In vitro effects of follicle-stimulating hormone, luteinizing hormone, and prolactin on follicular deoxyribonucleic acid synthesis in the hamster.
Follicles were dissected by hand or enzymatically from the ovary of the proestrous hamster at 0900 h and classified into 10 stages: stages 1-4, follicles with 1-4 layers of granulosa cells and no theca; stages 5-8, preantral follicles with 5 or more layers of granulosa cells and theca to small antral follicles; stage 9, intermediate-sized atretic antral follicles; and stage 10, healthy preovulatory antral follicles. Follicles were then incubated for 2 h with [3H]thymidine [( 3H]Tdr) in the absence or presence of gonadotropins and with incorporation of radionuclide into DNA as the end point. FSH (25 ng) significantly stimulated [3H]Tdr incorporation in all stages of follicular development with a latency of 2 h, and this effect was inhibited by 2 micrograms unlabeled Tdr. While FSH and PRL (25 and 100 ng) stimulated [3H]Tdr incorporation in all stages, LH (0.2-5 ng) action began from stage 5 onward, when definitive thecal cells and LH receptors started appearing. LH (5 ng) also suppressed 25 ng FSH-induced DNA synthesis in stages 5-10; however, stages 1-4 were unaffected. Significant increases in both intra- and extracellular cAMP levels occurred in follicles at stages 2-10 after FSH administration. In contrast, LH was active in stages 5-10, whereas PRL was ineffective. Follicular DNA synthesis increased markedly when stimulated by 8-bromo-cAMP (0.01-2 mM). These results show that gonadotropins act directly as a primary stimulus at the level of small primary and secondary follicles to regulate DNA synthesis and, thus, perhaps the growth and differentiation of granulosa and thecal cells; cAMP functions as one of the possible intracellular mediators of gonadotropin action in initiating DNA replication.
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D006224:Cricetinae; D000242:Cyclic AMP / Q000096:biosynthesis; D004247:DNA / Q000096:biosynthesis*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology*; D007986:Luteinizing Hormone / Q000494:pharmacology*; D008647:Mesocricetus; D006080:Ovarian Follicle / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D011359:Proestrus / Q000378:metabolism; D011388:Prolactin / Q000494:pharmacology*
D015124:8-Bromo Cyclic Adenosine Monophosphate; D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D004247:DNA; D000242:Cyclic AMP; D015056:1-Methyl-3-isobutylxanthine