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Micioni Di Bonaventura E, Botticelli L, Del Bello F, Giorgioni G, Piergentili A, Quaglia W, Romano A, Gaetani S, Micioni Di Bonaventura MV, Cifani C. Investigating the role of the central melanocortin system in stress and stress-related disorders. Pharmacol Res 2022; 185:106521. [DOI: 10.1016/j.phrs.2022.106521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 10/13/2022] [Accepted: 10/18/2022] [Indexed: 11/30/2022]
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Todorovic A, Lensing CJ, Holder JR, Scott JW, Sorensen NB, Haskell-Luevano C. Discovery of Melanocortin Ligands via a Double Simultaneous Substitution Strategy Based on the Ac-His-dPhe-Arg-Trp-NH 2 Template. ACS Chem Neurosci 2018; 9:2753-2766. [PMID: 29783840 DOI: 10.1021/acschemneuro.8b00181] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The melanocortin system regulates an array of diverse physiological functions including pigmentation, feeding behavior, energy homeostasis, cardiovascular regulation, sexual function, and steroidogenesis. Endogenous melanocortin agonist ligands all possess the minimal messaging tetrapeptide sequence His-Phe-Arg-Trp. Based on this endogenous sequence, the Ac-His1-dPhe2-Arg3-Trp4-NH2 tetrapeptide has previously been shown to be a useful scaffold when utilizing traditional positional scanning approaches to modify activity at the various melanocortin receptors (MC1-5R). The study reported herein was undertaken to evaluate a double simultaneous substitution strategy as an approach to further diversify the Ac-His1-dPhe2-Arg3-Trp4-NH2 tetrapeptide with concurrent introduction of natural and unnatural amino acids at positions 1, 2, or 4, as well as an octanoyl residue at the N-terminus. The designed library includes the following combinations: (A) double simultaneous substitution at capping group position (Ac) together with position 1, 2, or 4, (B) double simultaneous substitution at positions 1 and 2, (C) double simultaneous substitution at positions 1 and 4, and (D) double simultaneous substitution at positions 2 and 4. Several lead ligands with unique pharmacologies were discovered in the current study including antagonists targeting the neuronal mMC3R with minimal agonist activity and ligands with selective profiles for the various melanocortin subtypes. The results suggest that the double simultaneous substitution strategy is a suitable approach in altering melanocortin receptor potency or selectivity or converting agonists into antagonists and vice versa.
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Affiliation(s)
- Aleksandar Todorovic
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
| | - Cody J. Lensing
- Department of Medicinal Chemistry and Institute for Translational Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Jerry Ryan Holder
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
| | - Joseph W. Scott
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
| | - Nicholas B. Sorensen
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
| | - Carrie Haskell-Luevano
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, Florida 32610, United States
- Department of Medicinal Chemistry and Institute for Translational Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, United States
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Serova LI, Laukova M, Alaluf LG, Sabban EL. Blockage of melanocortin-4 receptors by intranasal HS014 attenuates single prolonged stress-triggered changes in several brain regions. J Neurochem 2014; 131:825-35. [PMID: 25087915 DOI: 10.1111/jnc.12847] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 07/22/2014] [Accepted: 07/29/2014] [Indexed: 12/27/2022]
Abstract
Melanocortin receptor four (MC4R) is implicated in regulation of stress-related functions. We previously demonstrated that intranasal infusion of MC4R antagonist HS014, shortly before single prolonged stress (SPS) animal model of post-traumatic stress disorder, lessened the development of anxiety- and depression-like behavior depending on the dose. Here, we evaluated effects of HS014 on SPS-elicited changes in hypothalamic-pituitary-adrenal axis and expression of several genes of interest in mediobasal hypothalamus, hippocampus, and locus coeruleus. Rats were given intranasal infusion of HS014 (3.5 ng or 100 μg) and 30 min later subjected to SPS stressors. Short-term responses of HS014 rats in comparison with vehicle-treated, evident 30 min following SPS stressors, included smaller rise in plasma corticosterone (100 μg HS014), absence of induction of corticotrophin-releasing hormone mRNA in mediobasal hypothalamus and of mRNA for tyrosine hydroxylase and dopamine-β hydroxylase in locus coeruleus. Long-term responses found 7 days after SPS stressors, included lower induction corticotrophin-releasing hormone mRNA levels in the mediobasal hypothalamus without effect on mRNAs for the glucocorticoid receptor (GR) and FK506-binding protein 51 (FKBP5), a component of GR co-chaperone complex; and no induction of GR protein in ventral hippocampus. Thus, antagonism of MC4R prior to SPS attenuates development of several abnormalities in gene expression in regions implicated in post-traumatic stress disorder. Blockade of brain melanocortine receptor 4 (MC4R) with intranasal infusion of the MC4R antagonist HS014 to rats prior to single prolonged stress (SPS) leads to faster termination of stress responses (30 min later) and prevents or attenuates SPS-triggered abnormal gene expression related to post-traumatic stress disorder (7 days later). Targeting of brain MC4R is a promising strategy to protect HPA axis, LC-NE (locus coeruleus-norepinephrine) systems and hippocampus from overstimulation.
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Affiliation(s)
- Lidia I Serova
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York, USA
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De Jonghe BC, Hayes MR, Bence KK. Melanocortin control of energy balance: evidence from rodent models. Cell Mol Life Sci 2011; 68:2569-88. [PMID: 21553232 PMCID: PMC3135719 DOI: 10.1007/s00018-011-0707-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Revised: 04/19/2011] [Accepted: 04/20/2011] [Indexed: 01/18/2023]
Abstract
Regulation of energy balance is extremely complex, and involves multiple systems of hormones, neurotransmitters, receptors, and intracellular signals. As data have accumulated over the last two decades, the CNS melanocortin system is now identified as a prominent integrative network of energy balance controls in the mammalian brain. Here, we will review findings from rat and mouse models, which have provided an important framework in which to study melanocortin function. Perhaps most importantly, this review attempts for the first time to summarize recent advances in our understanding of the intracellular signaling pathways thought to mediate the action of melanocortin neurons and peptides in control of longterm energy balance. Special attention will be paid to the roles of MC4R/MC3R, as well as downstream neurotransmitters within forebrain and hindbrain structures that illustrate the distributed control of melanocortin signaling in energy balance. In addition, distinctions and controversy between rodent species will be discussed.
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Affiliation(s)
- Bart C. De Jonghe
- Dept. of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, 19104
| | - Matthew R. Hayes
- Dept. of Psychiatry, School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104
| | - Kendra K. Bence
- Dept. of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, 19104
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Molecular characterization of CART, AgRP, and MC4R genes and their expression with fasting and re-feeding in common carp (Cyprinus carpio). Mol Biol Rep 2011; 39:2215-23. [PMID: 21643748 DOI: 10.1007/s11033-011-0970-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2010] [Accepted: 05/26/2011] [Indexed: 02/01/2023]
Abstract
Cocaine and amphetamine-regulated transcript (CART), agouti-related proteins (AgRP) and Melanocortin 4 Receptor (MC4R) involves in the control of appetite. The genes were cloned and characterized, and their regulation was studied in common carp. The CARTI and CARTII genes encode 117- and 120-amino acids, respectively. The AgRP-1 and AgRP-2 genes encode 128- and 136-amino acids, respectively. CARTI was principally expressed in the brain, eye and ovary, while CARTII was highly expressed in the brain. AgRP-1 was strongly expressed in the brain, intestine, testis and eye, while AgRP-2 was highly expressed only in the gill and eye. The MC4R gene, encoding 326-amino acids, was mainly expressed in the brain testis, pituitary and eye. Phylogenetic analysis had been conducted which implied that both CARTI/CARTII and AgRP-1/AgRP-2 might derived from gene duplication events during genome evolution of common carp. CART, AgRP and MC4R gene expression in brain were decreased after fasting treatment and increased sharply after refeeding comparing with normal fed controls, which suggested that CART, AgRP and MC4R are involved in appetite regulation in common carp.
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Hruby VJ, Cai M, Nyberg J, Muthu D. Approaches to the rational design of selective melanocortin receptor antagonists. Expert Opin Drug Discov 2011; 6:543-57. [PMID: 22646078 DOI: 10.1517/17460441.2011.565743] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION When establishing the physiological roles of specific receptors in normal and disease states, it is critical to have selective antagonist ligands for each receptor in a receptor system with several subtypes. The melanocortin receptors have five subtypes referred to as the melanocortin 1 receptor, melanocortin 2 receptor, melanocortin 3 receptor, melanocortin 4 receptor and melanocortin 5 receptor, and they are of critical importance for many aspects of human health and disease. AREAS COVERED This article reviews the current efforts to design selective antagonistic ligands for the five human melanocortin receptors summarizing the currently published orthosteric and allosteric antagonists for each of these receptors. EXPERT OPINION Though there has been progress, there are still few drugs available that address the many significant biological activities and diseases that are associated with these receptors, which is possibly due to the lack of receptor selectivity that these designed ligands are currently showing. The authors believe that further studies into the antagonists' 3D conformational and topographical properties in addition to future mutagenesis studies will provide greater insight into these ligands which could play a role in the treatment of various diseases in the future.
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Affiliation(s)
- Victor J Hruby
- University of Arizona, Department of Chemistry and Biochemistry , 1306 E. University Blvd., Tucson, AZ 85721 , USA
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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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Steckler T. Developing small molecule nonpeptidergic drugs for the treatment of anxiety disorders: is the challenge still ahead? Curr Top Behav Neurosci 2010; 2:415-428. [PMID: 21309119 DOI: 10.1007/7854_2009_14] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Neuropeptide systems have been considered a major opportunity for the development of novel treatment approaches for anxiety disorders based on preclinical evidence and neurochemical alterations seen in anxiety disorders. This excitement was further facilitated by the fact that drugs acting at these systems, such as CRF1 antagonists, NK1 antagonists, NK3 antagonists or CCK2 antagonists, may have unique properties not seen with drugs affecting more classical mechanisms involved in anxiety. Consequently, there have been major efforts to develop such small-molecule, nonpeptide receptor ligands. A number of these molecules have been tested in the clinic, either in trials where levels of anxiety served as a secondary measure, or in a few studies with patients suffering from anxiety disorders. But unfortunately, and despite all the efforts of the field as a whole, we still lack convincing clinical proof-of-concept for any of the neuropeptidergic approaches in patients. It must, therefore, be concluded that neuropeptide targets remain a promising approach for the development of the next generation drugs to treat anxiety disorders, but that they continue to be high-risk targets for drug development.
