Meeting Abstract
Perchlorate is a contaminant and endocrine disrupting compound found throughout the United States that affects the production of thyroid hormone and thyroid morphology as well as sexual development in many species including the threespine stickleback (Gasterosteus aculeatus). We investigated the effects of perchlorate, iodide (I–) and thyroxine (T4) on the kidney and gonad morphology of stickleback. Following fertilization, fish were chronically exposed to nine treatments with three perchlorate concentrations (0, 10, 100 ppm) and three supplementation options (no supplement, I–, or T4). Fish were euthanized, fixed, sectioned and stained in order to perform histology measurements. The area and epithelial cell height of the kidneys were measured as was the testis area and stage and the number of oocytes per stage. We found that hypertrophy in the kidney caused by perchlorate was prevented by both exogenous I– and T4, although I– exerted a stronger effect. For the gonads, we found that T4 led to testis hypertrophy, and that oocyte development was delayed by perchlorate. These results suggest that effects of perchlorate are mediated through the thyroid, however, since iodide exerted stronger effects than T4 and oocyte development was not ameliorated by either supplement, it is possible that although the main pathway through which perchlorate functions is thyroidal, crosstalk with other endocrine axes, such as the hypothalamus-pituitary-gonadal axis, is also causing effects in the gonads and kidney. Future work should further investigate this possible crosstalk by analyzing the levels of thyroid and sex hormones (including estrogens, androgens, and aromatase) in relation to perchlorate.
