Regulation of ovarian steroidogenesis in vitro by IGF-I and insulin in common carp, Cyprinus carpio: stimulation of aromatase activity and P450arom gene expression.
Regulation of ovarian steroidogenesis in vitro by recombinant human insulin-like growth factor-I (IGF-I) and bovine insulin (b-insulin) was investigated in intact follicles and isolated follicular cells of carp, Cyprinus carpio at vitellogenic stage of oocyte maturation. In intact follicles, IGF-I and b-insulin stimulated testosterone and 17beta-estradiol production in vitro. In isolated theca cells, IGF-I and b-insulin stimulated testosterone production, whereas in granulosa cells, they stimulated 17beta-estradiol production when testosterone was added in the incubation medium as precursor substrate. In intact follicles and in theca cells, IGF-I and b-insulin had no effect on HCG-stimulated testosterone production. HCG-stimulated 17beta-estradiol production, however, was significantly increased by IGF-I and b-insulin. To clarify the mechanism of 17beta-estradiol production by the ovarian follicles during vitellogenic stage of carp, effects of IGF-I and b-insulin either alone or in combination with HCG on aromatase activity (conversion of testosterone to 17beta-estradiol) and cytochrome P450 aromatase (P450arom) gene expression were investigated in vitro. IGF-I and b-insulin alone stimulated aromatase activity and P450arom gene expression and significantly enhanced HCG-induced enzyme activity and P450arom gene expression. Our results thus indicate that IGF-I and b-insulin alone can stimulate testosterone and 17beta-estradiol production in vitellogenic follicles of C. carpio by stimulating aromatase activity and P450arom gene expression. Evidence also provided for the modulation of HCG-induced aromatase activity and P450arom gene expression by IGF-I and b-insulin in such follicles.
Paul
Sudipta
S
Endocrinology Laboratory, Department of Zoology, University of Kalyani, Kalyani 741235, West Bengal, India.
Pramanick
Kousik
K
Kundu
Sourav
S
Kumar
Dhyanendra
D
Mukherjee
Dilip
D
D000818:Animals; D001141:Aromatase / Q000235:genetics / Q000378:metabolism; D002347:Carps / Q000033:anatomy & histology / Q000378:metabolism; D002417:Cattle; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D010053:Ovary / Q000187:drug effects / Q000201:enzymology / Q000502:physiology; D012102:Reproductive Control Agents / Q000494:pharmacology; D013739:Testosterone / Q000378:metabolism*
D006063:Chorionic Gonadotropin; D007328:Insulin; D012102:Reproductive Control Agents; D013739:Testosterone; D004958:Estradiol; D007334:Insulin-Like Growth Factor I; D001141:Aromatase