Differential Modulation by Aromatic Hydrocarbon Receptor Agonist of Circulating Estradiol-17β and Estrogen-Receptor DNA-binding Capability in Female Rainbow Trout (Oncorhynchus mykiss)

Abstract

We report alterations in serum estradiol-17β (E2) and hepatic estrogen receptor (ER) DNA-binding activity in female rainbow trout given a single ip injection of 0, 6.25, 12.5, 25, or 50 mg ß-naphthoflavone (BNF)/kg body weight, followed by sacrifice at 24 or 48 hr. BNF affected E2 in a dichotomous fashion at 24 hr, and reduced E2 at 48 hr with increasing BNF. DNA binding by ER was decreased in an apparently dosedependent manner after 24 hr and increased after 48 hr. These data suggest that the regulation of ER by AHR agonists may occur both at the ER promoter, and also secondarily via E2, and that the differential effects observed are both time and dose dependent.