Effects of Steroid Hormone in Avian Follicles

The aim of the present study was to examine the effects of testosterone (T) and estradiol-17 beta (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 (F3-5) 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.