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Nategh M, Nikseresht S, Khodagholi F, Motamedi F. Nucleus incertus inactivation impairs spatial learning and memory in rats. Physiol Behav 2014; 139:112-20. [PMID: 25446222 DOI: 10.1016/j.physbeh.2014.11.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 11/03/2014] [Accepted: 11/04/2014] [Indexed: 11/15/2022]
Abstract
Nucleus incertus (NI) is a pontine nucleus which releases mainly GABA and relaxin-3 in rats. Its suggested functions include response to stress, arousal, and modulation of hippocampal theta rhythm. Since the role of NI in learning and memory has not been well characterized, therefore the involvement of this nucleus in spatial learning and memory and the aftermath hippocampal levels of c-fos and pCREB were evaluated. NI was targeted by implanting cannula in male rats. For reference memory, NI was inactivated by lidocaine (0.4 μl, 4%) at three stages of acquisition, consolidation and retrieval in Morris water maze paradigm. For working memory, NI was inactivated in acquisition and retrieval phases. Injection of lidocaine prior to the first training session of reference memory significantly increased the distance moved, suggesting that inactivation of NI delays acquisition in this spatial task. Inactivation also interfered with the retrieval phase of spatial reference memory, as the time in target quadrant for lidocaine group was less, and the escape latency was higher compared to the control group. However, no difference was observed in the consolidation phase. In the working memory task, with inter-trial intervals of 75 min, the escape latency was higher when NI was inactivated in the retrieval phase. In addition, c-fos and pCREB/CREB levels decreased in NI-inhibited rats. This study suggests that nucleus incertus might participate in acquisition of spatial reference, and retrieval of both spatial reference and working memory. Further studies should investigate possible roles of NI in the hippocampal plasticity.
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Affiliation(s)
- Mohsen Nategh
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Sara Nikseresht
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Neurobiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Fariba Khodagholi
- Neurobiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Fereshteh Motamedi
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Neurophysiology Research Center, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
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52
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Ma X, Han S, Zhang W, Fan YJ, Liu MN, Liu AY, Liu BR. Protection of cultured human hepatocytes from hydrogen peroxide‑induced apoptosis by relaxin‑3. Mol Med Rep 2014; 11:1228-34. [PMID: 25370004 DOI: 10.3892/mmr.2014.2842] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Accepted: 10/01/2014] [Indexed: 11/06/2022] Open
Abstract
Previous studies have suggested that hepatocyte apoptosis may be a fundamental underlying mechanism of liver injury and diseases, such as liver fibrosis. Relaxin‑3 has been reported to have anti‑fibrotic actions in the heart and to attenuate isoproterenol‑induced myocardial injury; however, the beneficial role of relaxin‑3 on hepatocyte apoptosis remains to be elucidated. The aim of the present study was to explore the role and possible mechanisms of relaxin‑3 through hydrogen peroxide (H2O2)‑induced apoptosis in primary human hepatocytes. Cells were treated with relaxin‑3 and then cell viability, morphological features, the presence of cleaved caspases as well as the levels of endoplasmic reticulum stress (ERS) protein markers and autophagy markers were evaluated. The H2O2 group showed significantly decreased cell viability, increased apoptosis as well as upregulation of caspases (cleaved caspase‑3, ‑8 and ‑9) and ERS protein markers compared with those of the control group. However, cells treated with relaxin‑3 (10 ng/ml) demonstrated improved cell viability, reduced apoptosis and decreased expression of cleaved caspases and ERS markers. However, the expression of autophagy markers remained unchanged following H2O2‑induced apoptosis and relaxin‑3 treatment. In conclusion, relaxin‑3 was shown to protect hepatocytes from H2O2‑induced apoptosis via downregulation of cleaved caspase‑8 and ‑9, as well as inhibition of the ERS pathway.
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Affiliation(s)
- Xiao Ma
- Department of Gastroenterology and Hepatology, The Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150086, P.R. China
| | - Su Han
- Department of Microbiology and Parasitology, The Heilongjiang Key Laboratory of Immunity and Infection, Pathogenic Biology, Harbin Medical University, Harbin, Heilongjiang 150086, P.R. China
| | - Wei Zhang
- Center for Endemic Disease Control, Chinese Center for Disease Control and Prevention, Harbin Medical University, Harbin, Heilongjiang 150081, P.R. China
| | - Yu-Jing Fan
- Department of Gastroenterology and Hepatology, The Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150086, P.R. China
| | - Ming-Na Liu
- Department of Gastroenterology and Hepatology, The Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150086, P.R. China
| | - Ai-Yun Liu
- Department of Gastroenterology and Hepatology, The Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150086, P.R. China
| | - Bing-Rong Liu
- Department of Gastroenterology and Hepatology, The Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150086, P.R. China
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Meadows KL, Byrnes EM. Sex- and age-specific differences in relaxin family peptide receptor expression within the hippocampus and amygdala in rats. Neuroscience 2014; 284:337-348. [PMID: 25313002 DOI: 10.1016/j.neuroscience.2014.10.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 09/04/2014] [Accepted: 10/03/2014] [Indexed: 01/04/2023]
Abstract
Relaxin is an essential pregnancy-related hormone with broad peripheral effects mediated by activation of relaxin-like family peptide 1 receptors (RXFP1). More recent studies suggest an additional role for relaxin as a neuropeptide, with RXFP1 receptors expressed in numerous brain regions. Neurons in an area of the brainstem known as the nucleus incertus (NI) produce relaxin 3 (RLN3), the most recently identified neuropeptide in the relaxin family. RLN3 has been shown to activate both RXFP1 and relaxin-like family peptide receptor 3 (RXFP3) receptor subtypes. Studies suggest wide-ranging neuromodulatory effects of both RXFP1 and RXFP3 activation, although to date the majority of studies have been conducted in young males. In the current study, we examined potential sex- and age-related changes in RLN3 gene expression in the NI as well as RXFP1 and RXFP3 gene expression in the dorsal hippocampus (HI), ventral hippocampus (vHI) and amygdala (AMYG) using young adult (9-12weeks) and middle-aged (9-12months) male and female rats. In addition, regional changes in RXFP1 and RXFP3 protein expression were examined in the CA1, CA2/CA3 and dentate gyrus (DG) as well as within basolateral (BLA), central (CeA), and medial (MeA) amygdaloid nuclei. In the NI, RLN3 showed an age-related decrease in males. In the HI, only the RXFP3 receptor showed an age-related change in gene expression, however, both receptor subtypes showed age-related changes in protein expression that were region specific. Additionally, while gene and protein expression of both receptors increased with age in AMYG, these effects were both region- and sex-specific. Finally, overall males displayed a greater number of cells that express the RXFP3 protein in all of the amygdaloid nuclei examined. Cognitive and emotional processes regulated by activity within the HI and AMYG are modulated by both sex and age. The vast majority of studies exploring the influence of sex on age-related changes in the HI and AMYG have focused on sex hormones, with few studies examining the role of neuropeptides. The current findings suggest that changes in relaxin family peptides may contribute to the significant sex differences observed in these brain regions as a function of aging.
