Meeting Abstract

P1.106  Jan. 4  Proliferation, differentiation and survival of newborn cells in adult amphibian brains SAIJO, E.*; ORCHINIK, M.; School of Life Sciences, Arizona State Univ m.orchinik@asu.edu

To understand the regulatory mechanisms and importance of naturally-occurring adult neurogenesis in vertebrates, we are investigating neurogenesis in adult bullfrogs (Rana catesbeiana). In previous studies, we found widespread cell proliferation in adult bullfrog brains, as evidenced by 5-bromo-3�-deoxyuridine (BrdU) incorporation. The current study examined the fate of newborn cells in the ependymal/subependymal layer and periventricular parenchyma of several regions with the highest level of BrdU incorporation: the lateral septum (LS), medial pallium, preoptic area, nucleus of the periventricular organ, ventral hypothalamic nucleus and pituitary. The distribution and phenotype of BrdU-labeled cells were examined at 2 days, 2 weeks and 2 months post-BrdU-injection (n=10 per group). At 2 days BrdU-positive cells were primarily found in the ependymal layer. At 2 months newborn cells were found in the parenchyma as well. The number of BrdU-positive cells in the LS decreased in the ependymal layer but increased in the parenchyma over 2 months, consistent with newborn cell migration. However, different distribution patterns were found in other regions. At 2 months, a fraction of BrdU-positive cells in the parenchyma was double-labeled with the mature neuron marker NeuN, suggesting that some newborn cells survive to assume a neuronal phenotype. In the pituitary pars distalis, robust seasonal differences were found more proliferating cells in the summer breeding season than in the autumn post-breeding season. We are analyzing the differentiation pattern of newborn cells in the brains to understand the differences in the fate of newborn cells between regions, with particular interest in the neuroendocrine regulatory regions. Support provided by NSF IBN-0346227 to M.O.