Somatostatin action on rat ovarian steroidogenesis

To date, very few studies on the effect of somatostatin on female reproductive function have been reported. In our study, we examined the effects of somatostatin on (i) androgen biosynthesis using whole ovarian dispersates, and (ii) aromatase activity and progesterone production using granulosa cells. Whole ovarian dispersates obtained from immature rats were cultured for 96 h in serum-free medium with human chorionic gonadotrophin (HCG; 25 ng/ml) and insulin (10 micrograms/ml) in the presence or absence of an increasing concentration of somatostatin (0.03-3.00 ng/ml). HCG- and insulin-stimulated accumulation of androsterone by these cells was inhibited significantly by somatostatin. Granulosa cells from diethylstilbestrol-treated rats were cultured for 48 h in serum-free medium with follicle-stimulating hormone (FSH; 20 ng/ml) and FSH plus insulin (1 microgram/ml) with or without somatostatin (0.03-3.00 ng/ml). Both aromatase activity and progesterone production stimulated by FSH and FSH plus insulin were significantly inhibited by somatostatin. Somatostatin by itself (1 ng/ml) did not have an effect on any of the evaluated parameters. The action of somatostatin could be immunoneutralized and did not influence the plated viable cell mass. These findings indicate that somatostatin can regulate ovarian steroidogenesis by mediating gonadotrophin and growth factor action on different ovarian cell types.