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Affiliation(s)
- K L Meadows
- Tufts University Cummings School of Veterinary Medicine, 200 Westboro Road, Grafton, MA 01536, United States.
| | - E M Byrnes
- Tufts University Cummings School of Veterinary Medicine, 200 Westboro Road, Grafton, MA 01536, United States.
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Hosken IT, Sutton SW, Smith CM, Gundlach AL. Relaxin-3 receptor (Rxfp3) gene knockout mice display reduced running wheel activity: implications for role of relaxin-3/RXFP3 signalling in sustained arousal. Behav Brain Res 2014; 278:167-75. [PMID: 25257104 DOI: 10.1016/j.bbr.2014.09.028] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 09/12/2014] [Accepted: 09/15/2014] [Indexed: 12/14/2022]
Abstract
Anatomical and pharmacological evidence suggests the neuropeptide, relaxin-3, is the preferred endogenous ligand for the relaxin family peptide-3 receptor (RXFP3) and suggests a number of putative stress- and arousal-related roles for RXFP3 signalling. However, in vitro and in vivo evidence demonstrates exogenous relaxin-3 can activate other relaxin peptide family receptors, and the role of relaxin-3/RXFP3 signalling in specific brain circuits and associated behaviours in mice is not well described. In this study, we characterised the behaviour of cohorts of male and female Rxfp3 gene knockout (KO) mice (C57/B6J(RXFP3TM1/DGen)), relative to wild-type (WT) littermates to determine if this receptor KO strain has a similar phenotype to its ligand KO equivalent. Rxfp3 KO mice displayed similar performance to WT littermates in several acute behavioural paradigms designed to gauge motor coordination (rotarod test), spatial memory (Y-maze), depressive-like behaviour (repeat forced-swim test) and sensorimotor gating (prepulse inhibition of acoustic startle). Notably however, male and female Rxfp3 KO mice displayed robust and consistent (dark phase) hypoactivity on voluntary home-cage running wheels (∼20-60% less activity/h), and a small but significant decrease in anxiety-like behavioural traits in the elevated plus maze and light/dark box paradigms. Importantly, this phenotype is near identical to that observed in two independent lines of relaxin-3 KO mice, suggesting these phenotypes are due to the elimination of ligand or receptor and RXFP3-linked signalling. Furthermore, this behavioural characterisation of Rxfp3 KO mice identifies them as a useful experimental model for studying RXFP3-linked signalling and assessing the selectivity and/or potential off-target actions of RXFP3 agonists and antagonists, which could lead to an improved understanding of dysfunctional arousal in mental health disorders, including depression, anxiety, insomnia and neurodegenerative diseases.
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Affiliation(s)
- Ihaia T Hosken
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Victoria, Australia; Florey Department of Neuroscience and Mental Health, The University of Melbourne, Victoria, Australia
| | - Steven W Sutton
- Neuroscience Drug Discovery, Janssen Pharmaceutical Companies of Johnson & Johnson, San Diego, CA, USA
| | - Craig M Smith
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Victoria, Australia; Florey Department of Neuroscience and Mental Health, The University of Melbourne, Victoria, Australia
| | - Andrew L Gundlach
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Victoria, Australia; Florey Department of Neuroscience and Mental Health, The University of Melbourne, Victoria, Australia; Department of Anatomy and Neuroscience, The University of Melbourne, Victoria, Australia.
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55
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Ryan PJ, Krstew EV, Sarwar M, Gundlach AL, Lawrence AJ. Relaxin-3 mRNA levels in nucleus incertus correlate with alcohol and sucrose intake in rats. Drug Alcohol Depend 2014; 140:8-16. [PMID: 24837581 DOI: 10.1016/j.drugalcdep.2014.04.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 04/02/2014] [Accepted: 04/09/2014] [Indexed: 11/17/2022]
Abstract
BACKGROUND Chronic alcohol intake produces multiple neuroadaptive changes, including up- and down-regulation of neuropeptides and receptors. There are widespread projections of relaxin-3 containing neurons to, and abundant relaxin family peptide 3 receptor (RXFP3) expression within, brain regions involved in modulating alcohol intake. Recently we demonstrated the involvement of relaxin-3/RXFP3 signalling in alcohol-seeking in rats; therefore in this study we examined whether relaxin-3 and/or RXFP3 expression were altered by chronic alcohol intake in alcohol-preferring iP rats. METHODS Expression of relaxin-3 mRNA in the hindbrain nucleus incertus and RXFP3 radioligand binding levels in discrete forebrain regions were investigated following voluntary intake of alcohol or sucrose for 12 weeks, with a 2 day washout, using quantitative in situ hybridisation histochemistry and in vitro receptor autoradiography, respectively, in cohorts of adult, male iP rats. RESULTS Levels of relaxin-3 mRNA in the hindbrain nucleus incertus were positively correlated with the level of intake of both alcohol (r(12)=0.59, p=0.03) and sucrose (r(7)=0.70, p=0.04) in iP rats. Dense binding of the RXFP3-selective radioligand, [(125)]-R3/I5, was detected in hypothalamic and extrahypothalamic sites, but no significant changes in the density of RXFP3 were observed in the brain regions quantified following chronic sucrose or ethanol intake. CONCLUSIONS Our findings suggest high endogenous relaxin-3 expression may be associated with higher intake of rewarding substances, rather than its expression being regulated in response to their intake, consistent with an active role for the relaxin-3/RXFP3 system in modulating ingestive and alcohol-related behaviours.
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Affiliation(s)
- P J Ryan
- The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia; Florey Department of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia
| | - E V Krstew
- The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - M Sarwar
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Parkville, Victoria, Australia; Department of Pharmacology, Monash University, Clayton, Victoria, Australia
| | - A L Gundlach
- The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia; Florey Department of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia; Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Victoria, Australia
| | - A J Lawrence
- The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia; Florey Department of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia.
