N-NITROSAMINES AND THEIR EFFECTS ON THE LEVEL OF GLUTATHIONE, GLUTATHIONE-REDUCTASE AND GLUTATHIONE-S-TRANSFERASE ACTIVITIES IN THE LIVER OF MALE-MICE

The present study investigates the influence of different chemical str ucture of N-nitroso compounds on the hepatic level of reduced glutathi one (GSH), glutathione reductase (GSH-R) and glutathione S-transferase (GST) activities in the liver of male Balb/C mice after treatment wit h 20 mg/kg body weight of each compound for 1 h as a single dose. The level of reduced glutathione decreased significantly between 37 and 70 %; after the treatment of male mice with ethylbutylnitrosamine (-37%), diphenylnitrosamine (-50%), propylbutylnitrosamine (-52%), diethylnit rosamine (-54%), ethylmethylnitrosamine (-55%), and dibutylnitrosamine (-70%), whereas, methylpropylnitrosamine increased the level of GSH b y 71%. All the N-nitrosamine compounds tested increased the activity o f glutathione reductase except ethylmethylnitrosamine had no effect. T he activity of glutathione S-transferase activity was inhibited after treatment of the male mice with diphenylnitrosamine (-60%), dibutylnit rosamine (-60%), and methylpropylnitrosamine (-81%), while, ethylmethy lnitrosamine and ethylbutylnitrosamine had no effect on such activity. On the other hand, diethylnitrosamine increased the activity of gluta thione S-transferase by 50%. It can be postulated from this study that the chemical structure of N-nitrosamines plays a significant role in the alteration of GSH level and GSH metabolizing enzymes, since the su bstitution of different groups on the nitroso group was found to be ca pable of causing an alteration in such activities.