Meeting Abstract

P3.88  Wednesday, Jan. 6  Sex differences in response to differing doses of the neuropeptide kisspeptin GREIVES, TJ; LONG, KL; BERGEON BURNS , CM; DEMAS, GE*; Max Planck Institute for Ornithology, Department of Migration and Immuno-ecology, Radolfzell, Germany, 78315; Indiana University, Department of Biology, Center for Integrative Study of Animal Behavior, Bloomington, IN, 47401 gdemas@indiana.edu

Many animals experience marked changes in reproductive status across seasons. These changes in reproductive function are regulated by the hypothalamo-pituitary-gonadal (HPG) axis. In temperate breeding rodents, activation of the HPG axis is triggered by long days. The neuropeptide kisspeptin has recently been shown to serve as a positive regulator of the HPG axis by eliciting GnRH secretion and may serve as a mechanism for gonadal activation by summer-like long days. The precise actions of kisspeptin on the HPG axis in animals of differing photoperiod-induced reproductive states, however, remains unresolved. Additionally, the cost of activating or maintaining reproductive physiology under varying environmental (i.e. photoperiodic) conditions may differ between the sexes. The current study investigated whether sensitivities to kisspeptin differ in male and female Siberian hamsters (Phodopus sungorus) held on reproductively inhibitory short-day or stimulatory long-day photoperiods. We found that both males and females displayed elevated LH in response to the highest dose of kisspeptin; this result differs from a previous finding where multiple injections of kisspeptin lead to decreased LH in non-reproductive females. Additionally, the sexes differed in LH response at an intermediate dose of kisspeptin, depending on their photoperiod-induced reproductive state. These findings provide further insight into the basic actions of kisspeptin in the regulation of reproduction, and indicate that this peptide may serve as a potential mechanism regulating differential reproductive responses between the sexes.