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56
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Wang XY, Guo YQ, Zhang WJ, Shao XX, Liu YL, Xu ZG, Guo ZY. The electrostatic interactions of relaxin-3 with receptor RXFP4 and the influence of its B-chain C-terminal conformation. FEBS J 2014; 281:2927-36. [PMID: 24802387 DOI: 10.1111/febs.12830] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 04/24/2014] [Accepted: 05/01/2014] [Indexed: 11/27/2022]
Affiliation(s)
- Xin-Yi Wang
- Institute of Protein Research; College of Life Sciences and Technology; Tongji University; Shanghai China
- Central Laboratory; Shanghai East Hospital; Tongji University School of Medicine; China
| | - Yu-Qi Guo
- Institute of Protein Research; College of Life Sciences and Technology; Tongji University; Shanghai China
| | - Wei-Jie Zhang
- Institute of Protein Research; College of Life Sciences and Technology; Tongji University; Shanghai China
| | - Xiao-Xia Shao
- Institute of Protein Research; College of Life Sciences and Technology; Tongji University; Shanghai China
| | - Ya-Li Liu
- Central Laboratory; Shanghai East Hospital; Tongji University School of Medicine; China
| | - Zeng-Guang Xu
- Central Laboratory; Shanghai East Hospital; Tongji University School of Medicine; China
| | - Zhan-Yun Guo
- Institute of Protein Research; College of Life Sciences and Technology; Tongji University; Shanghai China
- Central Laboratory; Shanghai East Hospital; Tongji University School of Medicine; China
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57
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Smith CM, Chua BE, Zhang C, Walker AW, Haidar M, Hawkes D, Shabanpoor F, Hossain MA, Wade JD, Rosengren KJ, Gundlach AL. Central injection of relaxin-3 receptor (RXFP3) antagonist peptides reduces motivated food seeking and consumption in C57BL/6J mice. Behav Brain Res 2014; 268:117-26. [PMID: 24681162 DOI: 10.1016/j.bbr.2014.03.037] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Revised: 03/17/2014] [Accepted: 03/18/2014] [Indexed: 01/10/2023]
Abstract
Behavioural arousal in mammals is regulated by various interacting central monoamine- and peptide-neurotransmitter/receptor systems, which function to maintain awake, alert and active states required for performance of goal-directed activities essential for survival, including food seeking. Existing anatomical and functional evidence suggests the highly-conserved neuropeptide, relaxin-3, which signals via its cognate Gi/o-protein coupled receptor, RXFP3, contributes to behavioural arousal and feeding behaviour in rodents. In studies to investigate this possibility further, adult male C57BL/6J mice were treated with the selective RXFP3 antagonist peptides, R3(B1-22)R/I5(A) and R3(B1-22)R, and motivated food seeking and consumption was assessed as a reflective output of behavioural arousal. Compared to vehicle treatment, intracerebroventricular (icv) injection of RXFP3 antagonists reduced: (i) food anticipatory activity before meal time during food restriction; (ii) consumption of highly palatable food; (iii) consumption of regular chow during the initial dark phase, and; (iv) consumption of regular chow after mild (∼4-h) food deprivation. Effects were not due to sedation and appeared to be specifically mediated via antagonism of relaxin-3/RXFP3 signalling, as RXFP3 antagonist treatment did not alter locomotor activity in wild-type mice or reduce palatable food intake in relaxin-3 deficient (knock-out) mice. Notably, in contrast to similar studies in the rat, icv injection of RXFP3 agonists and infusion into the paraventricular hypothalamic nucleus did not increase food consumption in mice, suggesting species differences in relaxin-3/RXFP3-related signalling networks. Together, our data provide evidence that endogenous relaxin-3/RXFP3 signalling promotes motivated food seeking and consumption, and in light of the established biological and translational importance of other arousal systems, relaxin-3/RXFP3 networks warrant further experimental investigation.
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Affiliation(s)
- Craig M Smith
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia; Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia
| | - Berenice E Chua
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia
| | - Cary Zhang
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia; Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia
| | - Andrew W Walker
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia; Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia
| | - Mouna Haidar
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia; Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia
| | - David Hawkes
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia
| | - Fazel Shabanpoor
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia
| | - Mohammad Akhter Hossain
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia; Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia; School of Chemistry, The University of Melbourne, Melbourne, VIC, Australia
| | - John D Wade
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia; Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia; School of Chemistry, The University of Melbourne, Melbourne, VIC, Australia
| | - K Johan Rosengren
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Andrew L Gundlach
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia; Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia; Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC, Australia.
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58
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Smith CM, Walker AW, Hosken IT, Chua BE, Zhang C, Haidar M, Gundlach AL. Relaxin-3/RXFP3 networks: an emerging target for the treatment of depression and other neuropsychiatric diseases? Front Pharmacol 2014; 5:46. [PMID: 24711793 PMCID: PMC3968750 DOI: 10.3389/fphar.2014.00046] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 02/28/2014] [Indexed: 12/17/2022] Open
Abstract
Animal and clinical studies of gene-environment interactions have helped elucidate the mechanisms involved in the pathophysiology of several mental illnesses including anxiety, depression, and schizophrenia; and have led to the discovery of improved treatments. The study of neuropeptides and their receptors is a parallel frontier of neuropsychopharmacology research and has revealed the involvement of several peptide systems in mental illnesses and identified novel targets for their treatment. Relaxin-3 is a newly discovered neuropeptide that binds, and activates the G-protein coupled receptor, RXFP3. Existing anatomical and functional evidence suggests relaxin-3 is an arousal transmitter which is highly responsive to environmental stimuli, particularly neurogenic stressors, and in turn modulates behavioral responses to these stressors and alters key neural processes, including hippocampal theta rhythm and associated learning and memory. Here, we review published experimental data on relaxin-3/RXFP3 systems in rodents, and attempt to highlight aspects that are relevant and/or potentially translatable to the etiology and treatment of major depression and anxiety. Evidence pertinent to autism spectrum and metabolism/eating disorders, or related psychiatric conditions, is also discussed. We also nominate some key experimental studies required to better establish the therapeutic potential of this intriguing neuromodulatory signaling system, including an examination of the impact of RXFP3 agonists and antagonists on the overall activity of distinct or common neural substrates and circuitry that are identified as dysfunctional in these debilitating brain diseases.