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Affiliation(s)
- Thomas Steckler
- Johnson & Johnson PRD, Turnhoutseweg 30, 2340 Beerse, Belgium.
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Structure-Activity Relationships (SAR) of Melanocortin and Agouti-Related (AGRP) Peptides. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 681:1-18. [DOI: 10.1007/978-1-4419-6354-3_1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
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Dubynina EV, Inozemtseva LS, Markov DD, Yatsenko KA, Dolotov OV, Grivennikov IA. Alpha-melanocyte-stimulating hormone increases the expression of vascular endothelial growth factor in rat hippocampal astrocytes in vitro. NEUROCHEM J+ 2009. [DOI: 10.1134/s1819712409040059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Schjolden J, Schiöth HB, Larhammar D, Winberg S, Larson ET. Melanocortin peptides affect the motivation to feed in rainbow trout (Oncorhynchus mykiss). Gen Comp Endocrinol 2009; 160:134-8. [PMID: 19027741 DOI: 10.1016/j.ygcen.2008.11.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2008] [Revised: 10/16/2008] [Accepted: 11/01/2008] [Indexed: 11/29/2022]
Abstract
In this study, we investigated the effects of one melanocortin receptor (MCR) agonist and two antagonists on food intake in juvenile rainbow trout. Baseline food intake was established prior to 1 microl intracerebroventricular injection (ICV) of the non-specific agonist MTII, the MC4R antagonist HS024 and the MC3/4R antagonist SHU9119 at concentrations of 0.3, 1 or 3 nM. Saline-injected fish and untreated fish served as controls. Changes in food intake were observed 1h after the ICV injections. Our results showed that treatment with MTII significantly decreased food intake at 3 nM compared to control, HS024 significantly increased food intake at 3 nM compared to control and saline-treated fish, and SHU9119 significantly increased food intake at 3 nM compared to saline-treated fish. In conclusion, our study provides further evidence, and hence strengthens the hypothesis, that MC4R participates in the control of energy balance in fish in the same manner as in mammals. Our findings that HS024 is more potent than SHU9119 in increasing food intake suggest that the effects of melanocortin on energy balance in rainbow trout are mainly regulated by activation of MC4R. Hence, HS024 seems an excellent tool as a MC4R antagonist in rainbow trout.
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Affiliation(s)
- Joachim Schjolden
- Department of Basic Sciences and Aquatic Medicine, Norwegian School of Veterinary Science, P.O. Box 8146 Dep, Ullevålsveien 72, N-0033 Oslo, Norway.
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Casper RC, Sullivan EL, Tecott L. Relevance of animal models to human eating disorders and obesity. Psychopharmacology (Berl) 2008; 199:313-29. [PMID: 18317734 DOI: 10.1007/s00213-008-1102-2] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Accepted: 02/07/2008] [Indexed: 12/19/2022]
Abstract
BACKGROUND AND RATIONALE This review addresses the role animal models play in contributing to our knowledge about the eating disorders anorexia nervosa (AN) and bulimia nervosa (BN) and obesity. OBJECTIVES Explore the usefulness of animal models in complex biobehavioral familial conditions, such as AN, BN, and obesity, that involve interactions among genetic, physiologic, psychological, and cultural factors. RESULTS AND CONCLUSIONS The most promising animal model to mimic AN is the activity-based anorexia rodent model leading to pathological weight loss. The paradigm incorporates reward elements of the drive for activity in the presence of an appetite and allows the use of genetically modified animals. For BN, the sham-feeding preparation in rodents equipped with a gastric fistula appears to be best suited to reproduce the postprandial emesis and the defects in satiety. Animal models that incorporate genes linked to behavior and mood may clarify biobehavioral processes underlying AN and BN. By contrast, a relative abundance of animal models has contributed to our understanding of human obesity. Both environmental and genetic determinants of obesity have been modeled in rodents. Here, we consider single gene mutant obesity models, along with models of obesigenic environmental conditions. The contributions of animal models to obesity research are illustrated by their utility for identifying genes linked to human obesity, for elucidating the pathways that regulate body weight and for the identification of potential therapeutic targets. The utility of these models may be further improved by exploring the impact of experimental manipulations on the behavioral determinants of energy balance.
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Affiliation(s)
- Regina C Casper
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 401 Quarry Road, Stanford, CA 94305-5723, USA.
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Feeding induced by cannabinoids is mediated independently of the melanocortin system. PLoS One 2008; 3:e2202. [PMID: 18493584 PMCID: PMC2386290 DOI: 10.1371/journal.pone.0002202] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2007] [Accepted: 04/08/2008] [Indexed: 12/15/2022] Open
Abstract
Background Cannabinoids, the active components of marijuana, stimulate appetite, and cannabinoid receptor-1 (CB1-R) antagonists suppress appetite and promote weight loss. Little is known about how CB1-R antagonists affect the central neurocircuitry, specifically the melanocortin system that regulates energy balance. Methodology/Principal Findings Here, we show that peripherally administered CB1-R antagonist (AM251) or agonist equally suppressed or stimulated feeding respectively in Ay , which lack a functional melanocortin system, and wildtype mice, demonstrating that cannabinoid effects on feeding do not require melanocortin circuitry. CB1-R antagonist or agonist administered into the ventral tegmental area (VTA) equally suppressed or stimulated feeding respectively, in both genotypes. In addition, peripheral and central cannabinoid administration similarly induced c-Fos activation in brain sites suggesting mediation via motivational dopaminergic circuitry. Amperometry-detected increases in evoked dopamine (DA) release by the CB1-R antagonist in nucleus accumbens slices indicates that AM251 modulates DA release from VTA terminals. Conclusions/Significance Our results demonstrate that the effects of cannabinoids on energy balance are independent of hypothalamic melanocortin circuitry and is primarily driven by the reward system.
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Pickering C, Avesson L, Liljequist S, Lindblom J, Schiöth HB. The role of hypothalamic peptide gene expression in alcohol self-administration behavior. Peptides 2007; 28:2361-71. [PMID: 17976860 DOI: 10.1016/j.peptides.2007.09.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2007] [Revised: 09/18/2007] [Accepted: 09/19/2007] [Indexed: 11/19/2022]
Abstract
Self-administration of ethanol and food share many common features and Richter hypothesized that an increase in ethanol consumption would decrease feeding to balance the excess calories contained in the ethanol. Previously, we have shown that individual alcohol consumption correlates with neurotransmitter gene expression, especially in the prefrontal cortex. To test the hypothesis of Richter, we measured hypothalamic gene expression of receptors or neuropeptides of known relevance for the regulation of food intake using qPCR and correlated this to individual ethanol consumption in Wistar rats. For validation, gene expression was first correlated with body weight. We found a correlation of dynorphin, somatostatin, melanocortin-4 receptor and serotonin 5-HT(2C) with body weight and trends to correlation for CART, thus confirming the established role of the hypothalamus in the regulation of weight. For ethanol consumption, correlations were found for CRH receptors 1 and 2 and vasopressin while strong trends were observed for galanin receptor 1, orexin receptor 1, MCH and adrenoceptor alpha(1B). Therefore, alcohol consumption does seem to involve several hypothalamic systems which also mediate feeding responses and suggests that the hypothalamus, together with the prefrontal cortex, may determine the 'stopping point' of an individual.
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Affiliation(s)
- Chris Pickering
- Uppsala University, Department of Neuroscience, Division of Pharmacology, BMC, Box 593, SE-75124 Uppsala, Sweden.
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Nozawa D, Okubo T, Chaki S, Okuyama S, Nakazato A. Identification of arginine analogues as antagonists and agonists for the melanocortin-4 receptor. Chem Pharm Bull (Tokyo) 2007; 55:1232-9. [PMID: 17666851 DOI: 10.1248/cpb.55.1232] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the present study, conducted to explore potent and small molecular melanocortin-4 (MC4) receptor ligands, we found that tripeptide 3a, containing a D-Phe-Arg-2-Nal (Nal; naphthylalanine) sequence, exhibited a moderate affinity for the MC4 receptor. Structural optimization led to the identification of a compound with a high affinity for the MC4 receptor, namely, tripeptide 3e, which showed a 70-fold higher affinity for the MC4 receptor than the lead compound 3a. Moreover, in an effort to further reduce the peptidic characters of tripeptide 3e, we found that dipeptide 3g exhibited a relatively high affinity for the MC4 receptor. Furthermore, in these analogues, the substituted position (1' vs. 2') of the naphthyl ring of Nal residue at position 7 was found to be important for the differentiation of agonist and antagonist activity. The synthesis and structure-activity relationships of the arginine analogues as MC4 receptor ligands were described in this paper.
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Affiliation(s)
- Dai Nozawa
- Medicinal Research Laboratories, Taisho Pharmaceutical Co., Ltd., Saitama, Japan.
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Abstract
PURPOSE OF REVIEW Health problems related to weight regulation are increasingly common in the USA and around the world. Although obesity and associated complications garner the most attention in the media, clinical problems at the opposite end of the spectrum, such as involuntary disease-associated weight loss or cachexia, are equally devastating. This review focuses on the role of the central melanocortin system in body weight regulation, and specifically on the anticatabolic properties of antagonists of the melanocortin-4 receptor. RECENT FINDINGS Over the past several years, the central melanocortin system has emerged as a major contributor to the body weight regulatory system in both animals and humans. In particular, the melanocortin-4 receptor, its endogenous agonist alpha-melanocyte stimulating hormone, and its endogenous antagonist agouti-related protein have been shown to be vital to the maintenance of normal body weight in both genetic and physiologic experiments. This system is now the target of multiple drug discovery endeavors, as the search continues for effective treatments for both obesity and cachexia. Several investigators have recently shown that selective synthetic antagonists of the melanocortin-4 receptor can prevent or attenuate the development of cachexia in animal models of acute and chronic disease. SUMMARY An understanding of the biology of weight regulation, including both appetite regulation and energy metabolism, is vital if we are to unravel the etiology of and develop effective treatment for obesity and cachexia. The data reviewed here supporting a role for melanocortin-4 receptor antagonists in the treatment of catabolism represent an important advance in this field.
