Protective Effect of Quercetin on Cadmium-Induced Oxidative Toxicity on Germ Cells in Male Mice

Cadmium is a toxic heavy metal that is widely distributed in the environment. As a critical process, oxidative toxicity mediates the morphological and functional damages in germ cells after cadmium exposure. In this study, the protective effect of quercetin on cadmium-induced oxidative toxicity was investigated in mouse testicular germ cells. After oral administration of cadmium chloride at 4 mg/kg body weight for 2 weeks, damages in spermatozoa occurred in the early stage of spermatogenesis. Cadmium treatment significantly decreased the testicular antioxidant system, including decreases in the glutathione (GSH) level, superoxide dismutase (SOD), and GSH peroxidase (GSH-Px) activities. Moreover, exposure to cadmium resulted in an increase of hydrogen peroxide production and lipid peroxidation in testes. In addition, cadmium provoked germ cell apoptosis by upregulating expression of the proapoptotic proteins Bax and caspase-3 and downregulating expression of the antiapoptotic protein Bcl-XL. However, combined administration of a common flavonoid quercetin at 75 mg/kg body weight significantly attenuated cadmium-induced germ cell apoptosis by suppressing the hydrogen peroxide production and lipid peroxidation in testicular tissue. Simultaneous supplementation of quercetin markedly restored the decrease in GSH level and SOD and GSH-Px activities elicited by cadmium treatment. Additionally, quercetin protected germ cells from cadmium-induced apoptosis by downregulating the expression of Bax and caspase-3 and upregulating Bcl-XL expression. These results indicate that quercetin, due to its antioxidative and antiapoptotic characters, may manifest effective protective action against cadmium- induced oxidative toxicity in mouse testicular germ cells. Anat Rec, 294:520-526, 2011. (C) 2010 Wiley-Liss, Inc.