Grape seed proanthocyanidin regulates expression of GSTM through Nrf2 in renal tissues of STZ-induced diabetic rats

AIM: To investigate the potential mechanisms of renoprotective effect of grape seed proanthocyanidin (GSP) on diabetic nephropathy.METHODS: Male Wistar rats were injected with 1% streptozotocin (STZ) intravenously to induce diabetes mellitus (DM). The diabetic rats were randomly divided into 2 groups: diabetes group (DM group) and GSP treatment group (GSP group, GSP 250 mg·kg^-1·d^-1). The normal Wistar rats served as control (C group). Body weight (BW), systolic pressure, kidney weight/body weight (KW/BW), fasting plasma glucose (FPG), blood urea nitrogen (BUN), serum creatinine (SCr), glycosylated hemoglobin (HbA1c) and 24 h urine protein were determined 24 weeks after STZ intervention. The pathological changes of the renal tissues were observed. The protein levels of glutathione S-transferase mu (GSTM) and nuclear factor-erythroid 2-related factor 2 (Nrf2) in the renal tissues were determined by Western blotting and immunohistochemistry. RESULTS: Compared with C group, BW in diabetic rats decreased (P<0.01). The levels of systolic pressure, FPG, HbA1c, KW/BW, 24 h urine protein, BUN and SCr in DM group were higher than those in C group (P<0.01). After treated with GSP, the levels of systolic pressure, KW/BW, 24 h urine protein, BUN and SCr in DM rats were lower than those in DM rats without treatment (P<0.01 or P<0.05). The pathological changes were ameliorated in GSP group. The expression of GSTM and Nrf2 was up-regulated in the kidneys of diabetic rats and down-regulated to the normal levels after GSP treatment. CONCLUSION: The renoprotective effect of GSP is associated with the down-regulation of GSTM through modulating the expression of Nrf2.     

Study on the role of oxidative stress in the kidneys of diabetic rats

AIM: To investigate the changes of oxidative stress in the kidneys and their roles in nephropathy in diabetic rats. METHODS: Diabetic rats were induced by streptozotocin (STZ). 36 rats were divided into three groups randomly: (1) NC group, normal control rats; (2) DM group, diabetic rats received protamine zinc insulin (PZI) 2U-4U/2 d; (3) DT group, diabetic rats received PZI 9-12 U/kg body weigh/day. 12 weeks later, rats were killed, blood glucose, blood cholesterol, serum creatinine, blood urea nitrogen, HbA1c, urinary creatinine, and urinary protein for 24 h were measured. The activities of antioxidant enzymes in renal cortex, including total superoxide dismutase (TSOD), Cu-Zn superoxide dismutase (Cu-Zn SOD), Mn superoxide dismutase (Mn SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and maleic dialdehyde (MDA) were measured by chromatometry. RT-PCR was performed to detect the expression of different antioxidant enzymes mRNA. RESULTS: For all the targets we measured, there was no significant difference between NC and DT groups. Compared with the other two groups, the levels of blood glucose, cholesterol, trigalloyl glycerol, HbA1c in DM group increased significantly. The activities of TSOD, Cu-Zn SOD and CAT decreased significantly. The activity of GSH-Px increased significantly. There was no significant difference among the activities of Mn SOD in all three groups. The level of MDA in DM group was much higher than that in NC or DT group. The relative expression levels of GSH-Px and Cu-Zn SOD mRNA in DM group were higher than those in other two groups, while the relative expression level of CAT decreased. Mn SOD mRNA was expressed without significant difference in all groups. Compared with NC or DT group, urinary protein in DM group increased significantly, while creatinine clearance rate decreased. CONCLUSIONS: Hyperglycemia affected the expression of antioxidant enzymes. Oxidative stress was caused by hyperglycemia in diabetic rats and may be an important factor in the etiology of diabetic nephropathy.     

