Meeting Abstract

P2.153  Monday, Jan. 5  Reproductive Profiles of Gonadotropin-inhibitory Hormone (GnIH) Gene Expression in White-crowned Sparrows (Zonotrichia leucophrys) O'BRIEN, S.*; MUKAI, M.; BENTLEY, G.E.; TSUTSUI, K.; WINGFIELD, J.C.; University of Washington-Seattle, WA USA; University of California-Davis, CA USA; University of California-Berkeley, CA USA; Waseda University-Tokyo, Japan; University of California-Davis, CA USA

Gonadotropin-inhibitory hormone (GnIH) is a recently discovered hypothalamic neuropeptide found in a variety of vertebrates. In white-crowned sparrows (WCSP) (Zonotrichia leucophrys), GnIH rapidly inhibits plasma luteinizing hormone (LH) in castrates, as well as in intact, gonadotropin-releasing hormone-treated birds, and in free-living WCSP with naturally high plasma LH. GnIH shows seasonal changes in neuronal attributes implying changes in storage and expression. Thus, we have evidence for potential roles for GnIH in the timing of breeding. Via collection and analysis of WCSP brain tissue, we investigate the changes in GnIH expression throughout breeding and non-breeding reproductive paradigms. We examine changes in GnIH expression through a variety of reproductive treatments: 1) castration and testosterone implants to elucidate the role of sex steroid feedback on the GnIH system. 2) GnIH mini-pump implants to uncover the role of negative feedback. 3) Seasonal collections of brain tissue to examine GnIH expression throughout the year. GnIH may play an important part in the regulation of reproductive function and these expression profiles may help to illuminate the ecological factors and reproductive mechanisms that influence seasonal breeding.