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BIOCHEMICAL INDICES OF EXPOSURE TO ENVIRONMENTAL ESTROGENS: A SPECIES COMPARISON
Citation:
Thompson, S. C., F. Tilton, D. K. Schlenk, AND W H. Benson. BIOCHEMICAL INDICES OF EXPOSURE TO ENVIRONMENTAL ESTROGENS: A SPECIES COMPARISON. SETAC 20th Annual Meeting, Philadephia, PA, November 14-18, 1999.
Description:
Existence of endocrine active substances in the aquatic environment has been clearly established in several studies. Exposure of organisms to both natural and synthetic xenoestrogens have been found to alter biochemical homeostatis and, in some cases, result in reproductive and developmental toxicity. A number of biochemical indices, such as vitellogin (VTG), plasma steroids and the estrogen receptor, are used as indicators of exposure to estrogenic compounds. There is some question, however, regarding the comparative response of these biochemical markers among various teleosts given that life histories and reproductive strategies vary greatly. In this regard, biochemical responses were compared among Japanese medaka, channel catfish and hybrid striped bass exposed to aqueous concentration of 17b-estradiol (E2) ranging logarithmically from 10 to 100,000 ng/L. Plasma VTG was detected by western blot analysis and EC50 values were determined for VTG induction in each species. The EC50 values for medaka, catfish and bass were 590, 710 and 1580 ng/L E2, respectively. Striped bass exhibited the largest range of VTG responses over the dosing regime compared to the other species. Maximal induction in bass was statistically elevated and the threshold response was decreased compared to both medaka and catfish. These data indicate species specificity in biochemical responses to E2 exposure among medaka, catfish and bass. Investigations such as that described are an important initial step in understanding species differences in reproductive and developmental toxicity from estrogens.