RESUMO
Objective To investigate the protective effect of quercetin on diabetic nephropathy and to explore its possible mechanism.Methods Type 2 diabetes mellitus rat model was established by feeding high-carbonhydrate-fat diet and injecting with streptozotocin.At 72 hour after injection,blood samples were collected from the tail veins of all rats.Those rats with blood glucose level ≥ 16.7 mmol/L were considered as the diabetes model been successfully established.The model rats were randomly divided into type 2 diabetic group ( group DM,n =9 ) and quercetin group ( group QUE,n =9 ).Other rats were used as normal controls (group NC,n =8).All rats were performed by intragastric administration for 8 weeks.At the end of experiment,the rats were sacrificed and fasting plasma glucose( FPG),fasting insulin( Flns),serum creatinine (SCr),blood urea nitrogen(BUN),TG,TC,LDL-C,24 h urine protein (24 h UP),and kidney index ( KI ) were evaluated.Pathological changes of kidney were observed by periodic acid-silver metheramine( PASM ).The expressions of ubiquitin and NF-κB p65 on glomeruli w ere examined by immunohistochemical method,and its association with the incidence of proteinuria was analyzed.Results In groups DM and QUE,the level of FPG [ ( 25.45 ± 1.23 ) mmol/L and ( 19.99 ± 1.20 ) mmoL/L],FIns [ ( 25.67 ± 2.58 ) mU/L and ( 19.29 ± 1.80 ) mU/L ],SCr[ ( 44.00 ± 2.53 ) μmol/L and ( 34.43 ± 2.23 )μmol/L],BUN[ ( 11.60 ± 0.39 )mmol/L and (8.20 ± 0.37) mmoL/L],TG [ (3.32 ± 0.22 ) mmol/L and (2.43±0.25)mmol/L],TC[(2.95 ±0.21) mmol/L and (2.24 ±0.17)mmol/L],LDL-C[(2.03 ±0.22 ) mmol/L and ( 1.49 ± 0.13 ) mmol/L ],24 h UP [ ( 46.67 ± 2.50 ) mg/24 h and ( 25.57 ± 2.82 )mg/24 h]and KI[ (9.76 ±0.30) × 103 and (8.44 ±0.26) × 103 ] were significantly increased than the indexes of group NC [ (6.56 ± 0.41 ) mmol/L,( 12.63 ± 1.41 ) mU/L,( 22.88 ± 2.36 ) μmol/L,( 5.45 ±0.51 ) mmoL/L,( 1.64 ± 0.1 1 ) mmol/L,( 1.33 ± 0.17 ) mmol/L,(0.46 ± 0.05 ) mmol/L,( 12.38 ±1.19)/24 h and (6.78 ±0.12) × 103].Moreover,the above indexes in group QUE were obviously lower than group DM.There was evidence of pathological changes associated with diabetes,such as focal and segmental sclerosis and thickened basement and mesangial expansion.The expressions of ubiquitin and NF-κB p65 in renal tissues of group DM increased significantly ( P ＜ 0.01 ).The expression of ubiquitin and NF-κB p65 were positively related with the level of 24 h UP ( r =0.893,0.879,P ＜ 0.01 ).Compared with group DM,all above indexes in group QUE were markedly alleviated ( P ＜ 0.01 ).The expression of ubiquitin and NF-κB p65 was reduced but didn't reach level in group NC ( P ＜ 0.01 ).Conclusion The increased expression of NF-κB induced by ubiquitin-proteasome system may participate in the pathogenesis of proteinuria in diabetic nephropathy.Quercetin has renal protective effects partly through reducing NF-κB p65 expression.
RESUMO
The effects of pioglitazone on the expressions of hypoxia-inducible factor-1 α (HIF-1 α) and vascular endothelial growth factor (VEGF) in renal tissues of diabetic rats were observed. Diabetic rat model was established by feeding high-carbonhydrate-fat diet and injecting streptozotocin. After the treatment with pioglitazone, the kidney index, 24 h urinary albumin, blood urea nitrogen, serum creatinine, fasting blood glucose, fasting insulin, homeostasis model assessment for insulin resistance (HOMA-IR), total cholesterol,triglycerides, and low-density lipoprotein-cholesterol of diabetic rats were significantly lower than those of untreated ones, high-density lipoprotein-cholesterol was increased, the expressions of HIF-1α and VEGF in renal tissue were decreased ( all P＜0. 01 ). It suggested that pioglitazone may improve renal function and the balance of glucose-lipid metabolism in diabetic rats via down-regulating HIF-1/VEGF pathway.
