Effect of nanoparticle-rich diesel exhaust on testosterone biosynthesis in adult male mice

Abstract

The effect of nanoparticle-rich diesel exhaust (NR-DE) on the testicular function and factors related with the biosynthesis of testosterone gene expression were investigated in mice. Male C57BL/Jcl mice were exposed to clean air, low-dose NR-DE (Low NR-DE), high-dose NR-DE (High NR-DE) or filtered diesel exhaust (F-DE) for 8 weeks. We found that the mice exposed to High NR-DE had significantly higher testosterone levels than those in the control and F-DE groups. To determine the effects of NR-DE on testicular testosterone production, interstitial cells dissected from the male mice which were exposed to NR-DE, F-DE, or clean air for 8 weeks were incubated with or without human chorionic gonadotropin (hCG; 0.1 IU/mL) for 4 h. The concentrations of testosterone in the culture media were measured. The testosterone production was significantly increased in with or without hCG of High NR-DE exposed group, and significantly decreased in both with or without hCG of F-DE exposed groups. Moreover, several genes, which is associated with testicular cholesterol synthesis, HMG-CoA, LDL-R, SR-B1, PBR, and P450scc, P450 17α, and 17β-HSD were determined in the testis of adult male mice. The results showed High NR-DE exposure significantly increased the expression of these genes. Whereas, the levels in the F-DE exposure group returned to those in the control group, implicating that the nanoparticles in DE contribute to the observed reproductive toxicity. We conclude that enhancement of testosterone biosynthesis by NR-DE exposure may be regulated by increasing testicular enzymes of testosterone biosynthesis.

Keywords::

• Nanoparticles
• diesel exhaust
• Leydig cell culture
• testosterone biosynthesis
• mouse

Acknowledgments

We are grateful to Dr. G. D. Niswender, Animal Reproduction and Biotechnology Laboratory, Colorado State University, Fort Collins, CO, USA, for providing antiserum to progesterone (GDN 337) and testosterone (GDN250).

Declaration of interest

This study was supported in part by Grants-in-Aid for Scientific Research (P07582) from the Japan Society for the Promotion of Science (JSPS), the Ministry of Environment, Japan (C0901) and from the Fundamental Research Funds for the Central Universities (KYJ200910) and (2012BAD39B02).