Meeting Abstract

P2-117  Sunday, Jan. 5  Central oxytocin and vasopressin receptor distributions in the house mouse, Mus domesticus, and non-commensal congeners, M. spretus and M. spicilegus JOHNSTON, M*; FINTON, C; BRASS, K; OPHIR, AG; CAMPBELL, P; Oklahoma State University, Department of Integrative Biology, Stillwater, OK; Cornell University, Department of Psychology, Ithaca, NY; Oklahoma State University, Department of Integrative Biology, Stillwater, OK; Cornell University, Department of Psychology, Ithaca, NY; University of California Riverside, Department of Evolution, Ecology, and Organismal Biology, Riverside, CA polly.campbell@ucr.edu

The neuropeptides oxytocin (OT) and arginine vasopressin (AVP), together with their non-mammalian homologs, modulate a broad range of vertebrate social and reproductive behaviors. In mammals, species differences in forebrain distributions of the oxytocin receptor (OTR) and vasopressin receptor 1a (Avpr1a) evolve rapidly, often in association with differences in sociality or mating system. We used autoradiography to compare the distribution and density of OTR and Avpr1a expression in three closely related species of Old World mice that differ in social structure and population density: the house mouse, Mus domesticus, the Algerian mouse, M. spretus, and the mound-building mouse, M. spicilegus (n = 9-11/sex/species). The most striking species differences were found for OTR, which was significantly higher in M. domesticus and statistically identical in M. spretus and M. spicilegus in the majority of analyzed brain regions. House mice live at high population densities relative to the two non-commensal species; we speculate that higher forebrain sensitivity to oxytocin evolved in association with selection to enhance social memory and reduce social aggression under commensal conditions. As the first comparative analysis of OTR and Avpr1a in Mus, this study lays the groundwork for experimental tests of ecologically relevant functions of OT and AVP in this highly tractable system.