Protective effect of taurine on diabetic rat endothelial dysfunction

Abstract

As increasing evidence suggest that oxidative stress plays an important role in the developing angiopathy in diabetes, we studied the effects of taurine, a free radical scavenger, on diabetesinduced angiopathy in the rat aorta. Six-week-old male Wistar rats were randomly divided into three groups; control group (Cont), diabetes group (DM) and diabetes group treated with taurine for four weeks, 500 mg/kg/day, intraperitoneally (i.p.) (DM+T). Diabetes was induced by streptozotocin (50 mg/kg i.p.). Four weeks after the induction of diabetes, serum glucose and malondialdehyde concentrations were measured. Additionally, organ bath studies and real-time PCR on muscarinic M 3 receptor and eNOS were performed. Although taurine treatment failed to decrease serum glucose levels, the increased serum malondialdehyde levels in diabetic rats were significantly decreased after taurine treatment. Norepinephrine-induced hyper-contractility as well as acetylcholine-induced, endothelium-dependent hypo-relaxation in diabetes were significantly prevented after taurine treatment. The differences in the expressions of muscarinic M 3 receptor mRNAs were statistically non-significant between groups. Moreover, diabetes-induced up-regulation of eNOS mRNAs was slightly prevented after taurine treatment. These data suggest that taurine acts beneficially against the diabetes-induced vascular dysfunction. Its potential action as a radical scavenger ameliorates the vascular disorders in diabetes.Vascular disease is a prominent sequela of both type-1 and type-2 diabetes (7). Cardiovascular disease alters vascular responsiveness to several vasoconstrictors and vasodilators and is a major factor underlying the development of this disease (21). Most of the complications in diabetes are caused by the increased serum glucose and the increased generation of oxygen-derived free radicals, which lead to endothelium dysfunction and neuropathy. Although strict glycemic control delays the onset and slows down the progression of diabetic vascular complications (8, 25), this strategy is not successful in all patients. It has been demonstrated that there are functional changes in various smooth muscle cells in diabetic animals (16). Oxidative stress plays a pivotal role in the development of diabetes complications, both microvascular and cardiovascular. The metabolic abnormalities of diabetes cause mitochondrial superoxide overproduction in endothelial cells of both large and small vessels, as well as in the myocardium. The increased superoxide production causes the activation of five major pathways involved in the pathogenesis of microvascular and cardiovascular damage: polyol pathway flux, increased formation of advanced glycation end products (AGEs), increased expression of the receptor for AGEs and its activating ligands, activation of protein kinase C

Taurine Supplementation Reduces Blood Pressure and Prevents Endothelial Dysfunction and Oxidative Stress in Post-Weaning Protein-Restricted Rats

“…Taurine supplementation restored the endothelial function in young smokers [37], as well as in type I diabetic rats [38], [39]. Here, chronic taurine supplementation restored the impaired endothelium-dependent acetylcholine-induced relaxation in aorta from protein-restricted rats, associated with reduced ROS generation and enhanced acetylcholine-induced NO release.…”

Sexual dimorphism in rat aortic endothelial function of streptozotocin-induced diabetes: Possible involvement of superoxide and nitric oxide production

“…However, previous studies demonstrated both an increase (Ikubo et al, 2011; Kazuyama et al, 2009) and a decrease (Fu et al, 2007; Olukman et al, 2010) in eNOS expression in diabetic rat aortae. Therefore, the second aim of this study was to investigate whether sex and STZ-diabetes altered NO and eNOS expression in rat aorta.…”

An Insight in to the Pathogenesis of Diabetic Vascular Diseases: Role of Oxidative Stress and Antioxidants

“…A study by Wang et al [98] demonstrated the protective effects of Taurine against diabetesmediated vascular endothelial dysfunction by downregulating the expression of lectin-like oxLDL receptor-1 (LOX-1) a well-known receptor for intercellular adhesion molecule-1 (ICAM-1) in the aorta. In line with these findings, the beneficial role of taurine on diabetic vasculature was extensively evaluated by other experimental and clinical studies [99,100]. Zhu et al [101] investigated the rescue potential of lycopene, a potent antioxidant compound, in endothelial dysfunction by reducing the oxidative stress, hence indicating its use in preventing DVD associated with endothelial dysfunction.…”