RETINOIDS REGULATE GONADOTROPIN ACTION IN CULTURED RAT SERTOLI CELLS

The effect of retinoids on cultured rat Sertoli cells was studied by evaluation of cAMP and estradiol production after gonadotropin stimulation in the presence or absence of the retinoid. Sertoli cells cultured in the presence of FSH produce a high amount of cAMP and increase their aromatase activity. The addition of retinol alone has no effect on cAMP and estradiol production; however, the presence of retinol in the culture medium exerts an inhibitory effect on Sertoli cell response to FSH stimulation. In particular, FSH-induced cAMP production of rat Sertoli cells was significantly reduced (50-60% decrease) both by retinol and by retinoic acid. This effect was observable during the first ten days of culture and was also evident when Sertoli cells were cultured in the presence of retinol and methylisobutylxanthine, an inhibitor of phosphodiesterase activity. Cholera toxin-stimulated cAMP levels were reduced by retinol, whereas forskolin-induced elevation of cAMP levels was not affected by vitamin treatment. The inhibitory effect of retinoids on FSH-stimulated aromatase activity of Sertoli cells, which is cAMP mediated, was also evident. In conclusion, the present study demonstrates that retinoids modulate FSH action on cultured rat Sertoli cells and decrease cAMP production.