Diesel exhaust (DE) affects the regulation of testicular function in male Fischer 344 rats

To investigate the effects of diesel exhaust (DE) particles on the reproduc tive system, male Fischer 344 rats at 13 mo of age were exposed to clean ai r or DE at particle concentrations or 0.3, 1, or 3 mg/m(3) for 8 mo. DE did not markedly affect testicular and body weights. However, DE at 0.3 mg/m(3 ) significantly decreased prostate and coagulating gland weights, accompani ed by a reduction in thymus and adrenal gland weight. In contrast there was a significant rise in the weights of prostate, seminal vesicles, and coagu lating glands in the 3 mg/m(3) DE group. In rats exposed to 0.3 or 1 mg/m(3 ) DE, serum luteinizing hormone (LH) and testosterone increased significant ly, while a rise in testicular testosterone was noted with 3 mg/m(3) DE. Th e concentrations of follicle-stimulating hormone (FSH) and inhibin as well as the sperm head counts were not markedly altered in any treatment group. Positive staining with inhibin-a subunit and 3 beta -hydroxysteroid dehydro genase (3 beta -HSD) were observed in Sertoli cells and Leydig cells, respe ctively. Immunolocalization of inhibin-alpha subunit and 3 beta -HSD was no t changed by exposure to DE. In conclusion. DE appears to exert greater eff ects on accessory glands than on testes in Fischer 344 rats, and the respon siveness of rats is less than that found in mice.