Aims: In order to evaluate the role of metallothionein (MT)-III in cadmium (Cd)-induced testicular toxicity, we examined the sensitivity of MT-III null mice to severe testicular injury caused by Cd.
Main methods: Male MT-III null mice, MT-I/II null mice and wild-type mice were given a subcutaneous injection of CdCl(2) (15μmol/kg). The testis was collected from each mouse at 6, 12 and 24h after Cd administration.
Key findings: Testicular hemorrhages by evaluating morphology, hemoglobin content and histological parameters in the 3 types of mice were elevated by Cd injection in a time-dependent manner. The degree of hemorrhage in Cd-injected MT-I/II null mice was similar to that in the wild-type mice. In contrast, hemorrhage in the MT-III null mice was attenuated compared with that in wild-type mice and MT-I/II null mice. Cd levels, MT-I and MT-II mRNA levels and Cd-binding molecules in the testis were similar between MT-III null mice and wild-type mice. In microarray analysis, high expression of purine-nucleoside phosphorylase 2 (Pnp2), retinal degeneration 3 (Rd3), and cadherin-like 24 (Cdh24) was revealed in the testis of MT-III null mice under normal or Cd-treated conditions.
Significance: MT-III null mice were found to show attenuation of Cd-induced severe testicular toxicity. These results suggest the lack of MT-III contributes to protection of testis from Cd. In addition, regulation of Pnp2, Rd3, and Cdh24 mRNA levels may involve the sensitivity of MT-III null mice to Cd.
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