RESUMO
OBJECTIVE To explore the role and underlying mechanism of tournefolic acid B （TAB） on the improvement of glucose metabolism and renal function in diabetic nephropathy （DN） model mice. METHODS DN model mice were established by high-fat diet combined with streptozotocin， and then randomly divided into model group， positive control group （vitamin E， 20 mg/kg）， TAB low-dose， medium-dose and high-dose groups （1， 2， 4 mg/kg）， with 12 mice in each group； normal control group was given regular diet. Each group was given relevant medicine or normal saline intragastrically， once a day， for 4 consecutive weeks. The glucose metabolic function was estimated by fasting blood glucose， glucose tolerance test， insulin tolerance test and serum insulin concentration. The renal coefficients and biochemical indicators related to renal function [serum uric acid， blood urea nitrogen， creatinine levels， and ratio of urine microalbumin to creatinine] were detected in mice； the contents of biochemical indicators related to oxidative stress [superoxide dismutase （SOD）， glutathione peroxidase （GSH-Px）， malondialdehyde （MDA）， 8-hydroxydeoxyguanosine （8-OHdG）] were determined in renal tissue of mice； the pathological morphology of renal tissue was observed； the expressions of extracellular matrix （ECM） deposition related factors [transforming growth factor β1 （TGF- β1）， fibronectin （Fn）， type Ⅳ collagen （Col Ⅳ）] and protein kinase B （Akt）/nuclear factor erythroid 2-related factor 2 （Nrf2）/heme oxygenase-1 （HO-1） pathway related proteins were determined in renal tissue of mice. RESULTS Compared with normal control group， fasting blood glucose， area under glucose tolerance curve， area under insulin tolerance curve， serum insulin content， the levels of uric acid， urea nitrogen and creatinine @qq.com and ratio of urinary microalbumin to creatinine in serum， the contents of MDA and 8-OHdG and the protein expressions of TGF-β1， Fn and Col Ⅳ were increased significantly in model group （P＜0.05）， while the contents of SOD， GSH-Px and the protein expressions of p-Akt， Nrf2， HO-1 in renal tissue were decreased significantly （P＜0.05）； the significant thickening of the basement membrane， accumulation of mesangial matrix， glomerulosclerosis and interstitial fibrosis of the renal tubules were all found. Compared with model group， above indexes of mice were all reversed significantly in TAB groups （P＜0.05）， and pathological changes were alleviated in a dose-dependent manner. CONCLUSIONS TAB can improve blood glucose metabolism and kidney function and alleviate renal tubulointerstitial fibrosis in DN model mice， the mechanism of which may be associated with activating the Akt/Nrf2/HO-1 signaling pathway and suppressing ECM deposition.