Induction of oxidative stress in the rat testis after short-term exposure to the organochlorine pesticide methoxychlor

Abstract

The ability of 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD) to induce oxidative stress in various tissues of animals has been reported. The nature and mechanism of action of TCDD on the antioxidant system of sperm has not been studied. In the present study we have sought to investigate whether TCDD induces oxidative stress in the epididymal sperm of rats. Subchronic doses of TCDD (1, 10, and 100 ng/kg body weight per day) were administered orally to male Wistar strain rats for 45 days. After 24 h of the last treatment the rats were killed using diethyl ether. The epididymides were removed and cleared from the adhering tissues. Epididymal sperm were collected by cutting the epididymides into small pieces in Ham's F12 medium, and counted using a hemocytometer. The epididymal sperm counts in the TCDD-treated groups decreased in a dose-dependent manner from the control value of 8.2+/-0.14 x 10(8) to 5.31+/-0.15 x 10(8). Since a positive correlation (r=0.95; n=24) was observed between sperm count and DNA content of the epididymal sperm, DNA content was routinely used as an indicator of sperm count, and the results were expressed in terms of both protein and DNA. There was a significant decline in the activities of superoxide dismutase (40+/-2.17 to 27.1+/-0.76/mg protein and 32.41 to 18.07+/-0.76/mg DNA), catalase (2.49+/-0.13 to 2.03+/-0.05/mg protein and 2.01+/-0.05 to 1.35+/-0.05/mg DNA), glutathione reductase (71.2+/-3.87 to 48+/-1.79/mg protein and 57.58+/-1.52 to 31.94/mg DNA) and glutathione peroxidase (22.4+/-1.43 to 16.9+/-1.57/mg protein and 18.08+/-0.61 to 11.38+/-1.22/mg DNA) while there were increases in the levels of hydrogen peroxide (20.8+/-1.96 to 55.3+/-0.88/ mg protein and 16.18+/-1.88 to 36.87+/-0.88/ mg DNA) and lipid peroxidation (2.17+/-0.2 to 6.08/mg protein and 1.75+/-0.12 to 4.05+/-0.12/mg DNA) in the epididymal sperm. The results suggest that graded doses of TCDD elicit depletion of antioxidant defense system in sperm, indicating TCDD-induced oxidative stress in the epididymal sperm. In conclusion, the adverse effect on male reproduction in TCDD-treated rats may be due to the induction of oxidative stress in sperm.

An aminoglycoside antibiotic gentamycin induces oxidative stress, reduces antioxidant reserve and impairs spermatogenesis in rats

“…Estimation of this free radical was based on a previously employed method (Podczasy and Wei, 1988;Latchoumycandane and Mathur, 2002). A reaction mixture was obtained by adding 4.9 mM iodonitrotetrazolium violet, 0.3 mM EDTA, and 0.92 mM sodium carbonate (pH 10.2) to 25 μL tissue homogenate.…”

“…A reaction mixture was obtained by adding 4.9 mM iodonitrotetrazolium violet, 0.3 mM EDTA, and 0.92 mM sodium carbonate (pH 10.2) to 25 μL tissue homogenate. The tubes were then incubated for a period of 15 min and then kept in boiling water for a minute and then cooled to room temperature and the absorbance was read at 505 nm against blank (Latchoumycandane and Mathur, 2002).…”

“…Glutathione peroxidase was estimated by a spectrophotometric method (Latchoumycandane and Mathur, 2002). The test mixture was prepared by mixing 10 μL homogenate, 1.59 ml of 100 mM phosphate buffer (pH 7.6), 100 μL of 10 mM EDTA, 50 μL of glutathione reductase, 100 μL sodium azide, 100 μL of reduced glutathione, 100 μL of 200 mM NADPH and 10 μL hydrogen peroxide.…”

“…The lipid peroxidation was estimated by a spectrophotometric method in terms of thiobarbituric acid reactive substances (Latchoumycandane and Mathur, 2002). One volume of homogenate was mixed with 2 volume of stock reagent (15% w/v trichloroacetic acid in 0.25 N HCl, and 0.375% w/v thiobarbituric acid in 0.25 N HCl) in a centrifuge tube, vortexed, and heated for 15 min in a water bath.…”

Supraphysiological Free Radical Levels and their Pathogenesis in Male Infertility

“…Oral administration of phthalate esters to rats is reported to increase the generation of ROS within the testis and a concomitant decrease in antioxidant levels, culminating in impaired spermatogenesis [98]. Several other pollutants like pesticides [99], preservatives and diesel [100] have been related to oxidative stress. Paternal exposure to heavy metals such as lead, arsenic and mercury is associated with decreased fertility and pregnancy delay according to recent studies [101].…”