Meeting Abstract

P3.101  Saturday, Jan. 5  Kisspeptin-like immunoreactive neuron distribution in green treefrogs (Hyla cinerea) LUTTERSCHMIDT, D.I.*; WILCZYNSKI, W.; Georgia State Univ., Atlanta; Georgia State Univ., Atlanta Lutterschmidt@gsu.edu

Kisspeptins, a family of neuropeptides encoded by the KiSS-1 gene, promote the secretion of gonadotropin-releasing hormone (GnRH) and are endogenous ligands for the G protein-coupled receptor GPR54. In mammals, kisspeptin nerve fibers innervate GnRH neurons and also extend throughout the hypothalamus, with dense populations in the rostral preoptic area and arcuate nucleus. Despite growing evidence for kisspeptin as a key regulator of reproduction, virtually nothing is known about the distribution of kisspeptin cells and fibers in any ectothermic species. We examined the distribution of kisspeptin-immunoreactive neuronal cell bodies and fibers using immunohistochemistry in green treefrogs (Hyla cinerea). We demonstrate the presence of kisspeptin-like immunoreactive cells in the hypothalamus of male frogs, with prominent populations in the periventricular area of the suprachiasmatic region and the posterior tuberculum. Both cell populations are associated with vesiculated fibers traveling mainly through the paraventricular zone of the hypothalamus and preoptic area. Importantly, these immunoreactive fibers extend rostrally into the rostral-most preoptic area and median septal region where GnRH neurons are localized. Vesiculated fibers also extend caudally to at least the caudal extent of the ventral hypothalamus. These results should be interpreted cautiously, however, as preadsorption of the kisspeptin antiserum with other related RFamide peptides (e.g., gonadotropin-inhibitory hormone) eliminates or greatly reduces immunoreactive staining. Nevertheless, the results indicate that ectothermic species also have a hypothalamic kisspeptin-like immunoreactive cell population and fiber system similar to that seen in mammals.