Direct inhibitory effects of estrogens on rat Leydig cells in vitro

In dispersed rat interstitial cells in vitro both natural and synthetic estrogens inhibited the action of pituitary luteinizing hormone (LH), as assessed by testosterone production. The estrogens also inhibited dibutyryl cyclic AMP induced steroidogenesis, suggesting that one point of inhibition could be distal to the formation of cyclic AMP in the cells. Diethyl stilbestrol and its clinically used sodium phosphate derivative (Honvol), also affected hormone-receptor interaction when tested with rat testicular homogenates. Among estradiol, estradiol benzoate, Honvol and diethyl stilbestrol only the latter at high concentration had toxic effects on Leydig cells as noted from loss of thier viability.