Serum levels of inflammatory factors and adiponectin in type 2 diabetic retinopathy patients

AIM: To investigate the serum levels of inflammatory factors and adiponectin in type 2 diabetic retinopathy (DR) patients.METHODS: One hundred and ten cases of type 2 diabetic patients were divided into 3 groups: no diabetic retinopathy group (DM, n=35), non-proliferative diabetic retinopathy group (NPDR, n=45), and proliferative diabetic retinopathy group (PDR, n=30). Other 40 normal persons served as controls (NC group). The physical examinated was performed for each patient. Serum levels of fasting plasma glucose (FPG), glycated hemoglobin A1c (HbA1c), 2 h postprandial plasma glucose (2hPG), fasting insulin (FINS), total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), adiponectin, intercellular adhesion molecule-1(ICAM-1), tumor necrosis factor-α (TNF-α) and high-sensitivity C-reactive protein (hs-CRP) were measured. Insulin resistance index (HOMA-IR) was also calculated.RESULTS: The systolic blood pressure, body-mass index, waist-hip ratio, serum levels of TG, LDL-C, FPG, 2hPG, HbA1c, ICAM-1, TNF-α, hs-CRP and HOMA-IR were significantly higher in DM group, NPDR group and PDR group than those in NC group (P<0.05). The systolic blood pressure, serum levels of ICAM-1, TNF-α, hs-CRP and HOMA-IR were higher in NPDR group and PDR group than those in DM group (P<0.05). The serum concentration of adiponectin was lower in DM group, NPDR group and PDR group than that in NC group (P<0.05), and that was also lower in NPDR group and PDR group than that in DM group (P<0.05). The negative correlations between adiponectin and ICAM-1 (r=-0.735,P<0.01), TNF-α (r=-0.781,P<0.01), hs-CRP (r=-0.768, P<0.01) or HOMA-IR (r=-0.752, P<0.01) were observed. The relationships between HOMA-IR and ICAM-1 (r=0.857,P<0.01), TNF-α (r=-0.906, P<0.01) or hs-CRP (r=-0.888,P<0.01) were positive.CONCLUSION: The results suggest that inflammatory refactors and adiponectin play important roles in the pathophysiology and progression of DR. The protective effects of adiponectin on DR may be related with its anti-inflammatory reactions to improve insulin resistant.     

Relationship between the changes of angiotensin Ⅱ and vascular endothelial growth factor in plasma and the occurrence of diabetic nephropathy

AIM:To measure the concentrations of angiotensinⅡ(ATⅡ) and vascular endothelial growth factor(VEGF) in plasma of diabetics and investigate the relationship between ATⅡ and VEGF and the role of VEGF in occurrence and development of diabetic nephropathy(DN). METHODS:98 type Ⅱ diabetics were divided into two groups: 43 were in diabetic nephropathy group and 55 in non-diabetic nephropathy (NDN) group, and 25 healty persons were in control group. We measured the levels of ATⅡ, VEGF, glycosylated hemoglobinC (GHbAlc) in plasma and urinary microalbumin(UmALB), respectively.RESULTS:The levels of ATⅡ, VEGF, HbAlc and UmALB in DN group and NDN group were increased significantly compared with control group(P＜0.01); The concentrations of ATⅡ, VEGF and UmALB in DN group were obviously higher than that in NDN group(P＜0.01), but there was no significant difference of GHbAlc between DN and NDN; There was a positive correlation between ATⅡ and VEGF(r=0.465,P＜0.05), and VEGF was positively correlated with UmALB(r=0.540,P＜0.01). CONCLUSION:The levels of ATⅡand VEGF increased significantly in plasma of diabetics, and ATⅡ and VEGF may involve in the occurrence and development of diabetic nephropathy.     

The protective effects of angiotensin Ⅱ receptor blocker irbesartan on kidney function in diabetic rats

AIM: To investigate the effects and mechanisms of irbesartan, one of the angiotensin Ⅱreceptor blockers, on kidney function in diabetic rats. METHODS: Forty adult male Wistar rats were randomly divided into four groups: control group, diabetes group, irbesartan group and captopril group. At the end of 12 weeks, the rats were sacrificed. Urine volume, body weight, kidney weight/body weight, plasma, glucose, glycosylated hemoglobin (HbA₁c), urinary β₂-microglobulin (β₂-MG) excretion, urinary albumin excretion rate (UAR), creatinine clearance (Ccr) were measured. Nitric oxide (NO) and endothelin-1 (ET-1) levels in plasma, urinary and renal tissues were determined. RESULTS: Urine volume, kidney weight/body weight, plasma glucose, HbA1C, UAR, Ccr, urinary β₂-MG excretion, NO and ET-1 levels of urinary, blood and renal tissue in diabetic rats were significantly higher than those of normal controls ( P<0.01). UAR, Ccr, urinary β₂-MG excretion, ET-1 and NO levels of urinary and renal tissue in rats of irbesartan and captopril groups were significantly lower than those of DM rats ( P<0.01). There were positive relationships among the levels of plasma, urinary, renal tissue ET-1, NO and UAR, Ccr and urinary β₂-MG excretion. CONCLUSION: Irbesartan could prevent from the injury of renal function in STZ-induced diabetic rats. And it maybe one of the most importan mechanisms that irbesartan could reduce the NO and ET-1 levels in STZ-induced diabetic rats.     

