Reproductive toxicity of manganese dioxide in forms of micro- and nanoparticles in male rats

Background: Manganese Dioxide (MnO ${}_2$ ) has long been used in industry, and its application has recently been increasing in the form of nanoparticle. Objective: The present study was an attempt to assess the effects of MnO ${}_2$ nanoparticles on spermatogenesis in male rats.

Materials and methods: Micro- and nanoparticles of MnO ${}_2$ were injected (100 mg/kg) subcutaneously to male Wistar rats (150 $\pm$ 20 gr) once a week for a period of 4 weeks, and the vehicle group received only normal saline (each group included 8 rats). The effect of these particles on the bodyweight, number of sperms, spermatogonia, spermatocytes, diameter of seminiferous tubes, testosterone, estrogen, follicle stimulating factor, and the motility of sperms were evaluated and then compared among the control and vehicle groups as the criteria for spermatogenesis.

Results: The results showed that a chronic injection of MnO ${}_2$ nanoparticles caused a significant decrease in the number of sperms, spermatogonia, spermatocytes, diameter of seminiferous tubes (p $<$ 0.001) and in the motility of sperms. However, no significant difference was observed in the weight of prostate, epididymis, left testicle, estradiol (p = 0.8) and testosterone hormone (p = 0.2).

Conclusion: It seems that the high oxidative power of both particles was the main reason for the disturbances in the function of the testis. It is also concluded that these particles may have a potential reproductive toxicity in adult male rats. Further studies are thus needed to determine its mechanism of action upon spermatogenesis.