EFFECTS OF ETHANE DIMETHANESULFONATE (EDS) ON ADULT AND IMMATURE RABBIT LEYDIG-CELLS - COMPARISON WITH EDS-TREATED RAT LEYDIG-CELLS

Ethane-dimethanesulfonate (EDS) has been shown to selectively kill Ley dig cells and depress testosterone production in adult rats. A recent study has shown that immature rat Leydig cells are less sensitive to E DS exposure. There is evidence that the rabbit metabolizes EDS to meth ane sulfonic acid more rapidly than does the rat, reducing exposure to the parent compound. In the study reported here, we examined the effe cts of EDS on the Leydig cells in both adult and immature rabbits and compared the effects found with those previously reported in the rat. In vivo, EDS exposure demonstrated that Leydig cells from adult rabbit s were affected, with both serum and interstitial testosterone product ion depressed. EDS effects in adult rabbits and rats were compared by exposing explants of testicular parenchyma to EDS in vitro and evaluat ing testosterone production. With this procedure, the rabbit testis wa s less sensitive to EDS treatment than the rat, with a 50% reduction r ate (EC(50)) achieved with 2026 mu M EDS for the rabbit and with 336 m u M EDs for the rat. Perfusion of adult and immature rabbit testis wit h 430 mu M EDS demonstrated the insensitivity of the immature testis t o EDS exposure: adult testosterone production was reduced 50% in 3.5 h , whereas no diminution was found in the immature rabbit. EDS exposure of interstitial cell preparations further demonstrated the insensitiv ity of immature rabbit Leydig cells, with an EC(50) of 4397 mu M compa red to an EC(50) of 1137 mu M EDS in adult preparations. These and pre viously reported data in the rat provide evidence for the following or der in Leydig cell sensitivity to EDS exposure: adult rat > adult rabb it > immature rat >> immature rabbit.