Effects of protein deficiency on liver trace elements and antioxidant activity in carbon tetrachloride-induced liver cirrhosis

In liver cirrhosis, liver tissue becomes progressively substituted by fibrosis, ultimately leading to architectural distortion, liver circulatory changes, and liver failure. Some data support the hypothesis that protein undernutrition may play a role in the development and progression of nonalcoholic liver cirrhosis and that this progression is at least partially mediated by changes in glutathione peroxidase (GPX), superoxide dismutase (SOD), and other antioxidative systems, leading to an increase in lipid peroxidation. We analyzed the effects of protein deficiency on liver Cu, Fe, Zn, Mn, and Se in carbon tetrachloride (CCl₄)-induced liver cirrhosis, the relation of protein undernutrition and these trace elements with the activity of some hepatic antioxidative enzymatic mechanisms, and the relation of all of them with morphological and biochemical changes in 40 male adult Sprague-Dawley rats divided in four groups. Liver cirrhosis was induced by intraperitoneal injection of CCl₄ to 10 rats fed a 2% protein diet and another 10 fed a 18% protein control diet; two further groups included rats without cirrhosis fed the 2% protein and the 18% protein diets. The study period lasted 6 wk. GPX, SOD, and lipid peroxidation products as well as Zn, Cu, Mn, Se, and Fe were determined in liver samples. We found that liver GPX and Se were reduced in the cirrhotic animals, especially in the low-protein-fed ones, protein deficiency, but not cirrhosis, exerting the main effects. A close correlation was found between liver GPX and serum albumin and weight loss and an inverse one among GPX and hepatocyte ballooning, liver fibrosis, and fat, histomorphometrically determined. These results suggest a pathogenetic role of decreased GPX in the progression of liver disease, which may become enhanced by concomitant protein undernutrition. In addition to iron, the levels of which were increased in the malnourished rats, no differences were found regarding the other trace elements, SOD activity, and lipid peroxidation products.