Angiotensin II-induced non-alcoholic fatty liver disease is mediated by oxidative stress in transgenic TG(mRen2)27(Ren2) rats

Background/Aims: Non-alcoholic fatty liver disease (NAFLD) is a common health problem and includes a spectrum of hepatic steatosis, steatohepatitis and fibrosis. The renin-angiotensin system (RAS) plays a vital role in blood pressure regulation and appears to promote hepatic fibrogenesis. We hypothesized that increased RAS activity causes NAFLD due to increased hepatic oxidative stress. Methods: We employed the transgenic TG(mRen2)27(Ren2) hypertensive rat, harboring the mouse renin gene with elevated tissue Angiotensin II (Ang II). Results: Compared with normotensive Sprague-Dawley (SD) control rats, Ren2 developed significant hepatic steatosis by 9 weeks of age that progressed to marked steatohepatitis and fibrosis by 12 weeks. These changes were associated with increased levels of hepatic reactive oxygen species (ROS) and lipid peroxidation. Accordingly, 9-week-old Ren2 rats were treated for 3 weeks with valsartan, an angiotensin type I receptor blocker, or tempol, a superoxide dismutase/catalase mimetic. Hepatic indices for oxidative stress, steatosis, inflammation and fibrosis were markedly attenuated by both valsartan and tempol treatment. Conclusions: This study suggests that Ang II causes development and progression of NAFLD in the transgenic Ren2 rat model by increasing hepatic ROS. Our findings also support a potential role of RAS in prevention and treatment of NAFLD. (C) 2008 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.