A role for somatomedin C as a differentiating hormone and amplifier of hormone action on ovarian cells: studies with synthetically pure human somatomedin C and swine granulosa cells.
Isolated swine granulosa cells incubated in chemically defined medium in vitro responded to synthetically pure human somatomedin C/IGF-I in a dose and time-dependent fashion with increased pregnenolone, progesterone and estradiol biosynthesis. These stimulatory actions were not mimicked by growth hormone, proinsulin, desoctapeptide insulin, epidermal growth factor, or fibroblast growth factor. Moreover, somatomedin C/IGF-I augmented the steroidogenic response of granulosa cells to exogenously supplied sterol substrate in the form of low-density lipoprotein, and amplified the stimulatory actions of the classical ovarian effector hormones, estradiol and follicle-stimulating hormone, in a synergistic fashion. The ability of somatomedin C/IGF-I to stimulate estradiol production on the one hand, and to act synergistically with estradiol to stimulate progesterone biosynthesis on the other hand, suggests a unique intrafollicular mechanism for amplifying progestin biosynthetic capacity in granulosa cells.
D000616:Aminoglutethimide / Q000494:pharmacology; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D013196:Dihydrotestosterone / Q000031:analogs & derivatives / Q000494:pharmacology; D004958:Estradiol / Q000096:biosynthesis*; D005260:Female; D006107:Granulosa Cells / Q000187:drug effects* / Q000378:metabolism; D007334:Insulin-Like Growth Factor I; D008077:Lipoproteins, LDL / Q000494:pharmacology; D011374:Progesterone / Q000378:metabolism*; D013002:Somatomedins / Q000494:pharmacology*; D013552:Swine; D013739:Testosterone / Q000378:metabolism
D008077:Lipoproteins, LDL; D013002:Somatomedins; D013196:Dihydrotestosterone; D000616:Aminoglutethimide; D013739:Testosterone; D011374:Progesterone; D004958:Estradiol; D007334:Insulin-Like Growth Factor I; C009954:trilostane