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Lewis JE, Woodward OR, Nuzzaci D, Smith CA, Adriaenssens AE, Billing L, Brighton C, Phillips BU, Tadross JA, Kinston SJ, Ciabatti E, Göttgens B, Tripodi M, Hornigold D, Baker D, Gribble FM, Reimann F. Relaxin/insulin-like family peptide receptor 4 (Rxfp4) expressing hypothalamic neurons modulate food intake and preference in mice. Mol Metab 2022; 66:101604. [PMID: 36184065 PMCID: PMC9579047 DOI: 10.1016/j.molmet.2022.101604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 09/08/2022] [Accepted: 09/16/2022] [Indexed: 12/29/2022] Open
Abstract
OBJECTIVE Insulin-like peptide 5 (INSL5) signalling, through its cognate receptor relaxin/insulin-like family peptide receptor 4 (RXFP4), has been reported to be orexigenic, and the high fat diet (HFD) preference observed in wildtype mice is altered in Rxfp4 knock-out mice. In this study, we used a new Rxfp4-Cre mouse model to investigate the mechanisms underlying these observations. METHODS We generated transgenic Rxfp4-Cre mice and investigated central expression of Rxfp4 by RT-qPCR, RNAscope and intraparenchymal infusion of INSL5. Rxfp4-expressing cells were chemogenetically manipulated in global Cre-reporter mice using designer receptors exclusively activated by designer drugs (DREADDs) or after stereotactic injection of a Cre-dependent AAV-DIO-Dq-DREADD targeting a population located in the ventromedial hypothalamus (RXFP4VMH). Food intake and feeding motivation were assessed in the presence and absence of a DREADD agonist. Rxfp4-expressing cells in the hypothalamus were characterised by single-cell RNA-sequencing (scRNAseq) and the connectivity of RXFP4VMH cells was investigated using viral tracing. RESULTS Rxfp4-Cre mice displayed Cre-reporter expression in the hypothalamus. Active expression of Rxfp4 in the adult mouse brain was confirmed by RT-qPCR and RNAscope. Functional receptor expression was supported by cyclic AMP-responses to INSL5 application in ex vivo brain slices and increased HFD and highly palatable liquid meal (HPM), but not chow, intake after intra-VMH INSL5 infusion. scRNAseq of hypothalamic RXFP4 neurons defined a cluster expressing VMH markers, alongside known appetite-modulating neuropeptide receptors (Mc4r, Cckar and Nmur2). Viral tracing demonstrated RXFP4VMH neural projections to nuclei implicated in hedonic feeding behaviour. Whole body chemogenetic inhibition (Di-DREADD) of Rxfp4-expressing cells, mimicking physiological INSL5-RXFP4 Gi-signalling, increased intake of the HFD and HPM, but not chow, whilst activation (Dq-DREADD), either at whole body level or specifically within the VMH, reduced HFD and HPM intake and motivation to work for the HPM. CONCLUSION These findings identify RXFP4VMH neurons as regulators of food intake and preference, and hypothalamic RXFP4 signalling as a target for feeding behaviour manipulation.
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Affiliation(s)
- Jo E Lewis
- Wellcome Trust - MRC Institute of Metabolic Science Metabolic Research Laboratories, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK.
