HYDROXYL RADICAL-INDUCED DECLINE IN MOTILITY AND INCREASE IN LIPID-PEROXIDATION AND DNA MODIFICATION IN HUMAN SPERM

We employed the xanthine-xanthine oxidase system to produce H2O2 or si mply used commercially available H2O2 solution to investigate the effe cts of exogenous hydroxyl radicals on the motility characteristics and on lipid peroxidation and DNA modification of human sperm. The functi onal parameters of sperm motility declined concomitantly upon incubati on of sperm with hydroxyl radicals. After incubation of freshly ejacul ated human sperm with 0.23 mM H2O2 in the presence of 1.8 mM ADP and 2 .7 mM FeSO4 for 1 hr at 37 degrees C, 90 % reduction of motility was o bserved. Effect of hydroxyl radicals on sperm motility was dependent o n the concentrations of FeSO4 and H2O2, respectively. The remaining mo tility of sperm after 1 hr incubation showed negative linear correlati on with FeSO4 concentration. The response of sperm motility to FeSO4 w as also dependent on the concentration of H2O2. Except for the amplitu de of lateral head displacement, functional parameters of sperm declin ed with the increase of H2O2 concentration. Moreover, we found that li pid peroxidation measured as malondialdehyde (MDA) and accumulation of modified DNA indicated by 8-hydroxy-2'-deoxyguanosine (8-OH-dG) in hu man sperm were significantly accelerated by exogenous hydroxyl radical s. The contents of lipid peroxides and 8-OH-dG in the spermatozoa were increased from 23.6+/-2.4 nmol MDA/1x10(7) sperm and 0.17+/-0.02 % in the untreated group to 30.6+/-1.2 nmol MDA/1x10(7) sperm and 1.9+/-0. 47 %, respectively, in the sperm treated at 37 degrees C for 1 hr with 2.03 mM H2O2, 1.8 mM ADP and 4.5 mM FeSO4. Taken together, these resu lts suggest that the detrimental effects of hydroxyl radicals on human sperm functions may be mediated, at least partly, through lipid perox idation and DNA modification.