Steroid Secretion by Perifused Ovarian Follicles of Immature, Pmsg-Treated Immature, and Mature Rabbits
The follicle changes morphologically as it matures. To determine if this anatomical change is coincident with changes in steroidogenesis, follicles were removed from immature (Im) (2.0 kg), immature-PMSG (Im-P) (2.0 kg) and mature (M) (4.0 kg) rabbits and perifused constantly with Medium 199–0.1% BSA. Medium was assayed for estradiol-17-ß (E2), testosterone (T), and progesterone (P4). Follicular sizes were 1.0 mm (Im) and 1.5-2.0 mm (Im-P and M).After the establishment of a baseline, 100 ng of LH (NIH-S20) and 50 ng of FSH (50.3 x NIH-FSH-S1) were injected into the chambers. To eliminate the effect of follicular size on steroid secretion, the data were evaluated by considering the ratios of E2;T:P4 with E2=1.0. Independent “t” test and Behrens-Fisher tests were used to test for significance. Steroid secretion by Im-P follicles did not increase following LH:FSH but rather decreased gradually with time. The E2:T:P4 ratios before and 1 h after LH:FSH were 1.0:0.38:0.25 and 1.0:0.38:0.37 for Im-P follicles. Before gonadotropin stimulation there was no difference in the ratios E2:T (1.0:0.94 vs 1.0:).52) and E:P (1.0:0.26 vs 1.0:0.47) for Im and M follicles respectively. one h after LH:FSH, the E2:T and E2:P4for Im vs Mfollicles were 1.0:9.8 vs 1.0:3.8 and 1.0:0.41 vs 1.0:0.88 respectively (P < 0.05). There was significantly less T and more P4 relative to E2 secreted by M than Im follicles. These data suggest that as a follicle matures, the steroid profile changes.
KeywordsGranulosa Cell Adenylyl Cyclase Activity Basal Secretion Gonadotropin Stimulation Steroid Secretion
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