POTENTIATION BY EPIDERMAL GROWTH-FACTOR OF THE INVITRO HCG STIMULATION OF TESTICULAR STEROIDOGENESIS IN HAMSTERS

Epidermal Growth Factor (EGF) has been reported to stimulate or inhibit steroidogenesis in murid Leydig cells depending on the experimental conditions used. In the present study, testicular fragments from an adult cricetid rodent, the Syrian hamster, were incubated with various doses of mouse EGF (0-2.0-mu-g/ml media), in the presence or absence of HCG (0-12.5 mlU/ml media). Although EGF alone did not affect in vitro testicular steroidogenesis, it significantly potentiated the HCG-induced elevation of the accumulation of testosterone and 17-hydroxyprogesterone in the media. In contrast, the effect of HCG on media progesterone concentration was not affected by EGF. Since in the Syrian hamster intracellular calcium loading functions as a gonadotropic stimulus, the present results could be a consequence of the EGF-induced increase in cellular calcium levels.