The Effect of Exercise on Neurogenesis and BDNF Levels in the Green Anole Lizard Brain

Previous studies in mammals have shown that exercise promotes neurogenesis in the hippocampus, but not as much is known about how exercise affects neurogenesis in reptiles. The hippocampus is a major site of neurogenesis in the adult brain. It exhibits high levels of brain-derived neurotrophic factor (BDNF) and exercise has been associated with an upregulation of BDNF. The green anole lizard (Anolis carolinensis) is an ideal model organism for studies of neuroplasticity due to dramatic seasonal changes in circulating steroid hormone levels and brain morphology. We examined how exercise impacts neurogenesis and BDNF levels in the dorsal and medial cortex, the reptilian homolog of the hippocampus. To do that, two cohorts of adult breeding male lizards were injected subcutaneously with BrdU (50 mg/kg) five days prior to treatment. The exercise group underwent forced exercise on a treadmill for 30 minutes/day for three weeks. The control group was handled and put back in the cage every day for three weeks. Two hours prior to sacrifice a bolus of BrdU was injected. Tissue was collected, frozen and cryosectioned. An immunohistochemistry was performed to label cells with BrdU/Hu and double-positive cells were quantified. RNA extraction and qPCR were formed to quantify BDNF levels. We want to determine from this study whether exercise impacts neurogenesis and BDNF levels in the hippocampus. Because previous experiments have shown that exercise increases new neuron growth and an upregulation of BDNF levels, we predict that exercise lizards will show increased neurogenesis and increased BDNF compared to non-exercise lizards