Adrenomedullin Deficiency Increases the Susceptibility of Liver Fibrosis Induced by CCl 4

Adrenomedullin (AM) is a peptide expressed in all body tissues, and its related receptors are increased in liver fibrosis. In this study, we evaluated the effect of AM deficiency on liver fibrogenesis induced by CCl 4 using AM heterozygous (HT) mice. The animals received a single injection of CCl 4 or olive oil for the acute experiment, and received CCl 4 or olive oil three times a week for 6 weeks for the chronic experiment. Fibrosis was accessed using histopathological analysis and the western blot. The AM HT mice showed mild pericentrilobular degeneration when compared to the AM wild type (WT) mice. In the acute experiment, there was no significant difference between the AM WT and AM HT mice. However, in the chronic experiment, the CCl 4 -treated AM HT mice showed more severe liver fibrosis than that of the CCl 4 -treated AM WT mice. The AST and ALT levels of the AM HT CCl 4 group were higher than those of the AM WT CCl 4 group. Additionally, the collagen deposition, α-SMA protein and TGF-β protein were increased in the AM HT CCl 4 group when compared to the AM WT CCl 4 group. The AM HT mice also exhibited severe lipid peroxidation through the GSH decrement. Taken together, our data suggest that AM deficiency increases the susceptibility to liver fibrosis induced by CCl 4 , indicating a novel therapeutic target for patients with liver fibrosis.