| | - Orla Rm Woodward
- Wellcome Trust - MRC Institute of Metabolic Science Metabolic Research Laboratories, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
| | - Danaé Nuzzaci
- Wellcome Trust - MRC Institute of Metabolic Science Metabolic Research Laboratories, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
| | - Christopher A Smith
- Wellcome Trust - MRC Institute of Metabolic Science Metabolic Research Laboratories, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
| | - Alice E Adriaenssens
- Wellcome Trust - MRC Institute of Metabolic Science Metabolic Research Laboratories, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
| | - Lawrence Billing
- Wellcome Trust - MRC Institute of Metabolic Science Metabolic Research Laboratories, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
| | - Cheryl Brighton
- Wellcome Trust - MRC Institute of Metabolic Science Metabolic Research Laboratories, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
| | - Benjamin U Phillips
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - John A Tadross
- Wellcome Trust - MRC Institute of Metabolic Science Metabolic Research Laboratories, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK; Department of Pathology, University of Cambridge, Cambridge CB2 1QP, UK
| | - Sarah J Kinston
- Department of Haematology, Wellcome and MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
| | - Ernesto Ciabatti
- Department of Haematology, Wellcome and MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
| | - Berthold Göttgens
- Department of Haematology, Wellcome and MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
| | - Marco Tripodi
- MRC Laboratory of Molecular Biology, Neurobiology Division, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - David Hornigold
- Research and Early Development Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca Ltd, Cambridge, UK
| | - David Baker
- Research and Early Development Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca Ltd, Cambridge, UK
| | - Fiona M Gribble
- Wellcome Trust - MRC Institute of Metabolic Science Metabolic Research Laboratories, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK.
| | - Frank Reimann
- Wellcome Trust - MRC Institute of Metabolic Science Metabolic Research Laboratories, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK.
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2
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Pustovit RV, Zhang X, Liew JJ, Praveen P, Liu M, Koo A, Oparija-Rogenmozere L, Ou Q, Kocan M, Nie S, Bathgate RA, Furness JB, Hossain MA. A Novel Antagonist Peptide Reveals a Physiological Role of Insulin-Like Peptide 5 in Control of Colorectal Function. ACS Pharmacol Transl Sci 2021; 4:1665-1674. [PMID: 34661082 DOI: 10.1021/acsptsci.1c00171] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Indexed: 12/23/2022]
Abstract
Insulin-like peptide 5 (INSL5), the natural ligand for the relaxin family peptide receptor 4 (RXFP4), is a gut hormone that is exclusively produced by colonic L-cells. We have recently developed an analogue of INSL5, INSL5-A13, that acts as an RXFP4 agonist in vitro and stimulates colorectal propulsion in wild-type mice but not in RXFP4-knockout mice. These results suggest that INSL5 may have a physiological role in the control of colorectal motility. To investigate this possibility, in this study we designed and developed a novel INSL5 analogue, INSL5-A13NR. This compound is a potent antagonist, without significant agonist activity, in two in vitro assays. We report here for the first time that this novel antagonist peptide blocks agonist-induced increase in colon motility in mice that express RXFP4. Our data also show that colorectal propulsion induced by intracolonic administration of bacterial products (short-chain fatty acids, SCFAs) is antagonized by INSL5-A13NR. Therefore, INSL5-A13NR is an important research tool and potential drug lead for the treatment of colon motility disorders, such as bacterial diarrheas.
