The investigation of antioxidant effect of resveratrol on heart and liver in fructose induced-metabolic syndrome


Thesis Type: Doctorate

Institution Of The Thesis: Gazi Üniversitesi, Fen Bilimleri Enstitüsü, Turkey

Approval Date: 2014

Student: FİLİZ SEZEN BİRCAN

Supervisor: KANUNİ BARBAROS BALABANLI

Abstract:

Metabolic syndrome is a disease characterized by hypertension, dyslipidemia, insulin resistance, and is associated with increased risk for development of both cardiovascular diseases and type 2 diabetes. It was determined a close relationship between incidence of metabolic syndrome and increased fructose consumption in clinical and animal studies. On the other hand, resveratrol (3,4,5-trihydroxystilbene) that has antioxidant and antiinflammatory properties is a natural phytoalexin synthesized in a wide variety of plant species including grapes as a response to environmental stress or fungal infection. In the present study, investigation of possible protective effects of resveratrol treatment on metabolic changes, nitric oxide metabolism and oxidative/nitrosative stress in liver and heart tissues caused by high-fructose diet in rats were aimed. In our study, 32 male adult Sprague-Dawley rats were randomly divided into four groups (n=8); control, fructose, resveratrol and fructose+resveratrol. Transresveratrol (10 mg/kg daily by oral gavage) and fructose (20% in drinking water) were administered for 8 weeks. At the end of 8th week, the animals were sacrificed under anesthesia, and metabolic syndrome criteria in serum, protein levels of endothelial and inducible nitric oxide synthases (eNOS and iNOS), stable products of nitric oxide, NOx, levels of 3-nitrotyrosine and malondialdehyde, xanthine oxidase and NADPH oxidase activities in tissues which are markers of oxidative/nitrosative stress were analysed. Fructose administration caused statistically significant increases in systolic blood pressures, serum insulin, triglyceride and VLDL-cholesterol levels, compared to control group and metabolic syndrome model was successfully demonstrated. Fructose diet did not cause clear oxidative/nitrosative stress in liver. It significantly increased 3-nitrotyrosine levels but decreased iNOS protein levels in cardiac tissue. Although resveratrol treatment showed prooxidant effect on some parameters and has not positive effect on atherogenic lipid profile, it prevented increases in systolic blood pressure caused by high-fructose diet, and has protective effects on 3-nitrotyrosine and cardiac eNOS levels.