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Yuan XC, Tao YX. Ligands for Melanocortin Receptors: Beyond Melanocyte-Stimulating Hormones and Adrenocorticotropin. Biomolecules 2022; 12:biom12101407. [PMID: 36291616 PMCID: PMC9599618 DOI: 10.3390/biom12101407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 09/25/2022] [Accepted: 09/28/2022] [Indexed: 11/16/2022] Open
Abstract
The discovery of melanocortins in 1916 has resulted in more than 100 years of research focused on these peptides. Extensive studies have elucidated well-established functions of melanocortins mediated by cell surface receptors, including MSHR (melanocyte-stimulating hormone receptor) and ACTHR (adrenocorticotropin receptor). Subsequently, three additional melanocortin receptors (MCRs) were identified. Among these five MCRs, MC3R and MC4R are expressed primarily in the central nervous system, and are therefore referred to as the neural MCRs. Since the central melanocortin system plays important roles in regulating energy homeostasis, targeting neural MCRs is emerging as a therapeutic approach for treating metabolic conditions such as obesity and cachexia. Early efforts modifying endogenous ligands resulted in the development of many potent and selective ligands. This review focuses on the ligands for neural MCRs, including classical ligands (MSH and agouti-related peptide), nonclassical ligands (lipocalin 2, β-defensin, small molecules, and pharmacoperones), and clinically approved ligands (ACTH, setmelanotide, bremelanotide, and several repurposed drugs).
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Affiliation(s)
- Xiao-Chen Yuan
- College of Animal Science and Technology, Anhui Agricultural University, Hefei 230061, China
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA
- Correspondence:
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2
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Czerwińska M, Czarzasta K, Cudnoch-Jędrzejewska A. New Peptides as Potential Players in the Crosstalk Between the Brain and Obesity, Metabolic and Cardiovascular Diseases. Front Physiol 2021; 12:692642. [PMID: 34497533 PMCID: PMC8419452 DOI: 10.3389/fphys.2021.692642] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 08/03/2021] [Indexed: 01/09/2023] Open
Abstract
According to the World Health Organization report published in 2016, 650 million people worldwide suffer from obesity, almost three times more than in 1975. Obesity is defined as excessive fat accumulation which may impair health with non-communicable diseases such as diabetes, cardiovascular diseases (hypertension, coronary artery disease, stroke), and some cancers. Despite medical advances, cardiovascular complications are still the leading causes of death arising from obesity. Excessive fat accumulation is caused by the imbalance between energy intake and expenditure. The pathogenesis of this process is complex and not fully understood, but current research is focused on the role of the complex crosstalk between the central nervous system (CNS), neuroendocrine and immune system including the autonomic nervous system, adipose tissue, digestive and cardiovascular systems. Additionally, special attention has been paid to newly discovered substances: neuropeptide 26RFa, preptin, and adropin. It was shown that the above peptides are synthesized both in numerous structures of the CNS and in many peripheral organs and tissues, such as the heart, adipose tissue, and the gastrointestinal tract. Recently, particular attention has been paid to the role of the presented peptides in the pathogenesis of obesity, metabolic and cardiovascular system diseases. This review summarizes the role of newly investigated peptides in the crosstalk between brain and peripheral organs in the pathogenesis of obesity, metabolic, and cardiovascular diseases.
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Wang L, Yu CC, Li J, Tian Q, Du YJ. Mechanism of Action of Acupuncture in Obesity: A Perspective From the Hypothalamus. Front Endocrinol (Lausanne) 2021; 12:632324. [PMID: 33868169 PMCID: PMC8050351 DOI: 10.3389/fendo.2021.632324] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 03/16/2021] [Indexed: 01/22/2023] Open
Abstract
Obesity is a prevalent metabolic disease caused by an imbalance in food intake and energy expenditure. Although acupuncture is widely used in the treatment of obesity in a clinical setting, its mechanism has not been adequately elucidated. As the key pivot of appetite signals, the hypothalamus receives afferent and efferent signals from the brainstem and peripheral tissue, leading to the formation of a complex appetite regulation circuit, thereby effectively regulating food intake and energy homeostasis. This review mainly discusses the relationship between the hypothalamic nuclei, related neuropeptides, brainstem, peripheral signals, and obesity, as well as mechanisms of acupuncture on obesity from the perspective of the hypothalamus, exploring the current evidence and therapeutic targets for mechanism of action of acupuncture in obesity.
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Affiliation(s)
- Li Wang
- College of Acupuncture and Orthopedics, Hubei University of Chinese Medicine, Wuhan, China
| | - Chao-Chao Yu
- Department of Tuina, Shenzhen Traditional Chinese Medicine Hospital, Shenzhen, China
- The Fourth Clinical College, Guangzhou University of Chinese Medicine, Shenzhen, China
| | - Jia Li
- College of Acupuncture and Orthopedics, Hubei University of Chinese Medicine, Wuhan, China
| | - Qing Tian
- Department of Pathology and Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yan-Jun Du
- College of Acupuncture and Orthopedics, Hubei University of Chinese Medicine, Wuhan, China
- *Correspondence: Yan-Jun Du,
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The anorexigenic effect of beta-melanocyte-stimulating hormone involves corticotrophin-releasing factor and mesotocin in birds. Neurosci Lett 2020; 736:135282. [DOI: 10.1016/j.neulet.2020.135282] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 07/22/2020] [Accepted: 07/27/2020] [Indexed: 11/21/2022]
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Löw K, Roulin A, Kunz S. A proopiomelanocortin-derived peptide sequence enhances plasma stability of peptide drugs. FEBS Lett 2020; 594:2840-2866. [PMID: 32506501 DOI: 10.1002/1873-3468.13855] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 05/11/2020] [Accepted: 05/26/2020] [Indexed: 12/26/2022]
Abstract
Bioactive peptide drugs hold promise for therapeutic application due to their high potency and selectivity but display short plasma half-life. Examination of selected naturally occurring peptide hormones derived from proteolytic cleavage of the proopiomelanocortin (POMC) precursor lead to the identification of significant plasma-stabilizing properties of a 12-amino acid serine-rich orphan sequence NSSSSGSSGAGQ in human γ3-melanocyte-stimulating hormone (MSH) that is homologous to previously discovered NSn GGH (n = 4-24) sequences in owls. Notably, transfer of this sequence to des-acetyl-α-MSH and the therapeutically relevant peptide hormones neurotensin and glucagon-like peptide-1 likewise enhance their plasma stability without affecting receptor signaling. The stabilizing effect of the sequence module is independent of plasma components, suggesting a direct effect in cis. This natural sequence module may provide a possible strategy to enhance plasma stability, complementing existing methods of chemical modification.
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Affiliation(s)
- Karin Löw
- Institute of Microbiology, University Hospital Center and University of Lausanne, Switzerland.,Department of Ecology and Evolution, University of Lausanne, Switzerland
| | - Alexandre Roulin
- Department of Ecology and Evolution, University of Lausanne, Switzerland
| | - Stefan Kunz
- Institute of Microbiology, University Hospital Center and University of Lausanne, Switzerland
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Molecular evolution of the proopiomelanocortin system in Barn owl species. PLoS One 2020; 15:e0231163. [PMID: 32369484 PMCID: PMC7199972 DOI: 10.1371/journal.pone.0231163] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 03/17/2020] [Indexed: 01/20/2023] Open
Abstract
Examination of genetic polymorphisms in outbred wild-living species provides insights into the evolution of complex systems. In higher vertebrates, the proopiomelanocortin (POMC) precursor gives rise to α-, β-, and γ-melanocyte-stimulating hormones (MSH), which are involved in numerous physiological aspects. Genetic defects in POMC are linked to metabolic disorders in humans and animals. In the present study, we undertook an evolutionary genetic approach complemented with biochemistry to investigate the functional consequences of genetic polymorphisms in the POMC system of free-living outbred barn owl species (family Tytonidae) at the molecular level. Our phylogenetic studies revealed a striking correlation between a loss-of-function H9P mutation in the β-MSH receptor-binding motif and an extension of a poly-serine stretch in γ3-MSH to ≥7 residues that arose in the barn owl group 6–8 MYA ago. We found that extension of the poly-serine stretches in the γ-MSH locus affects POMC precursor processing, increasing γ3-MSH production at the expense of γ2-MSH and resulting in an overall reduction of γ-MSH signaling, which may be part of a negative feedback mechanism. Extension of the γ3-MSH poly-serine stretches ≥7 further markedly increases peptide hormone stability in plasma, which is conserved in humans, and is likely relevant to its endocrine function. In sum, our phylogenetic analysis of POMC in wild living owls uncovered a H9P β-MSH mutation subsequent to serine extension in γ3-MSH to 7 residues, which was then followed by further serine extension. The linked MSH mutations highlight the genetic plasticity enabled by the modular design of the POMC gene.
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7
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Florea A, El Hof FA, Hazi GM, Oprea MC. Bee Venom Stimulates Hormone Secretion in Rat Somatotroph and Corticotroph Cells: Digital Image Analysis of Secretory Granules. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2019; 25:1234-1245. [PMID: 31526405 DOI: 10.1017/s1431927619014910] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In this study, we characterized secretory granules in somatotroph (STCs) and corticotroph (CTCs) cells from the anterior pituitary of rats, in conjunction with different experimental treatments with bee venom (BV). In the rats injected for 30 days with daily BV doses equivalent to one sting, we found significant changes in secretory granules' diameter: reduced by 48.15% in STCs and increased by 5.09% in CTCs, and especially a shift to gray into their intensity profile: increased by 237.04% in STCs and by 212.38% in CTCs. In the rats injected with a single high BV dose, the granules' diameter was reduced in both STCs (by 7.14%) and CTCs (by 4.67%-significant) and their gray intensity profile increased by 200% in STCs and by 51.71% in CTCs (both are significant). The changes in the gray profile reflected a reduced content of granules in the cells, consistent with an increase of the plasma levels of GH and ACTH in all cases. We concluded that the reduced hormone cargo of granules in STCs and CTCs resulted from an accelerated cell secretion. The results obtained for the two types of cells correlated, indicating a similar reaction of these secretory cells to the prolonged and acute presence of BV in the organism.