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Affiliation(s)
- Lisa D Madison
- Department of Pediatrics, Oregon Health & Science University, Portland, Oregon 97239, USA
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Jobst EE, Enriori PJ, Sinnayah P, Cowley MA. Hypothalamic regulatory pathways and potential obesity treatment targets. Endocrine 2006; 29:33-48. [PMID: 16622291 DOI: 10.1385/endo:29:1:33] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2005] [Revised: 11/30/1999] [Accepted: 11/08/2005] [Indexed: 12/25/2022]
Abstract
With an ever-growing population of obese people as well as comorbidities associated with obesity, finding effective weight loss strategies is more imperative than ever. One of the challenges in curbing the obesity crisis is designing successful strategies for long-term weight loss and weight-loss maintenance. Currently, weight-loss strategies include promotion of therapeutic lifestyle changes (diet and exercise), pharmacological therapy, and bariatric surgery. This review focuses on several pharmacological targets that activate central nervous system pathways that normally limit food intake and body weight. Though it is likely that no single therapy will prove effective for everyone, this review considers several recent pre-clinical targets, and several compounds that have been in human clinical trials.
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Affiliation(s)
- Erin E Jobst
- Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA.
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Cabeza de Vaca S, Hao J, Afroz T, Krahne LL, Carr KD. Feeding, body weight, and sensitivity to non-ingestive reward stimuli during and after 12-day continuous central infusions of melanocortin receptor ligands. Peptides 2005; 26:2314-21. [PMID: 15894406 DOI: 10.1016/j.peptides.2005.03.041] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2004] [Revised: 03/21/2005] [Accepted: 03/22/2005] [Indexed: 10/25/2022]
Abstract
The brain melanocortin system mediates downstream effects of hypothalamic leptin and insulin signaling. Yet, there have been few studies of chronic intracerebroventricular (i.c.v.) melanocortin receptor (MCR) agonist or antagonist infusion. Although there is evidence of interaction between melanocortin and dopamine (DA) systems, effects of chronic MCR ligand infusion on behavioral sensitivity to non-ingestive reward stimuli have not been investigated. The objective of this study was to investigate effects of chronic i.c.v. infusion of the MCR agonist, MTII, and the MCR antagonist, SHU9119, on food intake, body weight, and sensitivity to rewarding lateral hypothalamic electrical stimulation (LHSS) and the reward-potentiating (i.e., threshold-lowering) effect of D-amphetamine. The MCR antagonist, SHU9119 (0.02 microg/h) produced sustained hyperphagia and weight gain during the 12-day infusion period, followed by compensatory hypophagia and an arrest of body weight gain during the 24-day post-infusion period. At no point during the experiment was sensitivity to LHSS or D-amphetamine (0.25mg/kg, i.p.) altered. The MCR agonist, MTII (0.02 microg/h) produced a brief hypophagia (3 days) followed by a return to control levels of daily intake, but with body weight remaining at a reduced level throughout the 12-day infusion period. This was followed by compensatory hyperphagia and weight gain during the 24-day post-infusion period. There was no change in sensitivity to non-ingestive reward stimuli during the infusion of MTII. However, sensitivity to D-amphetamine was increased during the 24-day post-infusion period. It therefore seems that changes in ingestive behavior that occur during chronic MCR ligand infusion may not affect the response to non-ingestive reward stimuli. However, it is possible that the drive to re-feed and restore body weight following MCR agonist treatment includes neuroadaptations that enhance the incentive effects of drug stimuli.
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Affiliation(s)
- S Cabeza de Vaca
- Department of Psychiatry, New York University School of Medicine, Millhauser Laboratories, 550 First Avenue, New York, NY 10016, USA.
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Bonetto S, Carlavan I, Baty D. Isolation and characterization of antagonist and agonist peptides to the human melanocortin 1 receptor. Peptides 2005; 26:2302-13. [PMID: 15893405 DOI: 10.1016/j.peptides.2005.04.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2005] [Revised: 04/11/2005] [Accepted: 04/12/2005] [Indexed: 10/25/2022]
Abstract
We identified a large number of peptide mimotopes of the adrenocorticotropic hormone (ACTH) and the alpha-melanocyte stimulating hormone (alpha-MSH) to analyze better the structure-function relationships of these hormones with the human MC1 receptor (hMC1R). We have investigated the use of phage-display technology to isolate specific peptides of this receptor by using three monoclonal anti-ACTH antibodies (mAbs). A library of 10(8) phage-peptides displaying randomized decapeptides was constructed and used to select phage-peptides that bind to mAbs. Forty-five phage-peptides have been isolated and from their amino acid sequences, we have identified two consensus sequences, EXFRWGKPA and WGXPVGKP, corresponding to the regions 5-13 and 9-16 of ACTH, respectively. A biological assay on cells expressing the hMC1-R was developed to determine the capacity of phage-peptides to stimulate the receptor. Only two phage-peptides showed detectable activity. Thirty-one peptides were synthesized to analyze their biological effect. We identified two weak agonists, EC50=16 and 11 microM, two strong agonists, EC50=25 and 14 nM and a partial antagonist, IC50=36 microM. This work confirmed the modulator agonist role of the regions 11-12 of alpha-MSH and ACTH, and the importance of the methionine residue at position 4 for the stimulation of the hMC1-R. We also identified analogues of the regions 8-17 of ACTH that exhibited a weak activator effect, and of one analogue of the N-terminal regions 1-9 of ACTH and alpha-MSH having a partial antagonist effect. These results may be useful in the development of potential agonists or antagonists of the hMC1R.
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Affiliation(s)
- Stéphane Bonetto
- Institut de Biologie Structurale et Microbiologie, Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UPR9027, CNRS, 31 chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
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20
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Irani BG, Haskell-Luevano C. Feeding effects of melanocortin ligands--a historical perspective. Peptides 2005; 26:1788-99. [PMID: 16046247 DOI: 10.1016/j.peptides.2004.11.038] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2004] [Accepted: 11/18/2004] [Indexed: 11/25/2022]
Abstract
The process of energy homeostasis is a highly regulated process involving interacting signals between a variety of anorexigenic and orexigenic peptides, proteins and signaling molecules. The melanocortin system is an important component of this complex regulatory network. Involvement of the melanocortin pathway in the control of food intake and body weight regulation has been studied extensively in the past two decades. Previous studies that involve central administration of melanocortin molecules and examination of molecules that effect food intake in melanocortin knockout (KO) mice (MC3R, MC4R, POMC, AGRP and NPY) have been examined. In this review, we have summarized feeding studies that have resulted in the recognition of the melanocortin system as a major contributor to the complex neuroendocrine system regulating energy homeostasis.
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Affiliation(s)
- Boman G Irani
- Department of Medicinal Chemistry, University of Florida, P.O. Box 100485, Gainesville, FL-32610, USA
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21
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Ye Z, MacNeil T, Weinberg DH, Kalyani RN, Tang R, Strack AM, Murphy BA, Mosley RT, Euan MacIntyre D, Van der Ploeg LHT, Patchett AA, Wyvratt MJ, Nargund RP. Structure-activity relationship of linear tetrapeptides Tic-DPhe-Arg-Trp-NH2 at the human melanocortin-4 receptor and effects on feeding behaviors in rat. Peptides 2005; 26:2017-25. [PMID: 15993513 DOI: 10.1016/j.peptides.2004.12.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2004] [Accepted: 12/09/2004] [Indexed: 11/26/2022]
Abstract
The melanocortin subtype-4 receptor (MC4R) has been implicated in the control of feeding behavior and body weight regulation. A series of tetrapeptides, based on Tic-DPhe-Arg-Trp-NH2-a mimic of the putative message sequence "His-Phe-Arg-Trp" and modified at the DPhe position, were prepared and pharmacologically characterized for potency and selectivity. Substitution of His with Tic gave peptides with significant increases in selectivity. The effects of the substitution pattern of DPhe were investigated and it has significant influences on potency and the level of the maximum cAMP accumulation. Intracerebroventricular administration of peptide 10 induced significant inhibition of cumulative overnight food intake and feeding duration in rats.
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Affiliation(s)
- Zhixiong Ye
- Department of Medicinal Chemistry, Merck Research Laboratories, Rahway, NJ 07065-0900, USA.
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22
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Daniel PB, Fernando C, Wu CSJ, Marnane R, Broadhurst R, Mountjoy KG. 1 kb of 5' flanking sequence from mouse MC4R gene is sufficient for tissue specific expression in a transgenic mouse. Mol Cell Endocrinol 2005; 239:63-71. [PMID: 15950372 DOI: 10.1016/j.mce.2005.03.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2004] [Revised: 03/10/2005] [Accepted: 03/16/2005] [Indexed: 10/25/2022]
Abstract
The melanocortin 4 receptor (MC4R) plays a critical role in the regulation of energy homeostasis, and the MC4R knockout mouse and humans with MC4R defective mutations in only one allele indicate that there is a gene dosage effect. Alterations in gene expression levels for MC4R could, therefore, have significant effects on energy homeostasis. To begin to develop a mouse model for studies on MC4R promoter in situ we used approximately 1 kb mouse MC4R promoter together with 426 bp MC4R 5' UTR, previously shown to support basal expression of reporter gene transcription in cell lines with endogenous MC4R mRNA, and fused this DNA to a nuclear localized LacZ reporter gene. The construct was injected into pronuclei from FVB mice. Five transgenic lines were identified as carrying autosomal transgene insertions; three of these had significant beta-galactosidase staining in brain and in a few cells in the heart but not in kidney, liver, lung, gonadal fat or testis. The pattern of transgene expression in the brain differed markedly for the three lines, and in one of these lines was remarkably similar to endogenous MC4R mRNA expression observed using in situ hybridisation. In conclusion, approximately 1 kb mouse MC4R promoter is sufficient to direct gene expression to the brain including regions that express endogenous MC4R mRNA.
