Hepatic antioxidant system response to a fructose-rich diet

FRANCINI F; SCHINELLA G; CASTRO MC; GAGLIARDINO JJ; MASSA L

Montreal, Canadá

Congreso; IDF 20th World Diabetes Congress; 2009

International Diabetes Federation

Aim: To study the changes induced in the hepatic antioxidant system by administration of fructose-rich diet. Materials and Methods: Normal male Wistar rats were fed with comercial diet and tap water (C) or the same diet plus 10% fructose  in the drinking water (F) for 21 days. Thereafter, glycemia (G) (GOD-PAP), triglyceridemia (TG) (commercial kit), insulinemia (In) (RIA),  HOMA-R (insulin resistance indicator) were measured and an intraperitoneal glucose load (IGL) was performed. After liver removal, we measured: 1) content of thiobarbituric acid reactive substances (TBARS) and reduced glutathion (GSH) (spectrophotometry); 2) mRNA (qPCR), protein expression (Western blot) and enzymatic activity (spectrophotometry) of superoxide dismutase (SOD), catalase (CAT) and glutathion peroxidase (GPx); 3) hepatic microsomal susceptibility to enzymatic and non enzymatic-induced lipid peroxidation, and 4) triglyceride content (TGC). Results: (means ± SEM; F vs. C): G 8.3 ± 0.2 vs. 7.2 ± 0.3 mM, p<0.005; TG 1.3 ± 0.1 vs. 0.8 ± 0.1 mM, p<0.001; In 4.7 ± 0.6 vs. 2.7 ± 0.5 ng/ml, p<0.02; HOMA-R 43 ± 3 vs. 26 ± 2, p<0.001; IGL (AUC) 4.31 ± 0.5 vs.1.57 ± 0.63 mM glucose/min, p < 0.01; TGC 379.7 ± 53.4 vs. 207.5 ± 12 µg TG/100 mg protein, p<0.01; GSH 3.2 ± 0.26 vs. 4.2 ± 0.28 µmol/g tissue, p<0.05; no significant changes were measured in hepatic TBARS levels. The genic expression of CAT, SOD and GPx was 43 ± 9 vs. 100 ± 5%, p<0.001; 28 ± 7 vs. 100 ± 22%, p<0.01; 51 ± 15 vs. 100 ± 4%, p<0.01, respectively. Protein levels (Western blot) of CAT, SOD and GPx were 79 ± 6 vs. 100 ± 3%, p<0.02; 70 ± 8 vs. 100 ± 2%, p<0.003, with no changes for GPx. Only CAT activity showed a significant reduction (15%; p<0.05). No significant differences were recorded in hepatic microsomal susceptibility to lipid peroxidation between C and F rats. Conclusions: High fructose feeding induces significant hormonal and metabolic changes accompanied by a decrease in the hepatic antioxidant system; in the period studied, however, these changes did not affect the peroxidation level of liver membrane lipids