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Affiliation(s)
- Adrian Florea
- Department of Cell and Molecular Biology, Faculty of Medicine, "Iuliu Haţieganu" University of Medicine and Pharmacy, 6 Louis Pasteur Street, 400349 Cluj-Napoca, Romania
| | - Fares Abu El Hof
- Department of Cell and Molecular Biology, Faculty of Medicine, "Iuliu Haţieganu" University of Medicine and Pharmacy, 6 Louis Pasteur Street, 400349 Cluj-Napoca, Romania
| | - Georgeta Maria Hazi
- Endocrinology Clinic Laboratory, Cluj-Napoca County Emergency Hospital, 3-5 Louis Pasteur Street, 400369 Cluj-Napoca, Romania
| | - Marius Cristian Oprea
- Department of Cell and Molecular Biology, Faculty of Medicine, "Iuliu Haţieganu" University of Medicine and Pharmacy, 6 Louis Pasteur Street, 400349 Cluj-Napoca, Romania
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Harno E, Gali Ramamoorthy T, Coll AP, White A. POMC: The Physiological Power of Hormone Processing. Physiol Rev 2019; 98:2381-2430. [PMID: 30156493 DOI: 10.1152/physrev.00024.2017] [Citation(s) in RCA: 97] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Pro-opiomelanocortin (POMC) is the archetypal polypeptide precursor of hormones and neuropeptides. In this review, we examine the variability in the individual peptides produced in different tissues and the impact of the simultaneous presence of their precursors or fragments. We also discuss the problems inherent in accurately measuring which of the precursors and their derived peptides are present in biological samples. We address how not being able to measure all the combinations of precursors and fragments quantitatively has affected our understanding of the pathophysiology associated with POMC processing. To understand how different ratios of peptides arise, we describe the role of the pro-hormone convertases (PCs) and their tissue specificities and consider the cellular processing pathways which enable regulated secretion of different peptides that play crucial roles in integrating a range of vital physiological functions. In the pituitary, correct processing of POMC peptides is essential to maintain the hypothalamic-pituitary-adrenal axis, and this processing can be disrupted in POMC-expressing tumors. In hypothalamic neurons expressing POMC, abnormalities in processing critically impact on the regulation of appetite, energy homeostasis, and body composition. More work is needed to understand whether expression of the POMC gene in a tissue equates to release of bioactive peptides. We suggest that this comprehensive view of POMC processing, with a focus on gaining a better understanding of the combination of peptides produced and their relative bioactivity, is a necessity for all involved in studying this fascinating physiological regulatory phenomenon.
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Affiliation(s)
- Erika Harno
- Division of Diabetes, Endocrinology and Gastrointestinal Sciences, Faculty of Biology, Medicine and Health, University of Manchester , Manchester , United Kingdom ; and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science , Cambridge , United Kingdom
| | - Thanuja Gali Ramamoorthy
- Division of Diabetes, Endocrinology and Gastrointestinal Sciences, Faculty of Biology, Medicine and Health, University of Manchester , Manchester , United Kingdom ; and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science , Cambridge , United Kingdom
| | - Anthony P Coll
- Division of Diabetes, Endocrinology and Gastrointestinal Sciences, Faculty of Biology, Medicine and Health, University of Manchester , Manchester , United Kingdom ; and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science , Cambridge , United Kingdom
| | - Anne White
- Division of Diabetes, Endocrinology and Gastrointestinal Sciences, Faculty of Biology, Medicine and Health, University of Manchester , Manchester , United Kingdom ; and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science , Cambridge , United Kingdom
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9
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Kirwan P, Kay RG, Brouwers B, Herranz-Pérez V, Jura M, Larraufie P, Jerber J, Pembroke J, Bartels T, White A, Gribble FM, Reimann F, Farooqi IS, O'Rahilly S, Merkle FT. Quantitative mass spectrometry for human melanocortin peptides in vitro and in vivo suggests prominent roles for β-MSH and desacetyl α-MSH in energy homeostasis. Mol Metab 2018; 17:82-97. [PMID: 30201275 PMCID: PMC6197775 DOI: 10.1016/j.molmet.2018.08.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 08/08/2018] [Accepted: 08/16/2018] [Indexed: 12/23/2022] Open
Abstract
OBJECTIVE The lack of pro-opiomelanocortin (POMC)-derived melanocortin peptides results in hypoadrenalism and severe obesity in both humans and rodents that is treatable with synthetic melanocortins. However, there are significant differences in POMC processing between humans and rodents, and little is known about the relative physiological importance of POMC products in the human brain. The aim of this study was to determine which POMC-derived peptides are present in the human brain, to establish their relative concentrations, and to test if their production is dynamically regulated. METHODS We analysed both fresh post-mortem human hypothalamic tissue and hypothalamic neurons derived from human pluripotent stem cells (hPSCs) using liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine the sequence and quantify the production of hypothalamic neuropeptides, including those derived from POMC. RESULTS In both in vitro and in vivo hypothalamic cells, LC-MS/MS revealed the sequence of hundreds of neuropeptides as a resource for the field. Although the existence of β-melanocyte stimulating hormone (MSH) is controversial, we found that both this peptide and desacetyl α-MSH (d-α-MSH) were produced in considerable excess of acetylated α-MSH. In hPSC-derived hypothalamic neurons, these POMC derivatives were appropriately trafficked, secreted, and their production was significantly (P < 0.0001) increased in response to the hormone leptin. CONCLUSIONS Our findings challenge the assumed pre-eminence of α-MSH and suggest that in humans, d-α-MSH and β-MSH are likely to be the predominant physiological products acting on melanocortin receptors.
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Affiliation(s)
- Peter Kirwan
- Metabolic Research Laboratories and Medical Research Council Metabolic Diseases Unit, Wellcome Trust-Medical Research Council Institute of Metabolic Science, University of Cambridge, Cambridge, CB2 0QQ, UK; The Anne McLaren Laboratory for Regenerative Medicine, Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Cambridge, CB2 0SZ, UK
| | - Richard G Kay
- Metabolic Research Laboratories and Medical Research Council Metabolic Diseases Unit, Wellcome Trust-Medical Research Council Institute of Metabolic Science, University of Cambridge, Cambridge, CB2 0QQ, UK
| | - Bas Brouwers
- Metabolic Research Laboratories and Medical Research Council Metabolic Diseases Unit, Wellcome Trust-Medical Research Council Institute of Metabolic Science, University of Cambridge, Cambridge, CB2 0QQ, UK; The Anne McLaren Laboratory for Regenerative Medicine, Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Cambridge, CB2 0SZ, UK
| | - Vicente Herranz-Pérez
- Laboratory of Comparative Neurobiology, Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, CIBERNED, 46980 Valencia, Spain; Predepartamental Unit of Medicine, Faculty of Health Sciences, Universitat Jaume I, 12071 Castelló de la Plana, Spain
| | - Magdalena Jura
- Metabolic Research Laboratories and Medical Research Council Metabolic Diseases Unit, Wellcome Trust-Medical Research Council Institute of Metabolic Science, University of Cambridge, Cambridge, CB2 0QQ, UK; The Anne McLaren Laboratory for Regenerative Medicine, Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Cambridge, CB2 0SZ, UK
| | - Pierre Larraufie
- Metabolic Research Laboratories and Medical Research Council Metabolic Diseases Unit, Wellcome Trust-Medical Research Council Institute of Metabolic Science, University of Cambridge, Cambridge, CB2 0QQ, UK
| | - Julie Jerber
- The Anne McLaren Laboratory for Regenerative Medicine, Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Cambridge, CB2 0SZ, UK; Open Targets, Wellcome Trust Sanger Institute, Hinxton, CB10 1SA, UK
| | - Jason Pembroke
- LGC Ltd., Newmarket Road, Fordham, Cambridgeshire, CB7 5WW, UK
| | - Theresa Bartels
- The Anne McLaren Laboratory for Regenerative Medicine, Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Cambridge, CB2 0SZ, UK
| | - Anne White
- Division of Diabetes, Endocrinology and Gastroenterology, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Fiona M Gribble
- Metabolic Research Laboratories and Medical Research Council Metabolic Diseases Unit, Wellcome Trust-Medical Research Council Institute of Metabolic Science, University of Cambridge, Cambridge, CB2 0QQ, UK
| | - Frank Reimann
- Metabolic Research Laboratories and Medical Research Council Metabolic Diseases Unit, Wellcome Trust-Medical Research Council Institute of Metabolic Science, University of Cambridge, Cambridge, CB2 0QQ, UK
| | - I Sadaf Farooqi
- Metabolic Research Laboratories and Medical Research Council Metabolic Diseases Unit, Wellcome Trust-Medical Research Council Institute of Metabolic Science, University of Cambridge, Cambridge, CB2 0QQ, UK
| | - Stephen O'Rahilly
- Metabolic Research Laboratories and Medical Research Council Metabolic Diseases Unit, Wellcome Trust-Medical Research Council Institute of Metabolic Science, University of Cambridge, Cambridge, CB2 0QQ, UK
| | - Florian T Merkle
- Metabolic Research Laboratories and Medical Research Council Metabolic Diseases Unit, Wellcome Trust-Medical Research Council Institute of Metabolic Science, University of Cambridge, Cambridge, CB2 0QQ, UK; The Anne McLaren Laboratory for Regenerative Medicine, Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Cambridge, CB2 0SZ, UK.
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Lei MM, Wei CK, Chen Z, Yosefi S, Zhu HX, Shi ZD. Anti-leptin receptor antibodies strengthen leptin biofunction in growing chickens. Gen Comp Endocrinol 2018; 259:223-230. [PMID: 29247679 DOI: 10.1016/j.ygcen.2017.12.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 12/13/2017] [Accepted: 12/13/2017] [Indexed: 12/11/2022]
Abstract
Antibodies against the extracellular domains of the chicken leptin receptor were used to study the biological function of leptin in growing chickens. Both polyclonal and monoclonal anti-LEPR antibodies were administered intramuscularly to 30-d-old Chinese indigenous Gushi pullets. Both antibody preparations increased feed intake for 6 h after injection and reduced plasma concentrations of glucose, triglycerides, and both high- and low-density lipoproteins. The antibody treatments also upregulated agouti-related peptide and neuropeptide Y in the hypothalamus and downregulated proopiomelanocortin, melanocortin 4 receptor, and leptin receptor. The treatments also upregulated leptin receptor, acetyl CoA carboxylase beta, and acyl-CoA oxidase in the liver, abdominal fat, and breast muscle and downregulated sterol regulatory element-binding protein-1 and fatty acid synthase. Furthermore, even though the anti-leptin receptor antibodies failed to affect leptin receptor signaling transduction when administered alone, they did augment the induction of leptin receptor signaling transduction by leptin. These results demonstrate that antibodies against the extracellular domains of leptin-specific receptor enhance, but do not mimic, the ability of leptin to activate receptors. Furthermore, the enhanced leptin bioactivity observed after the intramuscular injection of anti-LEPR antibodies confirmed the occurrence of de novo leptin in the peripheral tissues and blood of treated chickens.