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Affiliation(s)
- Ruslan V Pustovit
- The Florey Institute of Neuroscience and Mental Health; Department of Anatomy and Physiology; School of Biosciences, Melbourne Mass Spectrometry and Proteomics Facility, Bio21 Institute; Department of Biochemistry and Pharmacology; School of Chemistry; The University of Melbourne, Parkville, Victoria 3052, Australia
| | - Xiaozhou Zhang
- The Florey Institute of Neuroscience and Mental Health; Department of Anatomy and Physiology; School of Biosciences, Melbourne Mass Spectrometry and Proteomics Facility, Bio21 Institute; Department of Biochemistry and Pharmacology; School of Chemistry; The University of Melbourne, Parkville, Victoria 3052, Australia
| | - Jamie Jm Liew
- The Florey Institute of Neuroscience and Mental Health; Department of Anatomy and Physiology; School of Biosciences, Melbourne Mass Spectrometry and Proteomics Facility, Bio21 Institute; Department of Biochemistry and Pharmacology; School of Chemistry; The University of Melbourne, Parkville, Victoria 3052, Australia
| | - Praveen Praveen
- The Florey Institute of Neuroscience and Mental Health; Department of Anatomy and Physiology; School of Biosciences, Melbourne Mass Spectrometry and Proteomics Facility, Bio21 Institute; Department of Biochemistry and Pharmacology; School of Chemistry; The University of Melbourne, Parkville, Victoria 3052, Australia
| | - Mengjie Liu
- The Florey Institute of Neuroscience and Mental Health; Department of Anatomy and Physiology; School of Biosciences, Melbourne Mass Spectrometry and Proteomics Facility, Bio21 Institute; Department of Biochemistry and Pharmacology; School of Chemistry; The University of Melbourne, Parkville, Victoria 3052, Australia
| | - Ada Koo
- The Florey Institute of Neuroscience and Mental Health; Department of Anatomy and Physiology; School of Biosciences, Melbourne Mass Spectrometry and Proteomics Facility, Bio21 Institute; Department of Biochemistry and Pharmacology; School of Chemistry; The University of Melbourne, Parkville, Victoria 3052, Australia
| | - Lalita Oparija-Rogenmozere
- The Florey Institute of Neuroscience and Mental Health; Department of Anatomy and Physiology; School of Biosciences, Melbourne Mass Spectrometry and Proteomics Facility, Bio21 Institute; Department of Biochemistry and Pharmacology; School of Chemistry; The University of Melbourne, Parkville, Victoria 3052, Australia
| | - Qinghao Ou
- The Florey Institute of Neuroscience and Mental Health; Department of Anatomy and Physiology; School of Biosciences, Melbourne Mass Spectrometry and Proteomics Facility, Bio21 Institute; Department of Biochemistry and Pharmacology; School of Chemistry; The University of Melbourne, Parkville, Victoria 3052, Australia
| | - Martina Kocan
- The Florey Institute of Neuroscience and Mental Health; Department of Anatomy and Physiology; School of Biosciences, Melbourne Mass Spectrometry and Proteomics Facility, Bio21 Institute; Department of Biochemistry and Pharmacology; School of Chemistry; The University of Melbourne, Parkville, Victoria 3052, Australia
| | - Shuai Nie
- The Florey Institute of Neuroscience and Mental Health; Department of Anatomy and Physiology; School of Biosciences, Melbourne Mass Spectrometry and Proteomics Facility, Bio21 Institute; Department of Biochemistry and Pharmacology; School of Chemistry; The University of Melbourne, Parkville, Victoria 3052, Australia
| | - Ross Ad Bathgate
- The Florey Institute of Neuroscience and Mental Health; Department of Anatomy and Physiology; School of Biosciences, Melbourne Mass Spectrometry and Proteomics Facility, Bio21 Institute; Department of Biochemistry and Pharmacology; School of Chemistry; The University of Melbourne, Parkville, Victoria 3052, Australia
| | - John B Furness
- The Florey Institute of Neuroscience and Mental Health; Department of Anatomy and Physiology; School of Biosciences, Melbourne Mass Spectrometry and Proteomics Facility, Bio21 Institute; Department of Biochemistry and Pharmacology; School of Chemistry; The University of Melbourne, Parkville, Victoria 3052, Australia
| | - Mohammed Akhter Hossain
- The Florey Institute of Neuroscience and Mental Health; Department of Anatomy and Physiology; School of Biosciences, Melbourne Mass Spectrometry and Proteomics Facility, Bio21 Institute; Department of Biochemistry and Pharmacology; School of Chemistry; The University of Melbourne, Parkville, Victoria 3052, Australia
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3
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Brito LF, Oliveira HR, Houlahan K, Fonseca PA, Lam S, Butty AM, Seymour DJ, Vargas G, Chud TC, Silva FF, Baes CF, Cánovas A, Miglior F, Schenkel FS. Genetic mechanisms underlying feed utilization and implementation of genomic selection for improved feed efficiency in dairy cattle. CANADIAN JOURNAL OF ANIMAL SCIENCE 2020. [DOI: 10.1139/cjas-2019-0193] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The economic importance of genetically improving feed efficiency has been recognized by cattle producers worldwide. It has the potential to considerably reduce costs, minimize environmental impact, optimize land and resource use efficiency, and improve the overall cattle industry’s profitability. Feed efficiency is a genetically complex trait that can be described as units of product output (e.g., milk yield) per unit of feed input. The main objective of this review paper is to present an overview of the main genetic and physiological mechanisms underlying feed utilization in ruminants and the process towards implementation of genomic selection for feed efficiency in dairy cattle. In summary, feed efficiency can be improved via numerous metabolic pathways and biological mechanisms through genetic selection. Various studies have indicated that feed efficiency is heritable, and genomic selection can be successfully implemented in dairy cattle with a large enough training population. In this context, some organizations have worked collaboratively to do research and develop training populations for successful implementation of joint international genomic evaluations. The integration of “-omics” technologies, further investments in high-throughput phenotyping, and identification of novel indicator traits will also be paramount in maximizing the rates of genetic progress for feed efficiency in dairy cattle worldwide.