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Affiliation(s)
- Philip B Daniel
- Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1, New Zealand
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23
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Andersson PM, Boman A, Seifert E, Skottner A, Lundstedt T. Ligands to the melanocortin receptors. Expert Opin Ther Pat 2005. [DOI: 10.1517/13543776.11.10.1583] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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24
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Ling MK, Hotta E, Kilianova Z, Haitina T, Ringholm A, Johansson L, Gallo-Payet N, Takeuchi S, Schiöth HB. The melanocortin receptor subtypes in chicken have high preference to ACTH-derived peptides. Br J Pharmacol 2004; 143:626-37. [PMID: 15466451 PMCID: PMC1575423 DOI: 10.1038/sj.bjp.0705900] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1 Melanocortin (MC) receptors are widely distributed throughout the body of chicken, like in mammals, and participate in a wide range of physiological functions. 2 To clarify the pharmacological impact of ligands acting in the MC system, we expressed the chicken MC1, MC2, MC3, MC4 and MC5 (cMC1-5) receptors in eukaryotic cells and performed comprehensive pharmacological characterization of the potency of endogenous and synthetic melanocortin peptides. 3 Remarkably, the cMC receptors displayed high affinity for ACTH-derived peptides and in general low affinity for alpha-MSH. It is evident that not only the cMC2 receptor but also the other cMC receptors interact with ACTH-derived peptide through an epitope beyond the sequence of alpha-MSH. 4 The synthetic ligand MTII was found to be a potent agonist whereas HS024 was a potent antagonist at the cMC4 receptor, indicating that these ligands are suitable for physiological studies in chicken. 5 We also show the presence of prohormone convertase 1 (PC1) and PC2 genes in chicken, and that these peptides are coexpressed with proopiomelanocortin (POMC) in various tissues.
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Affiliation(s)
- Maria K Ling
- Department of Neuroscience, Uppsala University, BMC, Box 593, 751 24 Uppsala, Sweden
| | - Eri Hotta
- Department of Biology, Faculty of Science, Okayama University, Okayama, Japan
| | - Zuzana Kilianova
- Service of Endocrinology, Department of Medicine, University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Tatjana Haitina
- Department of Neuroscience, Uppsala University, BMC, Box 593, 751 24 Uppsala, Sweden
| | - Aneta Ringholm
- Department of Neuroscience, Uppsala University, BMC, Box 593, 751 24 Uppsala, Sweden
| | - Lisa Johansson
- Department of Neuroscience, Uppsala University, BMC, Box 593, 751 24 Uppsala, Sweden
| | - Nicole Gallo-Payet
- Service of Endocrinology, Department of Medicine, University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Sakae Takeuchi
- Department of Biology, Faculty of Science, Okayama University, Okayama, Japan
| | - Helgi B Schiöth
- Department of Neuroscience, Uppsala University, BMC, Box 593, 751 24 Uppsala, Sweden
- Author for correspondence:
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25
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Holder JR, Haskell-Luevano C. Melanocortin ligands: 30 years of structure-activity relationship (SAR) studies. Med Res Rev 2004; 24:325-56. [PMID: 14994367 DOI: 10.1002/med.10064] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The challenge of peptide and peptidomimetic research is the development of methods and techniques to improve the biological properties of native peptides and to convert peptide ligands into non-peptide compounds. Improved biological properties of peptides includes enhancement of stability, potency, and receptor selectivity, for both in vivo and in vitro applications. The design of a ligand with specific activity and desired biological properties is a complex task, and, to accomplish this objective, knowledge about putative interactions between a ligand and the corresponding receptor will be valuable. This includes interactions for both the binding and signal transduction processes. Structure-activity relationship (SAR) studies involve systematic modification of a lead peptide and are designed to provide insight into potential interactions involved in the formation of the ligand-receptor complex. It is desirable to have knowledge about both favorable and unfavorable processes that may occur in putative ligand-receptor interactions that result in either receptor stimulation or inhibition. Herein, we discuss various SAR studies that have involved melanocortin peptides over three decades and the information these studies have provided to the melanocortin field.
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Affiliation(s)
- Jerry Ryan Holder
- Department of Medicinal Chemistry, University of Florida, Gainesville, Florida 32610, USA
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26
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Skuladottir GV, Olason PI, Jonsson L, Skarphedinsson JO, Eriksdottir VH, Atlason PT, Franzson L, Schiöth HB. Hyperphagia modifies FA profiles of plasma phospholipids, plasma FFA, and adipose tissue TAG. Lipids 2004; 38:1127-32. [PMID: 14733357 DOI: 10.1007/s11745-003-1170-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Hyperphagia was achieved by continuous intracerebroventricular infusion of a melanocortin receptor antagonist (HS024; Neosystem, Strasbourg, France) in rats. The effects of hyperphagia on FA composition and concentration of plasma phospholipids (PL), plasma FFA, and adipose tissue TAG were studied in rats for 8 d [short-term hyperphagia (STH); n = 8], or 28 d [long-term hyperphagia (LTH); n = 9]. The control rats were treated with artificial cerebrospinal fluid for 8 d (n = 8) or 28 d (n = 10). The rats were fed the same regular diet. In STH rats the plasma PL and fasting plasma FFA contained higher concentrations of saturated FA (SFA) and monounsaturated FA (MUFA), and plasma FFA contained lower n-6 PUFA than in the control rats. In LTH rats the plasma PL contained higher concentrations of SFA, MUFA, and n-3 PUFA and higher proportions of 16:1n-7 and 18:1n-9 at the expense of 18:2n-6 than in the control rats. In LTH rats the abundant dietary intake of 18:2n-6 did not enrich 18:2n-6 of the plasma PL or adipose tissue TAG. In LTH rats the fasting plasma FFA contained more than twofold higher concentrations of SFA and MUFA, and higher proportions of 16:1n-7 and 18:1n-9 at the expense of 18:2n-6 than in the control rats. This animal obesity model shows that LTH affects the FA composition and concentration of plasma PL, plasma FFA, and adipose tissue TAG, a result consistent with changes associated with increased risk of various diseases in humans. These results also demonstrate that LTH alters the FA composition of plasma PL and adipose tissue TAG in a way that does not reflect the FA composition of dietary fat.
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27
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Chaki S, Ogawa SI, Toda Y, Funakoshi T, Okuyama S. Involvement of the melanocortin MC4 receptor in stress-related behavior in rodents. Eur J Pharmacol 2003; 474:95-101. [PMID: 12909200 DOI: 10.1016/s0014-2999(03)02033-8] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The melanocortin subtype 4 (MC4) receptor has been postulated to be involved in stress and stress-related behavior. We made use of melanocortin MC4 receptor agonists and antagonist to investigate the relationship between the melanocortin MC4 receptor and stress related disorders. The nonspecific melanocortin receptor agonist alpha-melanocyte stimulating hormone (alpha-MSH) and the melanocortin MC4 receptor agonist, Ac-[Nle4,Asp5,D-Phe7,Lys10]alpha-MSH-(4-10)-NH2 (MT II) dose-dependently and significantly reduced the number of licking periods in the rat Vogel conflict test, suggesting that stimulation of the melanocortin MC4 receptor causes anxiogenic-like activity in rats. We synthesized a peptidemimetic melanocortin MC4 receptor selective antagonist, Ac-D-2Nal-Arg-2Nal-NH2 (MCL0020), which has high affinity for the melanocortin MC4 receptor with IC50 values of 11.63 +/- 1.48 nM, in contrast, the affinities for melanocortin MC1 and MC3 receptors were negligible. In addition, MCL0020 significantly attenuated the cAMP formation induced by alpha-MSH in COS-1 cells expressing the melanocortin MC4 receptor without affecting basal cAMP contents. Thus, we considered MCL0020 to be a selective melanocrotin MC4 receptor antagonist among melanocortin receptors. Restraint stress significantly reduced food intake in rats, and i.c.v. administration of MCL0020 dose-dependently and significantly attenuated restraint stress-induced anorexia without affecting food intake. Swim stress induced reduction in the time spent in the light area in the mouse light/dark exploration test, and MCL0020 significantly prevented it. Taken together our findings suggest that the melanocortin MC4 receptor might be related to stress-induced changes in behavior, and blockade of the melanocortin MC4 receptor may prevent stress-induced disorders such as anxiety.
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MESH Headings
- Animals
- Behavior, Animal/drug effects
- Binding, Competitive
- COS Cells
- Chlorocebus aethiops
- Cyclic AMP/metabolism
- Dose-Response Relationship, Drug
- Exploratory Behavior/drug effects
- Feeding Behavior/drug effects
- Grooming/drug effects
- Humans
- Male
- Mice
- Mice, Inbred ICR
- Oligopeptides/pharmacology
- Rats
- Rats, Sprague-Dawley
- Rats, Wistar
- Receptor, Melanocortin, Type 1/agonists
- Receptor, Melanocortin, Type 1/antagonists & inhibitors
- Receptor, Melanocortin, Type 1/metabolism
- Receptor, Melanocortin, Type 3/agonists
- Receptor, Melanocortin, Type 3/antagonists & inhibitors
- Receptor, Melanocortin, Type 3/metabolism
- Receptor, Melanocortin, Type 4/agonists
- Receptor, Melanocortin, Type 4/antagonists & inhibitors
- Receptor, Melanocortin, Type 4/metabolism
- Restraint, Physical
- Stress, Physiological/metabolism
- Stress, Physiological/physiopathology
- Swimming
- Transfection
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Affiliation(s)
- Shigeyuki Chaki
- Psychiatric Diseases and Pain Research, Medicinal Pharmacology Laboratory, Medicinal Research Laboratories, Taisho Pharmaceutical Co., Ltd., 1-403 Yoshino-cho, Kita-ku, Saitama, Saitama 331-9530, Japan.
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28
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Foster AC, Joppa M, Markison S, Gogas KR, Fleck BA, Murphy BJ, Wolff M, Cismowski MJ, Ling N, Goodfellow VS, Chen C, Saunders J, Conlon PJ. Body weight regulation by selective MC4 receptor agonists and antagonists. Ann N Y Acad Sci 2003; 994:103-10. [PMID: 12851304 DOI: 10.1111/j.1749-6632.2003.tb03168.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
There has been great interest in melanocortin (MC) receptors as targets for the design of novel therapeutics to treat disorders of body weight, such as obesity and cachexia. Both genetic and pharmacological evidence points toward central MC4 receptors as the principal target. Using highly selective peptide tools for the MC4 receptor, which have become available recently, we have provided pharmacological confirmation that central MC4 receptors are the prime mediators of the anorexic and orexigenic effects reported for melanocortin agonists and antagonists, respectively. The current progress with receptor-selective small molecule agonist and antagonist drugs should enable the therapeutic potential of MC4 receptor activation and inhibition to be assessed in the clinic in the near future.
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Affiliation(s)
- Alam C Foster
- Neurocrine Biosciences Inc, San Diego, California 92121, USA.