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Affiliation(s)
- Craig M Smith
- Peptide Neurobiology Laboratory, Neuropeptides Division, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne VIC, Australia ; Florey Department of Neuroscience and Mental Health, The University of Melbourne VIC, Australia
| | - Andrew W Walker
- Peptide Neurobiology Laboratory, Neuropeptides Division, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne VIC, Australia ; Florey Department of Neuroscience and Mental Health, The University of Melbourne VIC, Australia
| | - Ihaia T Hosken
- Peptide Neurobiology Laboratory, Neuropeptides Division, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne VIC, Australia ; Florey Department of Neuroscience and Mental Health, The University of Melbourne VIC, Australia
| | - Berenice E Chua
- Peptide Neurobiology Laboratory, Neuropeptides Division, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne VIC, Australia
| | - Cary Zhang
- Peptide Neurobiology Laboratory, Neuropeptides Division, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne VIC, Australia ; Florey Department of Neuroscience and Mental Health, The University of Melbourne VIC, Australia
| | - Mouna Haidar
- Peptide Neurobiology Laboratory, Neuropeptides Division, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne VIC, Australia ; Florey Department of Neuroscience and Mental Health, The University of Melbourne VIC, Australia
| | - Andrew L Gundlach
- Peptide Neurobiology Laboratory, Neuropeptides Division, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne VIC, Australia ; Florey Department of Neuroscience and Mental Health, The University of Melbourne VIC, Australia ; Department of Anatomy and Neuroscience, The University of Melbourne VIC, Australia
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Zhang WJ, Wang XY, Guo YQ, Luo X, Gao XJ, Shao XX, Liu YL, Xu ZG, Guo ZY. The highly conserved negatively charged Glu141 and Asp145 of the G-protein-coupled receptor RXFP3 interact with the highly conserved positively charged arginine residues of relaxin-3. Amino Acids 2014; 46:1393-402. [DOI: 10.1007/s00726-014-1705-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 02/20/2014] [Indexed: 10/25/2022]
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60
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Shabanpoor F, Bathgate RAD, Wade JD, Hossain MA. C-terminus of the B-chain of relaxin-3 is important for receptor activity. PLoS One 2013; 8:e82567. [PMID: 24349312 PMCID: PMC3859608 DOI: 10.1371/journal.pone.0082567] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 10/24/2013] [Indexed: 01/23/2023] Open
Abstract
Human relaxin-3 is a neuropeptide that is structurally similar to human insulin with two chains (A and B) connected by three disulfide bonds. It is expressed primarily in the brain and has modulatory roles in stress and anxiety, feeding and metabolism, and arousal and behavioural activation. Structure-activity relationship studies have shown that relaxin-3 interacts with its cognate receptor RXFP3 primarily through its B-chain and that its A-chain does not have any functional role. In this study, we have investigated the effect of modification of the B-chain C-terminus on the binding and activity of the peptide. We have chemically synthesised and characterized H3 relaxin as C-termini acid (both A and B chains having free C-termini; native form) and amide forms (both chains’ C-termini were amidated). We have confirmed that the acid form of the peptide is more potent than its amide form at both RXFP3 and RXFP4 receptors. We further investigated the effects of amidation at the C-terminus of individual chains. We report here for the first time that amidation at the C-terminus of the B-chain of H3 relaxin leads to significant drop in the binding and activity of the peptide at RXFP3/RXFP4 receptors. However, modification of the A-chain C-terminus does not have any effect on the activity. We have confirmed using circular dichroism spectroscopy that there is no secondary structural change between the acid and amide form of the peptide, and it is likely that it is the local C-terminal carboxyl group orientation that is crucial for interacting with the receptors.
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Affiliation(s)
- Fazel Shabanpoor
- Florey Institute for Neuroscience & Mental Health, University of Melbourne, Melbourne, Victoria, Australia
- School of Chemistry, University of Melbourne, Melbourne, Victoria, Australia
| | - Ross A. D. Bathgate
- Florey Institute for Neuroscience & Mental Health, University of Melbourne, Melbourne, Victoria, Australia
- Florey Department of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
- Department of Biochemistry and Molecular Biology, University of Melbourne, Melbourne, Victoria, Australia
| | - John D. Wade
- Florey Institute for Neuroscience & Mental Health, University of Melbourne, Melbourne, Victoria, Australia
- School of Chemistry, University of Melbourne, Melbourne, Victoria, Australia
- Florey Department of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
- * E-mail: (MAH); (JDW)
| | - Mohammed Akhter Hossain
- Florey Institute for Neuroscience & Mental Health, University of Melbourne, Melbourne, Victoria, Australia
- School of Chemistry, University of Melbourne, Melbourne, Victoria, Australia
- Florey Department of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
- * E-mail: (MAH); (JDW)
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61
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Abstract
Relapse and hazardous drinking represent the most difficult clinical problems in treating patients with alcohol use disorders. Using a rat model of alcohol use and alcohol-seeking, we demonstrated that central administration of peptide antagonists for relaxin family peptide 3 receptor (RXFP3), the cognate receptor for the highly conserved neuropeptide, relaxin-3, decreased self-administration of alcohol in a dose-related manner and attenuated cue- and stress-induced reinstatement following extinction. By comparison, RXFP3 antagonist treatment did not significantly attenuate self-administration or reinstatement of sucrose-seeking, suggesting a selective effect for alcohol. RXFP3 is densely expressed in the stress-responsive bed nucleus of the stria terminalis, and bilateral injections of RXFP3 antagonist into the bed nucleus of the stria terminalis significantly decreased self-administration and stress-induced reinstatement of alcohol, suggesting that this brain region may, at least in part, mediate the effects of RXFP3 antagonism. RXFP3 antagonist treatment had no effect on general ingestive behavior, activity, or procedural memory for lever pressing in the paradigms assessed. These data suggest that relaxin-3/RXFP3 signaling regulates alcohol intake and relapse-like behavior, adding to current knowledge of the brain chemistry of reward-seeking.
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Dehghan F, Haerian BS, Muniandy S, Yusof A, Dragoo JL, Salleh N. The effect of relaxin on the musculoskeletal system. Scand J Med Sci Sports 2013; 24:e220-9. [PMID: 24283470 PMCID: PMC4282454 DOI: 10.1111/sms.12149] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/02/2013] [Indexed: 12/14/2022]
Abstract
Relaxin is a hormone structurally related to insulin and insulin-like growth factor, which exerts its regulatory effect on the musculoskeletal and other systems through binding to its receptor in various tissues, mediated by different signaling pathways. Relaxin alters the properties of cartilage and tendon by activating collagenase. This hormone is also involved in bone remodeling and healing of injured ligaments and skeletal muscle. In this review, we have summarized the literature on the effect of relaxin in musculoskeletal system to provide a broad perspective for future studies in this field.
