Modification of testicular cytochrome P-450 after fenitrothion administration

1. The effect of fenitrothion on testicular microsomal system was analyzed and compared to the modifications induced by the drug at the hepatic level. 2. Acute (165 mg/kg, 1 day) and subacute (55 mg/kg, 3 days) administration of fenitrothion caused a significant decrease on testicular cytochrome P-450 content (51 and 50% respectively) but no modification on cytochrome b5 and NADPH cytochrome c reductase. No changes were induced by fenitrothion in testicular microsomal system after chronic treatment (5.5 mg/ml, 30 days). 3. Results obtained in the liver were very similar to those observed in testis even though the percentage of cytochrome P-450 inhibition obtained after acute and subacute drug administration (45 and 43%) was smaller. 4. In addition, changes in testosterone blood concentrations were also analyzed. A significant reduction of hormone plasma levels were detected at 165 and 55 mg/kg doses of fenitrothion (98% in both cases). Fenitrothion was not able to modify the levels of testosterone in the blood after chronic administration.