Meeting Abstract

95.5  Saturday, Jan. 7  The role of plasma iodide and endocrine disrupting chemicals in predictive adaptive responses of Alligator mississippiensis BOGGS, Ashley S P*; LOWERS, Russell H; HAMLIN, Heather J; MCCOY, Jessica A; GUILLETTE, Louis J; Medical University of South Carolina / University of Florida; Innovative Health Applications, Kennedy Space Center, NASA; University of Maine / Medical University of South Carolina; Medical University of South Carolina; Medical University of South Carolina / University of Florida

Alterations to thyroid hormones during development could reset the hypothalamic-pituitary-thyroid (HPT) axis in a manner indicative of a predictive adaptive response. Endocrine disrupting chemicals (EDCs) such as PCBs and PBDEs have been shown to alter the regulation of thyroid hormones. However, the influence of these chemicals could be altered by iodide concentrations. American alligator eggs from an estuarine environment with high iodide availability, a freshwater environment contaminated with EDCs, and a reference freshwater environment were incubated under identical conditions. Hormone concentrations, thyroid histology, thyroid gene expression, and growth were recorded at hatch and after 10 months of ad libitum food and freshwater. Neonates from the estuarine site were hyperthyroid while those from the contaminated freshwater site were hypothyroid despite similar concentrations of PCBs and PBDEs in juveniles from both sites. Increased plasma iodide concentrations were correlated with increased thyroid hormone concentrations among the estuarine neonates. After 10 months, thyroid hormone concentrations returned to normal but thyroidal histology and gene expression, and somatic growth remained altered. This suggests a resetting of the HPT axis to compensate for EDCs or elevated iodide exposure through a predictive adaptive response.