Decreased hepatotoxicity of dimethylnitrosamine (DMN) following chronic alcohol consumption

Compared to controls receiving physiological saline, the i.p. administration of dimethylnitrosamine (DMN) on 5 consecutive days to rats fed a nutritionally adequate liquid diet resulted 24 hours after the last injection of significant increases in glutamic dehydrogenase (GDH), glutamic oxylacetate transaminase (GOT), and glutamic pyruvate transaminase (GPT) activities in the serum, indicating a striking hepatotoxic effect of this compound. This was confirmed by the histological demonstration of massive centrolobular necrosis. Conversely, following pretreatment of the rats with an ethanol containing liquid diet for 23 days and subsequent administration of DMN the increases of serum enzyme activities and massive centrolobular necrosis could not be observed. These results therefore suggest that chronic alcohol consumption protects from hepatotoxicity due to DMN, most probably due to an enhancement of detoxifying pathways of the parent component or one of its toxic metabolites.