Manganese deficiency: effects on susceptibility to ethanol toxicity in rats

Previous studies have shown that manganese (Mn) deficiency in rats results in reduced activity of manganese superoxide dismutase (MnSOD) and increased levels of mitochondrial lipid peroxidation. These findings suggested to us that the Mn-deficient rat may be especially susceptible to the toxic effects of ethanol, as the metabolism of this compound results in production of superoxide anion. Offspring from Mn-sufficient and Mn-deficient adult rats were given either 20% (wt/vol) ethanol or distilled-deionized water as their drinking fluid for 14 d. Response to ethanol feeding was different between Mn-sufficient and deficient rats as evidenced by severe reductions in caloric intake and body weight observed in the Mn-deficient rats. Furthermore, after 14 d of ethanol feeding, these rats were extremely lethargic and in poor physical condition. Although Mn-sufficient rats responded similarly to the deficient rats during the first 6 d of ethanol feeding, they increased their caloric intake and body weight during the remainder of the experimental period. MnSOD activity in the ethanol-fed Mn-sufficient and Mn-deficient rats was similar, thus the alcohol-induced toxicity observed in the deficient rats was not due to reduced MnSOD activity. Iron-induced lipid peroxidation may be one of the mechanisms leading to the toxicity observed, as ethanol feeding resulted in liver Fe levels that were 30% higher than those in Mn-deficient rats that were not fed ethanol.