Protective effects of Zhenwu decoction on kidney injury of diabetic rats induced by streptozotocin

AIM：To investigate the effects of Zhenwu decoction (ZWD) on the expression of α-smooth muscle actin (α-SMA) and NF-κB in diabetic nephropathy (DN) rats. METHODS：Diabetic rat model was induced by intrape-ritoneal injection of streptozotocin (STZ), and the animals were randomly divided into STZ group (n=22) and STZ+ZWD group (n=23). The normal rats served as control (n=16). All rats were sacrificed on 8 weeks after modeling. Biochemical assay and pathological observation (HE staining and transmission electron microscopy) were used to evaluate the effects of Zhenwu decoction on the renal function and pathological morphology. The body weight, renal index, blood glucose, total urinary protein in 24 h, and superoxide dismutase (SOD), malondialdehyde (MDA),inducible nitric oxide synthase (iNOS) were determined as well. Western blotting was used to observe the effects of Zhenwu decoction on the expression of α-SMA and NF-κB in diabetic nephropathy (DN) rats. RESULTS：Compared with normal group, the renal index, blood glucose concentration, total urinary protein in 24 h, blood urea nitrogen (BUN), serum creatinine (SCr) and MDA were significantly higher and body weight was lower in DN rats (P<0. 05). Pathological examination of the kidneys in DN group showed glomerular hypertrophy, glomerular basement membrane thickening, tubular epithelial cell degeneration, mesangial matrix proliferation, protein cast formation in some renal tubules. The protein expression levels of α-SMA and NF-κB were markedly increased (P<0.05). After ZWD treatment, the level of renal index, total urinary protein in 24 h, BUN, SCr and the expression of α-SMA and NF-κB at the protein level were significantly decreased (P<0.05). The renal histological injury in ZWD group was significantly ameliorated. CONCLUSION：Zhenwu decoction might protect kidney against STZ-induced injury via decreasing the expression of α-SMA and NF-κB.     

Relationship between levels of plasma endothelin-1/serum nitric oxide and hearing impairment in type 2 diabetes

AIM: To evaluate the relationship between endothelin-1 (ET-1)/nitric oxide (NO) and hearing impairment in type 2 diabetes mellitus (DM).METHODS: Eighty-eight type 2 diabetic patients with no signs of microangiopathy (retinopathy and nephropathy) or peripheral neuropathy, and 53 healthy subjects in the same period were enrolled in this study. Auditory function was evaluated using pure tone audiometry. Totally,type 2 DM group (n=88) and normal control group (NC, n=53) were divided into subgroups based on the presence and absence of hearing impairment. The concentration of plasma ET-1 was detected by radioimmunoassay. The concentration of serum NO was measured by the method of nitric acid reductase.RESULTS: Significantly increased plasma ET-1 and decreased serum NO were observed in diabetic patients with hearing impairment compared with those in diabetic patients without hearing impairment. The results of multivariate logistic regression analysis showed that hearing impairment in type 2 DM group was significantly associated with elevated level of HbA1c (OR＝4.525, P<0.05), LDL-C (OR=2.381,P<0.05) and plasma ET-1 (OR＝6.207,P<0.01). Besides, elevated serum level of NO (OR＝0.862, P<0.05) was associated with lower risk of hearing impairment in diabetics.CONCLUSION: Hearing impairment may happen earlier than other complications in diabetic patients. In addition to hyperglycemia and hyperlipemia, high level of ET-1 and low levels of NO might contribute to hearing impairment in diabetic patients.     