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Affiliation(s)
- M M Lei
- Key Laboratory of Control Technology and Standard for Agro-product Safety and Quality, MOA, Nanjing 210014, China; Laboratory of Animal Breeding and Reproduction, Institute of Animal Science, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
| | - C K Wei
- Key Laboratory of Control Technology and Standard for Agro-product Safety and Quality, MOA, Nanjing 210014, China; Laboratory of Animal Breeding and Reproduction, Institute of Animal Science, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
| | - Z Chen
- Key Laboratory of Control Technology and Standard for Agro-product Safety and Quality, MOA, Nanjing 210014, China; Laboratory of Animal Breeding and Reproduction, Institute of Animal Science, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
| | - S Yosefi
- Institute of Animal Science, Agricultural Research Organization, Volcani Center, PO Box 6, Bet Dagan 50250, Israel.
| | - H X Zhu
- Key Laboratory of Control Technology and Standard for Agro-product Safety and Quality, MOA, Nanjing 210014, China; Laboratory of Animal Breeding and Reproduction, Institute of Animal Science, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
| | - Z D Shi
- Key Laboratory of Control Technology and Standard for Agro-product Safety and Quality, MOA, Nanjing 210014, China; Laboratory of Animal Breeding and Reproduction, Institute of Animal Science, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
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11
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Mountjoy KG, Caron A, Hubbard K, Shome A, Grey AC, Sun B, Bould S, Middleditch M, Pontré B, McGregor A, Harris PWR, Kowalczyk R, Brimble MA, Botha R, Tan KML, Piper SJ, Buchanan C, Lee S, Coll AP, Elmquist JK. Desacetyl-α-melanocyte stimulating hormone and α-melanocyte stimulating hormone are required to regulate energy balance. Mol Metab 2017; 9:207-216. [PMID: 29226825 PMCID: PMC5869732 DOI: 10.1016/j.molmet.2017.11.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 11/08/2017] [Accepted: 11/14/2017] [Indexed: 01/15/2023] Open
Abstract
Objective Regulation of energy balance depends on pro-opiomelanocortin (POMC)-derived peptides and melanocortin-4 receptor (MC4R). Alpha-melanocyte stimulating hormone (α-MSH) is the predicted natural POMC-derived peptide that regulates energy balance. Desacetyl-α-MSH, the precursor for α-MSH, is present in brain and blood. Desacetyl-α-MSH is considered to be unimportant for regulating energy balance despite being more potent (compared with α-MSH) at activating the appetite-regulating MC4R in vitro. Thus, the physiological role for desacetyl-α-MSH is still unclear. Methods We created a novel mouse model to determine whether desacetyl-α-MSH plays a role in regulating energy balance. We engineered a knock in targeted QKQR mutation in the POMC protein cleavage site that blocks the production of both desacetyl-α-MSH and α-MSH from adrenocorticotropin (ACTH1-39). Results The mutant ACTH1-39 (ACTHQKQR) functions similar to native ACTH1-39 (ACTHKKRR) at the melanocortin 2 receptor (MC2R) in vivo and MC4R in vitro. Male and female homozygous mutant ACTH1-39 (Pomctm1/tm1) mice develop the characteristic melanocortin obesity phenotype. Replacement of either desacetyl-α-MSH or α-MSH over 14 days into Pomctm1/tm1 mouse brain significantly reverses excess body weight and fat mass gained compared to wild type (WT) (Pomcwt/wt) mice. Here, we identify both desacetyl-α-MSH and α-MSH peptides as regulators of energy balance and highlight a previously unappreciated physiological role for desacetyl-α-MSH. Conclusions Based on these data we propose that there is potential to exploit the naturally occurring POMC-derived peptides to treat obesity but this relies on first understanding the specific function(s) for desacetyl-α-MSH and α-MSH. KKRR → QKQR mutation in the cleavage site of POMC prevents the production of desacetyl-α-MSH and α-MSH in mice. Male and female mutant mice develop characteristic melanocortin obesity. Central administration of α-MSH is more potent at reducing body weight in female mutant mice. Central administration of desacetyl-α-MSH and α-MSH are similarly potent at reducing body weight in male mutant mice.
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Affiliation(s)
- Kathleen G Mountjoy
- Department of Physiology, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; Department of Molecular Medicine and Pathology, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
| | - Alexandre Caron
- Department of Internal Medicine, Division of Hypothalamic Research, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Kristina Hubbard
- Department of Physiology, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Avik Shome
- Department of Physiology, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Angus C Grey
- Department of Physiology, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; Department of Anatomy and Medical Imaging, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Bo Sun
- Department of Physiology, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Sarah Bould
- Department of Physiology, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Martin Middleditch
- Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Beau Pontré
- Department of Anatomy and Medical Imaging, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Ailsa McGregor
- Department of Pharmacy, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Paul W R Harris
- Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Renata Kowalczyk
- Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Margaret A Brimble
- Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Rikus Botha
- Department of Physiology, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Karen M L Tan
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, Addenbrooke's Hospital, Cambridge CB2 2QR, United Kingdom
| | - Sarah J Piper
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, Addenbrooke's Hospital, Cambridge CB2 2QR, United Kingdom
| | - Christina Buchanan
- Department of Molecular Medicine and Pathology, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Syann Lee
- Department of Internal Medicine, Division of Hypothalamic Research, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Anthony P Coll
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, Addenbrooke's Hospital, Cambridge CB2 2QR, United Kingdom; University of Cambridge Metabolic Research Laboratories, MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge CB2 0QQ, United Kingdom
| | - Joel K Elmquist
- Department of Internal Medicine, Division of Hypothalamic Research, The University of Texas Southwestern Medical Center, Dallas, TX, USA
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12
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Ericson MD, Lensing CJ, Fleming KA, Schlasner KN, Doering SR, Haskell-Luevano C. Bench-top to clinical therapies: A review of melanocortin ligands from 1954 to 2016. Biochim Biophys Acta Mol Basis Dis 2017; 1863:2414-2435. [PMID: 28363699 PMCID: PMC5600687 DOI: 10.1016/j.bbadis.2017.03.020] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 03/21/2017] [Accepted: 03/27/2017] [Indexed: 10/19/2022]
Abstract
The discovery of the endogenous melanocortin agonists in the 1950s have resulted in sixty years of melanocortin ligand research. Early efforts involved truncations or select modifications of the naturally occurring agonists leading to the development of many potent and selective ligands. With the identification and cloning of the five known melanocortin receptors, many ligands were improved upon through bench-top in vitro assays. Optimization of select properties resulted in ligands adopted as clinical candidates. A summary of every melanocortin ligand is outside the scope of this review. Instead, this review will focus on the following topics: classic melanocortin ligands, selective ligands, small molecule (non-peptide) ligands, ligands with sex-specific effects, bivalent and multivalent ligands, and ligands advanced to clinical trials. Each topic area will be summarized with current references to update the melanocortin field on recent progress. This article is part of a Special Issue entitled: Melanocortin Receptors - edited by Ya-Xiong Tao.
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Affiliation(s)
- Mark D Ericson
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Cody J Lensing
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Katlyn A Fleming
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Katherine N Schlasner
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Skye R Doering
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
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13
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Lear T, Liu L, O'Donnell M, McConn BR, Denbow DM, Cline MA, Gilbert ER. Alpha-melanocyte stimulating hormone-induced anorexia in Japanese quail (Coturnix japonica) likely involves the ventromedial hypothalamus and paraventricular nucleus of the hypothalamus. Gen Comp Endocrinol 2017; 252:97-102. [PMID: 28782535 DOI: 10.1016/j.ygcen.2017.08.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 07/14/2017] [Accepted: 08/03/2017] [Indexed: 10/19/2022]
Abstract
Alpha-melanocyte stimulating hormone (α-MSH) reduces food intake in birds and mammals. The objective of this experiment was to determine effects of α-MSH on food and water intake, and hypothalamic c-Fos immunoreactivity and appetite-associated factor mRNA in Japanese quail (Coturnix japonica), a species that has not undergone the same artificial selection for growth-related traits as the chicken. At 7days post-hatch, 3-h-fasted quail were intracerebroventricularly (ICV) injected into the lateral ventricle with 0 (vehicle), 0.5, 5, or 50pmol of α-MSH and food and water intake were recorded at 30min intervals for 180min. In the second and third experiment, quail were injected with 50pmol α-MSH and hypothalami were collected at 1h to determine c-Fos immunoreactivity and mRNA abundance, respectively. At 30min, quail injected with 5 or 50pmol of α-MSH ate and drank less than vehicle-injected quail. Quail injected with 50pmol ate less for the entire duration of the experiment and drank less than vehicle-injected quail for 120min post-injection. Hypothalamic expression of agouti-related peptide and DOPA decarboxylase were greater in vehicle- than α-MSH-injected quail, whereas melanocortin receptor 4 (MC4R) mRNA was greater in α-MSH- than vehicle-injected birds. Alpha-MSH injection was associated with more c-Fos immunoreactive cells in the ventromedial hypothalamus (VMH) and paraventricular nucleus (PVN) of the hypothalamus. Results suggest that the anorexigenic effect of α-MSH is conserved among avians and that effects in quail are associated with the VMH and PVN and involve MC4R.
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Affiliation(s)
- Taylor Lear
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Lingbin Liu
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Madison O'Donnell
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Betty R McConn
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - D Michael Denbow
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Mark A Cline
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Elizabeth R Gilbert
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA.
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Carvajal F, Lerma-Cabrera JM, Alcaraz-Iborra M, Navarro M, Thiele TE, Cubero I. Nucleus Accumbens MC4-R Stimulation Reduces Food and Ethanol Intake in Adult Rats Regardless of Binge-Like Ethanol Exposure during Adolescence. Front Behav Neurosci 2017; 11:167. [PMID: 28936166 PMCID: PMC5594710 DOI: 10.3389/fnbeh.2017.00167] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 08/22/2017] [Indexed: 11/13/2022] Open
Abstract
The melanocortin (MC) system regulates feeding and ethanol consumption. Recent evidence shows that melanocortin 4 receptor (MC4-R) stimulation within the nucleus accumbens (NAc) elicits anorectic responses and reduces ethanol consumption and ethanol palatability in adult rats. Ethanol exposure during adolescence causes long-lasting changes in neural pathways critically involved in neurobehavioral responses to ethanol. In this regard, binge-like ethanol exposure during adolescence reduces basal alpha-melanocyte-stimulating hormone (α-MSH) and alters the levels of agouti-related peptide (AgRP) in hypothalamic and limbic areas. Given the protective role of MC against excessive ethanol consumption, disturbances in the MC system induced by binge-like ethanol exposure during adolescence might contribute to excessive ethanol consumption during adulthood. In the present study, we evaluated whether binge-like ethanol exposure during adolescence leads to elevated ethanol intake and/or eating disturbance during adulthood. Toward that aim, Sprague-Dawley rats were treated with ethanol (3 g/kg i.p.; BEP group) or saline (SP group) for 14 days (PND 25 to PND 38). On PND73, all the groups were given access to 20% ethanol on an intermittent schedule. Our results showed that adult rats given intermittent access (IAE) to 20% ethanol achieved high spontaneous ethanol intake that was not significantly enhanced by binge-like ethanol pretreatment during adolescence. However, BEP group exhibited an increase in food intake without a parallel increase in body weight (BW) relative to SP group suggesting caloric efficiency disturbance. Additionally, we evaluated whether binge-like ethanol exposure during adolescence alters the expected reduction in feeding and ethanol consumption following NAc shell administration of a selective MC4-R agonist in adult rats showing high rates of ethanol consumption. For that, animals in each pretreatment condition (SP and BEP) were divided into three subgroups and given bilateral NAc infusions of the selective MC4-R agonist cyclo(NH-CH2-CH2-CO-His-D-Phe-Arg-Trp-Glu)-NH2 (0, 0.75 or 1.5 μg). Results revealed that MC4-R stimulation within the NAc reduced feeding and ethanol intake in high ethanol-drinking adult rats, regardless of previous binge-like ethanol exposure during adolescence, which adds new evidence regarding the dual ability of MC compounds to control excessive ethanol and food intake.
