Effect Of Arsenic And Zinc On Rat Testicular Tissue And Its Mechanisms

ObjectiveTo observe the effects of arsenic exposure on testicular toxicity inmale rats and the antagonism effects of different doses of zinc onreproductive toxicity induced by arsenic. To investigate the possiblemechanism of the antagonism effects of zinc on reproductive toxicity ofarsenic.Methods40male Sprague-Dawley rats of4weeks old were divided into fivegroups randomly and in each group there were8rats:①control group：double distilled water；②a rsenic group：4mg/kg NaAsO2；③arsenic pluslow-dose zinc group：4mg/kg NaAsO2+8mg/kg ZnSO4；④arsenic plusmid-dose zinc group：4mg/kg NaAsO2+20mg/kg ZnSO4；⑤arsenicplus high-dose zinc group：4mg/kg NaAsO2+50mg/kg ZnSO4. Afterintragastric administration applied for60days, sacrificed the rat forexperiments.The histological changes of testis were observed by HEstaining. The concentration of serum testosterone was examined by radioimmunoassay. The expression of Fas protein in testicular tissues wasexamined by immunohistochemistry staining. The levels of MDA, LDHand SOD were determined by enzyme-linked immunosorbent assay(ELISA). The expression of CuZn-SOD mRNA was determined byRT-PCR. The zinc content of testicular tissues was measured by atomicabsorbing spectrometry.ResultsThe body weight of rats in arsenic group was significantly lower thanthat in control group and the body weight in zinc groups were heavier thanarsenic group (P<0.05). The weight of testis decreased in arsenic group andit become heavier in mid-dose and high-dose zinc group (P<0.05). Thereare no statistically significant difference in testicular viscera coefficient(P>0.05).HE staining showed that: the spermatogenic cells in arsenic groupwere reduced and loosely arranged than contreol group. There were only asmall amount of sperms in the lumen. Spermatogenic cells and maturesperms in low-zinc group were less than contreol group, exfoliated cellsappeared in the lumen. Mature sperms in lumen and spermatogenic cells inmid-zinc group and high-zinc group were increased than arsenic group.Morphology in zinc group becomes normal.Immunohistochemical results: The expression of Fas in arsenic groupwas significantly up-regulated than control group. And that in zinc groups were significantly reduced than arsenic group. Compared to control group,the expression of Fas low-zinc and high-zinc group were higher (P <0.05).There was no significant difference between mid-zinc group and controlgroup (P>0.05).Radioimmunoassay results: Compared with the control group, serumtestosterone levels in arsenic group was significantly decreased, low-zinc,mid-zinc and high-zinc group were increased significantly (P <0.05),whereas testosterone level in high-zinc was lower than mid-zinc group.Atomic absorbing spectrometry results: Compared with controlgroup,zinc content in arsenic group and low-zinc group was decreasedsignificantly.And that in high-zinc group was higher than control group (P<0.05). There was no significant difference between mid-zinc group andcontrol group (P>0.05).PCR Results: Compared with the control group, the expressionCuZn-mRNA in arsenic group was reduced, while that in high-zinc groupincreased(P <0.05). The differences in low-zinc and mid-zinc group werenot statistically significant compared with the control group (P>0.05). Theexpression of CuZn-mRNA in mid-zinc and high-zinc group were highercompared to arsenic group (P <0.05).ELISA Results: Compared with the control group, the MDA level inarsenic, low-zinc and high-zinc group were significantly higher, while thatin mid-zinc group was significantly reduced. The MDA level in mid-zinc and high-zinc group were significantly lower than arsenic group (P <0.05).Compared with the control group, the LDH and SOD level in arsenic group,low-zinc and high-zinc group were significantly decreased. The SOD levelin mid-zinc group was significantly increased than control group(P<0.05).The LDH and SOD level in mid-zinc group and high-zinc groupwere increased significantly compared to arsenic group (P <0.05).ConclusionExposure to arsenic in drinking water can cause testicularhistopathological changes, decrease of testosterone secretion and testicularzinc content, increase of the expression of Fas protein, lipid peroxidationdamage, the impact of CuZn-SOD mRNA expression of rat testis andreproductive function damage in male rats. Appropriate doses of zinc canantagonize this toxic effect.