Diagnostic value of serum miR-21 for diabetic nephropathy

AIM:To evaluate the diagnostic value of serum miR-21 as a molecular biomarker in the patients with diabetic nephropathy (DN). METHODS:Twenty-five patients with DN, 50 patients with type II diabetes ［divided into DMA group and DMB group base on urinary microalbumin (UmAlb), 25 in each group］, 25 patients with diabetic nephropathy-induced uremia (UM) and 25 normal controls (NC) were included in the study. Total RNA was extracted from the serum samples for determining the miR-21 level using real-time PCR. The relationship between miR-21 level and clinical parameters of the patients with diabetic nephropathy was analyzed. RESULTS:The relative expression level of serum miR-21 was significantly lower in DN group than that in DMA group, DMB group and NC group, and was significantly higher than that in UM group (all P<001). The serum miR-21 level showed significant negative correlation with cystatin C, UmAlb, UmAlb/urinary creatinine in DN patients (P<0.01,P<0.05,P<0.05). For discriminating the DN patients from NC, DMA, DMB, DMA＋NC, DMB＋NC and DMA＋DMB, the areas under the receiver operating characteristic curve (AUC-ROC) for serum miR-21 were 0848 (95% CI: 0737~0959), 0896 (95% CI: 0812~0980), 0782 (95% CI: 0641~0922), 0838 (95% CI: 0743~0933), 0796 (95% CI: 0675~0917) and 0808 (95% CI: 0704~0911), and the sensitivity and specificity were 800% and 720%, 720% and 880%, 720% and 840%, 760% and 770%, 760% and 820%, 700% and 860%, respectively. For discriminating the DN patients from DMA＋DMB＋NC, the AUC-ROC was 0845 (95% CI: 0752~0939), and the sensitivity and specificity were 760% and 773%, respectively. CONCLUSION: Serum miR-21 can serve as a molecular diagnostic marker for diagnosis of diabetic nephropathy.     

Effect of rosiglitazone on serum resistin and glomerular sclerosis in type 2 diabetic rats

AIM: To observe the effect of rosiglitazone on serum resistin level and to investigate the possible mechanism of glomerular sclerosis in type 2 diabetic rats. METHODS: Ten-week-old Wistar rats were divided into diabetic nephropathy (DN) group (10 cases) and DN+rosiglitazone group (10 cases). The other 10 Wistar rats were used as normal control group. Type 2 diabetic rats were induced by cutting the right kidney and injecting small dose (35 mg/kg) of streptozocin (STZ). Rosiglitazone group received rosiglitazone 10 mg·kg-1·d-1 while normal control group and DN group were fed with normal chow diet. After 20 weeks, vessel blood was collected for plasma IL-1, TNF-α and resistin assayed by ELISA. The serum levels of glucose, creatinine, urea nitrogen and microalbum of 24 h urine were also detected. The expression of TGF-β1 in glomerulus was examined by immunohistochemistry. Smad2 phosphatase activity was detected by Western blotting. RESULTS: The plasma IL-1, TNF-α, hs-CRP and resistin, and microalbum of 24 h urine in rosiglitazone group, were significantly lower than those in DN group while the serum level of glucose was not different from that in DN group. The expression of TGF-β1 and phosphorylated level of Smad2 were lower in rosiglitazone group than those in DN group. The degree of glomerular sclerosis in rosiglitazone group was obviously lighter than that in DN group. CONCLUSION: Rosiglitazone delays and ameliorates the development of diabetic glomerular sclerosis. The mechanism is possibly related to the modulation of resistin and other inflammatory factors. Anti-inflammation is a potential way for controlling diabetic nephropathy.     

Effect of interlukin-22 antibody on diabetic nephropathy via inhibition on Snail1 expression

AIM:To investigate the effect of interlukin-22 (IL-22) on diabetic nephropathy (DN) and its possible mechanism. METHODS:C57BL/6 mice were randomized to normal control (NC) group,DN group, DN+recombinant IL-22 (rIL-22) group and DN+IL-22 antibody (anti-IL-22) group. After successful establishment of diabetes model for 8 weeks, the mice in DN+rIL-22 group and DN+anti-IL-22 group were intraperitoneally injected with rIL-22 (200 μg/kg) and anti-IL-22 (200 μg/kg), respectively, and the mice in NC group and DN group were intraperitoneally injected with 0.1% bovine serum albumin, twice a week for 4 weeks. After the intervention, blood glucose, kidney function, 24 h urine microalbumin (m-Alb) and 24 h urine creatinine (UCr) were measured. The pathological changes of renal tissues were observed under light microscope. The mRNA expression of Snail1 was detected by qPCR. The protein levels of fibronetin (FN) and E-cadherin were determined by Western blot. RESULTS:After the intervention, the ratio of 24 h m-Alb/UCr increased significantly in other model groups compared with NC group (P<0.05). The levels of 24 h m-Alb and 24 h UCr increased significantly in DN+rIL-22 group compared with DN group (P<0.05). However, in DN+anti-IL-22 group, the levels of 24 h m-Alb, 24 h UCr and 24 h m-Alb/UCr ratio were significantly lower than those in DN group and DN+rIL-22 group (P<0.05). The tubular epithelial cell vacuolar degeneration, protein cast formation and glomerular mesangial expansion in the renal tissues from diabetic mice were observed under light microscope. The lesions were more severe in DN+rIL-22 group, but attenuated in DN+anti-IL-22 group. The mRNA expression of Snail1 increased significantly in diabetic mice (P<0.05), but decreased significantly after a 4-week intervention by anti-IL-22 (P<0.05). The expression of FN, an extracellular matrix protein, increased significantly in DN+rIL-22 group (P<0.05). The expression of E-cadherin, an epithelial-mesenchymal transition marker, decreased significantly in DN+rIL-22 group as well (P<0.05). CONCLUSION:IL-22 neutralizing antibody may attenuate microalbuminuria and delay the progression of DN via inhibition of Snail1 expression in the renal tubular epithelial cells.     