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Affiliation(s)
- Luiz F. Brito
- Department of Animal Sciences, Purdue University, West Lafayette, IN 47907, USA
- Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Hinayah R. Oliveira
- Department of Animal Sciences, Purdue University, West Lafayette, IN 47907, USA
- Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Kerry Houlahan
- Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Pablo A.S. Fonseca
- Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Stephanie Lam
- Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Adrien M. Butty
- Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Dave J. Seymour
- Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON N1G 2W1, Canada
- Centre for Nutrition Modelling, Department of Animal Biosciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Giovana Vargas
- Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Tatiane C.S. Chud
- Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Fabyano F. Silva
- Department of Animal Sciences, Federal University of Viçosa, Viçosa, Minas Gerais 36570-000, Brazil
| | - Christine F. Baes
- Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON N1G 2W1, Canada
- Vetsuisse Faculty, Institute of Genetics, University of Bern, Bern 3001, Switzerland
| | - Angela Cánovas
- Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Filippo Miglior
- Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Flavio S. Schenkel
- Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON N1G 2W1, Canada
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4
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Zhou Y, Connor EE, Wiggans GR, Lu Y, Tempelman RJ, Schroeder SG, Chen H, Liu GE. Genome-wide copy number variant analysis reveals variants associated with 10 diverse production traits in Holstein cattle. BMC Genomics 2018; 19:314. [PMID: 29716533 PMCID: PMC5930521 DOI: 10.1186/s12864-018-4699-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 04/18/2018] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Copy number variation (CNV) is an important type of genetic variation contributing to phenotypic differences among mammals and may serve as an alternative molecular marker to single nucleotide polymorphism (SNP) for genome-wide association study (GWAS). Recently, GWAS analysis using CNV has been applied in livestock, although few studies have focused on Holstein cattle. RESULTS We describe 191 CNV detected using intensity data from over 700,000 SNP genotypes generated with the BovineHD Genotyping BeadChip (Illumina, San Diego, CA) in 528 Holstein cows. The CNV were used for GWAS analysis of 10 important production traits of 473 cattle related to feed intake, milk quality, and female fertility, as well as 2 composite traits of net merit and productive life. In total, we detected 57 CNV associated (P < 0.05 after false discovery rate correction) with at least one of the 10 phenotypes. Focusing on feed efficiency and intake-related phenotypes of residual feed intake and dry matter intake, we detected a single CNV associated with both traits which overlaps a predicted olfactory receptor gene OR2A2 (LOC787786). Additionally, 2 CNV within the RXFP4 (relaxin/insulin like family peptide receptor 4) and 2 additional olfactory receptor gene regions, respectively, were associated with residual feed intake. The RXFP4 gene encodes a receptor for an orexigenic peptide, insulin-like peptide 5 produced by intestinal L cells, which is expressed by enteric neurons. Olfactory receptors are critical for transmitting the effects of odorants, contributing to the sense of smell, and have been implicated in participating in appetite regulation. CONCLUSIONS Our results identify CNV for genomic evaluation in Holstein cattle, and provide candidate genes, such as RXFP4, contributing to variation in feed efficiency and feed intake-related traits. These results indicate potential novel targets for manipulating feed intake-related traits of livestock.