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Affiliation(s)
- F Dehghan
- Department of Physiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - B S Haerian
- Department of Pharmacology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - S Muniandy
- Department of Molecular Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - A Yusof
- Department of Physiology, Sports Center, University of Malaya, Kuala Lumpur, Malaysia
| | - J L Dragoo
- Department of Orthopaedic Surgery, Stanford University, Redwood City, California, USA
| | - N Salleh
- Department of Physiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
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63
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Lee LC, Rajkumar R, Dawe GS. Selective lesioning of nucleus incertus with corticotropin releasing factor-saporin conjugate. Brain Res 2013; 1543:179-90. [PMID: 24287211 DOI: 10.1016/j.brainres.2013.11.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 11/06/2013] [Accepted: 11/19/2013] [Indexed: 11/19/2022]
Abstract
The nucleus incertus (NI), a brainstem nucleus found in the pontine periventricular grey, is the primary source of the neuropeptide relaxin-3 in the mammalian brain. The NI neurons have also been previously reported to express several receptors and neurotransmitters, including corticotropin releasing hormone receptor 1 (CRF₁) and gamma-aminobutyric acid (GABA). The NI projects widely to putative neural correlates of stress, anxiety, depression, feeding behaviour, arousal and cognition leading to speculation that it might be involved in several neuropsychiatric conditions. On the premise that relaxin-3 expressing neurons in the NI predominantly co-express CRF₁ receptors, a novel method for selective ablation of the rat brain NI neurons using corticotropin releasing factor (CRF)-saporin conjugate is described. In addition to a behavioural deficit in the fear conditioning paradigm, reverse transcriptase polymerase chain reaction (RT-PCR), western blotting (WB) and immunofluorescence labelling (IF) techniques were used to confirm the NI lesion. We observed a selective and significant loss of CRF₁ expressing cells, together with a consistent decrease in relaxin-3 and GAD65 expression. The significant ablation of relaxin-3 positive neurons of the NI achieved by this lesioning approach is a promising model to explore the neuropsychopharmacological implications of NI/relaxin-3 in behavioural neuroscience.
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Affiliation(s)
- Liying Corinne Lee
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, 117597, Singapore; Neurobiology and Ageing Programme, Life Sciences Institute, National University of Singapore, 117456, Singapore; Singapore Institute for Neurotechnology (SINAPSE), 117456, Singapore
| | - Ramamoorthy Rajkumar
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, 117597, Singapore; Neurobiology and Ageing Programme, Life Sciences Institute, National University of Singapore, 117456, Singapore; Singapore Institute for Neurotechnology (SINAPSE), 117456, Singapore
| | - Gavin Stewart Dawe
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, 117597, Singapore; Neurobiology and Ageing Programme, Life Sciences Institute, National University of Singapore, 117456, Singapore; Singapore Institute for Neurotechnology (SINAPSE), 117456, Singapore.
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64
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Fiengo M, del Gaudio R, Iazzetti G, Di Giaimo R, Minucci S, Aniello F, Donizetti A. Developmental expression pattern of two zebrafish rxfp3 paralogue genes. Dev Growth Differ 2013; 55:766-75. [PMID: 24147554 DOI: 10.1111/dgd.12093] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Revised: 09/09/2013] [Accepted: 09/09/2013] [Indexed: 12/15/2022]
Abstract
In mammals, the RXFP3 is the cognate receptor of the relaxin-3 peptide (RLN3). In teleosts, many different orthologue genes for RXFP3 are present. In particular, two paralogue genes, rxfp3-2a and rxfp3-2b, likely encode the receptors for the Rln3a peptide. The transcription of these two rxfp3 genes is differentially regulated early during zebrafish embryogenesis. Indeed, reverse transcription-polymerase chain reaction analyses show that the rxfp3-2b transcript is always present during embryo development, while the rxfp3-2a transcript is detectable only at larval stage. By in situ hybridization experiments on embryos and larvae, the rxfp3-2b transcript was revealed in the brain and in the retinal ganglion cell layer and thymus. Particularly in the brain, many territories are involved in the rxfp3-2b expression, among them the optic tectum, thalamus, preoptic area, different nerve nuclei, habenula and pineal gland. The RXFP3 spatiotemporal expression pattern appears to be conserved between Danio rerio and mammals, as also previously showed for the corresponding ligand, the RLN3. Interestingly, the brain areas expressing the rxfp3-2b receptor gene are involved in the visual system, emotional behaviors and circadian rhythm and could be functionally related to the neurotransmitter Rln3a-expressing territories.
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Affiliation(s)
- Marcella Fiengo
- Department of Biology, University of Naples Federico II, Via Cinthia, 80126, Italy
| | - Rosanna del Gaudio
- Department of Biology, University of Naples Federico II, Via Cinthia, 80126, Italy
| | - Giovanni Iazzetti
- Department of Biology, University of Naples Federico II, Via Cinthia, 80126, Italy
| | - Rossella Di Giaimo
- Department of Biology, University of Naples Federico II, Via Cinthia, 80126, Italy
| | - Sergio Minucci
- Department of Experimental Medicine, Second University of Naples, Via Costantinopoli 16, Naples, 80138, Italy
| | - Francesco Aniello
- Department of Biology, University of Naples Federico II, Via Cinthia, 80126, Italy
| | - Aldo Donizetti
- Department of Biology, University of Naples Federico II, Via Cinthia, 80126, Italy
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65
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Ganella DE, Ma S, Gundlach AL. Relaxin-3/RXFP3 Signaling and Neuroendocrine Function - A Perspective on Extrinsic Hypothalamic Control. Front Endocrinol (Lausanne) 2013; 4:128. [PMID: 24065955 PMCID: PMC3776160 DOI: 10.3389/fendo.2013.00128] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Accepted: 09/02/2013] [Indexed: 01/08/2023] Open
Abstract
Complex neural circuits within the hypothalamus that govern essential autonomic processes and associated behaviors signal using amino acid and monoamine transmitters and a variety of neuropeptide (hormone) modulators, often via G-protein coupled receptors (GPCRs) and associated cellular pathways. Relaxin-3 is a recently identified neuropeptide that is highly conserved throughout evolution. Neurons expressing relaxin-3 are located in the brainstem, but broadly innervate the entire limbic system including the hypothalamus. Extensive anatomical data in rodents and non-human primate, and recent regulatory and functional data, suggest relaxin-3 signaling via its cognate GPCR, RXFP3, has a broad range of effects on neuroendocrine function associated with stress responses, feeding and metabolism, motivation and reward, and possibly sexual behavior and reproduction. Therefore, this article aims to highlight the growing appreciation of the relaxin-3/RXFP3 system as an important "extrinsic" regulator of the neuroendocrine axis by reviewing its neuroanatomy and its putative roles in arousal-, stress-, and feeding-related behaviors and links to associated neural substrates and signaling networks. Current evidence identifies RXFP3 as a potential therapeutic target for treatment of neuroendocrine disorders and related behavioral dysfunction.