Expression of OPN and macrophage colony stimulating factor in diabetic rats and intervention of mycophenolate mofetil

AIM: To explore the effect of mycophenolate mofetil (MMF) on expression of osteopotin (OPN) and macrophage colony stimulating factor (M-CSF) in diabetic rats with renal tubulo-interstitial injury. METHODS: Diabetes was induced in uninephrectomized male Wistar rats by peritoneal injection of streptozotocin (65 mg/kg). The rats were randomly divided into three groups: control group (NC), diabetic group (DM) and MMF treated group ［DM+MMF, treatment of MMF (15 mg·kg^-1·d^-1) by gavage from the next day of the induction for 8 weeks］. Serum biochemistry, 24 h urinary protein and the ratio of left kidney weight/body weight were determined after 8 weeks. The renal tubulo-interstitial morphological change was observed, immunohistochemical method was used to analyze the expression of OPN, M-CSF and CD68. The mRNA of OPN in renal tissue was amplified by quantitative real-time PCR. RESULTS: Compared with control group, serum glucose level, 24 h urinary protein and the ratio of left kidney weight/body weight were significantly increased (P<0.01), and the relative area of interstitial fibrosis was also significantly enlarged in DM group (P<0.01).Compared with NC group, the expressions of OPN, M-CSF, CD68 protein and OPN mRNA were significantly upregulated in DM group (P<0.01). After intervention with MMF, the upregulations of the above-mentioned parameters, except blood glucose and serum creatinine, were all significantly inhibited (P<0.05 or P<0.01). CONCLUSION: The expressions of OPN, M-CSF and CD68 in renal tubulointerstitial decrease in diabetic rats treated with MMF. MMF also inhibits the level of OPN mRNA, reduces proteinuria and prevents renal injury. MMF plays an apparently protective role in renal tubulointerstitial injury, probably associated with inhibiting chemokine and proliferation on macrophages.     

Factors affecting mean blood glucose level of newly diagnosed type 2 diabetes patients

AIM: To detect hemoglobin A1c (HbA1c) and parameters of blood glucose fluctuation in Chinese newly diagnosed type 2 diabetes mellitus (T2DM) patients, and further to specify the factors that were related to mean blood glucose (MBG) in this population. METHODS: Newly diagnosed T2DM patients (n=90) from 4 hospitals in Guangdong province were enrolled, and subjected to 3 d continuous glucose monitoring (CGM) after testing for HbA1c and other laboratory tests. Blood glucose data collected during CGM were used to calculate MBG and parameters of blood glucose fluctuation. RESULTS: Correlation analysis revealed that MBG was significantly related to all parameters of blood glucose fluctuation, HbA1c, fast plasma glucose (FPG) and 2 h postprandial glucose (P <0.01), but not to sex, age or blood lipid profile. Further analysis utilizing step-wise general linear model showed that HbA1c, absolute means of daily difference (MODD), difference between maximal and minimal glucose (DMMG) and FPG had the strongest relation to MBG. CONCLUSION: Factors affecting MBG of the newly diagnosed T2DMpatients in our country include HbA1c, FPG, DMMG and MODD, and thus it may be prone to misleading results that only HbA1c is applied to estimate MBG in this population.     

