In vitro effects of epidermal growth factor, insulin-like growth factor-I, fibroblast growth factor, and follicle-stimulating hormone on hamster follicular deoxyribonucleic acid synthesis and steroidogenesis.
Preantral (stages 1-6) and antral (stages 7-10) follicles from proestrous hamsters were exposed for 24 h to 1, 5, 10, 50, and 100 ng/ml of epidermal growth factor (EGF), insulin-like growth factor-I (IGF-I), and fibroblast growth factor (FGF) and 1 microCi [3H]thymidine to determine the rate of DNA replication. FSH (100 ng/ml) was used as a positive control. Synergism was also studied by using suboptimal doses of growth factors (1 ng/ml) and FSH (5 ng/ml). Optimal doses (50 ng/ml) of EGF, IGF-I, and FGF, and 100 ng/ml FSH significantly enhanced follicular DNA replication, whereas suboptimal doses of FSH, EGF, and IGF-I affected only a few preantral stages, and FGF was totally ineffective. FGF significantly inhibited DNA synthesis induced by a suboptimal dose of EGF but did not affect IGF-I-induced DNA replication. Paradoxically, a combination of suboptimal doses of all three growth factors significantly (p less than 0.05) stimulated DNA synthesis for all stages; FSH (5 ng/ml) had no additive effect. FSH significantly stimulated follicular progesterone (P4), androstenedione (A), and estradiol-17 beta (E2) accumulation, but significant P4 accumulation from stages 3-10 was observed only after optimal EGF exposure; A and E2 accumulations were unaffected by any of the growth factors. These results indicate that EGF, IGF-I, and FGF stimulate DNA replication to hamster preantral and antral follicles, and may play roles as intraovarian factors regulating folliculogenesis.(ABSTRACT TRUNCATED AT 250 WORDS)
Roy
S K
SK
Department of Obstetrics & Gynecology, University of Nebraska Medical Center, Omaha 68198.
Greenwald
G S
GS
D000818:Animals; D006224:Cricetinae; D004247:DNA / Q000096:biosynthesis; D004357:Drug Synergism; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005260:Female; D005346:Fibroblast Growth Factors / Q000494:pharmacology; D005640:Follicle Stimulating Hormone / Q000494:pharmacology*; D006133:Growth Substances / Q000008:administration & dosage / Q000494:pharmacology*; D066298:In Vitro Techniques; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D006080:Ovarian Follicle / Q000187:drug effects* / Q000378:metabolism; D013256:Steroids / Q000096:biosynthesis
D006133:Growth Substances; D013256:Steroids; D005346:Fibroblast Growth Factors; D004815:Epidermal Growth Factor; D007334:Insulin-Like Growth Factor I; D005640:Follicle Stimulating Hormone; D004247:DNA