VARIATION IN THE ANTIANDROGENIC ACTIVITY OF DIESEL EXHAUST PARTICULATES EMITTED UNDER DIFFERENT ENGINE LOADS

Abstract

We examined endocrine disruptors in diesel exhaust particulates (DEP) emitted from a diesel engine under different engine loads. The antiandrogenic and aryl hydrocarbon receptor (AhR) agonistic activity of DEP extracts (DEPE) were evaluated using PC-3/AR human prostate cancer cells transiently transfected with androgen- or AhR agonist-regulated luciferase reporter plasmids, respectively. The antiandrogenic and AhR agonistic activities were enhanced by higher engine load. The AhR antagonist α-naphthoflavone reversed the antiandrogenic activity of DEPE as seen through a reduction in AhR agonistic activity. The concentrations of polycyclic aromatic hydrocarbons (PAHs) with four or more rings, which are AhR agonists in DEPE, increased with higher engine load. Therefore, the enhanced antiandrogenic activity of DEPE is due in part to the increase in AhR agonists such as PAHs with higher engine load.

Keywords:

• antiandrogenic activity
• aryl hydrocarbon receptor agonists
• diesel exhaust particulates
• engine load
• PC3/AR cells
• polycyclic aromatic hydrocarbons

Acknowledgments

This work was supported by a Grant-in-Aid for Scientific Research on Priority Areas, The Environmental Risk of Endocrine Disruptor (no. 14042218); a Grant-in-Aid for Scientific Research (C) (no. 13672342) to R. Kizu; a Grant-in-Aid for Scientific Research (B) and a Grant-in-Aid for the Kanazawa University 21st-Century COE Program to K. Hayakawa from the Ministry of Education, Culture, Sports, Science and Technology of Japan. The authors thank Dr. R. H. Tukey for providing the pLUC1A1 plasmid.

Notes

^a JIS, Japanese industrial standard.

^a SOF, soluble organic fraction.