Influence of paricalcitol on renal tubulointerstitial fibrosis in diabetic nephropathy

AIM: To investigate the effect of paricalcitol (P) on renal tubulointerstitial fibrosis and the underlying mechanisms in diabetic nephropathy (DN).METHODS: DN rat model was induced by a single intraperitoneal injection of streptozotocin after fasting. The animals were randomly divided into 2 groups:the DN rats in paricalcitol-intervened group (group P) were injected intraperitoneally with paricalcitol dissolved in propylene glycol after the day when the model was induced successfully at a dose of 0.4 μg/kg (3 times a week); the DN rats in DN group (group D) were given isopyknic propylene glycol. Normal control group (group C) was also set up. The samples of blood, urine and renal tissue were collected after intervention of paricalcitol for 12 weeks. The biochemical indexes were measured. The renal tissues were used for pathologic observation and determining the expression of transforming growth factor-β1 (TGF-β1), Wnt-4, β-catenin and Klotho by immunohistochemistry and Western blotting. In addition, the correlation among the above indexes was analyzed.RESULTS: (1) Scr, BUN and 24 h urine protein increased significantly in group D compared with group C, while decreased in group P compared with group D (P<0.05). (2) The area of renal tubulointerstitial fibrosis increased in group D compared with group C, while decreased in group P compared with group D (P<0.05). (3) The expression of Klotho decreased, while the expression of TGF-β1, Wnt-4 and β-catenin increased in group D compared with group C (P<0.05). Compared with group D, the expression of Klotho increased, while the expression of TGF-β1, Wnt-4 and β-catenin decreased in group P (P<0.05). (4) The expression of Klotho was negatively correlated with the fibrosis area, TGF-β1, Wnt-4 and β-catenin (P<0.05).CONCLUSION: Paricalcitol inhibits renal tubulointerstitial fibrosis in DN by promoting the expression of renal Klotho, and inhibiting Wnt/β-catenin signaling pathway activation and TGF-β1 synthesis.     

Effect of astragalus polysaccharin on expression of nephrin and podocin in podocytes of early diabetic nephropathy rats

AIM: To observe the effects of astragalus polysaccharin (APS) on the expression of nephrin and podocin in podocytes of diabetic nephropathy (DN) rats.METHODS: The rat model of diabetes was induced by intraperitoneal injection of streptozotocin (STZ).The diabetic rats were randomly divided into 2 groups by the treatment without or with APS: STZ group (n=8) and STZ+APS group (n=8).In addition, 8 non-treated rats served as control.All the rats were treated with APS or normal saline orally by gavage for 8 weeks.The concentration of blood glucose was monitored on week 2, 5 and 8 after treatment.Eight weeks later, the body weight and renal index were measured.Total urine protein in 24 h, blood urea nitrogen (BUN) and serum creatinine (SCr) were detected by biochemical methods.The pathological changes of the kidneys were also observed under light microscope.The protein levels of nephrin and podocin in the kidney tissues were also determined by Western blotting.RESULTS: After APS intervention, the levels of renal index, blood glucose concentration, 24-hour total urine protein, BUN and SCr were significantly lower and body weight was higher than those in STZ group (P<0.05).The renal pathological status in APS group was significantly improved and the expression levels of nephrin and podocin also markedly increased (P<0.05).CONCLUSION: APS might protect kidney against STZ-induced injury via increasing the expression of nephrin and podocin in podocytes.     

Effects of atorvastatin on iopromide-induced apoptosis of renal tubular epithelial cells in diabetic rats

AIM：To investigate the protective effect of atorvastatin (ATO) against contrast medium (CM)-induced apoptosis of renal tubular epithelial cells in diabetic rats. METHODS：Streptozocin-induced diabetic Wistar rats were fed for 8 weeks and then randomly divided into 5 groups: diabetes mellitus (DM) group, DM with iopromide (a kind of CM) treatment group (DM+CM group), and groups of DM rats treated with ATO at 5 mg·kg-1·d-1 (ATO1 group), 10 mg·kg-1·d-1 (ATO2 group) and 30 mg·kg-1·d-1 (ATO3 group) before iopromide injection. Healthy Wistar rats served as normal controls (N group). Urine creatinine (UCr) and 24-hour urinary albumin (24 h-UAlb) were determined 24 h after iopromide injection. Serum creatinine (SCr) and blood urea nitrogen (BUN) were detected 48 h after iopromide injection, and then creatinine clearance (CCr) and 24-hour urinary albumin excretion rate (24 h-UAER) were calculated. The rats were sacrificed and both kidneys were removed 48 h after iopromide injection. For the left kidney, the morphology by HE staining, the renal tubular apoptosis by TUNEL and the expression of Bax and Bcl-2 by immunohistochemistry were detected. For the right kidney, the expression of Bax and Bcl-2 was measured by Western blotting. RESULTS：Compared with N and DM groups, the levels of SCr, BUN and 24 h-UAER, as well as the expression of Bax in the renal medulla were higher, the levels of Ccr and Bcl-2 expression in the renal medulla were lower and TUNEL-positive cells were more in DM+CM group. Compared with DM+CM group, ATO attenuated these changes, especially in ATO3 group. CONCLUSION: Iopromide could cause renal tubular apoptosis. Early application of ATO could dose-dependently attenuate the development of contrast-induced acute kidney injury, partly due to suppression of iopromide-induced renal tubular apoptosis.     