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Affiliation(s)
- Francisca Carvajal
- Institute of Biomedical Sciences, Universidad Autonoma de ChileSantiago, Chile
| | - José M Lerma-Cabrera
- Institute of Biomedical Sciences, Universidad Autonoma de ChileSantiago, Chile.,Department of Psychology, University of OviedoOviedo, Spain
| | | | - Montserrat Navarro
- Department of Psychology and Neuroscience, University of North CarolinaChapel Hill, NC, United States
| | - Todd E Thiele
- Department of Psychology and Neuroscience, University of North CarolinaChapel Hill, NC, United States
| | - Inmaculada Cubero
- Institute of Biomedical Sciences, Universidad Autonoma de ChileSantiago, Chile.,Department of Psychology, University of AlmeriaAlmeria, Spain
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15
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Mankowska M, Krzeminska P, Graczyk M, Switonski M. Confirmation that a deletion in the POMC gene is associated with body weight of Labrador Retriever dogs. Res Vet Sci 2017; 112:116-118. [DOI: 10.1016/j.rvsc.2017.02.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 02/13/2017] [Accepted: 02/15/2017] [Indexed: 01/06/2023]
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16
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Singh O, Kumar S, Singh U, Kumar V, Lechan RM, Singru PS. Cocaine- and amphetamine-regulated transcript peptide (CART) in the brain of zebra finch,Taeniopygia guttata: Organization, interaction with neuropeptide Y, and response to changes in energy status. J Comp Neurol 2016; 524:3014-41. [DOI: 10.1002/cne.24004] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Revised: 03/21/2016] [Accepted: 03/24/2016] [Indexed: 01/21/2023]
Affiliation(s)
- Omprakash Singh
- School of Biological Sciences; National Institute of Science Education and Research (NISER)-Bhubaneswar; Odisha India
| | - Santosh Kumar
- School of Biological Sciences; National Institute of Science Education and Research (NISER)-Bhubaneswar; Odisha India
| | - Uday Singh
- School of Biological Sciences; National Institute of Science Education and Research (NISER)-Bhubaneswar; Odisha India
| | - Vinod Kumar
- DST-IRHPA Centre for Excellence in Biological Rhythms Research and Indo-US Centre for Biological Timing, Department of Zoology; University of Delhi; Delhi India
| | - Ronald M. Lechan
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Tupper Research Institute; Tufts Medical Center; Boston Massachusetts USA
- Department of Neuroscience; Tufts University School of Medicine; Boston Massachusetts USA
| | - Praful S. Singru
- School of Biological Sciences; National Institute of Science Education and Research (NISER)-Bhubaneswar; Odisha India
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17
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Kang DY, Kim HC. Functional relevance of three proopiomelanocortin (POMC) genes in darkening camouflage, blind-side hypermelanosis, and appetite of Paralichthys olivaceus. Comp Biochem Physiol B Biochem Mol Biol 2015; 179:44-56. [DOI: 10.1016/j.cbpb.2014.09.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Revised: 08/21/2014] [Accepted: 09/10/2014] [Indexed: 12/12/2022]
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18
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McFarlane D. Pathophysiology and clinical features of pituitarypars intermediadysfunction. EQUINE VET EDUC 2014. [DOI: 10.1111/eve.12237] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- D. McFarlane
- Center for Veterinary Health Sciences; Oklahoma State University; Stillwater USA
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19
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The neuroanatomical function of leptin in the hypothalamus. J Chem Neuroanat 2014; 61-62:207-20. [PMID: 25007719 DOI: 10.1016/j.jchemneu.2014.05.004] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2013] [Revised: 05/09/2014] [Accepted: 05/28/2014] [Indexed: 02/07/2023]
Abstract
The anorexigenic hormone leptin plays an important role in the control of food intake and feeding-related behavior, for an important part through its action in the hypothalamus. The adipose-derived hormone modulates a complex network of several intercommunicating orexigenic and anorexigenic neuropeptides in the hypothalamus to reduce food intake and increase energy expenditure. In this review we present an updated overview of the functional role of leptin in respect to feeding and feeding-related behavior per distinct hypothalamic nuclei. In addition to the arcuate nucleus, which is a major leptin sensitive hub, leptin-responsive neurons in other hypothalamic nuclei, including the, dorsomedial-, ventromedial- and paraventricular nucleus and the lateral hypothalamic area, are direct targets of leptin. However, leptin also modulates hypothalamic neurons in an indirect manner, such as via the melanocortin system. The dissection of the complexity of leptin's action on the networks involved in energy balance is subject of recent and future studies. A full understanding of the role of hypothalamic leptin in the regulation of energy balance requires cell-specific manipulation using of conditional deletion and expression of leptin receptors. In addition, optogenetic and pharmacogenetic tools in combination with other pharmacological (such as the recent discovery of a leptin receptor antagonist) and neuronal tracing techniques to map the circuit, will be helpful to understand the role of leptin receptor expressing neurons. Better understanding of these circuits and the involvement of leptin could provide potential sites for therapeutic interventions in obesity and metabolic diseases characterized by dysregulation of energy balance.
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Abstract
Obesity and its related metabolic consequences represent a major public health problem. Huge changes within the environment have undoubtedly contributed to the increased prevalence of obesity but genetic factors are also critical in determining an individual's predisposition to gain weight. The last two decades have seen a huge increase in the understanding of the mechanisms controlling appetitive behavior, body composition, and energy expenditure. Many regions throughout the central nervous system play critical roles in these processes but the hypothalamus, in particular, receives and orchestrates a variety of signals to bring about coordinated changes in energy balance. Reviewing data from human genetic and model organism studies, we consider how disruptions of hypothalamic pathways evolved to maintain energy homeostasis and go on to cause obesity. We highlight ongoing technological developments which continue to lead to novel insights and discuss how this increased knowledge may lead to effective therapeutic interventions in the future.
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Affiliation(s)
- Rachel Larder
- University of Cambridge Metabolic Research Laboratories, MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, UK
| | - Chung Thong Lim
- University of Cambridge Metabolic Research Laboratories, MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, UK
| | - Anthony P Coll
- University of Cambridge Metabolic Research Laboratories, MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, UK.
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Caruso C, Carniglia L, Durand D, Scimonelli TN, Lasaga M. Astrocytes: new targets of melanocortin 4 receptor actions. J Mol Endocrinol 2013; 51:R33-50. [PMID: 23881919 DOI: 10.1530/jme-13-0064] [Citation(s) in RCA: 31] [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] [Indexed: 12/24/2022]
Abstract
Astrocytes exert a wide variety of functions with paramount importance in brain physiology. After injury or infection, astrocytes become reactive and they respond by producing a variety of inflammatory mediators that help maintain brain homeostasis. Loss of astrocyte functions as well as their excessive activation can contribute to disease processes; thus, it is important to modulate reactive astrocyte response. Melanocortins are peptides with well-recognized anti-inflammatory and neuroprotective activity. Although melanocortin efficacy was shown in systemic models of inflammatory disease, mechanisms involved in their effects have not yet been fully elucidated. Central anti-inflammatory effects of melanocortins and their mechanisms are even less well known, and, in particular, the effects of melanocortins in glial cells are poorly understood. Of the five known melanocortin receptors (MCRs), only subtype 4 is present in astrocytes. MC4R has been shown to mediate melanocortin effects on energy homeostasis, reproduction, inflammation, and neuroprotection and, recently, to modulate astrocyte functions. In this review, we will describe MC4R involvement in anti-inflammatory, anorexigenic, and anti-apoptotic effects of melanocortins in the brain. We will highlight MC4R action in astrocytes and discuss their possible mechanisms of action. Melanocortin effects on astrocytes provide a new means of treating inflammation, obesity, and neurodegeneration, making them attractive targets for therapeutic interventions in the CNS.
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Affiliation(s)
- Carla Caruso
- School of Medicine, Biomedical Research Institute (UBA-CONICET), University of Buenos Aires, Paraguay 2155 piso 10, 1121ABG Buenos Aires, Argentina IFEC (CONICET) Department of Pharmacology, School of Chemistry, National University of Córdoba, Córdoba, Argentina
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22
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Abstract
The melanocortin-4 receptor (MC4R) is a critical regulator of energy homeostasis and has emerged as a premier target for obesity treatment. Numerous mutations in transmembrane domain 6 (TM6) of MC4R resulting in functional alterations have been identified in obese patients. Several mutagenesis studies also provided some data suggesting the importance of this domain in receptor function. To gain a better understanding of the structure-function relationship of the receptor, we performed alanine-scanning mutagenesis in TM6 to determine the functions of side chains. Of the 31 residues, two were important for cell surface expression, five were indispensable for α-melanocyte-stimulating hormone (α-MSH) and β-MSH binding, and six were important for signaling in the Gs-cAMP-PKA pathway. H264A, targeted normally to the plasma membrane, was undetectable by competitive binding assay and severely defective in basal and stimulated cAMP production and ERK1/2 phosphorylation. Nine mutants had decreased basal cAMP signaling. Seven mutants were constitutively active in cAMP signaling and their basal activities could be inhibited by two MC4R inverse agonists, Ipsen 5i and ML00253764. Five mutants were also constitutively active in the MAPK pathway with enhanced basal ERK1/2 phosphorylation. In summary, our study provided comprehensive data on the structure-function relationship of the TM6 of MC4R. We identified residues that are important for cell surface expression, ligand binding, cAMP generation, and residues for maintaining the WT receptor in active conformation. We also reported constitutive activation of the MAPK pathway and biased signaling. These data will be useful for rationally designing MC4R agonists and antagonists for treatment of eating disorders.
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MESH Headings
- Blotting, Western
- Cell Line
- Cyclic AMP/metabolism
- Humans
- Imidazoles/pharmacology
- Immunohistochemistry
- Microscopy, Confocal
- Mutagenesis, Site-Directed
- Protein Binding/genetics
- Protein Binding/physiology
- Protein Structure, Tertiary/genetics
- Protein Structure, Tertiary/physiology
- Receptor, Melanocortin, Type 4/agonists
- Receptor, Melanocortin, Type 4/chemistry
- Receptor, Melanocortin, Type 4/genetics
- Receptor, Melanocortin, Type 4/metabolism
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Affiliation(s)
- Hui Huang
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, 212 Greene Hall, Auburn, Alabama 36849, USA
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23
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Honda K, Saneyasu T, Hasegawa S, Kamisoyama H. A comparative study of the central effects of melanocortin peptides on food intake in broiler and layer chicks. Peptides 2012; 37:13-7. [PMID: 22760063 DOI: 10.1016/j.peptides.2012.06.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 06/25/2012] [Accepted: 06/25/2012] [Indexed: 10/28/2022]
Abstract
Broiler chicks eat more food than layer chicks. However, the causes of the difference in food intake in the neonatal period between these strains are not clear. In this study, we examined the involvement of proopiomelanocortin (POMC)-derived melanocortin peptides α-, β- and γ-melanocyte-stimulating hormones (MSHs) in the difference in food intake between broiler and layer chicks. First, we compared the hypothalamic mRNA levels of POMC between these strains and found that there was no significant difference in these levels between broiler and layer chicks. Next, we examined the effects of central administration of MSHs on food intake in these strains. Central administration of α-MSH significantly suppressed food intake in both strains. Central administration of β-MSH significantly suppressed food intake in layer chicks, but not in broiler chicks, while central administration of γ-MSH did not influence food intake in either strain. It is therefore likely that the absence of the anorexigenic effect of β-MSH might be related to the increased food intake in broiler chicks.