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Affiliation(s)
- Yang Zhou
- Animal Genomics and Improvement Laboratory, BARC, USDA-ARS, 10300 Baltimore Avenue, Bldg. 306, BARC-East, Beltsville, MD, 20705, USA.,Shaanxi Key Laboratory of Agricultural Molecular Biology, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, Shaanxi, China.,Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction, Education Ministry of China, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
| | - Erin E Connor
- Animal Genomics and Improvement Laboratory, BARC, USDA-ARS, 10300 Baltimore Avenue, Bldg. 306, BARC-East, Beltsville, MD, 20705, USA
| | - George R Wiggans
- Animal Genomics and Improvement Laboratory, BARC, USDA-ARS, 10300 Baltimore Avenue, Bldg. 306, BARC-East, Beltsville, MD, 20705, USA
| | - Yongfang Lu
- Department of Animal Science, Michigan State University, East Lansing, MI, 48824, USA
| | - Robert J Tempelman
- Department of Animal Science, Michigan State University, East Lansing, MI, 48824, USA
| | - Steven G Schroeder
- Animal Genomics and Improvement Laboratory, BARC, USDA-ARS, 10300 Baltimore Avenue, Bldg. 306, BARC-East, Beltsville, MD, 20705, USA
| | - Hong Chen
- Shaanxi Key Laboratory of Agricultural Molecular Biology, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - George E Liu
- Animal Genomics and Improvement Laboratory, BARC, USDA-ARS, 10300 Baltimore Avenue, Bldg. 306, BARC-East, Beltsville, MD, 20705, USA.
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5
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Yeganeh IS, Taromchi AH, Fathabadi FF, Nejatbakhsh R, Novin MG, Shokri S. Expression and localization of relaxin family peptide receptor 4 in human spermatozoa and impact of insulin-like peptide 5 on sperm functions. Reprod Biol 2017; 17:327-332. [PMID: 28986276 DOI: 10.1016/j.repbio.2017.09.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 09/12/2017] [Accepted: 09/14/2017] [Indexed: 01/26/2023]
Abstract
Insulin-like peptide 5 (INSL5) is a member of the insulin superfamily peptide that interacts with the relaxin family peptide receptor 4 (RXFP4). Numerous recent studies have focused on the functional effects of INSL5 on fat and glucose metabolism. Although there is no evidence that the human sperm may be a candidate target of INSL5, it has been detected in mice testis and sperm. Therefore, the present study sought to analyze the localization and expression of RXFP4 on human sperm and determine the efficiency of INSL5 in human sperm. Normal semen samples were incubated in different doses and exposure time periods of INSL5. We analyzed sperm motility by computer-assisted sperm analysis (CASA) and ROS levels by flow cytometry using the MitoSOX™ Red probe. Localization and expression of RXFP4 were assayed by immunofluorescence and RT-PCR, respectively. The results confirmed the presence of RXFP4 in human spermatozoa, which localized in the neck and midpiece of sperm. Nested PCR showed the expression of RXFP4 in human sperm. INSL5 could attenuate generation of mitochondrial ROS at the 1, 10, 30, and 100nmol/L doses. This result was particularly noted in the 30nmol/L treated samples after 4h incubation. Total motility of sperm was significantly preserved in the 100nmol/L after 2h and in 30nmol/L after 4h incubation period. This study, for the first time, clarified the expression and localization of RXFP4 on human sperm and revealed the role of INSL5 in sperm motility and mitochondrial ROS generation in a dose-dependent manner.
