Inhibition of mouse sperm capacitation by ethanol

Ethanol reduced the in vitro fertilizing capacity of mouse spermatozoa in a dose-dependent manner, at concentrations commonly observed after ethanol ingestion by man and experimental animals (100-400 mg%). At these ethanol levels, sperm motility and the integrity and fertilizing capacity of the oocyte were not affected, nor was parthenogenic cleavage induced. Data indicated that ethanol prevents the capacitation of the spermatozoa. Its inhibitory effect could be reversed by incubation of the alcohol-treated spermatozoa in alcohol-free capacitation medium. At similar concentrations, t-butanol had no effect on fertilization, suggesting that inhibition by ethanol is mediated by a mechanism other than a "solvent" effect. Although the alcohol dehydrogenase inhibitor, pyrazole, prevented the inhibition of fertilization by ethanol, acetaldehyde (the product of ethanol oxidation) was without effect. These data indicate that the inhibition of capacitation by ethanol is mediated via its metabolism by spermatozoa but not by the immediate product of ethanol oxidation.