Localization of epoxide-metabolizing enzymes in rat testis.

Antibodies raised against rat hepatic epoxide hydrolase (EC 3.3.2.3) and glutathione S-transferases (EC 2.5.1.18) B, C and E were used to determine the presence and localizations of these epoxide-metabolizing enzymes in testes of sexually immature and mature Wistar and Holtzman rats. Unlabeled antibody peroxidase-antiperoxidase staining for each enzyme was readily detected in rat testes at the light microscopic level. Although significant strain-related differences were not apparent, staining intensity for certain enzymes differed markedly between Leydig cells and seminiferous tubules. Leydig cells of immature and mature rats were stained much more intensely for epoxide hydrolase and glutathione S-transferases B and E than were seminiferous tubules, whereas Sertoli cells, spermatogonia, spermatocytes and spermatids, as well as Leydig cells, were stained intensely by the anti-glutathione S-transferase C. Age-related differences in staining for glutathione S-transferase B were not obvious, while the anti-glutathione S-transferase C stained seminiferous tubules more intensely in immature rats, and antibodies to epoxide hydrolase and glutathione S-transferases C and E stained Leydig cells much more intensely in mature rats. These observations thus demonstrate that testes of both sexually immature and mature rats contain epoxide hydrolase and glutathione S-transferases. Except for glutathione S-transferase C in immature rats, Leydig cells appear to contain much higher levels of enzymes than do seminiferous tubules. During sexual maturation, the testicular level of glutathione S-transferase B appears to remain constant, while levels of epoxide hydrolase and glutathione S-transferases C and E increase within Leydig cells and the level of glutathione S-transferase C decreases within seminiferous tubules.