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Affiliation(s)
- Kazuhisa Honda
- Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan.
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24
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Suzuki K, Jayasena CN, Bloom SR. Obesity and appetite control. EXPERIMENTAL DIABETES RESEARCH 2012; 2012:824305. [PMID: 22899902 PMCID: PMC3415214 DOI: 10.1155/2012/824305] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Accepted: 06/20/2012] [Indexed: 01/01/2023]
Abstract
Obesity is one of the major challenges to human health worldwide; however, there are currently no effective pharmacological interventions for obesity. Recent studies have improved our understanding of energy homeostasis by identifying sophisticated neurohumoral networks which convey signals between the brain and gut in order to control food intake. The hypothalamus is a key region which possesses reciprocal connections between the higher cortical centres such as reward-related limbic pathways, and the brainstem. Furthermore, the hypothalamus integrates a number of peripheral signals which modulate food intake and energy expenditure. Gut hormones, such as peptide YY, pancreatic polypeptide, glucagon-like peptide-1, oxyntomodulin, and ghrelin, are modulated by acute food ingestion. In contrast, adiposity signals such as leptin and insulin are implicated in both short- and long-term energy homeostasis. In this paper, we focus on the role of gut hormones and their related neuronal networks (the gut-brain axis) in appetite control, and their potentials as novel therapies for obesity.
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Affiliation(s)
- Keisuke Suzuki
- Section of Investigative Medicine, Imperial College London, Commonwealth Building, Du Cane Road, London W12 0NN, UK
| | - Channa N. Jayasena
- Section of Investigative Medicine, Imperial College London, Commonwealth Building, Du Cane Road, London W12 0NN, UK
| | - Stephen R. Bloom
- Section of Investigative Medicine, Imperial College London, Commonwealth Building, Du Cane Road, London W12 0NN, UK
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25
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Stocker CJ, Wargent ET, Martin-Gronert MS, Cripps RL, O'Dowd JF, Zaibi MS, Cottrell EC, Mercer JG, Duncan JS, Cawthorne MA, Ozanne SE, Arch JRS. Leanness in postnatally nutritionally programmed rats is associated with increased sensitivity to leptin and a melanocortin receptor agonist and decreased sensitivity to neuropeptide Y. Int J Obes (Lond) 2012; 36:1040-6. [PMID: 22124449 PMCID: PMC3378483 DOI: 10.1038/ijo.2011.226] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
BACKGROUND Pups of normally nourished dams that are cross-fostered after birth to dams fed a low-protein (8% by weight) diet (postnatal low protein (PLP)) grow slower during the suckling period and remain small and lean throughout adulthood. At weaning, they have increased expression in the arcuate nucleus (ARC) of the hypothalamus of the orexigenic neuropeptide Y (NPY) and decreased expression of pro-opiomelanocortin, the precursor of anorexigenic melanocortins. OBJECTIVES AND METHODS We investigated, using third ventricle administration, whether 3-month-old male PLP rats display altered sensitivity to leptin with respect to food intake, NPY and the melanocortin 3/4-receptor agonist MTII, and using in situ hybridization or laser capture microdissection of the ARC followed by RT-PCR, whether the differences observed were associated with changes in the hypothalamic expression of NPY or the leptin receptor, NPY receptors and melanocortin receptors. RESULTS PLP rats were smaller and had reduced percentage body fat content and plasma leptin concentration compared with control rats. Leptin (5 μg) reduced food intake over 0-48 h more in PLP than control rats (P<0.05). Submaximal doses of NPY increased the food intake less in PLP rats than in controls, whereas submaximal doses of MTII reduced the food intake more in PLP rats. Maximal responses did not differ between PLP and control rats. Leptin and melanocortin-3 receptor (MC3R) expression were increased in both ARC and ventromedial hypothalamic nuclei in PLP animals compared with the controls. MC4R, NPY Y1R, Y5R and NPY expression were unchanged. CONCLUSION Postnatal undernourishment results in food intake in adult rats being more sensitive to reduction by leptin and melanocortins, and less sensitive to stimulation by NPY. We propose that this contributes to increased leptin sensitivity and resistance to obesity. Increased expression of ObRb and MC3R may partly explain these findings but other downstream mechanisms must also be involved.
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Affiliation(s)
- C J Stocker
- Clore Laboratory, University of Buckingham, Buckingham, UK.
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26
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Abstract
Obesity is one of the major challenges to human health worldwide; however, there are currently no effective pharmacological interventions for obesity. Recent studies have improved our understanding of energy homeostasis by identifying sophisticated neurohumoral networks which convey signals between the brain and gut in order to control food intake. The hypothalamus is a key region which possesses reciprocal connections between the higher cortical centres such as reward-related limbic pathways, and the brainstem. Furthermore, the hypothalamus integrates a number of peripheral signals which modulate food intake and energy expenditure. Gut hormones, such as peptide YY, pancreatic polypeptide, glucagon-like peptide-1, oxyntomodulin, and ghrelin, are modulated by acute food ingestion. In contrast, adiposity signals such as leptin and insulin are implicated in both short- and long-term energy homeostasis. In this paper, we focus on the role of gut hormones and their related neuronal networks (the gut-brain axis) in appetite control, and their potentials as novel therapies for obesity.
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27
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Harrold JA, Dovey TM, Blundell JE, Halford JC. CNS regulation of appetite. Neuropharmacology 2012; 63:3-17. [DOI: 10.1016/j.neuropharm.2012.01.007] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 01/05/2012] [Accepted: 01/10/2012] [Indexed: 12/14/2022]
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Jeong JK, Szabo G, Raso GM, Meli R, Diano S. Deletion of prolyl carboxypeptidase attenuates the metabolic effects of diet-induced obesity. Am J Physiol Endocrinol Metab 2012; 302:E1502-10. [PMID: 22454290 PMCID: PMC3378159 DOI: 10.1152/ajpendo.00544.2011] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
α-Melanocyte-stimulating hormone (α-MSH) is a critical regulator of energy metabolism. Prolyl carboxypeptidase (PRCP) is an enzyme responsible for its degradation and inactivation. PRCP-null mice (PRCP(gt/gt)) showed elevated levels of brain α-MSH, reduced food intake, and a leaner phenotype compared with wild-type controls. In addition, they were protected against diet-induced obesity. Here, we show that PRCP(gt/gt) animals have improved metabolic parameters compared with wild-type controls under a standard chow diet (SD) as well as on a high-fat diet (HFD). Similarly to when they are exposed to SD, PRCP(gt/gt) mice exposed to HFD for 13 wk showed a leaner phenotype due to decreased fat mass, increased energy expenditure, and locomotor activity. They also showed improved insulin sensitivity and glucose tolerance compared with WT controls and a significant reduction in fasting glucose levels. These improvements occured before changes in body weight and composition were evident, suggesting that the beneficial effect of PRCP ablation is independent of the adiposity levels. In support of a reduced gluconeogenesis, liver PEPCK and G-6-Pase mRNA levels were reduced significantly in PRCP(gt/gt) compared with WT mice. A significant decrease in liver weight and hepatic triglycerides were also observed in PRCP(gt/gt) compared with WT mice. Altogether, our data suggest that PRCP is an important regulator of energy and glucose homeostasis since its deletion significantly improves metabolic parameters in mice exposed to both SD and HFD.
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Affiliation(s)
- Jin Kwon Jeong
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine, New Haven, Connecticut 06520-208063, USA
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29
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Pastore MB, Jobe SO, Ramadoss J, Magness RR. Estrogen receptor-α and estrogen receptor-β in the uterine vascular endothelium during pregnancy: functional implications for regulating uterine blood flow. Semin Reprod Med 2012; 30:46-61. [PMID: 22271294 DOI: 10.1055/s-0031-1299597] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The steroid hormone estrogen and its classical estrogen receptors (ERs), ER-α and ER-β, have been shown to be partly responsible for the short- and long-term uterine endothelial adaptations during pregnancy. The ER-subtype molecular and structural differences coupled with the differential effects of estrogen in target cells and tissues suggest a substantial functional heterogeneity of the ERs in estrogen signaling. In this review we discuss (1) the role of estrogen and ERs in cardiovascular adaptations during pregnancy, (2) in vivo and in vitro expression of ERs in uterine artery endothelium during the ovarian cycle and pregnancy, contrasting reproductive and nonreproductive arterial endothelia, (3) the structural basis for functional diversity of the ERs and estrogen subtype selectivity, (4) the role of estrogen and ERs on genomic responses of uterine artery endothelial cells, and (5) the role of estrogen and ERs on nongenomic responses in uterine artery endothelia. These topics integrate current knowledge of this very rapidly expanding scientific field with diverse interpretations and hypotheses regarding the estrogenic effects that are mediated by either or both ERs and their relationship with vasodilatory and angiogenic vascular adaptations required for modulating the dramatic physiological rises in uteroplacental perfusion observed during normal pregnancy.
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Affiliation(s)
- Mayra B Pastore
- Department of Obstetrics/Gynecology, Perinatal Research Laboratories, University of Wisconsin-Madison, Madison, Wisconsin, USA
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30
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Biebermann H, Kühnen P, Kleinau G, Krude H. The neuroendocrine circuitry controlled by POMC, MSH, and AGRP. Handb Exp Pharmacol 2012:47-75. [PMID: 22249810 DOI: 10.1007/978-3-642-24716-3_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Obesity is one of the most challenging health problems worldwide. Over the past few decades, our knowledge concerning mechanisms of weight regulation has increased tremendously leading to the identification of the leptin-melanocortin pathway. The filling level of energy stores is signaled to the brain, and the information is integrated by hypothalamic nuclei, resulting in a well-orchestrated response to food intake and energy expenditure to ensure constant body weight. One of the key players in this system is proopiomelanocortin (POMC), a precursor of a variety of neuropeptides. POMC-derived alpha- and beta-MSH play an important role in energy homeostasis by activating melanocortin receptors expressed in the arcuate nucleus (MC3R) and in the nucleus paraventricularis (MC4R). Activation of these two G protein-coupled receptors is antagonized by agouti-related peptide (AgRP). Naturally occurring mutations in this system were identified in patients suffering from common obesity as well as in patients demonstrating a phenotype of severe early-onset obesity, adrenal insufficiency, red hair, and pale skin. Detailed understanding of the complex system of POMC-AgRP-MC3R-MC4R and their interaction with other hypothalamic as well as peripheral signals is a prerequisite to combat the obesity epidemic.
