Role of gangliosides in gonadotropin and cholera enterotoxin stimulated steroidogenesis in isolated rat ovarian cells

Abstract

Ovarian cells isolated from 26 day old rats responded to hCG (10 ng/ml) and cholera enterotoxin (100 ng/ml) with a forty-five to fifty-fold increase in progesterone production. Both cholera enterotoxin and hCG-stimulated progesterone response was accompanied by a lag period. The duration of the lag period in the production of the progesterone depended on the concentration of gonadotropin or cholera enterotoxin, and with maximally stimulating dose it was 20-30 minutes. Addition of highly purified mixed gangliosides to the incubation medium abolished the stimulatory effect of cholera enterotoxin on progesterone response. In contrast, under identical experimental conditions, ganglioside addition produced no effect on progesterone response elicited by hCG or LH. Similarly mixed gangliosides did not prevent the specific binding of [125I]hCG to the ovarian cells or to the membranes isolated from the ovary. In addition preincubation of [125I]hCG with ganglioside did not alter the subsequent binding of the hormone to the ovarian cell surface receptor. These findings suggest that gangliosides are not involved in the hormone receptor interactions and subsequent receptor mediated physiological response.