Estradiol regulates aryl hydrocarbon receptor expression in the rat uterus

Several authors have investigated the role of aryl hydrocarbon receptor (AHR) in the reproductive tract, but there are no data available whether 17β-estradiol (E2) regulates expression of members of the AHR pathway in the uterus. We therefore examined the mRNA expression of Ahr as well as the genes of the AHR dimerization partners ARNT1 and ARNT2 and the AHR regulated genes Cyp1a1 and Gsta2 in the uterus of ovariectomized rats after administration of E2 at two different doses. The data show that Ahr mRNA expression is downregulated while AHR protein amounts increased in all uterine tissue compartments. In addition we observed a downregulation of Arnt1, Arnt2 and Cyp1a1 while Gsta2 mRNA expression is upregulated by E2 in a dose-dependent manner. These results show that members of the AHR pathway are regulated by E2 in the uterus. AHR may therefore play an important role in the mediation of uterine estrogenic effects.