Abstract: Objective To explore the effect of carnosic acid（CA）on high-fat diet（HFD）-induced obese non-alcoholic steatohepatitis（NASH）in rats. Methods Twenty-eight male Sprague-Dawley rats were randomly divided into control group （n=8） and experimental group（n=20）. After 10 weeks,rats fed with HFD were assigned to model group（n=10） and treatment group （n=10）,which were both fed with HFD and treated with intragastric administration of either NS or CA（200mg.kg^-1.d^-1） for 6 weeks. Results The rats in model group developed abdominal obesity and NASH in liver histopathology;the body weights in control and model groups were 449.5±47.4 g vs 531.8±40.4 g,visceral fat weight：4.51±1.63g vs 6.37±1.66g,TC：1.58±0.14 mmol/L vs 3.21±0.71mmol/L,ALT：36±18U/L vs 144±80U/L,AST：132±29U/L vs 218±64U/L,MDA:5.93±1.14nmol/ml vs 18.89±7.04nmol/ml,HOMA-IR:0.30±0.15 vs 0.65±0.34 and SOD:24.61±0.43U/ml vs 22.91±0.93U/ml（P<0.01）;Compared with those in the model group, improvement of all above indexes was found in CA-treated group. Conclusion Carnosic acid has satisfactory therapeutic effects on obesity and steatohepatitis induced with high-fat diet. Inhibiting the accumulation of visceral fat,regulating lipid metabolism,improving insulin resistance,resisting oxidative stress and lipid peroxidation damage may be part of its therapeutic mechanisms.

Key words: Non-alcoholic steatohepatitis, Carnosic acid, Obesity, Rats