Zinc and low-dose of cadmium protect sertoli cells against toxic-dose of cadmium: The role of metallothionein

Background: The impact of cadmium (Cd) on male infertility may be related to the interaction with metal-binding proteins known as metallothioneins (Mts). Trace elements like zinc (Zn) have protective effects on testicular damage induced by Cd. Objective: We determined the effect of Zn and low-dose Cd pre-treatment on the expression of Mt1 and Mt2 genes on testicular Sertoli cells. Materials and Methods: The cultured TM4 mouse sertoli cells were treated with 50 μM ZnSO4 (Zn pre-treated group; ZnPG), 2 μM CdCl2 (Cd pre-treated group; CdPG), or distilled water (DW pre-treated group; DWPG). After 18 hour, all of these groups were exposed to 100 μM CdCl2 for different periods of time (1, 2, 3, and 6 hours). There was also a control group for all three groups, which was treated only with distilled water (without Cd or Zn pre-treatment). Cellular viability, Zn and Cd concentrations and gene expression were assessed by MTT, atomic absorption spectrometry and real time PCR methods, respectively. Results: The expression of Mt1 and Mt2 genes in ZnPG, CdPG, and DWPG was greater than the control group (p=0.02 and p=0.01, respectively). Cd concentrations in CdPG and DWPG were greater than the control group (p=0.00). Expression of both genes in ZnPG and CdPG increased after 3 hours of treatment and Cd concentration decreased simultaneously, which was more obvious in ZnPG. Conclusion: Zn and short term low-dose Cd pre-treatment might reduce the adverse effects of Cd by increasing expression of Mts genes in Sertoli cells. The protective effect of Zn was stronger than Cd