Effect of water deprivation on baseline and stress-induced corticosterone levels in the Children's python']python (Antaresia childreni)

Corticosterone (CORT) secretion is influenced by endogenous factors (e.g., physiological status) and environmental stressors (e.g., ambient temperature). Heretofore, the impact of water deprivation on CURT plasma levels has not been thoroughly investigated. However, both baseline CORT and stress-induced CURT are expected to respond to water deprivation not only because of hydric stress per se, but also because CURT is an important mineralocorticoid in vertebrates. We assessed the effects of water deprivation on baseline CURT and stress-induced CURT, in Children's pythons (Antaresia children, a species that experiences seasonal droughts in natural conditions. We imposed a 52-day water deprivation on a group of unfed Children's pythons (i.e., water-deprived treatment) and provided water ad libitum to another group (i.e., control treatment). We examined body mass variations throughout the experiment, and baseline CURT and stress-induced CURT at the end of the treatments. Relative body mass loss averaged similar to 10% in pythons without water, a value 2 to 4 times higher compared to control snakes. Following re-exposition to water, pythons from the water-deprived treatment drank readily and abundandy and attained a body mass similar to pythons from the control treatment. Together, these results suggest a substantial dehydration as a consequence of water deprivation. Interestingly, stress-induced but not baseline CURT level was significantly higher in water-deprived snakes, suggesting that baseline CURT might not respond to this degree of dehydration. Therefore, possible mineralocorticoid role of CURT needs to be clarified in snakes. Because dehydration usually induces adjustments (reduced movements, lowered body temperature) to limit water loss, and decreases locomotor performances, elevated stress-induced CURT in water-deprived snakes might therefore compensate for altered locomotor performances. Future studies should test this hypothesis. (C) 2013 Elsevier Inc All rights reserved.