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Affiliation(s)
- Heike Biebermann
- Institut für Experimentelle Pädiatrische Endokrinologie, Charité Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.
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31
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Both overexpression of agouti-related peptide or neuropeptide Y in the paraventricular nucleus or lateral hypothalamus induce obesity in a neuropeptide- and nucleus specific manner. Eur J Pharmacol 2011; 660:148-55. [DOI: 10.1016/j.ejphar.2010.12.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Revised: 11/18/2010] [Accepted: 12/11/2010] [Indexed: 10/18/2022]
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Saneyasu T, Honda K, Kamisoyama H, Nakayama Y, Ikegami K, Hasegawa S. Alpha-melanocyte stimulating hormone plays an important role in the regulation of food intake by the central melanocortin system in chicks. Peptides 2011; 32:996-1000. [PMID: 21402117 DOI: 10.1016/j.peptides.2011.03.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Revised: 03/03/2011] [Accepted: 03/03/2011] [Indexed: 11/29/2022]
Abstract
Proopiomelanocortin (POMC, a precursor of melanocortin peptides) neurons in the hypothalamus play an important role in the central regulation of food intake in mammals. There is evidence that human melanocortin peptides alpha-, beta- and gamma2-melanocyte-stimulating hormone (α-, β- and γ2-MSH) significantly decreased food intake in chickens. However, the amino acid sequences of β- and γ2-MSH of chickens are different from those of humans whereas the amino acid sequence of α-MSH is conserved between these species. In the present study, we examined the effects of the central administration of α-, chicken β-, and chicken γ2-MSH on food intake in chicks. Central administration of α-MSH significantly suppressed food intake in chicks. In contrast, β- and γ2-MSH did not influence food intake in chicks. Central administration of HS014, a melanocortin 4 receptor antagonist, significantly reversed the anorexigenic action of α-MSH, suggesting that this action is mediated by the melanocortin 4 receptor in chicks as well as in mammals. These results suggest that α-MSH may play an important role in the regulation of food intake by the central melanocortin system in chicks.
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Affiliation(s)
- Takaoki Saneyasu
- Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
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33
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Physiological roles of the melanocortin MC₃ receptor. Eur J Pharmacol 2011; 660:13-20. [PMID: 21211527 DOI: 10.1016/j.ejphar.2010.12.025] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Revised: 12/11/2010] [Accepted: 12/15/2010] [Indexed: 11/23/2022]
Abstract
The melanocortin MC(3) receptor remains the most enigmatic of the melanocortin receptors with regard to its physiological functions. The receptor is expressed both in the CNS and in multiple tissues in the periphery. It appears to be an inhibitory autoreceptor on proopiomelanocortin neurons, yet global deletion of the receptor causes an obesity syndrome. Knockout of the receptor increases adipose mass without a readily measurable increase in food intake or decrease in energy expenditure. And finally, no melanocortin MC(3) receptor null humans have been identified and associations between variant alleles of the melanocortin MC(3) receptor and diseases remain controversial, so the physiological role of the receptor in humans remains to be determined.
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Abstract
The melanocortin-4 receptor (MC4R) was cloned in 1993 by degenerate PCR; however, its function was unknown. Subsequent studies suggest that the MC4R might be involved in regulating energy homeostasis. This hypothesis was confirmed in 1997 by a series of seminal studies in mice. In 1998, human genetic studies demonstrated that mutations in the MC4R gene can cause monogenic obesity. We now know that mutations in the MC4R are the most common monogenic form of obesity, with more than 150 distinct mutations reported thus far. This review will summarize the studies on the MC4R, from its cloning and tissue distribution to its physiological roles in regulating energy homeostasis, cachexia, cardiovascular function, glucose and lipid homeostasis, reproduction and sexual function, drug abuse, pain perception, brain inflammation, and anxiety. I will then review the studies on the pharmacology of the receptor, including ligand binding and receptor activation, signaling pathways, as well as its regulation. Finally, the pathophysiology of the MC4R in obesity pathogenesis will be reviewed. Functional studies of the mutant MC4Rs and the therapeutic implications, including small molecules in correcting binding and signaling defect, and their potential as pharmacological chaperones in rescuing intracellularly retained mutants, will be highlighted.
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Affiliation(s)
- Ya-Xiong Tao
- Department of Anatomy, Physiology, and Pharmacology, Auburn University, Alabama 36849-5519, USA.
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35
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Pétervári E, Garami A, Soós S, Székely M, Balaskó M. Age-dependence of alpha-MSH-induced anorexia. Neuropeptides 2010; 44:315-22. [PMID: 20382426 DOI: 10.1016/j.npep.2010.03.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Revised: 02/23/2010] [Accepted: 03/17/2010] [Indexed: 11/20/2022]
Abstract
Long-term regulation of energy balance involves two major trends: first age-related obesity develops in the middle-aged, later it is followed by anorexia of aging (sarcopenia and/or cachexia). A dynamic balance between orexigenic and anorexigenic neuropeptides is essential for the regulation of energy homeostasis. Special imbalances of neuropeptide effects may be assumed corresponding to different age-periods. Anorexia induced by acute alpha-MSH (alpha-melanocyte stimulating hormone; endogenous melanocortin agonist) injections was analyzed in male Wistar rats aged 6-9 weeks (juvenile), 3-4 months (young adult), 6 or 12 months (two middle-aged groups), 18 months (aging) and 24-26 months (old). Alpha-MSH injected through a preimplanted intracerebroventricular (ICV) cannula (compared with saline injection) dose-dependently suppressed spontaneous food intake and also re-feeding following 24-h fasting, but the rate of suppression varied between age-groups. An ICV injection of 5 microg alpha-MSH attenuated the 2-h re-feeding by 21.9+/-3.2% in juvenile rats, strongly (68.7+/-2.5%) suppressed it in young adults, the suppression became progressively weaker in the two middle-aged groups (55.7+/-4.9%, vs. 26.4+/-4.9%, respectively), but it turned extreme in aging (94.7+/-4.2%) and old (74.3+/-4.5%) rats. Body composition also changed with age: unlike the tibialis anterior muscle, the epididymal and retroperitoneal fat pads increased until middle-age and remained large even in old animals, while the measured indicator of muscle mass decreased in the oldest group. The food intake suppressing and body weight decreasing effects of a 7-day-long ICV infusion of 1 microg/h alpha-MSH were weakest in the 12-month-old and most pronounced in the 24 month-old rats. In conclusion, responsiveness to the anorexic effect of alpha-MSH varies with age, with a nadir of the curve in the middle-aged, and a peak in the aging and old animals. This age-related nadir of melanocortin-responsiveness may promote obesity in middle-aged rats, while the tendency for anorexia and incipient sarcopenia of old (still obese) rats may result from age-related melanocortin-hypersensitivity rather than from adiposity.
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Affiliation(s)
- E Pétervári
- Department of Pathophysiology and Gerontology, Medical School, University of Pécs, Pécs, Hungary
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36
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D'Agostino G, Diano S. Alpha-melanocyte stimulating hormone: production and degradation. J Mol Med (Berl) 2010; 88:1195-201. [PMID: 20617297 DOI: 10.1007/s00109-010-0651-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Revised: 06/21/2010] [Accepted: 06/24/2010] [Indexed: 10/19/2022]
Abstract
Proopiomelanocortin (POMC) is a polypeptide hormone precursor that is expressed in the brain and in peripheral tissues such as in the pituitary gland, immune system, and skin. In the brain, POMC is processed to form several peptides including alpha-melanocyte stimulating hormone (α-MSH). alpha-MSH is expressed in the hypothalamic arcuate nucleus and in the nucleus tractus solitarius of the brainstem where it has a crucial role in the regulation of metabolic functions. Specifically, α-MSH is an anorexigenic peptide. Its production and maturation processes have been shown to be regulated according to the metabolic condition of the organism. This review summarizes our current knowledge on α-MSH processing including its maturation and degradation processes and pharmacological aspects of its manipulation.
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Affiliation(s)
- Giuseppe D'Agostino
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine, New Haven, CT 06520, USA
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37
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Abstract
Melanocortin peptides, derived from POMC (pro-opiomelanocortin) are produced in the ARH (arcuate nucleus of the hypothalamus) neurons and the neurons in the commissural NTS (nucleus of the solitary tract) of the brainstem, in anterior and intermediate lobes of the pituitary, skin and a wide range of peripheral tissues, including reproductive organs. A hypothetical model for functional roles of melanocortin receptors in maintaining energy balance was proposed in 1997. Since this time, there has been an extraordinary amount of knowledge gained about POMC-derived peptides in relation to energy homoeostasis. Development of a Pomc-null mouse provided definitive proof that POMC-derived peptides are critical for the regulation of energy homoeostasis. The melanocortin system consists of endogenous agonists and antagonists, five melanocortin receptor subtypes and receptor accessory proteins. The melanocortin system, as is now known, is far more complex than most of us could have imagined in 1997, and, similarly, the importance of this system for regulating energy homoeostasis in the general human population is much greater than we would have predicted. Of the known factors that can cause human obesity, or protect against it, the melanocortin system is by far the most significant. The present review is a discussion of the current understanding of the roles and mechanism of action of POMC, melanocortin receptors and AgRP (agouti-related peptide) in obesity and Type 2 diabetes and how the central and/or peripheral melanocortin systems mediate nutrient, leptin, insulin, gut hormone and cytokine regulation of energy homoeostasis.
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Lopaschuk GD, Ussher JR, Jaswal JS. Targeting intermediary metabolism in the hypothalamus as a mechanism to regulate appetite. Pharmacol Rev 2010; 62:237-64. [PMID: 20392806 DOI: 10.1124/pr.109.002428] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The central nervous system mediates energy balance (energy intake and energy expenditure) in the body; the hypothalamus has a key role in this process. Recent evidence has demonstrated an important role for hypothalamic malonyl CoA in mediating energy balance. Malonyl CoA is generated by the carboxylation of acetyl CoA by acetyl CoA carboxylase and is then either incorporated into long-chain fatty acids by fatty acid synthase, or converted back to acetyl-CoA by malonyl CoA decarboxylase. Increased hypothalamic malonyl CoA is an indicator of energy surplus, resulting in a decrease in food intake and an increase in energy expenditure. In contrast, a decrease in hypothalamic malonyl CoA signals an energy deficit, resulting in an increased appetite and a decrease in body energy expenditure. A number of hormonal and neural orexigenic and anorexigenic signaling pathways have now been shown to be associated with changes in malonyl CoA levels in the arcuate nucleus (ARC) of the hypothalamus. Despite compelling evidence that malonyl CoA is an important mediator in the hypothalamic ARC control of food intake and regulation of energy balance, the mechanism(s) by which this occurs has not been established. Malonyl CoA inhibits carnitine palmitoyltransferase-1 (CPT-1), and it has been proposed that the substrate of CPT-1, long-chain acyl CoA(s), may act as a mediator(s) of appetite and energy balance. However, recent evidence has challenged the role of long-chain acyl CoA(s) in this process, as well as the involvement of CPT-1 in hypothalamic malonyl CoA signaling. A better understanding of how malonyl CoA regulates energy balance should provide novel approaches to targeting intermediary metabolism in the hypothalamus as a mechanism to control appetite and body weight. Here, we review the data supporting an important role for malonyl CoA in mediating hypothalamic control of energy balance, and recent evidence suggesting that targeting malonyl CoA synthesis or degradation may be a novel approach to favorably modify appetite and weight gain.
