Date of Award

6-2017

Degree Name

MS in Biological Sciences

Department/Program

Biological Sciences

Advisor

Christy Strand

Abstract

Neurogenesis is an important and vastly under-explored area in reptiles. While the ability to generate new brain cells in the adult mammalian brain is limited, reptiles are able to regenerate large populations of neuronal cells. Pythons exhibit a characteristic specific dynamic action (SDA) response after food intake with an increase in metabolic rate that facilitates processing the meal. Associated with this change in SDA, pythons (Python spp.) also exhibit impressive plasticity in their digestive and cardiovascular physiology due to the sheer magnitude of the increase in organ growth that occurs after a meal to speed digestion, absorption, and assimilation of nutrients. While this systemic growth in response following food consumption is well documented, whether the python brain exhibits associated changes in cell proliferation following food consumption and digestion is currently unexplored. For this study, juvenile male ball pythons (Python regius) were used to test the hypothesis that postprandial neurogenesis is associated with food consumption. We used the thymidine analog 5-bromo-12’-deoxyuridine (BrdU) to quantify and compare cell proliferation in the brain of fasted snakes and at two time points: two days and six days after a meal, which span time periods of during and after SDA response, respectively. Quantification of BrdU-labeled cells in the ventricular regions relealed that – consistent with other reptile species – the retrobulbar and olfactory regions had the highest numbers of proliferating cells in the python brain, regardless of sampling time. Throughout the telencephalon, cell proliferation was significantly greater in the six-day post-feeding group, with no difference between the two-day post-feeding group and controls. Most other postprandial systemic plasticity occurs within a day or two after a meal and decreases thereafter; however, the brain displays a more delayed response, with a surge of cell proliferation after most of the digestion and absorption is complete. Our results support our hypothesis that food consumption does affect cell proliferation in the python brain, and indicates that the degree of increased proliferation is dependent on the time since feeding.

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