3389/fendo.2018.00123] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 03/12/2018] [Indexed: 12/12/2022] Open
Abstract
A large body of data has established the hypothalamic kisspeptin (KP) and its receptor, KISS1R, as major players in the activation of the neuroendocrine reproductive axis at the time of puberty and maintenance of reproductive capacity in the adult. Due to its strategic location, this ligand-receptor pair acts as an integrator of cues from gonadal steroids as well as of circadian and seasonal variation-related information on the reproductive axis. Besides these cues, the activity of the hypothalamic KP signaling is very sensitive to the current metabolic status of the body. In conditions of energy imbalance, either positive or negative, a number of alterations in the hypothalamic KP signaling pathway have been documented in different mammalian models including nonhuman primates and human. Deficiency of metabolic fuels during fasting causes a marked reduction of Kiss1 gene transcript levels in the hypothalamus and, hence, decreases the output of KP-containing neurons. Food intake or exogenous supply of metabolic cues, such as leptin, reverses metabolic insufficiency-related changes in the hypothalamic KP signaling. Likewise, alterations in Kiss1 expression have also been reported in other situations of energy imbalance like diabetes and obesity. Information related to the body's current metabolic status reaches to KP neurons both directly as well as indirectly via a complex network of other neurons. In this review article, we have provided an updated summary of the available literature on the regulation of the hypothalamic KP-Kiss1r signaling by metabolic cues. In particular, the potential mechanisms of metabolic impact on the hypothalamic KP-Kiss1r signaling, in light of available evidence, are discussed.
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Affiliation(s)
- Fazal Wahab
- Platform Degenerative Diseases, German Primate Center, Leibniz Institute for Primate Research, Göttingen, Germany
- *Correspondence: Fazal Wahab,
| | - Bibi Atika
- Department of Developmental Biology, Faculty of Biology, University of Göttingen, Göttingen, Germany
| | - Farhad Ullah
- Department of Zoology, Islamia College University, Peshawar, Pakistan
| | - Muhammad Shahab
- Laboratory of Reproductive Neuroendocrinology, Department of Animal Sciences, Faculty of Biological Sciences, Quiad-i-Azam University, Islamabad, Pakistan
| | - Rüdiger Behr
- Platform Degenerative Diseases, German Primate Center, Leibniz Institute for Primate Research, Göttingen, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
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Khandekar N, Berning BA, Sainsbury A, Lin S. The role of pancreatic polypeptide in the regulation of energy homeostasis. Mol Cell Endocrinol 2015; 418 Pt 1:33-41. [PMID: 26123585 DOI: 10.1016/j.mce.2015.06.028] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 03/16/2015] [Accepted: 06/03/2015] [Indexed: 12/13/2022]
Abstract
Imbalances in normal regulation of food intake can cause obesity and related disorders. Inadequate therapies for such disorders necessitate better understanding of mechanisms that regulate energy homeostasis. Pancreatic polypeptide (PP), a robust anorexigenic hormone, effectively modulates food intake and energy homeostasis, thus potentially aiding anti-obesity therapeutics. Intra-gastric and intra-intestinal infusion of nutrients stimulate PP secretion from the gastrointestinal tract, leading to vagal stimulation that mediates complex actions via the neuropeptide Y4 receptor in arcuate nucleus of the hypothalamus, subsequently activating key hypothalamic nuclei and dorsal vagal complex of the brainstem to influence energy homeostasis and body composition. Novel studies indicate affinity of PP for the relatively underexplored neuropeptide y6 receptor, mediating actions via the suprachiasmatic nucleus and pathways involving vasoactive intestinal polypeptide and insulin like growth factor 1. This review highlights detailed mechanisms by which PP mediates its actions on energy balance through various areas in the brain.
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Affiliation(s)
- Neeta Khandekar
- Neurological Diseases Division, Research Program, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, Sydney, NSW 2010, Australia
| | - Britt A Berning
- Neurological Diseases Division, Research Program, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, Sydney, NSW 2010, Australia
| | - Amanda Sainsbury
- The Boden Institute of Obesity, Nutrition, Exercise & Eating Disorders, Sydney Medical School, The University of Sydney, NSW 2006, Australia
| | - Shu Lin
- Neurological Diseases Division, Research Program, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, Sydney, NSW 2010, Australia; School of Medical Sciences, University of New South Wales, Sydney, NSW 2052, Australia.