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Affiliation(s)
- Despina E. Ganella
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia
- Department of Biochemistry and Molecular Biology, The University of Melbourne, Melbourne, VIC, Australia
| | - Sherie Ma
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia
| | - Andrew L. Gundlach
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia
- Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC, Australia
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Ma S, Blasiak A, Olucha-Bordonau FE, Verberne AJM, Gundlach AL. Heterogeneous responses of nucleus incertus neurons to corticotrophin-releasing factor and coherent activity with hippocampal theta rhythm in the rat. J Physiol 2013; 591:3981-4001. [PMID: 23671163 DOI: 10.1113/jphysiol.2013.254300] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The nucleus incertus (NI) of the rat hindbrain is a putative node in the ascending control of the septohippocampal system and hippocampal theta rhythm and is stress and arousal responsive. NI contains GABA neurons that express multiple neuropeptides, including relaxin-3 (RLN3) and neuropeptide receptors, including corticotrophin-releasing factor receptor-1 (CRF-R1), but the precise anatomical and physiological characteristics of NI neurons are unclear. Therefore, we examined the firing properties of NI neurons and their responses to CRF, the correlation of these responses with occurrence of relaxin-3, and NI neuron morphology in the rat. Most NI neurons excited by intracerebroventricular CRF infusion were RLN3-positive (9 of 10), whereas all inhibited cells were RLN3-negative (8 of 8). The spontaneous firing of RLN3 (n = 6) but not non-RLN3 neurons (n = 6) was strongly modulated and phase-locked with the initial ascending phase of hippocampal theta oscillations. In brain slices, the majority of recorded NI neurons (15 of 19) displayed excitatory responses to CRF, which uniformly increased action potential frequency and membrane potential depolarization in the presence of tetrodotoxin, indicating a direct, postsynaptic action of CRF on NI neurons. This excitation was associated with reduction in the slow component of afterhyperpolarization and a strong depolarization. Quantitative analysis in naïve rats of validated CRF-R1, RLN3 and neuronal nuclear antigen (NeuN) immunoreactivity revealed 52% of NI neurons as CRF-R1 positive, of which 53% were RLN3 positive, while 48% of NI neurons lacked CRF-R1 and RLN3. All RLN3 neurons expressed CRF-R1. CRF neurons that projected to the NI were identified in lateral preoptic hypothalamus, but not in paraventricular hypothalamus, bed nucleus of stria terminalis or central amygdala. Our findings suggest NI is an important site for CRF modulation of hippocampal theta rhythm via effects on GABA/RLN3 transmission.
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Affiliation(s)
- Sherie Ma
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Victoria 3010, Australia.
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67
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Rajkumar R, See LKY, Dawe GS. Acute antipsychotic treatments induce distinct c-Fos expression patterns in appetite-related neuronal structures of the rat brain. Brain Res 2013; 1508:34-43. [DOI: 10.1016/j.brainres.2013.02.050] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 02/23/2013] [Accepted: 02/28/2013] [Indexed: 10/27/2022]
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Chemical synthesis and orexigenic activity of rat/mouse relaxin-3. Amino Acids 2013; 44:1529-36. [PMID: 23456488 DOI: 10.1007/s00726-013-1478-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Accepted: 02/18/2013] [Indexed: 10/27/2022]
Abstract
The insulin-like peptide, relaxin-3 was first identified just a decade ago via a genomic database search and is now recognized to be a key neuropeptide with several roles including the regulation of arousal, stress responses and neuroendocrine homeostasis. It also has significant potential as a drug to treat stress and obesity. Its actions are mediated via its cognate G protein-coupled receptor, RXFP3, which is found in abundant numbers in the brain. However, much remains to be determined with respect to the mechanism of neurological action of this peptide. Consequently, the chemical synthesis of the rat and mouse (which share identical primary structures) two-chain, three disulfide peptide was undertaken and the resulting peptide subjected to detailed in vitro and in vivo assay. Use of efficient solid-phase synthesis methods provided the two regioselectively S-protected A- and B-chains which were readily combined via sequential disulfide bond formation. The synthetic rat/mouse relaxin-3 was obtained in high purity and good overall yield. It demonstrated potent orexigenic activity in rats in that central intracerebroventricular infusion led to significantly increased food intake and water drinking.
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69
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Bathgate RAD, Halls ML, van der Westhuizen ET, Callander GE, Kocan M, Summers RJ. Relaxin family peptides and their receptors. Physiol Rev 2013; 93:405-80. [PMID: 23303914 DOI: 10.1152/physrev.00001.2012] [Citation(s) in RCA: 379] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
There are seven relaxin family peptides that are all structurally related to insulin. Relaxin has many roles in female and male reproduction, as a neuropeptide in the central nervous system, as a vasodilator and cardiac stimulant in the cardiovascular system, and as an antifibrotic agent. Insulin-like peptide-3 (INSL3) has clearly defined specialist roles in male and female reproduction, relaxin-3 is primarily a neuropeptide involved in stress and metabolic control, and INSL5 is widely distributed particularly in the gastrointestinal tract. Although they are structurally related to insulin, the relaxin family peptides produce their physiological effects by activating a group of four G protein-coupled receptors (GPCRs), relaxin family peptide receptors 1-4 (RXFP1-4). Relaxin and INSL3 are the cognate ligands for RXFP1 and RXFP2, respectively, that are leucine-rich repeat containing GPCRs. RXFP1 activates a wide spectrum of signaling pathways to generate second messengers that include cAMP and nitric oxide, whereas RXFP2 activates a subset of these pathways. Relaxin-3 and INSL5 are the cognate ligands for RXFP3 and RXFP4 that are closely related to small peptide receptors that when activated inhibit cAMP production and activate MAP kinases. Although there are still many unanswered questions regarding the mode of action of relaxin family peptides, it is clear that they have important physiological roles that could be exploited for therapeutic benefit.
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Affiliation(s)
- R A D Bathgate
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences & Department of Pharmacology, Monash University, Victoria, Australia
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70
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Blasiak A, Blasiak T, Lewandowski MH, Hossain MA, Wade JD, Gundlach AL. Relaxin-3 innervation of the intergeniculate leaflet of the rat thalamus - neuronal tract-tracing and in vitro electrophysiological studies. Eur J Neurosci 2013; 37:1284-94. [PMID: 23432696 DOI: 10.1111/ejn.12155] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 01/16/2013] [Indexed: 11/29/2022]
Abstract
Behavioural state is controlled by a range of neural systems that are sensitive to internal and external stimuli. The relaxin-3 and relaxin family peptide receptor 3 (RXFP3) system has emerged as a putative ascending arousal network with putative involvement in regulation of stress responses, neuroendocrine control, feeding and metabolism, circadian activity and cognition. Relaxin-3/γ-aminobutyric acid neuron populations have been identified in the nucleus incertus, pontine raphe nucleus, periaqueductal grey (PAG) and an area dorsal to the substantia nigra. Relaxin-3-positive fibres/terminals densely innervate arousal-related structures in the brainstem, hypothalamus and limbic forebrain, but the functional significance of the heterogeneous relaxin-3 neuron distribution and its inputs to specific brain areas are unclear. Therefore, in this study, we used neuronal tract-tracing and immunofluorescence staining to explore the source of the dense relaxin-3 innervation of the intergeniculate leaflet (IGL) of the thalamus, a component of the neural circadian timing system. Confocal microscopy analysis revealed that relaxin-3-positive neurons retrogradely labelled from the IGL were predominantly present in the PAG and these neurons expressed corticotropin-releasing factor receptor-like immunoreactivity. Subsequently, whole-cell patch-clamp recordings revealed heterogeneous effects of RXFP3 activation in the IGL by the RXFP3 agonist, relaxin-3 B-chain/insulin-like peptide-5 A-chain (R3/I5). Identified, neuropeptide Y-positive IGL neurons, known to influence suprachiasmatic nucleus activity, were excited by R3/I5, whereas neurons of unidentified neurotransmitter content were either depolarized or displayed a decrease in action potential firing and/or membrane potential hyperpolarization. Our data identify a PAG to IGL relaxin-3/RXFP3 pathway that might convey stress-related information to key elements of the circadian system and influence behavioural state rhythmicity.
