Detection and localization of immunoreactive alcohol dehydrogenase protein in the rat testis

Alcohol dehydrogenase in the testis metabolizes ethanol and a variety of physiological substrates such as dihydrotestosterone and vitamin A. Studies of the localization of enzyme activity in the testis have revealed its presence in either interstitial cells or seminiferous tubules alone or in both places. The purpose of this study was to detect and localize immunoreactive alcohol dehydrogenase in the testis. The testis enzyme had similar antigenicity than the liver enzyme as demonstrated by double immunodiffusion and inhibition titration using antibody to the liver enzyme. The concentration of immunoreactive enzyme protein was 1.7 +/- 0.1 micrograms/mg of cytosol protein in the testis as compared with 9.3 +/- 0.3 micrograms/mg of cytosol protein in the liver. Isoelectric focusing revealed eight isoenzyme bands. Only the three bands with the highest isoelectric points precipitated with antibody to liver alcohol dehydrogenase. By immunohistochemistry using this antibody, the enzyme was localized principally to the Leydig cells which are also the site of steroidogenesis. The presence in the seminiferous tubules of isoenzymes of lower isoelectric point, which do not react with the antibody to the liver enzyme, can not be excluded.