P 9: Taurine protects against impairment of mitochondrial function and oxidative stress in the heart of rats with fructose-induced insulin resistance

Abstract

Background and aims Taurine (2-aminoethanesulfonic acid) is a free amino acid found in substantial amounts in all mammalian tissues. Recently, data is accumulating that show the effectiveness of T against diabetes mellitus, insulin resistance and its complications, including retinopathy, nephropathy, neuropathy, atherosclerosis and cardiomyopathy, independent of hypoglycemic effect. Numerous experimental and several clinical studies demonstrated that T helps the cardiovascular system through a variety of mechanisms including modulation of intracellular calcium concentration, antagonism of angiotensin II action, membrane-stabilizing, antioxidant, and lipid-lowering effects. The aim of the study was to assess the effects of T on mitochondrial respiratory chain activity and lipid peroxidation in the heart of prediabetic rats fed a high-fructose diet. Materials and Methods Male Wistar rats were divided into three groups: the control group fed on a regular diet (C, n=8), the high fructose-fed group (F, n=8), which had free access to 250 g/L solutions of fructose for 8 weeks and the fructose-fed group treated with taurine (F+T, n=8) for 8 weeks (100 mg/kg/day per os). Mitochondria were isolated by differential centrifugation from the hearts of fed rats. Oxygen consumption rate was measured polarographically at 37°C using a Clark-type oxygen electrode with either glutamate/malate or succinate as energy substrates of complex I or II, respectively. Levels of lipid hydroperoxides, reduced glutathione (GSH) and glutathione reductase (GR) activity were determined in mitochondrial preparations. Result We found reduction of NAD-dependent substrate oxidation rate in metabolic state 3 in the heart mitochondria of rats with fructose-induced insulin resistance by 30% in comparison with intact control (p Conclusion These results demonstrate that taurine protects against impairment of respiratory chain activity complex I and attenuates oxidative stress in the heart mitochondria of rats with fructose-induced insulin resistance. Thus, this action of taurine could be an important mechanism for providing benefits to the cardiovascular system in patients with insulin resistance and type 2 diabetes.