| Abstract: | Estradiol has previously been shown to suppress the response of the cellular immune system of the rat while enhancing the production of IgM antibodies. Analysis of the cytosol from rat splenocytes showed saturation of specific binding sites at concentrations of between 80 and 160 nM 3H]-estradiol with an approximate Kd of 12 nM. Competitive binding studies showed a dose-dependent decrease in the binding of 3H]-estradiol to the receptor in the presence of increasing concentrations of unlabeled estradiol. Dexamethasone, progesterone and R1881 (synthetic androgen) had no effect on the binding of 3H]-estradiol. The in vivo administration of estradiol resulted in increased nuclear binding of 3H]-estradiol as compared to vehicle treated controls. These results indicate that rat splenocytes possess specific, translocatable estrogen receptors which may be responsible for the observed modulation of the immune system. |