Construction of a New Zealand rabbit model of diabetic nephropathy

AIM: To establish a method to produce animal model of diabetic nephropathy (DN) in New Zealand rabbits using alloxan (ALX). METHODS: Twenty male New Zealand rabbits were randomly divided into 2 groups: 8 rabbits in control group were fed with conventional feed such as buffer solution;12 in diabetes milleuts (DM) group were fed with high-sugar and high-fat diet (conventional feed plus 5% sucrose, 5% pork fat and 1% cholesterol) for 2 weeks, then intravenous injection of ALX at 50 mg/kg was given, and another dosage of 100 mg/kg ALX was intravenously injected after 48 h. The levels of blood glucose, blood cholesterol, triglyceride, urine microalbumin, and serum creatinine were detected before and 12 weeks after the processes of modeling. After 12 weeks, the rabbits were sacrificed,and the kidneys were taken for pathological examination. RESULTS: The successful model of DN in the rabbits had the characteristics of high blood glucose, abundant urine microalbumin (P<0.01), and corresponding morphological and functional changes of the kidneys. CONCLUSION: Rabbits with high-sugar and high-fat diet plus twice intravenous injection of ALX at a total dose of 150 mg/kg (50 mg/kg and 100 mg/kg, respectively) shows low mortality and stable diabetes mellitus state. This method induces a typical DN model in 12 weeks.     

Effect of irbesartan on nephrin expression in the podocyte of early diabetic nephropathy rats

AIM: To investigate the expression of the nephrin in podocyte of the diabetic nephropathy(DN) rats and the mechanism of irbesartan-induced renal protection.METHODS: The DN model was established by a single injection of streptozotocin(STZ),and DN rats were randomly divided into 2 groups: model group and irbesartan treatment group.In addition,the normal rats served as a normal control group. All the rats were received daily gavage respectively for 8 weeks. The urinary protein quality in 24 hours,body weight(BW),kidney weight (KW),KW/BW,glucemia,urea nitrogen,creatinine,total cholesterol, triacylglycerol were detected with correlative methods and the pathological changes of kidney were also detected with optic microscope and transmission electron microscope.The expression of nephrin in podocyte were detected by immunohistochemistry. RESULTS: In DN rats, irbesartan reduced the urinary protein quality in 24 hours (P<0.01) and alleviated the damage of kidney. Meanwhile，the expression of nephrin was declined remarkably in podocytes in irbesartan treatment group compared with model group（P<0.05）.CONCLUSION: Irbesartan might protect kidney against STZ-induced injury via decreasing the expression of nephrin in podocytes.     

Role of focal adhesion kinase expression in renal tissues of type 2 diabetic rats

AIM：To explore the dynamic change of focal adhesion kinase (FAK) in renal tissues of rats with type 2 diabetes mellitus (T2DM), and to investigate its role in the pathogenesis of diabetic nephropathy (DN). METHODS：The rat model of T2DM was established and the diabetic rats were randomly divided into 8-week DM (DM8), 12-week DM (DM12) and 16-week DM (DM16) groups. Meanwhile, normal control (NC) and high-fat high-sucrose control (HC) groups were also established. The protein expression of FAK, transforming growth factor β1 (TGF-β1), extracellular signal-regulated kinase 1/2 (ERK1/2), p-ERK1/2 and fibronectin (FN) was detected by immunohistochemical staining. The protein levels of FAK and p-FAK (Tyr397) were detected by Western blotting. The mRNA level of FAK in the renal cortex was examined by RT-PCR. RESULTS：The expression of FAK protein in renal tubular epithelial cells in DM12 and DM16 groups was significantly higher than that in NC, HC and DM8 groups (P<0.05). Moreover, TGF-β1, p-ERK1/2 and FN protein expression in DM groups was significantly increased compared with NC and HC groups (P<0.05). The levels of FAK and p-FAK (Tyr397) in the renal cortex in DM12 and DM16 groups were significantly up-regulated compared with NC, HC and DM8 groups (P<0.05), and the expression trend of p-FAK in different groups was in accordance with that of total FAK. The FAK protein expression was positively correlated with the expression of TGF-β1, p-ERK1/2 and FN proteins (P<0.01). Compared with NC, HC and DM8 groups, the expression of FAK mRNA increased remarkably in DM12 and DM16 groups (P<0.05). CONCLUSION: There is a possibility that FAK is activated as a downstream effector of TGF-β1 in T2DM, which enhances the expression of FN protein through activating ERK1/2, and therefore plays an important role in the pathogenesis of type 2 diabetic nephropathy.     

