Meeting Abstract

12.6  Thursday, Jan. 3  Characterization of the corticosteroid stress response in the Atlantic stingray EVANS, A.N.*; NUNEZ, B.S.; University of Texas Marine Science Institute aevans@utmsi.utexas.edu

A critical component of the vertebrate response to stress is the synthesis of adrenocortical steroid hormones termed glucocorticoids (GCs). Elasmobranchs produce a unique GC, 1α-hydroxycorticosterone (1α-B). While much is known regarding the GC stress response in other vertebrates, studies in elasmobranchs are lacking, in a large part due to the absence of a simple and specific assay to measure 1α-B. Because corticosterone antibodies sometimes also bind 1α-hydroxycorticosterone, we have evaluated the ability of a commercial corticosterone EIA kit to detect 1α-B. Using purified 1α-B we have determined that this assay is able to detect physiologically relevant levels of the elasmobranch GC. Consistent with previous reports, basal 1α-B values in laboratory-adapted animals were determined to be in the nanomolar range using this EIA. We then utilized this assay to examine the elasmobranch stress response in Atlantic stingrays captured via hook-and-line for either 1 hour (short series) or 8 hours (long series). In each series plasma samples were taken at specific intervals to determine the effects of stress on 1α-B synthesis. Preliminary results indicate that elasmobranchs display a delayed GC peak relative to other vertebrates, as plasma 1α-B peaks between 2 and 4 hours following the onset of stress, with maximum values approaching 1 micromolar. The 1α-B assay used in this study provides a critical tool for clarifying the physiological role of 1α-B as well as furthering our understanding of the evolution of GC synthesis and the vertebrate stress response.