Dose-dependent short-term study of di-n-butyl phthalate on the testicular antioxidant system of Wistar rats.

Di-n-butyl phthalate (DBP), a xenobiotic, is widely used in industries as a softener for polyvinyl chloride resins. The aim of the present study was to evaluate whether DBP induces oxidative stress in testes of Wistar rats. DBP at doses of 500, 1,000 and 1,500 mg/kg b.wt. (doses below LD50) was given orally for 7 days. After 24 hrs from the last dose, the animals were killed under ether anesthesia. Nonsignificant increase in testicular weight was observed. Histological studies indicated a dose-related degeneration of germinal, Leydig and Sertoli cells along with loss of spermatozoa in the lumen. The concentrations of malondialdehyde (TBARS), lipid hydroperoxides, water-soluble antioxidant capacity, glutathione-S-transferase, catalase and trace elements-zinc and copper increased while concentrations of total protein, lipid soluble antioxidant capacity, ascorbic acid, glutathione, total superoxide dismutase (SOD), Cu-ZnSOD, MnSOD, glutathione peroxidase, glutathione reductase and metallothionein decreased at all the dose levels. The data suggests that the cellular functions were adversely affected due to impairment of spermatogenesis indicative of oxidative stress as evident by altered antioxidative defense system which appears to mediate through hypothalamo-pituitary-gonadal axis. The spectrum of changes in testes reflects its susceptibility to phthalate even at low dose with the potential to interfere with critical reproductive function.