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Affiliation(s)
- Imaneh Shamayeli Yeganeh
- Department of Biology and Anatomical Sciences, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Ph.D. Student in Anatomical Sciences, International Branch, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | - Amir Hossein Taromchi
- Department of Medical Biotechnology and Nanotechnology, Faculty of Medicine, Zanjan University of Medical Sciences (ZUMS), Zanjan, Iran.
| | - Fatemeh Fadaei Fathabadi
- Department of Biology and Anatomical Sciences, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | - Reza Nejatbakhsh
- Department of Anatomical Sciences, Faculty of Medicine, Zanjan University of Medical Sciences (ZUMS), Zanjan, Iran.
| | - Marefat Ghaffari Novin
- Department of Biology and Anatomical Sciences, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | - Saeed Shokri
- Department of Anatomical Sciences, Faculty of Medicine, Zanjan University of Medical Sciences (ZUMS), Zanjan, Iran.
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6
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Zhang C, Baimoukhametova DV, Smith CM, Bains JS, Gundlach AL. Relaxin-3/RXFP3 signalling in mouse hypothalamus: no effect of RXFP3 activation on corticosterone, despite reduced presynaptic excitatory input onto paraventricular CRH neurons in vitro. Psychopharmacology (Berl) 2017; 234:1725-1739. [PMID: 28314951 DOI: 10.1007/s00213-017-4575-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 02/16/2017] [Indexed: 02/06/2023]
Abstract
Relaxin-3/RXFP3 signalling is proposed to be involved in the neuromodulatory control of arousal- and stress-related neural circuits. Furthermore, previous studies in rats have led to the proposal that relaxin-3/RXFP3 signalling is associated with activation of the hypothalamic-pituitary-adrenal axis, but direct evidence for RXFP3-related actions on the activity of hypothalamic corticotropin-releasing hormone (CRH) neurons is lacking. In this study, we investigated characteristics of the relaxin-3/RXFP3 system in mouse hypothalamus. Administration of an RXFP3 agonist (RXFP3-A2) intra-cerebroventricularly or directly into the paraventricular nucleus of hypothalamus (PVN) of C57BL/6J mice did not alter corticosterone levels. Similarly, there were no differences between serum corticosterone levels in Rxfp3 knockout (C57BL/6JRXFP3TM1) and wild-type mice at baseline and after stress, despite detection of the predicted stress-induced increases in serum corticosterone. We examined the nature of the relaxin-3 innervation of PVN in wild-type mice and in Crh-IRES-Cre;Ai14 mice that co-express the tdTomato fluorophore in CRH neurons, identifying abundant relaxin-3 fibres in the peri-PVN region, but only sparse fibres associated with densely packed CRH neurons. In whole-cell voltage-clamp recordings of tdTomato-positive CRH neurons in these mice, we observed a reduction in sEPSC frequency following local application of RXFP3-A2, consistent with an activation of RXFP3 on presynaptic glutamatergic afferents in the PVN region. These studies clarify the relationship between relaxin-3/RXFP3 inputs and CRH neurons in mouse PVN, with implications for the interpretation of current and previous in vivo studies and future investigations of this stress-related signalling network in normal and transgenic mice, under normal and pathological conditions.
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Affiliation(s)
- C Zhang
- The Florey Institute of Neuroscience and Mental Health, 30 Royal Parade, Parkville, VIC, 3052, Australia.,Florey Department of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - D V Baimoukhametova
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - C M Smith
- The Florey Institute of Neuroscience and Mental Health, 30 Royal Parade, Parkville, VIC, 3052, Australia.,Florey Department of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - J S Bains
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Andrew L Gundlach
- The Florey Institute of Neuroscience and Mental Health, 30 Royal Parade, Parkville, VIC, 3052, Australia. .,Florey Department of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, 3010, Australia.
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