Down-regulation of CatSper 1 and CatSper 2 genes by lead and mercury

Abstract

In the study of the expression of CatSper genes, consideration of the effects of environmental metal toxicity is very important. Therefore, in this study, the effects of lead acetate and mercury chloride exposure on expression of CatSper genes, sperm parameters, histology of testis and prooxidant antioxidant balance (PAB) values of serum were investigated. A total of 28 mice was divided into four groups. The control group did not receive injections. The sham group received normal saline intraperitoneally. Lead and mercury groups were injected 60 and 1.25 mg/kg/daily lead acetate and mercury chloride respectively intraperitoneally for 2 weeks. After 35 days, the sperm analysis and histology of left testis were performed. In addition, serum was obtained to measure the PAB values. The right testis was used for molecular analysis of real-time PCR. Administration with either lead acetate or mercury caused significant damage to the seminiferous tubules as well as a reduction in sperm parameters compared to the control group. The relative expression of CatSper 1 and CatSper 2 in the lead group was lower than that of the control group (-0.01 ± 0.24, -0.007 ± 0.52 vs. 1 ± 0.50, P = 0.34). The relative expression of CatSper 1 and CatSper 2 was significantly lower in the mercury group compared to the control ones (-0.24 ± 2.28, -4.49 ± 4.86 vs. 1 ± 0.50, P = 0.21). PAB values significantly increased in lead or mercury exposed- mice compared to the control ones (0.93 ± 0.17, 1.54 ± 0.17 vs. 0.51 ± 0.11; P ≤ 0.000). The results of this study showed that administration with either lead acetate or mercury chloride caused degenerative damage in seminiferous tubules and reduction in sperm quality and expression of CatSper 1, 2 genes in mice. Therefore, it is possible in infertile men who have had exposure to lead acetate or mercury chloride. Owing to structural similarities, these metals are substitutes for calcium ions and have effects on calcium channels. These cause immobility in sperm by blocking CatSper-specific calcium channels. However, more studies are required to elucidate the mechanism underlying the impact of different doses of heavy metals on CatSper genes expression.

Keywords: CatSper gene expression; Lead; Mercury; Mouse.