PLATFORM SESSION 2: REGULATION OF OVARIAN FOLLICULAR EXPRESSION
Chair: Adashi, Eli1, 1
Co-chair: Salvador, Lisa1, 1
4:30 PM-6:30 PM
(11) IN VITRO EFFECTS OF 5--DIHYDROTESTOSERONE ON GRANULOSA CELLS FROM GILTS: DIFFERENTIAL RESPONSE BETWEEN MURAL GRANULOSA CELLS AND CUMULUS-OOCYTE COMPLEXES.
Hickey, Theresa1, Gilchrist, Robert1, Ritter, Lesley1, Norman, Robert1, Armstrong, David1, 1 Reproductive Medicine Unit, Adelaide, Australia
ABSTRACT- Androgens acting via the androgen receptor (AR) have been implicated in ovarian follicle recruitment, growth, and oocyte maturation in many animal species. In vivo treatment of gilts with the non-aromatisable androgen 5--dihydrotestosterone (DHT) increases ovulation rate. These effects are possibly mediated via enhancement of FSH and/or IGF activity in granulosa cells, which contain high levels of AR protein. We examined the in vitro effect of DHT on the proliferative and steroidogenic activities of follicular cells to FSH and IGF, alone or in combination. Cells from antral follicles were aspirated from gilt ovaries obtained from an abattoir and fractioned into aggregated mural granulosa cells (MGCs) and cumulus-oocyte complexes (COCs) for subsequent cell culture. Proliferation was measured by incorporation of tritiated thymidine after 24 hours of treatment and progesterone was measured by RIA in conditioned media. DHT had no effect on the proliferation or progesterone secretion of MGCs under any treatment condition. Conversely, DHT significantly enhanced the proliferative response but suppressed the steroidogenic response of COCs to FSH, by 2-fold in both instances (p<0.05). DHT did not alter COC responses to IGF. When MGCs were co-cultured with denuded oocytes (DO) they acquired androgen-mediated responsiveness similar to those of COCs. Measurement of AR mRNA by real-time quantitative RT-PCR confirmed that the lack of androgen effect in MGCs cultured in the absence of DO is not due to down-regulation of AR, which is thought to occur in mature follicles. We conclude that while granulosa cells of antral follicles are the sites of androgen receptor-mediated activity, this activity is influenced by oocyte-secreted factors.
KEY WORDS: androgen, ovary, granulosa, pig