Estrogen receptors in the uterus and ovarian follicles of gilts treated with dihydrotestosterone

Experiments were conducted to evaluate expression of the estrogen receptor (ER) α and ERβ genes in the uterus and ovarian follicles of gilts treated with 5α-dihydrotestosterone (DHT) during the follicular phase of the estrous cycle. This DHT treatment has enhanced ovulation rate but decreased blastocyst survival in previous experiments. Gilts received daily i.m. injections of 10 mg of DHT from day 13 (day 0 = onset of estrus) to day 18 (experiment 1), or from day 13 to 16 (experiment 2) of the estrous cycle. Gilts that served as controls received vehicle. The ovaries and a portion of uterine horn were surgically removed 24 h after the last treatment. Administration of DHT from day 13 to 18 of the estrous cycle decreased uterine wet weight (tendency, P = 0.10), and the relative amounts (ratios to ribosomal protein L19) of endometrial mRNA for the estrogen-responsive gene complement component C3. Gilts receiving DHT had greater amounts of ERβ mRNA in the endometrium than those treated with vehicle in both experiments, but DHT did not alter the overall amounts of endometrial ERα mRNA. Immunohistochemical (IHC) analysis demonstrated that DHT did not alter the relative amounts of ERα in the myometrium, glandular and luminal epithelia and endometrial subepithelial stroma. In the ovary, amounts of ERα and ERβ mRNAs in surface walls of follicles ≥6 mm in diameter were not altered by DHT treatments, however, DHT treatment from day 13 to 16 decreased the amounts of immunoreactive ERα in the theca interna at the surface walls of day 17 follicles (experiment 2). The amounts of immunoreactive ERα were greater in the granulosa than in the theca interna, and within cell type, the amounts of ERα were greater at the surface than at the basal region of the follicles, with the exception of the theca interna in follicles evaluated on day 19 (experiment 1). Treatment of gilts with DHT during the follicular phase of the estrous cycle increased ERβ mRNA in the endometrium and influenced the amounts of immunoreactive ERα in ovarian follicles in a cell type-, day of development- and region-specific manner.