Rat model of nonalcoholic steatohepatitis created by methionine and choline deficiency: biochemical and histological analyses

Abstract

Shinichi Nagai1, Jun Iwamoto2, Masakazu Suzuki1, Azusa Seki11Hamri Co Ltd, Koga, Ibaraki, Japan; 2Institute for Integrated Sports Medicine, Keio University School of Medicine, Shinjuku-ku, Tokyo, JapanBackground: The purpose of this study was to establish a Sprague-Dawley rat model of nonalcoholic steatohepatitis (NASH) due to combined methionine and choline deficiency (MCD). Methods: Eighty nine-week-old male Sprague-Dawley rats were randomized into two groups (n = 40), comprising an MCD diet group and a standard diet (control) group. After fasting blood was collected, 10 rats from each group were scheduled to be sacrificed at weeks 4, 8, 12, and 16 from the start of the experiment. Body weight and liver wet weight were measured, and histological examination of the liver was performed after hematoxylin and eosin and Oil Red O staining. Results: In the MCD group, body weight and liver wet weight were decreased compared with the control group, while serum levels of albumin, γ-glutamyltranspeptidase, alkaline phosphatase, and total bilirubin were increased, but serum levels of total cholesterol and triglycerides were decreased. Histological examination of the liver revealed centrilobular hepatocellular fatty change from as early as four weeks, with mild fibrosis after 12 weeks. Conclusion: These findings suggested the onset of NASH with liver dysfunction and bile duct damage in rats fed with the MCD diet. Increased fatty acid uptake and decreased cholesterol secretion were considered to be important mechanisms by which the MCD diet promoted intrahepatic lipid accumulation in this model.Keywords: nonalcoholic steatohepatitis, rat, methionine, choline, fatty liver