Effect of 3-amino-1,2,4-triazole on narcosis time and lethality of ethanol in UChA rats.

The capacity of rat brain homogenates to oxidize ethanol by catalase peroxidative system, previously reported, was reevaluated in experiments using lower ethanol concentration, showing that the effect of this system can be observed even with a concentration of 50 mM, equivalent to non lethal blood level. The involvement of catalase was confirmed by its blocking by aminotriazole (AT) or methanol but not by pyrazole or butanol. Evidence for a functional role of ethanol oxidation by brain catalase in the action of this substance was given by the fact that rats pretreated with AT (1 g/kg IP) exhibited a significant shorter narcosis than untreated controls, strongly suggesting the mediation of acetaldehyde in this effect. Previous results with doses of 60 mmole/kg IP were confirmed with 70 mmole/kg IP, but not with 90 mmole/kg IP. A significant prolonging of narcosis time was observed when AT was administered after any of these doses by an unknown mechanism. Furthermore it was observed that AT pretreatment reduced significantly the lethal effect of 110 mmole/kg IP ethanol; but when AT was given after ethanol (90 mmole/kg IP) it enhanced the lethality. These results suggest that catalase peroxidative pathway might play a role not only in narcosis time but also in ethanol toxicity.