O’BRIEN, S.*; BENTLEY, G.E.; WINGFIELD, J.C.; Univ. of Washington: KiSS Increases LH in Gambel’s White-crowned Sparrows (Zonotrichia leucophrys gambelii)

Kisspeptin (KiSS), a recently discovered hypothalamic neuropeptide, has been found to stimulate luteinizing hormone (LH) release in rodents & humans. KiSS receptor, GPR54, mRNA expression is found in gonadotropin releasing hormone (GnRH) neurons as well as other areas implicated in hypothalamo-pituitary-gonadal axis regulation. Intercerebroventricular (ICV) injections of KiSS cause dose- & time-dependent increases in circulating LH and increases in cFOS expression in GnRH neurons. Acycline, a GnRH antagonist, blocks the KiSS-induced LH release. mRNA expression of KiSS and its receptor are influenced by steroid feedback and reproductive state. Thus, evidence suggests a central role for KiSS in the timing of breeding. Gambel’s white-crowned sparrows (GWCS) are arctic breeding birds that must precisely time the onset and cessation of breeding in order to maximize fitness in harsh arctic environments. The goal of this study was to determine if KiSS ICV-injections in GWCS increase plasma levels of LH in both a dose- & time-dependent manner. Non-breeding birds were given 4�l injections of KiSS over a 6 week period at three doses (1.7×10⁵, 1.7×10¹ & 3.3×10^-1 fmol/�l). Saline ICV-injections served as reciprocal controls. Blood samples were collected at 10, 30 & 60 minutes post-injection. Data show the highest dose of KiSS rapidly increased plasma LH. In sum, KiSS presumably acts on GnRH neurons to stimulate increases in plasma LH levels in non-breeding birds. Future experiments examining different life history stages and comparing subspecies exhibiting various degrees of breeding flexibility will further elucidate KiSS’s role as a reproductive regulator.