Prevention of c-Jun/activator protein-1 activation and microsomal epoxide hydrolase induction in the rat liver by cysteine during protein–calorie malnutrition

Abstract

Protein–calorie malnutrition (PCM), a major global health problem, arises during protein and/or energy deficit due to disease and nutritional inadequacy. To date, cellular adaptive responses and gene expression associated with PCM remain poorly understood. In view of the primary role of the liver in energy conversion, the present study was designed to investigate changes in hepatic morphology and molecular alterations during PCM. PCM caused marked decreases in the cytoplasmic eosinophilic content and nuclear shrinkage in the hepatocytes with a decrease in glutathione content. The nuclear activator protein-1 (AP-1) complex was activated in the liver of PCM rats. AP-1-binding activity of nuclear extracts produced from PCM rats was reduced by the presence of anti-c-Jun antibody. Microsomal epoxide hydrolase (mEH), a phase II detoxifying enzyme, was 4-fold induced, with a 20-fold increase in the mRNA level during PCM. In contrast to the PCM-induced changes in hepatic morphology, PCM rats supplemented with cysteine showed an increase in the GSH level and well-preserved hepatic structures with mild fat degeneration. Cysteine supplementation inhibited the activation of AP-1 and the induction of mEH in PCM rats. These results provided evidence: (i) that PCM alters liver morphology with a decrease in the glutathione level; (ii) that cysteine may serve as a key element responsible for preserving hepatic morphology and maintaining the glutathione level; and (iii) that cysteine was active in preventing the activation of AP-1 and mEH induction in the liver during PCM.