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29
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Schiöth HB, Lagerström MC, Watanobe H, Jonsson L, Vergoni AV, Ringholm A, Skarphedinsson JO, Skuladottir GV, Klovins J, Fredriksson R. Functional role, structure, and evolution of the melanocortin-4 receptor. Ann N Y Acad Sci 2003; 994:74-83. [PMID: 12851300 DOI: 10.1111/j.1749-6632.2003.tb03164.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The melanocortin (MC)-4 receptor participates in regulating body weight homeostasis. We demonstrated early that acute blockage of the MC-4 receptor increases food intake and relieves anorexic conditions in rats. Our recent studies show that 4-week chronic blockage of the MC-4 receptor leads to robust increases in food intake and development of obesity, whereas stimulation of the receptor leads to anorexia. Interestingly, the food conversion ratio was clearly increased by MC-4 receptor blockage, whereas it was decreased in agonist-treated rats in a transient manner. Chronic infusion of an agonist caused a transient increase in oxygen consumption. Our studies also show that the MC-4 receptor plays a role in luteinizing hormone and prolactin surges in female rats. The MC-4 receptor has a role in mediating the effects of leptin on these surges. The phylogenetic relation of the MC-4 receptor to other GPCRs in the human genome was determined. The three-dimensional structure of the protein was studied by construction of a high-affinity zinc binding site between the helices, using two histidine residues facing each other. We also cloned the MC-4 receptor from evolutionary important species and showed by chromosomal mapping a conserved synteny between humans and zebrafish. The MC-4 receptor has been remarkably conserved in structure and pharmacology for more than 400 million years, implying that the receptor participated in vital physiological functions early in vertebrate evolution.
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Affiliation(s)
- Helgi B Schiöth
- Department of Neuroscience, Uppsala University, BMC, 751 24, Uppsala, Sweden.
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30
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Small CJ, Liu YL, Stanley SA, Connoley IP, Kennedy A, Stock MJ, Bloom SR. Chronic CNS administration of Agouti-related protein (Agrp) reduces energy expenditure. Int J Obes (Lond) 2003; 27:530-3. [PMID: 12664087 DOI: 10.1038/sj.ijo.0802253] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE To investigate whether the Agouti-related protein (Agrp), the melanocortin receptor antagonist, alters oxygen consumption, as a measure of energy expenditure. DESIGN A 7-day intracerebroventricular administration of Agrp (1 nmol/day) in rats. MEASUREMENTS Oxygen consumption was determined in closed-circuit respirometers on days 1 and 8. BRL-35135, a beta3-adrenoreceptor agonist known to activate the brown adipose tissue (BAT) thermogenesis directly and increase core temperature, was administered i.p. (40 microg/kg) on day 9 to challenge functionally the BAT. RESULTS Agrp treatment caused a 54% increase in daily food intake and a 12% increase in body weight. An 8% decrease in VO(2) measurements was observed following ICV Agrp treatment on day 1. A similar decrease (7%) was observed on day 8. BRL-35135 stimulated colonic temperature in control rats. However, in the rats that had previously been treated with Agrp this effect was significantly blunted. CONCLUSION Chronic CNS administration of Agrp decreases oxygen consumption and decreases the capacity of BAT to expend energy. The obesity observed following CNS administration of Agrp is the result of decreased energy expenditure and increased food intake.
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Affiliation(s)
- C J Small
- Department of Metabolic Medicine, Division of Investigative Science, Imperial College School of Medicine, Hammersmith Hospital, London, UK
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31
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Danho W, Swistok J, Cheung AWH, Kurylko G, Franco L, Chu XJ, Chen L, Yagaloff K. Structure-activity relationship of linear peptide Bu-His6-DPhe7-Arg8-Trp9-Gly10-NH2 at the human melanocortin-1 and -4 receptors: DPhe7 and Trp9 substitution. Bioorg Med Chem Lett 2003; 13:649-52. [PMID: 12639550 DOI: 10.1016/s0960-894x(02)01052-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of pentapeptides, based on hMC4R pentapeptide agonist (Bu-His(6)-DPhe(7)-Arg(8)-Trp(9)-Gly(10)-NH(2)), was prepared in which either DPhe(7) or Trp(9) residue was systematically substituted. A number of interesting DPhe surrogates (D-Thi, D-3-CF(3)Phe, D-2-Nal and D-3,4-diClPhe) as well as Trp surrogates (2-Nal and Bta) were identified in this study.
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Affiliation(s)
- Waleed Danho
- Roche Research Center, Hoffmann-La Roche Inc., Nutley, NJ 07110, USA.
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32
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Schiöth HB, Kask A, Mutulis F, Muceniece R, Mutule I, Mutule I, Mandrika I, Wikberg JES. Novel selective melanocortin 4 receptor antagonist induces food intake after peripheral administration. Biochem Biophys Res Commun 2003; 301:399-405. [PMID: 12565874 DOI: 10.1016/s0006-291x(02)03065-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We synthesized a new series of small cyclic melanocyte-stimulating hormone (MSH) analogues and screened them for binding affinity at the four MSH binding melanocortin (MC) receptors. We identified a novel substance HS131, with about 20-fold higher affinity for the MC4 receptor than the MC3 receptor. This substance proved to be antagonist for all the four MC receptors in a cAMP assay. HS131 is a six amino acid long peptide, has a molecular weight below 1000, and has only two amino acids in common with the natural MSH peptides. HS131 potently and dose dependently increased food intake after i.c.v. administration. Moreover, s.c. administration of HS131 (1.0 mg/kg) increased food intake, suggesting that HS131 may be able to pass the blood brain barrier. This cyclic low molecular weight peptidomimetic will enable studies of the functional role of the MC4 receptors by peripheral administration and it may be used as a template for further development of low molecular weight substances for the MC receptors.
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Affiliation(s)
- Helgi B Schiöth
- Department of Neuroscience, Uppsala University, BMC, Box 593, 751 24 Uppsala, Sweden.
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33
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Nijenhuis WAJ, Kruijtzer JAW, Wanders N, Vrinten DH, Garner KM, Schaaper WMM, Meloen RH, Gispen WH, Liskamp RM, Adan RAH. Discovery and in vivo evaluation of new melanocortin-4 receptor-selective peptides. Peptides 2003; 24:271-80. [PMID: 12668212 DOI: 10.1016/s0196-9781(03)00032-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The melanocortin-4 receptor (MC4R) is involved in several physiological processes, including body weight regulation and grooming behaviour in rats. It has also been suggested that the MC4R mediates the effects of melanocortin ligands on neuropathic pain. Selective compounds are needed to study the exact role of the MC4R in these different processes. We describe here the development and evaluation of new melanocortin compounds that are selective for the MC4R as compared with the other centrally expressed receptors, MC3R and MC5R. First, a library of 18 peptides, in which a melanocortin-based sequence was systematically point-mutated, was screened for binding to and activity on the MC3R, MC4R and MC5R. Compound Ac-Nle-Gly-Lys-D-Phe-Arg-Trp-Gly-NH(2) (JK1) appeared to be the most selective MC4R compound, based on affinity. This compound is 90- and 110-fold selective for the MC4R as compared to the MC3R and MC5R, respectively. Subsequent modification of JK1 yielded compound Ac-Nle-Gly-Lys-D-Nal(2)-Arg-Trp-Gly-NH(2) (JK7)(,) a selective MC4R antagonist with 34-fold MC4R/MC3R and 109-fold MC4R/MC5R selectivity. The compounds were active in vivo as determined in a grooming assay and a model for neuropathic pain in rats. Intravenous (i.v.) injections suggested that they were able to pass the blood-brain barrier.The compounds identified here will be useful in further research on the physiological roles of the MC4R.
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MESH Headings
- Amino Acid Substitution
- Animals
- Behavior, Animal/drug effects
- Binding Sites
- Binding, Competitive
- Cell Line
- Cell Line, Tumor
- Cold Temperature
- Dose-Response Relationship, Drug
- Grooming/drug effects
- Humans
- Inhibitory Concentration 50
- Male
- Oligopeptides/chemical synthesis
- Oligopeptides/metabolism
- Oligopeptides/pharmacology
- Pain Measurement/drug effects
- Rats
- Rats, Wistar
- Receptor, Melanocortin, Type 4/antagonists & inhibitors
- Receptor, Melanocortin, Type 4/metabolism
- Receptors, Melanocortin/antagonists & inhibitors
- Receptors, Melanocortin/metabolism
- Time Factors
- alpha-MSH/metabolism
- alpha-MSH/pharmacology
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Affiliation(s)
- Wouter A J Nijenhuis
- Department of Pharmacology, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG, Utrecht, The Netherlands
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34
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Ringholm A, Klovins J, Fredriksson R, Poliakova N, Larson ET, Kukkonen JP, Larhammar D, Schiöth HB. Presence of melanocortin (MC4) receptor in spiny dogfish suggests an ancient vertebrate origin of central melanocortin system. EUROPEAN JOURNAL OF BIOCHEMISTRY 2003; 270:213-21. [PMID: 12605672 DOI: 10.1046/j.1432-1033.2003.03371.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We report the cloning, expression, pharmacological characterization and tissue distribution of a melanocortin (MC) receptor gene in a shark, the spiny dogfish (Squalus acanthias) (Sac). Phylogenetic analysis showed that this receptor is an ortholog of the MC4 subtype, sharing 71% overall amino acid identity with the human (Hsa) MC4 receptor. When expressed and characterized by radioligand binding assay for the natural MSH (melanocyte-stimulating hormone) peptides alpha-, beta-, and gamma-MSH, the SacMC4 receptor showed pharmacological properties very similar to the HsaMC4 receptor. Stimulation of SacMC4 receptor transfected cells with alpha-MSH caused a dose-dependent increase in intracellular cAMP levels. The SacMC4 receptor has Ala in position 59 where all other cloned MC receptors have Glu. We confirmed that this was not due to individual polymorphism and subsequently mutated the residue 'back' to Glu but the mutation did not affect the pharmacological properties of the receptor. SacMC4 receptor mRNA was detected by RT-PCR in the optic tectum, hypothalamus, brain stem, telencephalon and olfactory bulb but not in cerebellum or in peripheral tissues. This study describes the first characterization of an MC receptor in a cartilaginous fish, the most distant MC receptor gene cloned to date. Conservation of gene structure, pharmacological properties and tissue distribution suggests that this receptor may have similar roles in sharks as in mammals and that these were established more than 450 million years ago.
