SPONTANEOUS LIPID-PEROXIDATION AND SPERM METABOLISM DURING INCUBATIONIN MEDIA SIMULATING THE OVIDUCTAL MICROENVIRONMENT

It has been suggested that along the female genital tract spontaneous lipid peroxidation regulates the limit of the lifetime of spermatozoa. We have studied some aspects of rabbit and mouse spermatozoal metabol ism during spontaneous lipid peroxidation in the course of the incubat ion in media which simulate the oviductal environment. The spermatozoa collected at regular intervals after the beginning of incubation were processed for cytochemical detection of cytochrome oxidase, lactate d ehydrogenase and glucose-6-phosphate dehydrogenase activities. Quantit ative cytochemical assays were made in situ in individual spermatozoa by microdensitometry. The cytochrome oxidase activity significantly de creased in both species because of damage to mitochondrial enzymes and membranes by radical and non-radical products of lipid peroxidation. The change in lactate dehydrogenase activity indicates that under our experimental conditions the lipid peroxidation process damages membran e permeability more markedly in mouse spermatozoa. The glucose-6-phosp hate dehydrogenase activity, which should influence the concentration of reduced glutathione through production of NADPH, is more extensivel y enhanced in mouse spermatozoa than in rabbit spermatozoa. This is in agreement with the fact that in mouse spermatozoa the glutathione sys tem is the major protective defence against oxidative damage while in rabbit spermatozoa it is superoxide dismutase.