Toxic Effects Of Fluoride And The Combination Of Fluoride And Aluminum On Reproduction Of Male Rat

This study investigated the toxic effects of fluoride (F) and combination of F and aluminum (Al) on reproduction of male rats and their possible mechanisms by establishing animal model. Fifty-six male Wistar rats with sexual maturation were divided into seven groups randomly, including control group with normal saline solution,1.0,2.0, and 3.0 mg sodium fluoride (NaF)/kg groups and each NaF-treated groups＋0.1 mg aluminium ion (Al3+)/kg groups with intragastric gavage for 90 days. The body and relative testes weights were calculated. The sperm motion parameters were measured by the WLJY-9000 color-detection system of sperm quality. The activities of superoxide dismutase (SOD), catalase (CAT) and nitricoxide synthase (NOS) and the contents of malondialdehyde (MDA), hydrogen peroxide (H2O2) and nitrogen monoxidum (NO) in the testis tissue were determined with spectrophotometric assay. The contents of calcium (Ca), ferri (Fe), zincum (Zn), cuprum (Cu) and magnesium (Mg) in the testis tissue were measured by atomic absorption spectrophotometry. The protein expression of Fos in the testis cell was detected by Western blotting. The testicular cell cycle and cell apoptosis were measured by flow cytometry. The results were showed as follows:1. During the 90-day period of treatment and observation, there were no significant changes in body and relative testes weights between the control and any of the groups (p>0.05), and no death occured in any of the groups.2. There were no significant differences in curvilinear velocity (VCL) of spermatozoa between the control and any of the groups (p>0.05). Significant increases were observed in velocity of average path (VAP) in the 3.0 mg NaF group and 3.0 mg NaF＋Al3＋group and beat cross-frequency (BCF) in the 3.0 mg aF group (p<0.05). Significant decreases in straightness (STR) and amplitude of lateral head displacement (ALH) of spermatozoa were observed in the 1.0 mg NaF group (p <0.05). There were significant decreases in mean angular deviation (MAD) in any of the groups and linearity (LIN) in all NaF-treated groups compared with the control group (p<0.05). In the 1.0 and 2.0 mg NaF groups, density (P) of spermatozoa was significantly lower compared with that in the control and 3.0 mg NaF groups (p <0.05). At the same time, significant increases in LIN in the 3.0 mg NaF＋Al3＋group andρin all NaF＋Al3+-treated groups were observed compared with the corresponding NaF-treated groups (p<0.05).3. No significant changes in SOD and CAT activities in the testis tissue were observed in any of the groups (p>0.05). There were, however, significant increases in the level of MDA in the 1.0 mg NaF group, H2O2 in the 2.0 mg NaF group and NO in the 3.0 mg NaF＋Al3＋group and significant decrease in NOS activity in the 1.0 mg NaF group compared with the control group (p<0.05). At the same time, there were significant decreases in H2O2 in the 2.0 mg NaF＋Al3＋group and significant increases in NO in the 1.0 and 3.0 mg NaF＋Al3＋groups and NOS in all NaF＋Al3＋groups compared with the corresponding NaF-treated groups (p<0.05).4. Compared with the control group, significant decreases were observed in the contents of Ca in the 1.0 mg NaF group, Fe in the 2.0 mg NaF group＋Al3＋group, Zn in the all NaF-treated groups and 2.0 and 3.0 mg NaF groups＋Al3＋groups and Mg in the 3.0 mg NaF group in the testis tissue (p<0.01). The content of Ca increased significantly in the 1.0 mg NaF＋Al3＋group compared with the 1.0 mg NaF group (p <0.01).5. The protein expression of Fos in the testis tissue increased significantly in the 1.0 and 2.0 mg NaF groups compared with the control group (p<0.01), whereas decreased significantly in all NaF＋Al3＋groups compared with the corresponding NaF-treated groups (p<0.01).6. Compared with the control group, significant increases in the percentage of G0/G1 stage cells in all the NaF-treated groups and in the 1.0 mg NaF＋Al3＋group and significant decreases in the percentage of S stage cells in all the NaF-treated groups and in the 3.0 mg NaF＋Al3＋group were observed (P<0.05). On the other hand, the percentage of G2 stage cells decreased significantly in the 3.0 mg NaF group, whereas inecreased significantly in the 3.0 mg NaF＋Al3＋group compared with the control group (p<0.05). At the same time, there were significant decrease in the percentage of G0/G1 stage cells and significant increase in the percentage of G2 stage cells in the 3.0 mg NaF＋Al3＋group compared with the 3.0 mg NaF group (p <0.01).7. The testicular cell apoptosis ratios in all the NaF-treated groups were higher than that in the control group, but only the 2.0 and 3.0 mg NaF groups exhibited significant increases compared with the control group (p<0.05).The results of this study indicated that excess F exposure has been found to produce adverse effects on the reproduction of male rats by changing the contents of metal elements in the testis tissue and the protein expression of Fos in the testis cell, inducing oxidative stress, changing testicular cell cycle and causing testicular cell apoptosis, especially at a comparatively lower level of exposure. However, the changes of testicular cell cycle and apoptosis do not appear to be directly connected with the increased level of oxidative stress, since some deleterious effects were more prominent at lower F intake. At the same time, Al has the antagonistic effect on the reproductive toxicity of F. The possible reason is that aluminum could inhibit the absorption and increase the excretion of F in intestinal tract.