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Affiliation(s)
- Aneta Ringholm
- Department of Neuroscience, Uppsala University, Uppsala, Sweden
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35
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MacNeil DJ, Howard AD, Guan X, Fong TM, Nargund RP, Bednarek MA, Goulet MT, Weinberg DH, Strack AM, Marsh DJ, Chen HY, Shen CP, Chen AS, Rosenblum CI, MacNeil T, Tota M, MacIntyre ED, Van der Ploeg LHT. The role of melanocortins in body weight regulation: opportunities for the treatment of obesity. Eur J Pharmacol 2002; 450:93-109. [PMID: 12176114 DOI: 10.1016/s0014-2999(02)01989-1] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Five G-protein-coupled melanocortin receptors (MC(1)-MC(5)) are expressed in mammalian tissues. The melanocortin receptors support diverse physiological functions, including the regulation of hair color, adrenal function, energy homeostasis, feed efficiency, sebaceous gland lipid production and immune and sexual function. The melanocortins (adrenocorticotropic hormone (ACTH), alpha-melanocyte-stimulating hormone (alpha-MSH), beta-MSH and gamma-MSH) are agonist peptide ligands for the melanocortin receptors and these peptides are processed from the pre-prohormone proopiomelanocortin (POMC). Peptide antagonists for the melanocortin MC(1), MC(3) and MC(4) receptors include agouti-related protein (AgRP) and agouti. Diverse lines of evidence, including genetic and pharmacological data obtained in rodents and humans, support a role for the melanocortin MC(3) and MC(4) receptors in the regulation of energy homeostasis. Recent advances in the development of potent and selective peptide and non-peptide melanocortin receptor ligands are anticipated to help unravel the roles for the melanocortin receptors in humans and to accelerate the clinical use of small molecule melanocortin mimetics.
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36
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Holder JR, Bauzo RM, Xiang Z, Haskell-Luevano C. Structure-activity relationships of the melanocortin tetrapeptide Ac-His-DPhe-Arg-Trp-NH(2) at the mouse melanocortin receptors: part 2 modifications at the Phe position. J Med Chem 2002; 45:3073-81. [PMID: 12086493 DOI: 10.1021/jm010524p] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The melanocortin pathway is an important participant in skin pigmentation, steroidogenesis, obesity, energy homeostasis and exocrine gland function. The centrally located melanocortin-3 and melanocortin-4 receptors (MC3R, MC4R) are involved in the metabolic and food intake aspects of energy homeostasis and are stimulated by melanocortin agonists such as alpha-melanocyte stimulation hormone (alpha-MSH). The melanocortin agonists contain the putative message sequence "His-Phe-Arg-Trp," and it has been well-documented that inversion of chirality of the Phe to DPhe results in a dramatic increase in melanocortin receptor potency. Herein, we report a tetrapeptide library, based upon the template Ac-His-DPhe-Arg-Trp-NH(2), consisting of 26 members that have been modified at the DPhe(7) position (alpha-MSH numbering) and pharmacologically characterized for agonist and antagonist activity at the mouse melanocortin receptors MC1R, MC3R, MC4R, and MC5R. The most notable results of this study include the identification of the tetrapeptide Ac-His-(pI)DPhe-Arg-Trp-NH(2) that is a full nanomolar agonist at the mMC1 and mMC5 receptors, a mMC3R partial agonist with potent antagonist activity (pA(2) = 7.25, K(i) = 56 nM) and, but unexpectedly, is a potent agonist at the mMC4R (EC(50) = 25 nM). This ligand possesses novel melanocortin receptor pharmacology, as compared to previously reported peptides, and is potentially useful for in vivo studies to differentiate MC3R vs MC4R physiological roles in animal models, such as primates, where "knockout" animals are not viable options. The DNal(2') substitution for DPhe resulted in a mMC3R partial agonist with antagonist activity (pA(2) = 6.5, K(i) = 295 nM) and a mMC4R (pA(2) = 7.8, K(i) = 17 nM) antagonist possessing 60- and 425-fold decreased potency, respectively, as compared with SHU9119 at these receptors. Examination of this DNal(2')-containing tetrapeptide at the F254S and F259S mutant mMC4Rs resulted in agonist activity of this mMC4R tetrapeptide antagonist, similar to that observed for the SHU9119 peptide, supporting our previously proposed hypothesis that the Phe 254 and 259 transmembrane six receptor residues are important for differentiating melanocortin sequence-based MC4R antagonists vs the agouti-related protein (AGRP) sequence-based antagonists.
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MESH Headings
- Amino Acid Substitution
- Animals
- Cell Line
- Humans
- Mice
- Oligopeptides/chemical synthesis
- Oligopeptides/chemistry
- Oligopeptides/pharmacology
- Phenylalanine/chemistry
- Receptor, Melanocortin, Type 3
- Receptor, Melanocortin, Type 4
- Receptors, Corticotropin/agonists
- Receptors, Corticotropin/antagonists & inhibitors
- Receptors, Corticotropin/drug effects
- Receptors, Melanocortin
- Receptors, Peptide/agonists
- Receptors, Peptide/antagonists & inhibitors
- Receptors, Peptide/drug effects
- Structure-Activity Relationship
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Affiliation(s)
- Jerry Ryan Holder
- University of Florida, Department of Medicinal Chemistry, P.O. Box 100485, Gainesville, FL 32610-0485, USA
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37
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Ringholm A, Fredriksson R, Poliakova N, Yan YL, Postlethwait JH, Larhammar D, Schiöth HB. One melanocortin 4 and two melanocortin 5 receptors from zebrafish show remarkable conservation in structure and pharmacology. J Neurochem 2002; 82:6-18. [PMID: 12091460 DOI: 10.1046/j.1471-4159.2002.00934.x] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
We report the cloning, genome mapping, functional expression, pharmacology and anatomical distribution of three melanocortin (MC) receptors from zebrafish (z). Phylogenetic analysis showed with high bootstrap support that these genes represent one MC4 receptor and two MC5 receptors. Chromosomal mapping showed conserved synteny between regions containing zMC4 and human (h) MC4 receptors, whereas the two zMC5 receptor genes map on chromosome segments in which the zebrafish has several genes with two orthologues of a single mammalian gene. It is likely that the two copies of zMC5 receptors arose through a separate duplication in the teleost lineage. The zMC4, zMC5a, and zMC5b receptors share 70-71% overall amino acid identity with the respective human orthologues and over 90% in three TM regions believed to be most important for ligand binding. All three zebrafish receptors also show pharmacological properties remarkably similar to their human orthologues, with similar affinities and the same potency order, when expressed and characterized in radioligand binding assay for the natural MSH) peptides alpha-, beta-, and gamma-MSH. Stimulation of transfected mammalian cells with alpha-MSH caused a dose-dependent increase in intracellular cAMP levels for all three zebrafish receptors. All three genes were expressed in the brain, eye, ovaries and gastrointestinal tract, whereas the zMC5b receptor was also found in the heart, as determined by RT-PCR. Our studies, which represent the first characterization of MC receptors in a nonamniote species, indicate that the MC receptor subtypes arose very early in vertebrate evolution. Important pharmacological and functional properties, as well as gene structure and syntenic relationships have been highly conserved over a period of more than 400 million years implying that these receptors participate in vital physiological functions.
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MESH Headings
- Animals
- Binding, Competitive
- Biological Assay
- Blotting, Southern
- Cell Line
- Chromosome Mapping
- Cloning, Molecular
- Conserved Sequence
- Humans
- Ligands
- Molecular Sequence Data
- Organ Specificity
- Phylogeny
- Radioligand Assay
- Receptor, Melanocortin, Type 4
- Receptors, Corticotropin/biosynthesis
- Receptors, Corticotropin/chemistry
- Receptors, Corticotropin/genetics
- Receptors, Melanocortin
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Homology, Amino Acid
- Zebrafish
- Zebrafish Proteins/biosynthesis
- Zebrafish Proteins/chemistry
- Zebrafish Proteins/genetics
- alpha-MSH/analogs & derivatives
- alpha-MSH/pharmacokinetics
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Affiliation(s)
- Aneta Ringholm
- Department of Neuroscience, Unit of Pharmacology, Uppsala University, BMC, 75 124 Uppsala, Sweden
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38
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Holder JR, Bauzo RM, Xiang Z, Haskell-Luevano C. Structure-activity relationships of the melanocortin tetrapeptide Ac-His-DPhe-Arg-Trp-NH(2) at the mouse melanocortin receptors. 1. Modifications at the His position. J Med Chem 2002; 45:2801-10. [PMID: 12061882 DOI: 10.1021/jm0104872] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The melanocortin pathway is an important participant in obesity and energy homeostasis. The centrally located melanocortin-3 and melanocortin-4 receptors (MC3R, MC4R) are involved in the metabolic and food intake aspects of energy homeostasis and are stimulated by melanocortin agonists such as alpha-melanocyte stimulation hormone (alpha-MSH). The melanocortin agonists contain the putative message sequence "His-Phe-Arg-Trp", and it has been well documented that inversion of chirality of the Phe to DPhe results in a dramatic increase in melanocortin receptor potency. Herein, we report a tetrapeptide library based on the template Ac-His-DPhe-Arg-Trp-NH(2), consisting of 17 members that have been modified at the His(6) position (alpha-MSH numbering) and pharmacologically characterized for agonist activity at the mouse melanocortin receptors MC1R, MC3R, MC4R, and MC5R. These studies provide further experimental evidence that the His(6) position can determine MC4R versus MC3R agonist selectivity and that chemically nonreactive side chains may be substituted for the imidazole ring (generally needs to be side chain protected in synthetic schemes) in the design of MC4R-selective, small-molecule, non-peptide agonists. Specifically, the tetrapeptide containing the amino-2-naphthylcarboxylic acid (Anc) amino acid at the His position resulted in a potent agonist at the mMC4R (EC(50) = 21 nM), was a weak mMC3R micromolar antagonist (pA(2) = 5.6, K(i) = 2.5 microM), and possessed >4700-fold agonist selectivity for the MC4R versus the MC3R. Substitution of the His(6) amino acid in the tetrapeptide template by the Phe, Anc, 3-(2-thienyl)alanine (2Thi), and 3-(4-pyridinyl)alanine (4-Pal) resulted in equipotency or only up to a 7-fold decrease in potency, compared to the His(6)-containing tetrapeptide at the mMC4R, demonstrating that these amino acid side chains may be substituted for the imidazole in the design of MC4R-selective non-peptide molecules.