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Affiliation(s)
- Anna Blasiak
- Department of Neurophysiology and Chronobiology, Jagiellonian University, Gronostajowa 9, 30-387, Krakow, Poland.
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Cernaro V, Lacquaniti A, Lupica R, Buemi A, Trimboli D, Giorgianni G, Bolignano D, Buemi M. Relaxin: new pathophysiological aspects and pharmacological perspectives for an old protein. Med Res Rev 2013; 34:77-105. [PMID: 23401142 DOI: 10.1002/med.21277] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Human relaxin-2 (hereafter simply defined as "relaxin") is a 6-kDa peptidic hormone best known for the physiological role played during pregnancy in the growth and differentiation of the reproductive tract and in the renal and systemic hemodynamic changes. This factor can also be involved in the pathophysiology of arterial hypertension and heart failure, in the molecular pathways of fibrosis and cancer, and in angiogenesis and bone remodeling. It belongs to the relaxin peptide family, whose members comprehensively exert numerous effects through interaction with different types of receptors, classified as relaxin family peptide (RXFP) receptors (RXFP1, RXFP2, RXFP3, RXFP4). Research looks toward the in-depth examination and complete understanding of relaxin in its various pleiotropic actions. The intent is to evaluate the likelihood of employing this substance for therapeutic purposes, for instance in diseases where a deficit could be part of the underlying pathophysiological mechanisms, also avoiding any adverse effect. Relaxin is already being considered as a promising drug, especially in acute heart failure. A careful study of the different RXFPs and their receptors and the comprehension of all biological activities of these hormones will probably provide new drugs with a potential wide range of therapeutic applications in the near future.
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Affiliation(s)
- Valeria Cernaro
- Department of Internal Medicine, University of Messina, Via Consolare Valeria, 1, 98100, Italy
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Ghattas MH, Mehanna ET, Mesbah NM, Abo-Elmatty DM. Relaxin-3 is associated with metabolic syndrome and its component traits in women. Clin Biochem 2013; 46:45-8. [DOI: 10.1016/j.clinbiochem.2012.09.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 08/24/2012] [Accepted: 09/16/2012] [Indexed: 11/28/2022]
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Bathgate RAD, Oh MHY, Ling WJJ, Kaas Q, Hossain MA, Gooley PR, Rosengren KJ. Elucidation of relaxin-3 binding interactions in the extracellular loops of RXFP3. Front Endocrinol (Lausanne) 2013; 4:13. [PMID: 23440673 PMCID: PMC3579193 DOI: 10.3389/fendo.2013.00013] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 01/31/2013] [Indexed: 12/28/2022] Open
Abstract
Relaxin-3 is a highly conserved neuropeptide in vertebrate species and binds to the Class A G protein-coupled receptor (GPCR) RXFP3. Relaxin-3 is involved in a wide range of behaviors, including feeding, stress responses, arousal, and cognitive processes and therefore targeting of RXFP3 may be relevant for a range of neurological diseases. Structural knowledge of RXFP3 and its interaction with relaxin-3 would both increase our understanding of ligand recognition in GPCRs that respond to protein ligands and enable acceleration of the design of drug leads. In this study we have used comparative sequence analysis, molecular modeling and receptor mutagenesis to investigate the binding site of the native ligand human relaxin-3 (H3 relaxin) on the human RXFP3 receptor. Previous structure function studies have demonstrated that arginine residues in the H3 relaxin B-chain are critical for binding interactions with the receptor extracellular loops and/or N-terminal domain. Hence we have concentrated on determining the ligand interacting sites in these domains and have focused on glutamic (E) and aspartic acid (D) residues in these regions that may form electrostatic interactions with these critical arginine residues. Conserved D/E residues identified from vertebrate species multiple sequence alignments were mutated to Ala in human RXFP3 to test the effect of loss of amino acid side chain on receptor binding using a Eu-labeled relaxin-3 agonist. Finally data from mutagenesis experiments have been used in ligand docking simulations to a homology model of human RXFP3 based on the peptide-bound chemokine receptor 4 (CXCR4) structure. These studies have resulted in a model of the relaxin-3 interaction with RXFP3 which will inform further interrogation of the agonist binding site.