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Affiliation(s)
- Gary D Lopaschuk
- 423 Heritage Medical Research Center, University of Alberta, Edmonton, Canada T6G2S2.
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39
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Yoshida K, Kim J, Nakajima K, Oomura Y, Wayner MJ, Sasaki K. Electrophysiological effects of neuropeptide S on rat ventromedial hypothalamic neurons in vitro. Peptides 2010; 31:712-9. [PMID: 19925841 DOI: 10.1016/j.peptides.2009.11.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2009] [Revised: 11/06/2009] [Accepted: 11/10/2009] [Indexed: 01/10/2023]
Abstract
The newly identified neuropeptide S (NPS) is a ligand for a previously orphan G protein-coupled GPR 154 receptor, now named the NPS receptor (NPSR). Previous studies have shown that NPS induces hyperlocomotion, increases arousal and suppresses anxiety-like behaviors via NPSR. Although NPS also inhibits food intake, nothing is known about the neuronal mechanisms underlying this action. Anatomical studies show that NPSRs are expressed abundantly in the dorsomedial part of the ventromedial hypothalamic nucleus (VMH), a satiety center for food intake. Hence, we examined the electrophysiological effects of NPS on rat VMH neurons in vitro. NPS predominantly depolarized the VMH neurons, and the effects were postsynaptic and dose-dependent. Membrane resistance was significantly decreased during the depolarization, suggesting an opening of some ionic channels. The NPS-induced depolarization was significantly attenuated in Ca(2+)-free, NiCl(2)-containing and mibefradil-containing TTX ACSFs, but it did not disappear. The NPS-induced depolarization was also attenuated in low-Na(+) TTX ACSF, and completely abolished in Ca(2+)-free/low-Na(+) TTX ACSF. Pretreatment with 30 microM KB-R7943, an inhibitor of forward-mode Na(+)/Ca(2+) exchanger, did not have any significant effect on the NPS-induced depolarization in Ca(2+)-free TTX ACSF. These results suggest that NPS depolarizes VMH neurons via activations of R- and T-type Ca(2+) channels and nonselective cation channels, and that VMH neurons might be involved in the cellular process through which NPS participates in the regulation of food intake and energy homeostasis.
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Affiliation(s)
- Keitaro Yoshida
- Division of Bio-Information Engineering, Faculty of Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan
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40
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Backholer K, Bowden M, Gamber K, Bjørbæk C, Iqbal J, Clarke IJ. Melanocortins mimic the effects of leptin to restore reproductive function in lean hypogonadotropic ewes. Neuroendocrinology 2010; 91:27-40. [PMID: 19923792 PMCID: PMC2857620 DOI: 10.1159/000260060] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2009] [Accepted: 05/25/2009] [Indexed: 02/02/2023]
Abstract
BACKGROUND/AIMS Leptin restores gonadotropic function in lean hypogonadotropic animals by an unknown mechanism. We aimed to test the hypothesis that restoration of gonadotropic function is a result of an upregulation of central acetylated melanocortin production. METHODS AND RESULTS Lean ovariectomised (OVX) ewes received intracerebroventricular (i.c.v.) infusions of leptin (or vehicle) for 3 days, which upregulated proopiomelanocortin (POMC) mRNA and restored pulsatile luteinizing hormone (LH) secretion. A melanocortin agonist (MTII), but not naloxone treatment, reinstated pulsatile LH secretion in lean OVX ewes. We treated (i.c.v.) lean OVX ewes with leptin (or vehicle) and measured peptide levels and post-translational modification in the arcuate nucleus (ARC). Levels of beta-endorphin (beta-END) were lower in lean animals, with no effect of leptin treatment. Desacetyl-alpha-MSH was the predominant form of alpha-melanocyte-stimulating hormone (alpha-MSH) in the ARC and levels were similar in all groups. In another group of lean and normal-weight OVX ewes, we measured the different forms of alpha-MSH in ARC, hypothalamus (ARC-removed) and the preoptic area (POA). Acetylated alpha-MSH levels were lower in lean animals in the terminal beds of the hypothalamus and POA but not the ARC. CONCLUSIONS Leptin corrects the hypogonadotropic state in the lean condition by upregulation of POMC gene expression, and may increase transport and acetylation of melanocortins to target cells in the brain. Melanocortin treatment restores LH secretion in lean animals.
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Affiliation(s)
- Kathryn Backholer
- Department of Physiology, Monash University, Monash, Vic., Australia
| | - Marissa Bowden
- Prince Henry's Institute of Medical Research, Clayton, Vic., Australia
| | - Kevin Gamber
- Division of Endocrinology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Mass., USA
| | - Christian Bjørbæk
- Division of Endocrinology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Mass., USA
| | - Javed Iqbal
- Department of Physiology, Monash University, Monash, Vic., Australia
| | - Iain J. Clarke
- Department of Physiology, Monash University, Monash, Vic., Australia
- *Iain J. Clarke, Department of Physiology, Monash University, PO Box 13F, Clayton, Vic. 3800 (Australia), Tel. +61 3 9905 2554, Fax +61 3 9905 2566, E-Mail
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41
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Suzuki K, Simpson KA, Minnion JS, Shillito JC, Bloom SR. The role of gut hormones and the hypothalamus in appetite regulation. Endocr J 2010; 57:359-72. [PMID: 20424341 DOI: 10.1507/endocrj.k10e-077] [Citation(s) in RCA: 181] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The World Health Organisation has estimated that by 2015 approximately 2.3 billion adults will be overweight and more than 700 million obese. Obesity is associated with an increased risk of diabetes, cardiovascular events, stroke and cancer. The hypothalamus is a crucial region for integrating signals from central and peripheral pathways and plays a major role in appetite regulation. In addition, there are reciprocal connections with the brainstem and higher cortical centres. In the arcuate nucleus of the hypothalamus, there are two major neuronal populations which stimulate or inhibit food intake and influence energy homeostasis. Within the brainstem, the dorsal vagal complex plays a role in the interpretation and relaying of peripheral signals. Gut hormones act peripherally to modulate digestion and absorption of nutrients. However, they also act as neurotransmitters within the central nervous system to control food intake. Peptide YY, pancreatic polypeptide, glucagon-like peptide-1 and oxyntomodulin suppress appetite, whilst ghrelin increases appetite through afferent vagal fibres to the caudal brainstem or directly to the hypothalamus. A better understanding of the role of these gut hormones may offer the opportunity to develop successful treatments for obesity. Here we review the current understanding of the role of gut hormones and the hypothalamus on food intake and body weight control.
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Affiliation(s)
- Keisuke Suzuki
- Section of Investigative Medicine, Imperial College London, London, UK
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42
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Backholer K, Smith J, Clarke IJ. Melanocortins may stimulate reproduction by activating orexin neurons in the dorsomedial hypothalamus and kisspeptin neurons in the preoptic area of the ewe. Endocrinology 2009; 150:5488-97. [PMID: 19819961 DOI: 10.1210/en.2009-0604] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
To further test the hypothesis that melanocortins stimulate the reproductive axis, we treated ewes with melanocortin agonist (MTII) in the luteal phase of the estrous cycle and during seasonal anestrus. Lateral ventricular infusion of MTII (10 microg/h) during the luteal phase increased LH secretion. Retrograde neuronal tracing in the brain showed few proopiomelanocortin or kisspeptin cells in the arcuate nucleus, but more than 70% of kisspeptin cells in the dorsolateral preoptic area (POA), projecting to the ventromedial POA in which GnRH cells are located. MTII infusion (20 h) was repeated in luteal phase ewes and brains were harvested to measure gene expression of preproorexin and kisspeptin. Expression of orexin in the dorsomedial hypothalamus and kisspeptin in the POA was up-regulated by MTII treatment and Kiss1 in the arcuate nucleus was down-regulated. Seasonally anestrous ewes were progesterone primed and then treated (lateral ventricular) with MTII (10 microg/h) or vehicle for 30 h, and blood samples were collected every 2 h from 4 h before infusion until 6 h afterward to monitor acute response in terms of LH levels. A rise in basal LH levels was seen, but samples collected around the time of the predicted LH surge did not indicate that an ovulatory event occurred. We conclude that melanocortins are positive regulators of the reproductive neuroendocrine system, but treatment with melanocortins does not fully overcome seasonal acyclicity. The stimulatory effect of melanocortin in the luteal phase of the estrous cycle may be via the activation of kisspeptin cells in the POA and/or orexin cells in the dorsomedial hypothalamus.
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Affiliation(s)
- Kathryn Backholer
- Department of Physiology, Monash University, Clayton, Victoria 3800, Australia
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43
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Gamma(2)-melanocyte stimulating hormone decreases food intake in chicks. Neurosci Lett 2009; 465:210-3. [DOI: 10.1016/j.neulet.2009.08.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2009] [Revised: 08/03/2009] [Accepted: 08/06/2009] [Indexed: 11/20/2022]
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44
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Wallingford N, Perroud B, Gao Q, Coppola A, Gyengesi E, Liu ZW, Gao XB, Diament A, Haus KA, Shariat-Madar Z, Mahdi F, Wardlaw SL, Schmaier AH, Warden CH, Diano S. Prolylcarboxypeptidase regulates food intake by inactivating alpha-MSH in rodents. J Clin Invest 2009; 119:2291-303. [PMID: 19620781 DOI: 10.1172/jci37209] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2008] [Accepted: 05/20/2009] [Indexed: 11/17/2022] Open
Abstract
The anorexigenic neuromodulator alpha-melanocyte-stimulating hormone (alpha-MSH; referred to here as alpha-MSH1-13) undergoes extensive posttranslational processing, and its in vivo activity is short lived due to rapid inactivation. The enzymatic control of alpha-MSH1-13 maturation and inactivation is incompletely understood. Here we have provided insight into alpha-MSH1-13 inactivation through the generation and analysis of a subcongenic mouse strain with reduced body fat compared with controls. Using positional cloning, we identified a maximum of 6 coding genes, including that encoding prolylcarboxypeptidase (PRCP), in the donor region. Real-time PCR revealed a marked genotype effect on Prcp mRNA expression in brain tissue. Biochemical studies using recombinant PRCP demonstrated that PRCP removes the C-terminal amino acid of alpha-MSH1-13, producing alpha-MSH1-12, which is not neuroactive. We found that Prcp was expressed in the hypothalamus in neuronal populations that send efferents to areas where alpha-MSH1-13 is released from axon terminals. The inhibition of PRCP activity by small molecule protease inhibitors administered peripherally or centrally decreased food intake in both wild-type and obese mice. Furthermore, Prcp-null mice had elevated levels of alpha-MSH1-13 in the hypothalamus and were leaner and shorter than the wild-type controls on a regular chow diet; they were also resistant to high-fat diet-induced obesity. Our results suggest that PRCP is an important component of melanocortin signaling and weight maintenance via control of active alpha-MSH1-13 levels.