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Affiliation(s)
- Jerry Ryan Holder
- Department of Medicinal Chemistry, University of Florida, Gainesville, FL 32610, USA
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39
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Schiöth HB, Bouifrouri AA, Rudzish R, Muceniece R, Watanobe H, Wikberg JES, Larhammar D. Pharmacological comparison of rat and human melanocortin 3 and 4 receptors in vitro. REGULATORY PEPTIDES 2002; 106:7-12. [PMID: 12047904 DOI: 10.1016/s0167-0115(02)00025-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The melanocortin 3 and 4 receptors are G-protein-coupled receptors found in the hypothalamus with important role in regulation of the energy balance. In this study, we performed pharmacological comparison of the rat and human melancortin (MC) 3 and MC4 receptors. We transiently expressed the genes for these receptors individually in a mammalian cell line and determined the binding affinities to several MSH peptides. The results showed no major difference between the rat and human MC3 receptors while the rat MC4 receptor had higher affinity to several peptides compared with the human MC4 receptor. NDP-, alpha-, beta-, gamma-MSH, ACTH(1-24), HS014 and MTII had from 5- to 34-fold higher affinity for the rat MC4 receptor, while SHU9119, HS024 and HS028 had similar affinity for both the MC4 receptors. Pharmacological species difference have earlier been reported for the MC1 and MC5 receptors but this is the first report showing important differences between the rat and human MC4 receptors.
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Affiliation(s)
- Helgi B Schiöth
- Department of Neuroscience, Biomedical Center, Box 593, 751 24 Uppsala University, Uppsala, Sweden.
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40
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Kim MS, Rossi M, Abbott CR, AlAhmed SH, Smith DM, Bloom SR. Sustained orexigenic effect of Agouti related protein may be not mediated by the melanocortin 4 receptor. Peptides 2002; 23:1069-76. [PMID: 12126733 DOI: 10.1016/s0196-9781(02)00039-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Intracerebroventricular (ICV) injection of Agouti related protein (AgRP), an endogenous melanocortin 3 and 4 receptor (MC3/4-R) antagonist, produces a prolonged increase in food intake. To clarify the roles of the MC3-R and MC4-R in AgRP-induced hyperphagia, the feeding effect of AgRP (83-132) was compared with that of the selective MC4-R antagonist, JKC-363 (cyclic [Mpr11, D-Nal14, Cys18, Asp22-NH2]-beta-MSH11-22). Single ICV administration of AgRP (83-132) increased food intake for 48 h whilst ICV JKC-363 increased food intake for 8h. An increase in body weight at 24 and 48 h was observed following AgRP (83-132) but not JKC-363 treatment. These data suggest that the sustained orexigenic action of AgRP (83-132) may not be through MC4-R antagonism.
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Affiliation(s)
- Min Seon Kim
- Department of Internal Medicine and Institute of Endocrinology, Nutrition and Metabolism, Medical Research Center, Seoul National University College of Medicine, 110-744, Seoul, South Korea
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41
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MacNeil DJ, Howard AD, Guan X, Fong TM, Nargund RP, Bednarek MA, Goulet MT, Weinberg DH, Strack AM, Marsh DJ, Chen HY, Shen CP, Chen AS, Rosenblum CI, MacNeil T, Tota M, MacIntyre ED, Van der Ploeg LHT. The role of melanocortins in body weight regulation: opportunities for the treatment of obesity. Eur J Pharmacol 2002; 440:141-57. [PMID: 12007532 DOI: 10.1016/s0014-2999(02)01425-5] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Five G-protein-coupled melanocortin receptors (MC(1)-MC(5)) are expressed in mammalian tissues. The melanocortin receptors support diverse physiological functions, including the regulation of hair color, adrenal function, energy homeostasis, feed efficiency, sebaceous gland lipid production and immune and sexual function. The melanocortins (adrenocorticotropic hormone (ACTH), alpha-melanocyte-stimulating hormone (alpha-MSH), beta-MSH and gamma-MSH) are agonist peptide ligands for the melanocortin receptors and these peptides are processed from the pre-prohormone proopiomelanocortin (POMC). Peptide antagonists for the melanocortin MC(1), MC(3) and MC(4) receptors include agouti-related protein (AgRP) and agouti. Diverse lines of evidence, including genetic and pharmacological data obtained in rodents and humans, support a role for the melanocortin MC(3) and MC(4) receptors in the regulation of energy homeostasis. Recent advances in the development of potent and selective peptide and non-peptide melanocortin receptor ligands are anticipated to help unravel the roles for the melanocortin receptors in humans and to accelerate the clinical use of small molecule melanocortin mimetics.
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42
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Kim MS, Small CJ, Russell SH, Morgan DGA, Abbott CR, alAhmed SH, Hay DL, Ghatei MA, Smith DM, Bloom SR. Effects of melanocortin receptor ligands on thyrotropin-releasing hormone release: evidence for the differential roles of melanocortin 3 and 4 receptors. J Neuroendocrinol 2002; 14:276-82. [PMID: 11963824 DOI: 10.1046/j.1365-2826.2002.00769.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The hypothalamic melanocortin system is important in the central regulation of food intake and body weight. We have previously demonstrated that intracerebroventricular administration of alpha-melanocyte stimulating hormone (alpha-MSH), a nonselective MC3 and MC4 receptor agonist, stimulated plasma thyroid-stimulating hormone, and agouti-related protein (AgRP), an MC3 and MC4 receptor antagonist, suppressed it. In this study, we investigated the effects of MC3 and MC4 receptor (MC3-R and MC4-R) selective agonists and antagonists on the release of thyrotropin-releasing hormone (TRH) from hypothalamic explants in vitro. alpha-MSH stimulated TRH release from the rat hypothalamic explants (alpha-MSH 100 nm 230 +/- 22.9% basal, P < 0.005). In contrast, gamma 2-MSH, a selective MC3-R agonist, suppressed TRH release (gamma 2-MSH 10 microns 76.2 +/- 7.4% basal, P < 0.05). AgRP (83-132), a nonselective MC3/4-R antagonist, induced no change in TRH release whilst JKC-363 (cyclic [Mpr11, D-Nal14, Cys18, Asp22-NH2]-beta-MSH 11-22), a selective MC4-R antagonist, suppressed it (JKC-363 10 nm 57.2 +/- 11.5% basal, P < 0.05). Both AgRP (83-132) and JKC-363 blocked alpha-MSH stimulated TRH release but only AgRP (83-132) blocked the inhibitory effect of gamma 2-MSH on TRH release. These data suggest differential roles for the MC3 and MC4 receptors in TRH release; MC3-R agonism inhibiting and MC4-R agonism stimulating TRH release.
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Affiliation(s)
- M S Kim
- Endocrine Unit, Department of Metabolic Medicine, Imperial College School of Medicine, Hammersmith Hospital, Du Cane Road, London W12 ONN, UK
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43
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Jonsson L, Skarphedinsson JO, Skuladottir GV, Atlason PT, Eiriksdottir VH, Franzson L, Schiöth HB. Melanocortin receptor agonist transiently increases oxygen consumption in rats. Neuroreport 2001; 12:3703-8. [PMID: 11726778 DOI: 10.1097/00001756-200112040-00020] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Acute injections of melanocortin (MC) agonist and antagonist are highly effective in reducing or increasing food take, respectively. Much less is known about how injection of MC receptor active substances affects metabolism, in particular during long term administration. Here we investigated the effect of 8 days continuous i.c.v. infusion of either MC receptor agonist MTII or the selective MC4 receptor antagonist HS024 on oxygen consumption, food intake and body weight in rats. We observed significant increase in oxygen consumption 2 days after the start of the MTII infusion. However, this increase had disappeared by day 4 of the study. No difference was observed in the oxygen consumption after injection of HS024. MTII substantially decreased the food intake during the first days, but then the feeding recovered and the body weight stabilised at a new level. The immediate effect of the MC receptor agonist on both food intake and metabolism was thus transient, even though the weight loss was maintained. The HS024 treated rats were hyperphagic throughout the test period, continuously gaining weight, resulting in increased fat pads and high leptin levels. This is the first study that describes long term effects of MC receptor agonist and antagonist on metabolism and energy balance.
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Affiliation(s)
- L Jonsson
- Department of Physiology, University of Iceland, Reykjavik
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44
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Bednarek MA, MacNeil T, Kalyani RN, Tang R, Van der Ploeg LH, Weinberg DH. Selective, high affinity peptide antagonists of alpha-melanotropin action at human melanocortin receptor 4: their synthesis and biological evaluation in vitro. J Med Chem 2001; 44:3665-72. [PMID: 11606131 DOI: 10.1021/jm010165y] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Peptide Ac-Nle(4)-cyclo(5beta-->10epsilon)(Asp(5)-His(6)-D-(2')Nal(7)-Arg(8)-Trp(9)-Lys(10))-NH(2), compound 1, a cyclic derivative of alpha-melanotropin, is a nonselective high affinity antagonist at human melanocortin receptors 3 and 4, and an agonist at melanocortin receptors 1 and 5. To differentiate between the physiological functions of these receptors, antagonists with improved receptor selectivity are needed. In this study, analogues of compound 1 without Ac-Nle(4) or His(6) and/or the amino group of Asp(5) were prepared and tested in binding assays and in functional assays on CHO cells expressing hMC3-5R. Several of these peptides were to be selective, high affinity hMC-4R antagonists. The most interesting was compound 10, named MBP10, cyclo(6beta-->10epsilon)(succinyl(6)-D-(2')Nal(7)-Arg(8)-Trp(9)-Lys(10))-NH(2), an antagonist (IC(50) = 0.5 nM) with 125-fold selectivity over hMC-3R (and of >300-fold selectivity over MC-1RB). This compound had no agonist activity at hMC-3R or hMC-4R and only weak agonist activity at hMC-5R. Examination of the sequences of these new peptides revealed that the D-(2')Nal(7)-Arg(8)-Trp(9) segment of peptide 1 forms the "essential core" required for high affinity and high selectivity of analogues of peptide 1 at hMC-4R, but the "extended core", His(6)-D-(2')Nal(7)-Arg(8)-Trp(9), is necessary for the maximum affinity for hMC-3R and hMC-5R.
