Effect of food deprivation on glutathione and amino acid levels in brain and liver of young and aged rats

Abstract

The effect of short-term food deprivation on glutathione (GSH) and amino acid levels in brain regions of young and aged rats was compared with changes observed in liver. Animals aged 3 months and 24 months were deprived of food for 48 h. GSH and amino acid levels from cerebral cortex, cerebellum, pons medulla, and liver were assayed and compared with levels in animals of the same age fed normal diets. In liver in both young and old rats, GSH levels fell 30%, from 13 μmol/g tissue to 8/7 μmol/g tissue. Significant changes were observed in other amino acids, including an increase of 30–50% in methionine, glycine, and glutamine, and a decrease of 30–50% in alanine in liver of both young and aged rats, and a 4-fold increase in taurine in young. In brain, little change was observed upon food deprivation. No decrease was observed in GSH, and only small changes were observed in other amino acids. In the aged animal aspartate, glutamate, and alanine levels were slightly lower; tyrosine in cerebellum was reduced by 30%, and both glycine and tyrosine in the pons medulla were reduced by 20–30%. In the brain areas examined, levels of GSH ranged from 1–2 μmol/g in young and 0.8–1.4 μmol/g in old; with levels in pons medulla being lower than those in cerebral cortex. In brain, in contrast to liver, levels were scarcely affected by short-term food deprivation. The relative stability of amino acids paralleled that of brain proteins, which did not significantly decrease even under conditions in which protein content of most other tissues was greatly reduced, indicating specific control of cerebral protein metabolism in protection in malnutrition.