Meeting Abstract

P2.193  Saturday, Jan. 5  Seasonal changes in neurogenesis in red-sided garter snakes: Neurons or glial cells? MAINE, AR*; POWERS, SD; LUTTERSCHMIDT, DI; Portland State University, Oregon; Portland State University, Oregon; Portland State University, Oregon Amaine@pdx.edu

Seasonal rhythms in physiology and behavior may be regulated by neuroplasticity, including the generation of new cells. In the current study, we investigated whether seasonal variation in neurogenesis (i.e., cell proliferation, migration, differentiation) occurs in the highly seasonal red-sided garter snake (Thamnophis sirtalis parietalis). We collected male snakes from the den site during the spring mating season or fall pre-hibernation period and treated them with bromodeoxyuridine (BrdU), a thymidine analog that is incorporated into newly synthesized DNA. Snakes were euthanized at 1, 5, or 10 days post-BrdU treatment and the brains were processed for BrdU immunohistochemistry to visualize newly proliferated cells. Fall-collected snakes had significantly more BrdU-labeled cells in the dorsal cortex (F= 5.276; p= 0.032), nucleus sphericus (F= 12.275; p= 0.003), and septal nucleus (F= 5.357; p= 0.033) than those collected in the spring. Within the nucleus sphericus, significantly more BrdU-labeled cells migrated into the parenchymal layer during the fall (F= 13.464; p= 0.002). Days post-BrdU treatment did not significantly affect the number of BrdU cells in any brain region. These results suggest that increased neurogenesis during the fall may play a role in preparing for winter dormancy (e.g., neuroprotection). Furthermore, we show that cell migration increases during the fall in the nucleus sphericus, a structure important for processing information from the vomeronasal system. Using double-label immunohistochemistry for BrdU and neuron-specific nuclear protein (NeuN), we are examining whether these newly generated brain cells differentiate into neurons or glial cells. Collectively, these data will provide insight into the functional significance of neurogenesis in a seasonal breeder.