OBJECTIVEAs an endogenous antioxidant, taurine could retard the development of diabetic cardiovascular complications. Whereas, whether TAU has a protective effect on diabetic vascular endothelium in young patients is still unclear. This study aimed to investigate the protective effect of taurine on early vascular endothelial dysfunction and its possible mechanism by detecting the changes of oxLDL/LOX-1 system in young STZ-induced diabetic rats. Doing so, the authors expect to find an effective approach in clinical practice to the prevention and treatment of diabetic vascular complication.

METHODSix-week-old rats were divided randomly into normal control (CN group, n=8), diabetes mellitus group (DM group, n=8) and taurine supplement group (DM+TAU group, n=8). Diabetes was induced in the rats by intraperitoneal injection of streptozotocin (STZ, 60 mg/kg) and after the onset of diabetes, the rats in DM+TAU group were given free access to drinking water containing 1% taurine. At the end of 4 weeks, blood glucose, serum total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL) and high-density lipoprotein (HDL), oxidized low density lipoprotein (oxLDL) and sICAM-1 levels were determined, meanwhile LOX-1 and ICAM-1 expression on abdominal aortas were examined by immunostaining, Western blotting and reverse transcription PCR, respectively. The results were quantified by densitometry.

RESULTCompared to normal control, in STZ-induced diabetic rats, the levels of serum TC, TG, LDL, oxLDL and sICAM-1 were all increased (P<0.01 for all), meanwhile LOX-1 and ICAM-1 expression (protein and mRNA) in the endothelium layers of abdominal aortas were also markedly enhanced (P<0.01 for all); while in taurine supplemented rats, the levels of serum TG (0.64+/-0.12 vs. 0.97+/-0.18), TC (0.82+/-0.18 vs. 1.01+/-0.23), oxLDL (3.1+/-0.6 vs. 4.2+/-0.6), sICAM-1 (108.3+/-18.0 vs. 130.7+/-17.4), expression of LOX-1 and ICAM-1 protein (1.02+/-0.19 vs. 2.60+/-0.33, 1.21+/-0.22 vs. 2.98+/-0.31) as well as mRNA (0.45+/-0.09 vs. 0.96+/-0.15, 0.50+/-0.07 vs. 0.87+/-0.16) were all markedly lower than those of untreated diabetic rats (P<0.05 for all). Also, the level of LOX-1 protein expression was positively correlated with levels of serum oxLDL (r=0.922, P=0.001), sICAM-1 (r=0.753, P=0.031) and ICAM-1 expression on abdominal aorta (r=0.849, P=0.008).

CONCLUSIONVascular endothelial dysfunction was present in early stage of young diabetic rats and taurine supplement could protect against this early endothelial dysfunction by its antioxidation to inhibit the role of oxLDL/LOX-1 system in young rats with diabetes mellitus.