Effects of Steroid Hormone in Avian Follicles

The aim of the present study was to examine the effects of testosterone (T) and estradiol-17β (E(2)) on the production of progesterone (P(4)) by granulosa cells, and of the E(2) on the production of P(4) and T by theca internal cells. In the first experiment, granulosa cells isolated from the largest (F(1)) and third largest (F(3)) preovulatory follicle were incubated for 4 h in short-term culture system, P(4) production by granulosa cells of both F(1) and F(3) was increased in a dose-dependent manner by ovine luteinizing hormone (oLH), but not T or E(2). In the second experiment, F(1) and F(3) granulosa cells cultured for 48 h in the developed monolayer culture system were recultured for an additional 48 h with increasing doses of various physiological active substances existing in the ovary, including T and E(2). Basal P(4) production for 48 h during 48 to 96 h of the cultured was about nine fold greater by F(1) granulosa cells than by F(3) granulosa cells. In substances examined oLH, chicken vasoactive intestinal polypeptide (cVIP) and T, but not E(2), stimulated in a dose-dependent manner P(4) production in both F(1) and F(3) granulosa cells. In addition, when the time course of P(4) production by F(1) granulosa cells in response to oLH, cVIP, T and E(2) was examined for 48 h during 48 to 96 h of culture, although E(2) had no effect on P(4) production by granulosa cells of F(1) during the period from 48 to 96 h of culture, P(4) production with oLH was found to be increased at 4 h of the culture, with a maximal 9.14 fold level at 6 h. By contrast, P(4) production with cVIP and T increased significantly (p<0.05) from 8 and 12 h of the culture, respectively, with maximal 6.50 fold response at 12 h and 6, 48 fold responses at 36 h. Furthermore, when F(1) granulosa cells were precultured with E(2) for various times before 4 h culture with oLH at 96 h of culture, the increase in P(4) production in response to oLH with a dose-related manner was only found at a pretreatment time of more than 12 h. In the third experiment, theca internal cells of F(1), F(2) and the largest third to fifth preovulatory follicles (F(3-5)) were incubated for 4 h in short-term culture system with increasing doses of E(2). The production of P(4) and T by theca internal cells were increased with the addition of E(2) of 10(−6) M. These increases were greater in smaller follicles. These results indicate that, in granulosa cells of the hen, T may have a direct stimulatory action in the long term on P(4) production, and on E(2) in long-term action which may enhance the sensitivity to LH for P(4) production, and thus, in theca internal cells, E(2) in short term action may stimulate the production of P(4) and T.