The aim of the present study was to investigate the regulation of the in vitro DNA synthesis of ovarian cells recovered from prepubertal rats 48 h after administration of pregnant mare’s serum gonadotrophin alone (granulosa cells) or followed by human chorionic gonadotrophin (luteal cells). Isolated granulosa cells were cultured in serum-free medium, different stimuli added for periods of 48 h, and3H-thymidine incorporation was measured. Both follicle-stimulating hormone (FSH) and luteinizing hormone (LH) inhibited3H-thymidine incorporation by cultured granulosa cells in a dose-dependent manner (FSH: 10, 100, 200 ng/mL-26, 41, 49% inhibition, respectively; LH: 0.1, 1, 10 ng/mL=11, 37, 75% inhibition, respectively). On the other hand, estradiol was found to stimulate3H-thymidine incorporation in granulosa cells (Estradiol: 5, 50, 500 ng/mL=17, 37, 76% stimulation, respectively). In luteal cells, the rate of basal3H-thymidine incorporation was very low (granulosa cells: 2560±310; luteal cells: 661±92 cpm/100,000 cells) and not modified by any stimulus. To determine the possible production of an inhibitory growth factor by the early corpus luteum,3H-thymidine incorporation by granulosa cells was assessed in the presence of 10% conditioned media (CM) recovered from luteal cell cultures. A marked inhibition both in basal and estradiol-stimulated3H-thymidine incorporation was observed (74 and 76% of inhibition, respectively). Results suggest that an inhibitory growth factor produced by luteal cells after luteinizing gonadotrophin stimulus could be involved in the differentiation of growing follicles to corpus luteum.
Follicle differentiation ovary corpus luteum granulosa cell
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