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Affiliation(s)
- Ross A. D. Bathgate
- Florey Institute of Neuroscience and Mental Health, University of MelbourneParkville, VIC, Australia
- Department of Biochemistry and Molecular Biology, University of MelbourneParkville, VIC, Australia
- *Correspondence: Ross A. D. Bathgate, Florey Institute of Neuroscience and Mental Health, University of Melbourne, 3010 Victoria, Australia. e-mail:
| | - Maria H. Y. Oh
- Florey Institute of Neuroscience and Mental Health, University of MelbourneParkville, VIC, Australia
- Department of Biochemistry and Molecular Biology, University of MelbourneParkville, VIC, Australia
| | - W. J. Jason Ling
- Florey Institute of Neuroscience and Mental Health, University of MelbourneParkville, VIC, Australia
- Department of Biochemistry and Molecular Biology, University of MelbourneParkville, VIC, Australia
| | - Quentin Kaas
- Institute for Molecular Bioscience, The University of QueenslandBrisbane, QLD, Australia
| | - M. Akhter Hossain
- Florey Institute of Neuroscience and Mental Health, University of MelbourneParkville, VIC, Australia
- School of Chemistry, University of MelbourneParkville, VIC, Australia
| | - Paul R. Gooley
- Department of Biochemistry and Molecular Biology, University of MelbourneParkville, VIC, Australia
| | - K. Johan Rosengren
- School of Biomedical Sciences, The University of QueenslandBrisbane, QLD, Australia
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Ganella DE, Callander GE, Ma S, Bye CR, Gundlach AL, Bathgate RAD. Modulation of feeding by chronic rAAV expression of a relaxin-3 peptide agonist in rat hypothalamus. Gene Ther 2012; 20:703-16. [PMID: 23135160 DOI: 10.1038/gt.2012.83] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 08/30/2012] [Accepted: 09/20/2012] [Indexed: 11/09/2022]
Abstract
Relaxin-3 is a neuropeptide that is abundantly expressed by discrete brainstem neuron populations that broadly innervate forebrain areas rich in the relaxin-3 G-protein-coupled-receptor, RXFP3. Acute and subchronic central administration of synthetic relaxin-3 or an RXFP3-selective agonist peptide, R3/I5, increase feeding and body weight in rats. Intrahypothalamic injection of relaxin-3 also increases feeding. In this study, we developed a recombinant adeno-associated virus 1/2 (rAAV1/2) vector that drives expression and constitutive secretion of bioactive R3/I5 and assessed the effect of intrahypothalamic injections on daily food intake and body weight gain in adult male rats over 8 weeks. In vitro testing revealed that the vector rAAV1/2-fibronectin (FIB)-R3/I5 directs the constitutive secretion of bioactive R3/I5 peptide. Bilateral injection of rAAV1/2-FIB-R3/I5 vector into the paraventricular nucleus produced an increase in daily food intake and body weight gain (P<0.01, ~23%, respectively), relative to control treatment. In a separate cohort of rats, quantitative polymerase chain reaction analysis of hypothalamic mRNA revealed strong expression of R3/I5 transgene at 3 months post-rAAV1/2-FIB-R3/I5 infusion. Levels of mRNA transcripts for the relaxin-3 receptor RXFP3, the hypothalamic 'feeding' peptides neuropeptide Y, AgRP and POMC, and the reproductive hormone, GnRH, were all similar to control, whereas vasopressin and oxytocin (OT) mRNA levels were reduced by ~25% (P=0.051) and ~50% (P<0.005), respectively, in rAAV1/2-FIB-R3/I5-treated rats (at 12 weeks, n=9/8 rats per group). These data demonstrate for the first time that R3/I5 is effective in modulating feeding in the rat by chronic hypothalamic RXFP3 activation and suggest a potential underlying mechanism involving altered OT signalling. Importantly, there was no desensitization of the feeding response over the treatment period and no apparent deleterious health effects, indicating that targeting the relaxin-3-RXFP3 system may be an effective long-term therapy for eating disorders.
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Affiliation(s)
- D E Ganella
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia
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75
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Design, recombinant expression and convenient A-chain N-terminal europium-labelling of a fully active human relaxin-3 analogue. FEBS J 2012; 279:1505-12. [DOI: 10.1111/j.1742-4658.2012.08550.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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76
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Alvarez-Jaimes L, Sutton SW, Nepomuceno D, Motley ST, Cik M, Stocking E, Shoblock J, Bonaventure P. In vitro pharmacological characterization of RXFP3 allosterism: an example of probe dependency. PLoS One 2012; 7:e30792. [PMID: 22347403 PMCID: PMC3274524 DOI: 10.1371/journal.pone.0030792] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Accepted: 12/29/2011] [Indexed: 11/18/2022] Open
Abstract
Recent findings suggest that the relaxin-3 neural network may represent a new ascending arousal pathway able to modulate a range of neural circuits including those affecting circadian rhythm and sleep/wake states, spatial and emotional memory, motivation and reward, the response to stress, and feeding and metabolism. Therefore, the relaxin-3 receptor (RXFP3) is a potential therapeutic target for the treatment of various CNS diseases. Here we describe a novel selective RXFP3 receptor positive allosteric modulator (PAM), 3-[3,5-Bis(trifluoromethyl)phenyl]-1-(3,4-dichlorobenzyl)-1-[2-(5-methoxy-1H-indol-3-yl)ethyl]urea (135PAM1). Calcium mobilization and cAMP accumulation assays in cell lines expressing the cloned human RXFP3 receptor show the compound does not directly activate RXFP3 receptor but increases functional responses to amidated relaxin-3 or R3/I5, a chimera of the INSL5 A chain and the Relaxin-3 B chain. 135PAM1 increases calcium mobilization in the presence of relaxin-3(NH2) and R3/I5(NH2) with pEC50 values of 6.54 (6.46 to 6.64) and 6.07 (5.94 to 6.20), respectively. In the cAMP accumulation assay, 135PAM1 inhibits the CRE response to forskolin with a pIC50 of 6.12 (5.98 to 6.27) in the presence of a probe (10 nM) concentration of relaxin-3(NH2). 135PAM1 does not compete for binding with the orthosteric radioligand, [(125)I] R3I5 (amide), in membranes prepared from cells expressing the cloned human RXFP3 receptor. 135PAM1 is selective for RXFP3 over RXFP4, which also responds to relaxin-3. However, when using the free acid (native) form of relaxin-3 or R3/I5, 135PAM1 doesn't activate RXFP3 indicating that the compound's effect is probe dependent. Thus one can exchange the entire A-chain of the probe peptide while retaining PAM activity, but the state of the probe's c-terminus is crucial to allosteric activity of the PAM. These data demonstrate the existence of an allosteric site for modulation of this GPCR as well as the subtlety of changes in probe molecules that can affect allosteric modulation of RXFP3.
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Affiliation(s)
- Lily Alvarez-Jaimes
- Janssen Pharmaceutical Companies of Johnson & Johnson, San Diego, California, United States of America
| | - Steven W. Sutton
- Janssen Pharmaceutical Companies of Johnson & Johnson, San Diego, California, United States of America
| | - Diane Nepomuceno
- Janssen Pharmaceutical Companies of Johnson & Johnson, San Diego, California, United States of America
| | - S. Timothy Motley
- Janssen Pharmaceutical Companies of Johnson & Johnson, San Diego, California, United States of America
| | - Miroslav Cik
- Janssen Pharmaceutical Companies of Johnson & Johnson, San Diego, California, United States of America
| | - Emily Stocking
- Janssen Pharmaceutical Companies of Johnson & Johnson, San Diego, California, United States of America
| | - James Shoblock
- Janssen Pharmaceutical Companies of Johnson & Johnson, San Diego, California, United States of America
| | - Pascal Bonaventure
- Janssen Pharmaceutical Companies of Johnson & Johnson, San Diego, California, United States of America
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Ransome MI, Hannan AJ. Behavioural state differentially engages septohippocampal cholinergic and GABAergic neurons in R6/1 Huntington’s disease mice. Neurobiol Learn Mem 2012; 97:261-70. [DOI: 10.1016/j.nlm.2012.01.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 12/18/2011] [Accepted: 01/04/2012] [Indexed: 12/15/2022]
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78
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Site-specific DOTA/europium-labeling of recombinant human relaxin-3 for receptor-ligand interaction studies. Amino Acids 2011; 43:983-92. [DOI: 10.1007/s00726-011-1164-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Accepted: 11/17/2011] [Indexed: 10/14/2022]
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