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Abstract
Obesity has become one of the most significant public health problems facing the world today. However, the pathogenesis of obesity is multifactorial and involves the interaction of genetic and environmental factors. There is a pressing need to better understand the biochemical pathways that control energy intake and expenditure. In the last few years, a number of important signalling molecules have been identified that play important roles in obesity. One family of these molecules is the melanocortin system, which consists of several components: (1) melanocortin peptides; (2) the five seven-transmembrane G-protein coupled melanocortin receptors (MCRs); (3) the endogenous MCR antagonists, agouti and agouti-related protein; (4) the endogenous melanocortin mediators, mahogany, and syndecan. This system plays a key role in the central nervous system control of feeding behaviour and energy expenditure. This article will provide an overview of the anatomy, physiology, and molecular biology of the melanocortin system, and recent developments in our understanding of this system in obesity.
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Affiliation(s)
- Y K Yang
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL 35233, USA.
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Abstract
An increase in the risk of cancer is one of the consequences of obesity. The predominant cancers associated with obesity have a hormonal base and include breast, prostate, endometrium, colon and gallbladder cancers. As the basis for understanding the problem of obesity has advanced, a number of new ideas have emerged about the relationship of obesity to cancer. The conversion of androstenedione secreted by the adrenal gland into estrone by aromatase in adipose tissue stroma provides an important source of estrogen for the postmenopausal woman. This estrogen may play an important role in the development of endometrial and breast cancer. Of interest is that experimental animals lacking aromatase or the estrogen receptor alpha are obese. Leptin is one of the many products produced by fat cells and has given rise to the ideas that the fat cell is an endocrine cell and that adipose tissue is an endocrine organ. The increased release of cytokines from this tissue may play a role in the inflammatory state that is associated with obesity. The gut also plays an important role in signaling satiety in response to food intake. Colon cancer is an important human disease, and experimental mice lacking gastrin are obese and have an increased risk of developing colon cancer in response to carcinogenic drugs. Efforts to control obesity through preventive strategies and treatment can be expected to have a benefit in reducing the risk of cancer.
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Affiliation(s)
- George A Bray
- Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA.
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Tschöp M, Statnick MA, Suter TM, Heiman ML. GH-releasing peptide-2 increases fat mass in mice lacking NPY: indication for a crucial mediating role of hypothalamic agouti-related protein. Endocrinology 2002; 143:558-68. [PMID: 11796511 DOI: 10.1210/endo.143.2.8633] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Ghrelin, an endogenous GH secretagogue, is capable of stimulating adiposity in rodents. Because such adiposity was thought to be mediated by hypothalamic NPY neurons, we investigated by which mechanism a synthetic ghrelin receptor agonist, GHRP-2, would generate a positive energy balance in NPY-deficient [Npy(-/-) mice] and wild-type controls. A dose-dependent increase in body weight and food intake was observed during daily sc injections with GHRP-2. Pre- and posttreatment analysis of body composition indicated increased fat mass and bone mass but not lean mass. Respiratory quotient was increased in GHRP-2-treated mice, indicating preservation of fat. Hypothalamic mRNA levels of agouti- related protein (AGRP), an orexigenic melanocortin receptor antagonist, increased after GHRP-2 treatment. Competitive blockade of AGRP action by melanocortin-receptor agonist MT-II prevented GHRP-induced weight gain in Npy(-/-) mice. In conclusion, chronic peripheral treatment with a ghrelin receptor agonist induced a positive energy balance leading to fat gain in the absence of NPY. These effects could be mediated in part by AGRP. To date, there are few therapeutics that can produce a positive energy balance. Ghrelin receptor agonists offer a treatment option for syndromes like anorexia nervosa, cancer cachexia, or AIDS wasting.
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MESH Headings
- Absorptiometry, Photon
- Adipose Tissue/drug effects
- Adipose Tissue/physiology
- Agouti-Related Protein
- Animals
- Body Weight/drug effects
- Bone Development/drug effects
- Calorimetry, Indirect
- Chromatography, High Pressure Liquid
- Eating/drug effects
- Genotype
- Hormones/blood
- Hypothalamus/physiology
- Intercellular Signaling Peptides and Proteins
- Male
- Mice
- Mice, Knockout
- Neuropeptide Y/genetics
- Neuropeptide Y/physiology
- Oligopeptides/pharmacology
- Proteins/physiology
- Receptors, Cell Surface/agonists
- Receptors, Cell Surface/physiology
- Receptors, Corticotropin/agonists
- Receptors, G-Protein-Coupled
- Receptors, Ghrelin
- Receptors, Melanocortin
- Reverse Transcriptase Polymerase Chain Reaction
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Affiliation(s)
- Matthias Tschöp
- Endocrine Research, Lilly Research Laboratories, Eli Lilly & Co., Indianapolis, Indiana 46285, USA.
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