矮化苹果负载量对氮素吸收、分配及利用的影响

以5年生‘烟富3’/M26/平邑甜茶为试材,采用~(15)N同位素示踪技术,研究不同负载量对氮素吸收、分配及利用的影响。结果表明:与高负载量[对照,单株留果量(120±8)个]相比,中负载量(2/3负载量)和低负载量(1/3负载量)植株的叶面积、叶绿素含量、叶片总氮量和单果质量显著增加,平均单果质量分别增加了19.02%和37.38%,但其平均单株产量却显著降低。3个处理各器官的Ndff值表现一致,果实的Ndff值最大,其次是一年生枝、叶片和根;随着负载量的增加,果实的Ndff值增大,一年生枝、叶片及根的Ndff值减小。高负载量、2/3负载量和1/3负载量单株总氮量和~(15)N利用率分别为65.85 g和19.59%、70.96 g和22.01%、92.67 g和26.13%;高负载量、2/3负载量和1/3负载量果实15N分配率分别为35.32%、18.18%和8.40%,一年生枝、叶片和根的~(15)N分配率则随着负载量的增加而减小。疏果(2/3负载量和1/3负载量)虽然降低单株产量但显著改善果实品质,显著提高氮肥利用率,综合效益,以2/3负载量,即单株留果量为(80±7)个最好。     

Effect of blood glucose control on expression of Smad7 and renal fibrosis in diabetic rats

AIM： To verify the hypothesis that treatment with insulin to control the blood glucose (BG) may relieve or slow down the development of diabetic nephropathy (DN) in diabetic rats by increasing the expression of Smad7. METHODS：The diabetic rat model was established by tail-vein injection of streptozotocin. Sixteen rats were divided into 2 groups. Eight of these animals in diabetes mellitus (DM) group had no treatment. The remaining eight of them in insulin treatment (INS) group were injected with insulin. After 13 weeks, the rats in INS group were given individual treatment with insulin to let the blood glucose level keep within 4 to 7 mmol/L. Meanwhile, 8 rats were used for normal control (NC group). After 16 weeks, the rats were sacrificed to detect the relevant biochemical parameters, and to observe the histophathological changes of the kidney and pancreas. In addition, immunohistochemical staining and Western blotting were employed to detect the protein expression of transforming growth factor β1 (TGF-β1), Smad ubiquitin regulatory factor 2 (Smurf2), Smad7, E-cadherin, α-sooth muscle actin (α-SMA), fibronectin (FN) and collagen I. RESULTS：Compared with NC group, the body weight was significantly reduced in DM group, whereas the body weight in INS group increased gradually. Compared with NC group, the levels of 24 h urine protein (24 h UP), BG and triglyceride (TG) were remarkably increased in DM group. Pathological detection on pancreas indicated that the islet was destroyed. The levels of TGF-β1, Smurf2, α-SMA, FN and collagenⅠ in the kidneys were increased in DM group, and the expression of Smad7 and E-cadherin, which were mainly located in renal tubular epithelial cells, was significantly reduced. Compared with DM group, the levels of 24 h UP and BG were significantly reduced in INS group, and the alleviated renal fibrosis was observed under light microscope. In addition, the protein levels of TGF-β1, Smurf2, α-SMA, FN and collagenⅠ in INS group were decreased compared with DM group, and the expression of Smad7 and E-cadherin was increased significantly. CONCLUSION：Target glucose control with insulin treatment restores the protein expression of Smad7 in the kidney of diabetic rats, reduces the accumulation of extracellular matrix and slows down DN progress. The decrease in TGF-β1 and Smurf2 expression, and the attenuation of Smad7 ubiquitination in renal tissues are the crucial parts in this process.