SUPEROXIDE PRODUCTION AND ANTIOXIDANT ENZYMES IN AMMONIA INTOXICATIONIN RATS

Injection of large doses of ammonium salts lead to the rapid death of animals. However, the molecular mechanisms involved in ammonia toxicit y remain to be clarified. We have tested the effect of injecting 7 mmo l/kg of ammonium acetate on the production of superoxide and on the ac tivities of some antioxidant enzymes in rat liver, brain, erythrocytes and plasma. Glutathione peroxidase, superoxide dismutase and catalase activities were decreased in liver and brain (both in cytosolic and m itochondrial fractions) and also in blood red cells, while glutathione reductase activity remained unchanged. Superoxide production in submi tochondrial particles from liver and brain was increased by more than 100% in both tissues. Both diminished activity of antioxidant enzymes and increased superoxide radical production could lead to oxidative st ress and cell damage, which could be involved in the mechanism of acut e ammonia toxicity.