Proteomic analysis of the protective effects of Platycodi Radix in liver of chronically alcoholic rats

In this study, we examined the effect of Platycodi Radix (PR) supplementation in chronically alcoholic rats. Sprague-Dawley rats were divided into three groups: control group (no alcohol), alcohol group (36.8% of total calories), and 0.3% PR group. The levels of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were increased by alcohol treatment, and PR supplementation normalized the AST level. Moreover, alcohol-induced cytochrome P450 2E1 was decreased by PR treatment. Proteomic analysis of liver tissues of alcohol-exposed rats and PR-supplemented rats revealed that 50 different proteins functionally characterized as involved with cytoskeleton regulation, signal transduction, cytokine, apoptosis, and reactive oxygen species metabolism showed significant quantitative changes. The expression levels of glutathione S-transferase mu, Bcl-2-like protein, and peroxiredoxin IV were decreased in the alcoholic group, whereas the levels of these proteins were increased more than threefold in the PR group. However, the expression levels of smooth muscle actin, cytochrome P450 2D, mitogen-activated protein kinase 8, and 3alpha-hydroxysteroid dehydrogenase were increased in the alcohol group and were decreased in the PR group. These data suggest that the antioxidant enzymes may play a protective role against alcohol-induced damage via oxidative stress defense mechanisms induced by PR supplementation.