Meeting Abstract

48.2  Thursday, Jan. 6  The effects of acute stress on corticosterone, leukocytes, testosterone, and prostaglandin E2 in male Southeastern Five-lined Skinks (Plestiodon inexpectatus) SEDDON, Ryan*; KLUKOWSKI, Matthew; Middle Tennessee State University; Middle Tennessee State University rs2r@mtmail.mtsu.edu

Increased glucocorticoid levels are an important component of the stress response. Corticosterone (CORT), the major glucocorticoid in reptiles, induces physiological and behavioral changes by binding to three different types of receptors. While immunosuppressive effects of chronically elevated corticosterone are well known, acutely elevated CORT levels may actually enhance immunity. For example, acute stress has been reported to increase the granulocyte (e.g., heterophil):lymphocyte ratio in the blood, and transient increases in CORT may alter prostaglandin levels which are important mediators of fever and inflammation. We tested whether male lizards subjected to an acute confinement stress of one hour had elevated plasma prostaglandin E2 levels and increased granulocyte:lymphocyte ratios. Corticosterone levels and eosinophil:lymphocyte ratios were significantly elevated in confined lizards. The change in the eosinophil:lymphocyte ratio could be used to prepare the immune system for potential effects of stressors, such as injury. While confinement did not have a significant effect on plasma PGE2 levels, PGE2 and CORT levels were positively correlated. In mammals, PGE2 has a very short half-life; thus in experiment two, we determined the effects of shorter periods of confinement on plasma PGE2 levels and CORT. Male lizards subjected to 15 or 30 minutes of confinement had elevated CORT levels compared to control males, but PGE2 levels were unaffected by treatment and were not correlated with CORT. Results from a third experiment in which we tested the effects of a two hour confinement on plasma CORT, testosterone, and leukocyte ratios will also be discussed.