LOCALIZATION OF ESTROGEN-RECEPTORS IN RHESUS-MONKEY OVARY

We have previously demonstrated that the exogenous administration of e stradiol-17 beta (E(2)) to rhesus monkeys induces atresia of the domin ant preovulatory follicle (DF); and that this effect is mediated centr ally, via the inhibition of follicle-stimulating hormone, and is also exerted directly at the level of the ovarian granulosa cell. We wished to investigate whether the local effect of E(2) is transduced through interaction with the nuclear receptor for estrogen, particularly in l ight of certain evidence that suggests a general lack of estrogen rece ptor (E-R) in the rhesus monkey ovary, except in the germinal epitheli um. In the present study, we evaluated the presence of E-R by both aut oradiographic and immunocytochemical techniques. Frozen sections of ov aries from rhesus females were incubated in experiment 1 with either H -3-E(2) or I-125-E(2) in the presence or absence of excess, non-radioa ctive ligand or analogues diethylstilbestrol (DES) or the receptor ant agonist 4-OH-tamoxifen (TAM). 3H-E(2) binding was most intense over fu nctional corpora lutea, and was reduced to background with excess DES; label was also evident over antral follicles. Image analysis showed s pecific binding of I-125-E(2) by ovaries. In experiment 2, cryostat se ctions were processed for immunocytochemical staining using the peroxi dase-anti-peroxidase (PAP) method and the H222 monoclonal antibody to the E-R. Intense, specific label was observed over nuclei of germinal epithelium, but, additionally, for the first time, to granulosa cells of antral follicles and other compartments of the ovary. In this paper , we report the first evidence for estrogen binding to rhesus monkey o vary; this binding is specific, apparently receptor mediated, and corr oborated independently by autoradiographic and immunocytochemical mean s. We herein provide substantial support for estrogen's dramatic effec ts being exerted directly at the level of the monkey ovary. (C) 1993 W iley-Liss, Inc.