PROGESTERONE-RECEPTOR, BUT NOT ESTRADIOL-RECEPTOR, MESSENGER-RIBONUCLEIC-ACID IS EXPRESSED IN LUTEINIZING GRANULOSA-CELLS AND THE CORPUS-LUTEUM IN RHESUS-MONKEYS

Estrogens (i.e. estradiol) and progestins (i.e. progesterone) may act as local regulators of ovarian function in various species. This study tested the hypothesis that if progesterone and estradiol act via rece ptor-mediated pathways in the primate ovary, then receptor messenger R NAs (mRNAs) should be detectable in ovarian cells. The reverse transcr iption-polymerase chain reaction (RT-PCR) was employed to detect proge sterone and estradiol receptor (PR and ER, respectively) mRNAs in the rhesus monkey ovary. Total RNA was isolated from macaque uterine myome trium (positive control), spleen (negative control), whole ovary, germ inal (surface) epithelium-enriched cortical and medullary compartments of the ovary, granulosa cells in preovulatory follicles before and af ter an ovulatory stimulus, and corpora lutea from early (days 3-5), mi d (days 7 and 8)-, and late (days 14 and 15) luteal phase of the menst rual cycle. Using primers to the hormone-binding region encoded by the receptor mRNAs, RT-PCR products of the expected sizes were detected f or PR and ER from 1 mu g myometrial RNA, whereas products were not obt ained from spleen. PR mRNA product was detected in all ovaries, germin al epithelium-enriched cortical and medullary compartments, and corpor a lutea from all three stages of the luteal phase (n = 3/stage). PR mR NA product was detected as a strong band in one of three preparations obtained from granulosa cells before an ovulatory stimulus. In contras t, PR mRNA was detected in granulosa cells from all animals after an o vulatory dose of hCG. ER mRNA was detected in whole ovary and in germi nal epithelium-enriched cortical compartments, with a barely visible p roduct occasionally observed in medullary compartments of the ovary. I n contrast to PR mRNA, ER mRNA was not detected in any corpora lutea t hroughout the luteal phase or in granulosa cells obtained before or af ter an ovulatory stimulus. To confirm the specificity of the RT-PCR pr oducts, restriction enzymes cleaved the PR product from myometrium, ge rminal epithelium-enriched cortical compartment, and corpus luteum int o the predicted size fragments. Similarly, the ER product from the myo metrium and the germinal epithelium-enriched compartment was cleaved i nto the expected size fragments. Sequence analysis of the PR and ER RT -PCR products revealed 99% homology to the complementary DNA for the h ormone-binding region of human PR and ER, respectively. Thus, PR mRNA detection supports the hypothesis of progesterone action via classical receptor-mediated pathways in the luteinizing follicle and corpus lut eum of the primate ovary. The apparent absence of ER mRNA in these ova rian compartments suggests a lesser, if any, role for estradiol.