OBJECTIVETo investigate the renoprotective effect of adiponectin in streptozotocin (STz)-induced diabetic rats and explore its association with oxidation stress.

METHODSType 2 diabetes mellitus was induced in rats by high-lipids and high-sucrose feeding and intraperitoneal STZ injection. The recombinant plasmid pIRES2-EGFP-gAd expressing globular adiponectin was intraperitoneally injected in the rats mediated by liposome. Thirty-two Wistar rats were randomized into 4 groups, namely the normal control group (NC), diabetic group without any therapy (DM), diabetic group treated with pIRES2-EGFP-gAd (DA) and diabetic group treated with pIRES2-EGFP (DP). After the corresponding treatments for 8 weeks, the blood glucose, HbA1c and urine albumin excretion rate (UAER) were measured, and the kidneys were collected to determine the production of reactive oxygen species (ROS) and assess renal pathologies. Immunohistochemistry and Western blot were employed to determine the protein levels of endothelial nitric oxide synthesis (eNOS) and phosphorylated AMP-activated protein kinase (pAMPK).

RESULTSUAER and ROS production increased significantly in DM group as compared with that in the control group (P<0.05), while no significant differences were found in UARE among the DM, DA, and DP groups (P>0.05). Blood glucose level, HbA1c and ROS were significantly decreased in DA group in comparison with those in DM group (P<0.05). Glomerular hypetrophy, mesangial expansion, basal membrane thickening, tubular epithelial cells cavitation and exfoliation, and mononuclear lymphocyte infiltration occurred in DM group, while these changes were ameliorated in gAd transfection group. The renal expression levels of eNOS and p-AMPK proteins in DM group were significantly lower than those in the control group (P<0.05) and gAd transfection group (P<0.05).

CONCLUSIONSThe renoprotective effect of adiponectin may be at least partially mediated by the activation of the AMPK signaling passway, ROS production inhibition, relief of the oxidative stress, and up-regulation of eNOS expression in the renal tissue of diabetic rats.