Urantide decreases hepatic steatosis in rats with experimental atherosclerosis via the MAPK/Erk/JNK pathway

Abstract

Hepatic steatosis, an indicator of atherosclerosis (AS), is always accompanied by inflammatory responses and disturbances in lipid metabolism. The present study investi- gated the protective effect of urantide, a urotensin II (UII) receptor antagonist, on the liver of rats with AS with hepatic steatosis by regulating the MAPK pathway. AS was induced in rats via an intraperitoneal injection of vitamin D3 and the administration of a high-fat diet. Urantide treatment was then administered to the rats. Pathology, liver index, lipid levels and liver function were measured to determine liver injury. The expression levels of UII and G protein-coupled receptor 14 (GPR14) were determined using immunohistochemistry, reverse transcription-quantitative PCR and western blotting. The expression levels of MAPK-related proteins in hepato- cytes from each group were quantified using western blotting and immunofluorescence staining. Rats with AS had typical pathological changes associated with AS and hepatic steatosis, which were significantly improved by urantide treatment. Blood lipid levels, body weight, liver index and liver function were recovered in rats with AS after urantide treatment. Urantide downregulated the expression levels of UII and GPR14 in the livers of rats with AS; concurrently, the phosphorylation of Erk1/2 and JNK was significantly decreased. Moreover, no significant changes were observed in the phosphorylation of p38 MAPK in AS rat livers. In conclusion, urantide inhibits the activation of Erk1/2 and JNK by blocking the binding of UII and GPR14, thereby alleviating hepatic steatosis in rats with AS, ultimately restoring lipid metabolism in the liver and alleviating AS lesions.