OBJECTIVETo establish an oxidative stress model induced by cumene hydroperoxide (cHP) in testis and epididymis of rats in vivo, and to understand the peroxidative damage of oxidative stress in testis, epididymal sperm and its propensity to induce nuclear DNA damage during spermatogenesis and sperm maturation in vivo.

METHODSAn organic hydroperoxide, cHP, 70% aqueous, diluted by 0.9% NaCl, was employed as model prooxidant. Ninety-day-old male Wistar rats were divided into a control and three cHP groups, and were administered intraperitoneally 0, 1/10, 1/6 and 1/4 LD50 cHP per day respectively at a dose of 2 ml/kg, for 7 consecutive days and were observed for any toxic symptoms and mortality. Twenty-four hours after the last dose, rats were sacrificed and induction of oxidative stress was ascertained by monitoring the degree of lipid peroxidation expressed as nano molar of malondialdehyde (MDA) in testicular homogenate and epididymal sperm. Nuclear DNA damage in testes and epididymal sperms was determined by comet assay. Motility of caudal sperms was counted and the morphology of testes and epididymis was observed under light microscope.

RESULTSRats of cHP administered groups were less vigorous than those of the control, but there were not death of rats during treatment. 1/10 LD50 per day for 7 consecutive days resulted in only a marginal increase in testicular MDA levels. However, 1/6 and 1/ 4 LD50 per day for 7 days of cHP administered to adult rats induced marked oxidative stress in testis and epididymal sperms as evidenced by a marked increase in MDA or nuclear DNA damage in testis and caput sperms, as well as significant decreases both in the body weight-and motility of caudal sperms. While the nuclear DNA damage caput sperms of 1/6 and 1/4 LD50 cHP administered rats increased significantly, nuclear DNA damage in caudal sperms showed no treatment related alterations.

CONCLUSIONOxidative stress in testis and epididymal sperms can be safely induced by applying multiple doses of cHP (1/6 and 1/4 LD50 per day for seven consecutive days). DNA damage caused by cHP induced oxidative stress may occurred mainly in testes.