In vivo and in vitro evaluations of spermatotoxicity induced by 2-ethoxyethanol treatment.

2-Ethoxyethanol (EE), a member of the glycol ethers, has been shown to produce testicular atrophy in laboratory animals. The present study further identified the spectrum of effects on the male reproductive system in vivo and initiated in vitro studies on possible mechanisms of action. Adult, male rats were treated (po) with 0 or 936 mg EE/kg, 5 days/week for 6 weeks. Semen samples were collected on a weekly basis during the exposure period from ovariectomized, hormonally primed females immediately following mating and analyzed for sperm count, sperm morphology, and sperm motility. Sperm count and percent normal morphology were decreased at Weeks 5 and 6, and sperm motility was decreased at Week 6. These data, along with other studies, indicated that the pachytene spermatocyte was the most sensitive target for EE. In vitro studies monitored O2 consumption and ATP concentrations in isolated pachytene spermatocytes which were treated with 10 mM EE or 1 or 10 mM ethoxyacetic acid (EAA), the reported active metabolite of EE. An increase in respiratory ratio for the lactate rate/endogenous rate and a decrease in the 2,4-dinitrophenol rate/lactate rate were observed only for cells treated with 10 mM EAA. Additionally, a decrease in ATP concentration was seen only with 10 mM EAA. These results indicated that EAA interfered with energy metabolism in the pachytene spermatocyte. This effect may, in part, explain the testicular toxicity produced by this compound.