| Objective: The objective of this research was to demonstrate whether Tea polyphenols could antagonize cadmium-induced male subchronic reproductive toxicity and by which mechanisms it worked. This study was also to provide the evidences for the prevention and treatment of reproductive toxicity induced by environmental cadmium exposure. Methods: (1) Establishing the model of male reproductive toxicity induced by sub-chronic cadmium exposure: 24 male Sprague-Dawley rats were randomly divided into four groups. 0,0.1,0.2 and 0.4mg cd2+/kg.bw were injected subcutaneously in different groups, five times per week for 5 weeks. After the exposure, the rats were sacrificed and the testis, epididymis were separated. Testes were selected to examine the pathology. while sperm concentration,sperm activity and sperm malformation were detected from epididymises. (2) the Antagonistic effect and mechanism of Tea Polyphenols (TP) on Cadmium -induced Subchronic Reproductive Toxicity :60 male Sprague-Dawley rats were randomly divided into six groups: control, Cd, Cd +low-dose TP, Cd +middle-dose TP, Cd +high-dose TP and TP groups. The rats in control and TP groups were injected (sc) with saline, while others with Cd at a dose of 0.4mg/kg, five days a week.. Mean while ,the rats in Cd +low-dose TP, Cd +middle-dose TP, Cd+high-dose TP and TP groups were given TP( 50 mg/kg, 100 mg/kg, 200 mg/kg ,100mg/kg respectively) orally once a day , while others were given distilled water instead. After five weeks , the rats were killed and the samples of serum, urine, feces, liver, kidney and testis were take for test.Results: (1) TP could antagonize cadmium-induced male subchronic reproductive toxicity: A significant reduction in the sperm population, motility, serum testosterone concentration and testicular LDH-X activity were recorded in rats treated with cadmium alone, which was accompanied by an increase of malformed sperm. Middle and high-dose TP given resulted in partial recovery of the reproductive parameters above studied (P<0.05). Through the pathological examination of the testes we could find out that: treatment with cadmium resulted in testicular edema lightly and less sperm in seminiferous tubule. However testes from rats that were treated with TP appeared to show much less cadmium-induced damage, especially in middle and high-dose TP group.(2) The mechanisms of TP antagonize cadmium-induced male subchronic reproductive toxicity:â‘ The effects of TP on cadmium -induced testicular oxidative stress: After 5 weeks of cadmium treatment, MDA level and GSH-PX activity in testis were significantly higher (P<0.05) while SOD activity and GSH concentration were significantly lower (P<0.05) than those in the control group respectively. As compared to Cd group, middle and high dose TP taken had lower MDA level, higher GSH concentration and SOD activity in testis, which showed that TP could against testicular oxidative stress induced by cadmium.â‘¡The effects of TP on cadmium accumulation in different tissues: Compared with the control group, the administration of Cd led to a manifold increase of its level in all investigated organs such as liver, kidney and testes, the Cd concentration in urine and feces was also increased. Middle and high dose TP taken significantly decreased Cd accumulation in the testes and liver, increased Cd concentration in urine and feces as compared to Cd group. TP had no effect on the serum ALT,AST,BUN,CRE level,which shows that TP could promote accumulative cadmium to excretion without increasing the hurt of liver and kidney. Conclusion:1 Subchronic Cd exposure could damage male reproductive system.2 Spermatogenic lesion and inhibition of testosterone production are early events after subchronic Cd exposure.3 Oxidative stress and endocrine disruption are two important mechanisms of male reproductive toxicity induced by subchronic Cd exposure.4 Tea polyphenols could antagonize cadmium-induced male subchronic reproductive toxicity.5 Inhibition of oxidative stres...
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