Mice strain differences in effects of fetal exposure to diesel exhaust gas on male gonadal differentiation.

We have shown that in ICR pregnant mice exposed to diesel exhaust (DE), mRNA expression of mällerian inhibiting substance (MIS) and a steroid hormone transcription factor (Ad4BP/SF-1), which are essential in male gonadal differentiation, decreases in a DE concentration-dependent manner. To further investigate whether these effects differ among strains, we conducted the present study in 3 different strains: ICR mice, ddY mice, and C57BL/6J mice. The response to DE exposure differed among the 3 strains. In C57BL/6J male fetuses, only MIS mRNA expression significantly decreased, and in ddY male fetuses, there was no change in either MIS or Ad4BP/SF-1 mRNA expression. Although there was no definite correlation between mouse strain characteristics and differences in the effects of DE, our findings suggest strain-related variations in DE sensitivity with respect to gene expression regulating male gonadal differentiation.