Abstract:

[Objective] This study aimed to assess the effects of sub-chronic arsenic poisoning on the protein expression levels of AQP-8 and survivin in rat testicular tissues. [Method] A total of 40 healthy adult clean-grade SD male rats were randomly assigned into a control group and the low-, medium- and high-dose arsenic exposure groups, with 10 rats in each group. Using free drinking water poisoning, the concentrations of sodium arsenate in drinking water of the low-, medium- and high-dose exposure groups were 2.4, 12.0 and 60.0 mg/L, respectively. The arsenic exposure experiment lasted for 15 consecutive weeks. The control group was given distilled water. At the end of the exposure experiment, sperm count were measured on rats in each group to calculate sperm survival rate. Testicular tissue sections were prepared for pathological observation. Immunohistochemical and Western blotting analyses were used to determine the protein expression levels of AQP-8 and survivin in rat testicular tissues. [Result] Compared with the control group, the sperm count and sperm survival rate in the medium- and high-dose exposure groups decreased significantly （P<0.05）. There was no obvious alteration in the seminiferous tubules of the rats in the low-dose exposure group. In the medium-dose exposure group, the number of seminiferous epithelial layers decreased and the seminiferous tubule gaps widened. In the high-dose exposure group, part of the seminiferous tubules showed dissolved basal membrane, disordered seminiferous epithelial cell layers and increased intercellular gaps, and interstitial edema and exudation. According to the immunohistochemical analysis, AQP-8 protein was primarily expressed in the cell membrane and sperm cells of spermatogenic cells at all levels. Compared with the control group, the mean optical density of AQP-8 positive cells in the testicular tissues of the rats in various arsenic exposure groups significantly （P<0.05） increased. Survivin protein was mainly expressed in the cytoplasm of secondary spermatocytes and sperm cells. In comparison with the control group, the mean optical density of survivin positive cells in the testicular tissues of the rats exposed to various doses of sodium arsenate significantly （P<0.05） decreased. Western blotting analysis showed that both the control group and the sodium arsenate exposed groups had AQP-8 and survivin protein expressions in the testicular tissues. In the low-, medium- and high-dose exposure groups, the protein expression level of AQP-8 was significantly （P=0） up regulated, while that of survivin was significantly （P=0） down regulated compared with the control group. [Conclusion] The up regulation of AQP-8 protein expression and down regulation of survivin protein expression in testicular tissues caused by arsenic exposure may be one of the mechanisms leading to its male reproductive toxicity.

Key words: sub-chronic arsenic poisoning, SD rat, AQP-8, survivin