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MESH Headings
- Animals
- Binding, Competitive
- CHO Cells
- Chromatography, High Pressure Liquid
- Cricetinae
- Cyclic AMP/metabolism
- Humans
- Molecular Conformation
- Peptides, Cyclic/chemical synthesis
- Peptides, Cyclic/chemistry
- Peptides, Cyclic/metabolism
- Receptor, Melanocortin, Type 3
- Receptor, Melanocortin, Type 4
- Receptors, Corticotropin/antagonists & inhibitors
- Receptors, Corticotropin/metabolism
- Receptors, Melanocortin
- Signal Transduction
- Structure-Activity Relationship
- alpha-MSH/metabolism
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Affiliation(s)
- M A Bednarek
- Department of Medicinal Chemistry, Merck Research Laboratories, Rahway, NJ 07065, USA.
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45
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Abstract
Since its discovery, leptin (a 167-amino acid product of the OB gene) has quickly moved to the forefront as an important hormone for regulation of energy balance. It closes a feedback loop from adipose tissue to hypothalamic neuropeptide-containing neural circuitry involved in regulation of food intake and neuroendocrine/autonomic outflow. While increased central leptin signalling reduces adiposity via a reduction in food intake, it also has remarkable metabolic effects that promote leanness, independent of food intake. These include: (i) increased energy expenditure, (ii) in-place degradation of fat, and (iii) increased thermogenesis. Hypothalamic neurones that synthesize corticotropin releasing hormone and melanocortins (i.e. alpha-melanocyte-stimulating hormone and agouti-related protein) are likely effector pathways that mediate the anorexigenic and metabolic effects of leptin. Activation of sympathetic outflow (via neuropeptidergic effector pathways of central leptin) to a number of tissues that store fat might be an important mechanism through which these peripheral metabolic effects are elicited. It is proposed that these peripheral metabolic effects contribute to the satiating properties of leptin.
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Affiliation(s)
- G van Dijk
- Department of Animal Physiology, Division Neuroendocrinology, School of Behavioural and Cognitive Neurosciences, University of Groningen, Haren, The Netherlands.
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46
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Hypothalamic, metabolic, and behavioral responses to pharmacological inhibition of CNS melanocortin signaling in rats. J Neurosci 2001. [PMID: 11331393 DOI: 10.1523/jneurosci.21-10-03639.2001] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The CNS melanocortin (MC) system is implicated as a mediator of the central effects of leptin, and reduced activity of the CNS MC system promotes obesity in both rodents and humans. Because activation of CNS MC receptors has direct effects on autonomic outflow and metabolism, we hypothesized that food intake-independent mechanisms contribute to development of obesity induced by pharmacological blockade of MC receptors in the brain and that changes in hypothalamic neuropeptidergic systems known to regulate weight gain [i.e., corticotropin-releasing hormone (CRH), cocaine-amphetamine-related transcript (CART), proopiomelanocortin (POMC), and neuropeptide Y (NPY)] would trigger this effect. Relative to vehicle-treated controls, third intracerebroventricular (i3vt) administration of the MC receptor antagonist SHU9119 to rats for 11 d doubled food and water intake (toward the end of treatment) and increased body weight ( approximately 14%) and fat content ( approximately 90%), hepatic glycogen content ( approximately 40%), and plasma levels of cholesterol ( approximately 48%), insulin ( approximately 259%), glucagon ( approximately 80%), and leptin ( approximately 490%), whereas spontaneous locomotor activity and body temperature were reduced. Pair-feeding of i3vt SHU9119-treated animals to i3vt vehicle-treated controls normalized plasma levels of insulin, glucagon, and hepatic glycogen content, but only partially reversed the elevations of plasma cholesterol ( approximately 31%) and leptin ( approximately 104%) and body fat content ( approximately 27%). Reductions in body temperature and locomotor activity induced by i3vt SHU9119 were not reversed by pair feeding, but rather were more pronounced. None of the effects found can be explained by peripheral action of the compound. The obesity effects occurred despite a lack in neuropeptide expression responses in the neuroanatomical range selected across the arcuate (i.e., CART, POMC, and NPY) and paraventricular (i.e., CRH) hypothalamus. The results indicate that reduced activity of the CNS MC pathway promotes fat deposition via both food intake-dependent and -independent mechanisms.
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Adage T, Scheurink AJ, de Boer SF, de Vries K, Konsman JP, Kuipers F, Adan RA, Baskin DG, Schwartz MW, van Dijk G. Hypothalamic, metabolic, and behavioral responses to pharmacological inhibition of CNS melanocortin signaling in rats. J Neurosci 2001; 21:3639-45. [PMID: 11331393 PMCID: PMC6762466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023] Open
Abstract
The CNS melanocortin (MC) system is implicated as a mediator of the central effects of leptin, and reduced activity of the CNS MC system promotes obesity in both rodents and humans. Because activation of CNS MC receptors has direct effects on autonomic outflow and metabolism, we hypothesized that food intake-independent mechanisms contribute to development of obesity induced by pharmacological blockade of MC receptors in the brain and that changes in hypothalamic neuropeptidergic systems known to regulate weight gain [i.e., corticotropin-releasing hormone (CRH), cocaine-amphetamine-related transcript (CART), proopiomelanocortin (POMC), and neuropeptide Y (NPY)] would trigger this effect. Relative to vehicle-treated controls, third intracerebroventricular (i3vt) administration of the MC receptor antagonist SHU9119 to rats for 11 d doubled food and water intake (toward the end of treatment) and increased body weight ( approximately 14%) and fat content ( approximately 90%), hepatic glycogen content ( approximately 40%), and plasma levels of cholesterol ( approximately 48%), insulin ( approximately 259%), glucagon ( approximately 80%), and leptin ( approximately 490%), whereas spontaneous locomotor activity and body temperature were reduced. Pair-feeding of i3vt SHU9119-treated animals to i3vt vehicle-treated controls normalized plasma levels of insulin, glucagon, and hepatic glycogen content, but only partially reversed the elevations of plasma cholesterol ( approximately 31%) and leptin ( approximately 104%) and body fat content ( approximately 27%). Reductions in body temperature and locomotor activity induced by i3vt SHU9119 were not reversed by pair feeding, but rather were more pronounced. None of the effects found can be explained by peripheral action of the compound. The obesity effects occurred despite a lack in neuropeptide expression responses in the neuroanatomical range selected across the arcuate (i.e., CART, POMC, and NPY) and paraventricular (i.e., CRH) hypothalamus. The results indicate that reduced activity of the CNS MC pathway promotes fat deposition via both food intake-dependent and -independent mechanisms.
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Affiliation(s)
- T Adage
- Department of Animal Physiology, University of Groningen, 9750 AA Haren, the Netherlands
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Small CJ, Kim MS, Stanley SA, Mitchell JR, Murphy K, Morgan DG, Ghatei MA, Bloom SR. Effects of chronic central nervous system administration of agouti-related protein in pair-fed animals. Diabetes 2001; 50:248-54. [PMID: 11272133 DOI: 10.2337/diabetes.50.2.248] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The melanocortin receptor (MC3-R and MC4-R) antagonist, agouti-related protein (AGRP), is a potent stimulant of food intake. We examined the effect of chronic intracerebroventricular (ICV) AGRP treatment on energy metabolism and pituitary function in ad libitum fed rats and rats administered AGRP and then pair-fed to a saline control group. Chronic ICV AGRP (83-132) administration (1 nmol/day for 7 days) significantly increased food intake and body weight in ad libitum fed animals compared with saline-treated controls (body weight on day 7: 272 +/- 6 [saline] vs. 319 +/- 8 g [AGRP ad libitum fed]; P < 0.001). A significant increase in the epididymal fat pad weight, interscapular brown adipose tissue (BAT) weight, and plasma leptin was also observed in the ad libitum fed group. In the AGRP pair-fed group, a significant increase in the epididymal fat pad weight, BAT weight, and plasma leptin was again observed, suggesting that AGRP caused metabolic changes independent of increased food intake. BAT uncoupling protein 1 (UCP-1) content was significantly decreased compared with saline controls in both the AGRP ad libitum fed (21 +/- 8% of saline control; P < 0.01) and AGRP pair-fed groups (24 +/- 7% of saline control; P < 0.01). Plasma thyroid-stimulating hormone (TSH) was significantly suppressed compared with saline controls in both the AGRP ad libitum fed and AGRP pair-fed groups (3.5 +/- 0.3 [saline] vs. 2.7 +/- 0.4 [AGRP ad libitum fed] vs. 2.1 +/- 0.2 ng/ml [AGRP pair-fed]; P < 0.01). This study demonstrates that independent of its orexigenic effects, chronic AGRP treatment decreased BAT UCP-1, suppressed plasma TSH, and increased fat mass and plasma leptin, suggesting that it may play a role in energy expenditure.
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Affiliation(s)
- C J Small
- Department of Metabolic Medicine, Imperial College School of Medicine, Hammersmith Hospital, London, UK
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Affiliation(s)
- H B Schiöth
- Department of Neuroscience, Biomedical Center, Uppsala University, Sweden
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Nijenhuis WA, Oosterom J, Adan RA. AgRP(83-132) acts as an inverse agonist on the human-melanocortin-4 receptor. Mol Endocrinol 2001; 15:164-71. [PMID: 11145747 DOI: 10.1210/mend.15.1.0578] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The central melanocortin (MC) system has been demonstrated to act downstream of leptin in the regulation of body weight. The system comprises alpha-MSH, which acts as agonist, and agouti-related protein (AgRP), which acts as antagonist at the MC3 and MC4 receptors (MC3R and MC4R). This property suggests that MCR activity is tightly regulated and that opposing signals are integrated at the receptor level. We here propose another level of regulation within the melanocortin system by showing that the human (h) MC4R displays constitutive activity in vitro as assayed by adenylyl cyclase (AC) activity. Furthermore, human AgRP(83-132) acts as an inverse agonist for the hMC4R since it was able to suppress constitutive activity of the hMC4R both in intact B16/G4F melanoma cells and membrane preparations. The effect of AgRP(83-132) on the hMC4R was blocked by the MC4R ligand SHU9119. Also the hMC3R and the mouse(m)MC5R were shown to be constitutively active. AgRP(83-132) acted as an inverse agonist on the hMC3R but not on the mMC5R. Thus, AgRP is able to regulate MCR activity independently of alpha-MSH. These findings form a basis to further investigate the relevance of constitutive activity of the MC4R and of inverse agonism of AgRP for the regulation of body weight.
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Affiliation(s)
- W A Nijenhuis
- Molecular Neuroscience Rudolf Magnus Institute for Neurosciences University Medical Center Utrecht Utrecht, the Netherlands 3584 CG
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