Study of quinalphos (an environmental oestrogenic insecticide) formulation (Ekalux 25 E.C.)-induced damage of the testicular tissues and antioxidant defence systems in Sprague-Dawley albino rats.

The effect of quinalphos (O-O-diethyl-O-[quinoxalinyl-(2)-thionophosphate]), an environmental oestrogenic organophosphorus insecticide pollutant, was studied on Sprague-Dawley albino rats at doses of 250 and 500 microgram kg(-1) body wt. i.p. for 3, 8 and 15 days, respectively. After the treatment with quinalphos there was an increase in the lipid peroxides (as measured by manoldialdehyde production) and a decrease in the total lipid content for the testicular membrane. The effects were more pronounced at the low doses than at the higher doses, indicating that some physiological defence mechanisms were in operation at higher doses. The free-radical-scavenging enzymes (superoxide dismutase, catalase and glutathione peroxidase) showed significantly higher activity at high dose in comparison to their activities at low-dose treatment. Glutathione content was gradually reduced after quinalphos treatment, both in low and high doses. Histomorphohological studies showed that after the low-dose treatment shrinkage of the tubular diameter and testicular atrophy leading to degenerative changes in the germinal epithelium were observed. But at high dose, gradual recovery of various germ cell layers and significant expansion of seminiferous tubules of Sprague-Dawley rat testes were found; the latter is generally believed to be a useful index of testicular activity through the hypothalamo-hypophyseal-gonadal axis. The present study indicates that quinalphos caused damage and degeneration of the testicular tissues due to free-radical-mediated lipid peroxidation at low doses. We have also demonstrated that, in response to the damage, an endogenous antioxidant enzyme defence system became operative at the higher dose of treatment. Copyright 2000 John Wiley & Sons, Ltd.