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EFFECTS OF CYTOSOLIC CONVERSION OF ESTRONE TO ESTRADIOL ON RAINBOW TROUT ER BINDING AFFINITY
Citation:
Tapper, M A., R C. Kolanczyk, J. S. Denny, T. R. Henry, AND P. K. Schmieder. EFFECTS OF CYTOSOLIC CONVERSION OF ESTRONE TO ESTRADIOL ON RAINBOW TROUT ER BINDING AFFINITY. Presented at Joint Regional SETAC/SOT Annual Meeting, USEPA, Duluth, MN, April 9-10, 2002.
Description:
Relative binding affinity (RBA) for estrone (E1) to the rainbow trout (Oncorhynchus mykiss) estrogen receptor (rtER) was measured as part of a larger effort to determine chemical structural features predictive of chemical estrogenicity in fish. Estrone RBA was found to vary considerably (^ to 68%) among cytosolic preparations. Cytosolic concentrations of E1 we re subsequently found to vary from 32 to 85% of the original E1 concentration, raising concerns over possible differences in 17B-hydroxysteroid dehydrogenase (HSD) activity in individual fish. HSD's are responsible for the conversion of estrogens and androgens to and from active forms. HSD-1 has been identified as the primary enzyme responsible for the conversion of E1 to 17 -estradiol (E2) in mammals. Little is known about HSD activity in fish but likely a HSD-1-like enzyme in liver cytosol convert E1 to E2. Depending on the cytosol used, 15 to 68% of the initial E1 was converted to E2. A positive attributable to the interaction of E2 with the rtER. Therefore measurable HSD-like activity in fish cytosol can alter steroid concentrations thereby altering RBA measurements, and the RBA of rtER for E1 is closer to 6% than 68%.
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