Meeting Abstract

47.6  Jan. 6  Reproductive and Immune Consequences of Intermittent Increases in Corticosterone in the White-Crowned Sparrow Zonotrichia leucophrys gambelii: An Experimental Paradigm for Repeated Acute Stressors. BOYD, EB*; BUSCH, DS; WINGFIELD, JC; Univ. of Washington ellen@boydvet.com

Animals secrete glucocorticoids in response to stressful events. These elevated levels of glucocorticoids suppress reproduction and regulate the immune system to promote survival in the face of acute stress but can be deleterious in the long term. We investigated the link between the acute stress response and the development of long term chronic stress. Though little is known about glucocorticoid�s direct role in these events in a natural setting, measurement of glucocorticoids as an indicator of individual and population well being is becoming more prevalent in research and as a management tool. We tested whether intermittent increases in the glucocorticoid corticosterone (CORT), at different frequencies, can cause similar effects to chronic stress. White-crowned sparrows were treated one or three times daily with a topical solution of ten ug CORT in 20 ul DMSO or 20 ul DMSO as a control for two or five weeks. All birds were exposed to ten hours of light and 14 hours of dark (10L:14L) per day for one week then changed to 20L:4D for the remainder of the treatments so the experiment encompassed the transition from short to long days. There was a significant affect on gonadal development (testis mass) in birds treated with CORT three times per day for five weeks compared to controls. This group also experienced a decline in health, and changes in white blood cell count consistent with chronic immune suppression. There were no differences between the once a day group or the group treated for two weeks and the controls. These results show that intermittent increases of corticosterone simulating acute stress responses, if frequent, can cause the deleterious effects associated with chronic stress.