title: Central injection of relaxin-3 receptor (RXFP3) antagonist peptides reduces motivated food seeking and consumption in C57BL/6J mice.
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.
authors.affiliation: 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.
authors.forename: Craig M
authors.initials: CM
authors.lastname: Smith
authors.affiliation: The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia.
authors.forename: Berenice E
authors.initials: BE
authors.lastname: Chua
authors.affiliation: 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.
authors.forename: Cary
authors.initials: C
authors.lastname: Zhang
authors.affiliation: 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.
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Walker
authors.affiliation: 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.
authors.forename: Mouna
authors.initials: M
authors.lastname: Haidar
authors.affiliation: The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Hawkes
authors.affiliation: The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia.
authors.forename: Fazel
authors.initials: F
authors.lastname: Shabanpoor
authors.affiliation: 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.
authors.forename: Mohammad Akhter
authors.initials: MA
authors.lastname: Hossain
authors.affiliation: 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.
authors.forename: John D
authors.initials: JD
authors.lastname: Wade
authors.affiliation: School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia.
authors.forename: K Johan
authors.initials: KJ
authors.lastname: Rosengren
authors.affiliation: 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. Electronic address: andrew.gundlach@florey.edu.au.
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Gundlach
mesh_terms: D000818:Animals; D059031:Anticipation, Psychological / Q000187:drug effects / Q000502:physiology; D001070:Appetitive Behavior / Q000187:drug effects* / Q000502:physiology; D002491:Central Nervous System Agents / Q000008:administration & dosage*; D003624:Darkness; D004032:Diet; D004435:Eating / Q000187:drug effects* / Q000502:physiology; D005508:Food Deprivation; D008297:Male; D008810:Mice, Inbred C57BL; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D010455:Peptides / Q000008:administration & dosage*; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D002491:Central Nervous System Agents; D010455:Peptides; D043562:Receptors, G-Protein-Coupled; C505050:SALPR protein, mouse
keywords: Arousal; Feeding; Motivation; Neuropeptide; RXFP3; Relaxin-3