Differentiation between the effects of IGF-1 and GH on PMSG-induced progesterone production by rat granulosa cells.
The effects of insulin-like growth factor-1 (IGF-1) and growth hormone (GH) on pregnant mare serum gonadotropin (PMSG)-induced progesterone production by cultured granulosa cells have been studied. Rat granulosa cells were cultured in different concentrations of PMSG (0-100 mU/ml) plus or minus IGF-1 (4 nM) or GH (hGH, 2.5 or 10 nM) in the presence or absence of cortisol (2.4 micrograms/ml) and/or insulin (68 nM) in low (5 micrograms/ml) or high (50 micrograms/ml) concentrations of transferrin (TRF). IGF-1 augmented PMSG-induced progesterone production in both low and high TRF. The maximal increments were 6.6 and 4.5 times at 20 mU/ml PMSG respectively in low and high TRF. The enhancement by IGF-1 of PMSG-induced progesterone production was greater at low TRF concentrations. When cortisol was added in both low and high TRF, the enhancement by IGF-1 of PMSG-induced progesterone production was reversed and IGF-1 inhibited PMSG-induced progesterone production by 25.9% (low TRF) and 62.3% (high TRF) respectively. When a high dose of insulin was added instead of IGF-1, there was no obvious inhibition of the insulin stimulation by cortisol. In contrast, the IGF-1 inhibition in the presence of cortisol still existed in the presence of a high dose of insulin. These data indicate that insulin must have a direct effect of its own rather than simply acting as a surrogate IGF-1. GH inhibited PMSG-induced progesterone production by 37.2% and 61% respectively at 2.5 and 10 nM GH at low TRF concentration and 100 mU/ml PMSG.(ABSTRACT TRUNCATED AT 250 WORDS)
Hong
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Prince Henry's Institute of Medical Research, Monash Medical Centre, Melbourne, Victoria, Australia.
Herington
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AC
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D004357:Drug Synergism; D005260:Female; D006064:Gonadotropins, Equine / Q000494:pharmacology*; D006107:Granulosa Cells / Q000187:drug effects* / Q000378:metabolism; D013006:Growth Hormone / Q000494:pharmacology; D006854:Hydrocortisone / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D011374:Progesterone / Q000378:metabolism*; D051381:Rats; D014168:Transferrin / Q000494:pharmacology
D006064:Gonadotropins, Equine; D014168:Transferrin; D011374:Progesterone; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D006854:Hydrocortisone