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Affiliation(s)
- Nicholas Wallingford
- Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale University School of Medicine, New Haven, Connecticut, USA
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45
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Semjonous NM, Smith KL, Parkinson JRC, Gunner DJL, Liu YL, Murphy KG, Ghatei MA, Bloom SR, Small CJ. Coordinated changes in energy intake and expenditure following hypothalamic administration of neuropeptides involved in energy balance. Int J Obes (Lond) 2009; 33:775-85. [PMID: 19488048 PMCID: PMC2711051 DOI: 10.1038/ijo.2009.96] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Objective The hypothalamic control of energy balance is regulated by a complex network of neuropeptide-releasing neurons. Whilst the effect of these neuropeptides on individual aspects of energy homeostasis has been studied, the coordinated response of these effects has not been comprehensively investigated. We have simultaneously monitored a number of metabolic parameters following ICV administration of 1nmol and 3nmol of neuropeptides with established roles in the regulation of feeding, activity and metabolism. Ad libitum fed rats received the orexigenic neuropeptides neuropeptide Y (NPY), agouti-related protein (AgRP), melanin-concentrating hormone (MCH) or orexin-A. Overnight food deprived rats received an ICV injection of the anorectic peptides α-MSH, corticotrophin releasing factor (CRF) or neuromedin U (NMU). Results Our results reveal the temporal sequence of the effects of these neuropeptides on both energy intake and expenditure, highlighting key differences in their function as mediators of energy balance. NPY and AgRP increased feeding and decreased oxygen consumption, with the effects of AgRP being more prolonged. In contrast, orexin-A increased both feeding and oxygen consumption, consistent with an observed increase in activity. The potent anorexigenic effects of CRF were accompanied by a prolonged increase in activity whilst NMU injection resulted in significant but short-lasting inhibition of food intake, ambulatory activity and oxygen consumption. Alpha-MSH injection resulted in significant increases in both ambulatory activity and oxygen consumption, and reduced food intake following administration of 3nmol of the peptide. Conclusion We have for the first time, simultaneously measured several metabolic parameters following hypothalamic administration of a number of neuropeptides within the same experimental system. This work has demonstrated the interrelated effects of these neuropeotides on activity, energy expenditure and food intake thus facilitating comparison between the different hypothalamic systems.
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Affiliation(s)
- N M Semjonous
- Department of Investigative Medicine, Imperial College London, London, UK
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46
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Ladyman SR, Tups A, Augustine RA, Swahn-Azavedo A, Kokay IC, Grattan DR. Loss of hypothalamic response to leptin during pregnancy associated with development of melanocortin resistance. J Neuroendocrinol 2009; 21:449-56. [PMID: 19302191 DOI: 10.1111/j.1365-2826.2009.01862.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hypothalamic leptin resistance during pregnancy is an important adaptation that facilitates the state of positive energy balance required for fat deposition in preparation for lactation. Within the arcuate nucleus, pro-opiomelanocortin (POMC) neurones and neuropeptide Y (NPY)/agouti-related gene protein (AgRP) neurones are first-order leptin responsive neurones involved in the regulation of energy balance. The present study aimed to investigate whether the regulation of these neuropeptides is disrupted during pregnancy in association with the development of leptin resistance. As measured by quantitative in situ hybridisation, POMC and AgRP mRNA levels were not significantly different during pregnancy, whereas NPY mRNA levels increased such that, by day 21 of pregnancy, levels were significantly higher than in nonpregnant, animals. These data suggest that these neurones were not responding normally to the elevated leptin found during pregnancy. To further characterise the melanocortin system during pregnancy, double-label immunohistochemistry was used to quantify leptin-induced phosphorylation of signal transducer and activator of transcription 3 (pSTAT3) in POMC neurones, using α-melanocyte-stimulating hormone (MSH) as a marker. The percentage of α-MSH neurones containing leptin-induced pSTAT3 did not significantly differ from nonpregnant animals, indicating that there was no change in the number of POMC neurones that respond to leptin during pregnancy. Treatment with α-MSH significantly reduced food intake in nonpregnant rats, but not in pregnant rats, indicating resistance to the satiety actions of α-MSH during pregnancy. The data suggest that multiple mechanisms contribute to leptin resistance during pregnancy. As well as a loss of responses in first-order leptin-responsive neurones in the arcuate nucleus, there is also a downstream disruption in the melanocortin system.
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Affiliation(s)
- S R Ladyman
- Centre for Neuroendocrinology, Department of Anatomy and Structural Biology, University of Otago, Dunedin, New Zealand
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47
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Kamisoyama H, Honda K, Saneyasu T, Sugahara K, Hasegawa S. Corticotropin-releasing factor is a downstream mediator of the beta-melanocyte-stimulating hormone-induced anorexigenic pathway in chicks. Neurosci Lett 2009; 458:102-5. [PMID: 19393716 DOI: 10.1016/j.neulet.2009.04.041] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Revised: 03/12/2009] [Accepted: 04/19/2009] [Indexed: 01/19/2023]
Abstract
Proopiomelanocortin (POMC, a precursor of anorexigenic neuropeptides) neurons in hypothalamus suppresses food intake in both mammals and chickens. In mammals, several lines of evidence suggest that POMC-derived anorexigenic peptides upregulate mRNA levels of anorexigenic peptides such as corticotropin-releasing factor (CRF) and thyrotropin-releasing factor and downregulate mRNA levels of orexigenic peptides such as orexin and melanin-concentrating hormone. However, the POMC-induced anorexigenic pathway in chickens has not been well characterized. In the present study, we investigated how POMC neurons regulate mechanisms of food intake using an anorexigenic peptide, beta-melanocyte-stimulating hormone (beta-MSH), derived from the post-transcriptional cleavage of POMC. Central administration of beta-MSH in chicks significantly suppressed food intake, and importantly, this suppression was accompanied by a significant upregulation of CRF mRNA levels. Furthermore, the CRF type 2 receptor antagonist alpha-helical CRF significantly reversed the anorexigenic action of beta-MSH. These findings indicate that CRF and its receptor, CRF type 2 receptor, act as the major mediators in beta-MSH-induced anorexigenic action in chicks. beta-MSH significantly increased orexin mRNA levels and did not alter mRNA levels of thyrotropin-releasing factor and melanin-concentrating hormone in chicks, suggesting that the beta-MSH-induced anorexigenic pathway in chicks is different from that in mammals. Increases in orexin mRNA levels were accompanied by significant decreases in plasma glucose concentration, suggesting that orexin mRNA might be stimulated by beta-MSH-induced hypoglycemia. Thus, this study demonstrates the direct evidence that CRF is a critical downstream target in the beta-MSH-induced anorexigenic pathway in chicks.
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Affiliation(s)
- Hiroshi Kamisoyama
- Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
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48
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Tiesjema B, Merkestein M, Garner KM, de Krom M, Adan RAH. Multimeric α-MSH has increased efficacy to activate the melanocortin MC4 receptor. Eur J Pharmacol 2008; 585:24-30. [PMID: 18378226 DOI: 10.1016/j.ejphar.2008.02.046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2007] [Revised: 02/11/2008] [Accepted: 02/12/2008] [Indexed: 11/19/2022]
Affiliation(s)
- Birgitte Tiesjema
- Rudolf Magnus Institute of Neuroscience, Department of Neuroscience and Pharmacology, University Medical Center Utrecht, The Netherlands
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49
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Lee M, Kim A, Conwell IM, Hruby V, Mayorov A, Cai M, Wardlaw SL. Effects of selective modulation of the central melanocortin-3-receptor on food intake and hypothalamic POMC expression. Peptides 2008; 29:440-7. [PMID: 18155809 PMCID: PMC2278043 DOI: 10.1016/j.peptides.2007.11.005] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2007] [Revised: 11/08/2007] [Accepted: 11/09/2007] [Indexed: 11/27/2022]
Abstract
Hypothalamic POMC neurons regulate energy balance via interactions with brain melanocortin receptors (MC-Rs). POMC neurons express the MC3-R which can function as an inhibitory autoreceptor in vitro. We now demonstrate that central activation of MC3-R with ICV infusion of the specific MC3-R agonist, [D-Trp(8)]-gamma-MSH, transiently suppresses hypothalamic Pomc expression and stimulates food intake in rats. Conversely, we also show that ICV infusion of a low dose of a selective MC3-R antagonist causes a transient decrease in feeding and weight gain. These data support a functional inhibitory role for the MC3-R on POMC neurons that leads to changes in food intake.
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Affiliation(s)
- Michelle Lee
- Department of Medicine, Columbia University College of Physicians & Surgeons, New York, NY
| | - Andrea Kim
- Department of Medicine, Columbia University College of Physicians & Surgeons, New York, NY
| | - Irene M. Conwell
- Department of Medicine, Columbia University College of Physicians & Surgeons, New York, NY
| | - Victor Hruby
- Department of Chemistry, University of Arizona, Tucson, AZ
| | | | - Minying Cai
- Department of Chemistry, University of Arizona, Tucson, AZ
| | - Sharon L. Wardlaw
- Department of Medicine, Columbia University College of Physicians & Surgeons, New York, NY
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50
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Smith ML, Prall B, Nandar W, Cline MA. Beta-melanocyte-stimulating hormone potently reduces appetite via the hypothalamus in chicks. J Neuroendocrinol 2008; 20:220-6. [PMID: 18088360 DOI: 10.1111/j.1365-2826.2007.01639.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The melanocortin system together with other appetite-related systems plays a significant role in appetite regulation. The appetite-related effects of one such melanocortin, beta-melanocyte-stimulating hormone (MSH), are well documented in rodents; however, its effects in the avian class are not thoroughly understood. Thus, we designed a study to determine the effects of i.c.v. beta-MSH injection on food and water intake, plasma corticosterone concentration, ingestive and non-ingestive behaviours, and hypothalamic neuronal activation using Cobb-500 chicks. Chicks responded to beta-MSH-treatment with a reduction in food and water intake; however when water intake was measured independently of food intake, it was not affected. beta-MSH-treated chicks also had increased plasma corticosterone concentrations and increased c-Fos reactivity in the periventricular, paraventricular and infundibular nuclei, and the ventromedial hypothalamus; however, the lateral hypothalamus was not affected. The effect on food intake is primary because behaviours that may be competitive with food intake were not increased in beta-MSH-treated chicks. Based on these results, we conclude that beta-MSH causes anorexigenic effects that are likely primarily mediated via stimulation of satiety-related hypothalamic nuclei in broiler-type chicks.
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Affiliation(s)
- M L Smith
- Department of Cellular, Molecular, and Systemic Physiology, Southern Illinois University School of Medicine, Carbondale, IL, USA
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