Fluctuating Hormone Levels during Reproduction in Freshwater Turtles

Vertebrates respond to seasonal changes and environmental stressors by modulating their circulating glucocorticoid levels. Fluctuations in glucocorticoids alter various aspects of an organism's physiology and mediate behaviors such as appropriate reactions to unexpected threats or to expected annual challenges such as reproduction. This study examined corticosterone, the most important glucocorticoid in reptiles, levels in gravid and postoviposition adult female Painted Turtles ( Chrysemys picta ) during the reproductive season to understand how circulating glucocorticoid levels change with reproductive status. Gravid females exhibited higher levels of circulating corticosterone for both baseline measurements and the stress response series. Understanding such endocrinological variation with reproductive status can provide additional insight into the role of corticosterone during the nesting process in freshwater turtles.