The Protective Effects of Taurine against Early Renal Injury in STZ-Induced Diabetic Rats, Correlated with Inhibition of Renal LOX-1-Mediated ICAM-1 Expression

Abstract

Oxidative stress is a key cause in the development of diabetic nephropathy (DN). As a main receptor of oxidized low-density lipoprotein (oxLDL), LOX-1 plays an important role in the induction of leukocyte adhesion molecules, such as intercellular cell adhesion molecule-1 (ICAM-1). Taurine (TAU), a potent endogenous antioxidant, showed renoprotective effects in several model animals. This study was designed to determine the renoprotective effect and possible mechanism involved LOX-1 and ICAM-1 expression of taurine in early DN. Six-week-old male Wistar rats were divided into three groups: normal control (NC), diabetes mellitus (DM), and taurine-treated DM (DM+TAU). Diabetes was induced by streptozotocin (STZ, 60 mg/kg, i.p.). After the onset of diabetes, drinking water containing 1% taurine was given to rats in the DM+TAU group. After six weeks of treatment, blood glucose (BG), serum levels of creatinine (sCr) and BUN, and LOX-1 and ICAM-1 expression (protein and gene) in kidney cortices were estimated. Meanwhile, renal malondialdehyde (MDA) levels and glutathione peroxidase (GSH-Px) activities were examined as parameters of oxidative stress in diabetic rats. For DM+TAU rats, when compared with DM rats, the levels of serum BUN, sCr, and renal MDA were reduced, and the activities of renal GSH-Px were increased, but the BG levels were not influenced. Simultaneously, taurine attenuated histopathologic evidence of renal damages and reduced the overexpression of LOX-1 and ICAM-1 in kidney cortices of diabetic rats. In conclusion, taurine showed protective effects against early renal injury in diabetic rats. These renoprotective effects may be partly caused by suppression of oxLDL/LOX-1 system and subsequently ICAM-1 overexpression on renal cortex via its antioxidative property.