Abstract: AIM: To investigate the possible in vivo protective effects of pioglitazone (Pio) on hepatic lesions in metabolic syndrome (MS) rats.METHODS: Normal 7-week-old SD rats were fed with a high-fat, high-salt diet plus 20% sucrose solution for 16 weeks. Pio (10 and 3 mg·kg^-1·d^-1) was orally administered in MS rats from 8 weeks to the end of this study. Systolic blood pressure (SBP) was measured monthly. Liver wet weight (LW) was recorded and liver weight/body weight (LW/BW) ratio was calculated. Levels of fasting blood glucose (FBG), alanine aminotranferease (ALT), aspartate aminotransferase (AST), total cholesterol (TC), triglycerides (TG), fasting insulin (FIns) were determined. Insulin resistance (HOMA-IR) was calculated. Hepatic total-antioxidant capacity (T-AOC), malondialdehyde (MDA) content, inducible nitric oxide synthase (iNOS) and antioxidant enzyme activities, and protein level of nitrotyrosine (NT) were measured. In addition, pathological changes were observed with HE staining.RESULTS: Compared with MS rats, treatment with Pio decreasd the SBP, LW, LW/BW, ALT, AST, TC, TG, FIns and HOMA-IR(P<0.05). Furthermore, treatment with Pio enhanced the hepatic T-AOC and SOD activity, reduced the iNOS activity and protein level of NT(P<0.05), and obviously ameliorated hepatic pathologic lesions.CONCLUSION: Pio improves lesions of hepatic structure and function in MS rats through alleviation of oxidative and nitrative stress.

Key words: Pioglitazone, Metabolic syndrome, Oxidative stress, Nitrative stress