Atorvastatin inhibits high glucose-induced oxidative stress by depressing PKC activity in human umbilical vein endothelial cells

AIM:To explore the effect of atorvastatin on high glucose-induced oxidative stress and underlying mechanisms in human endothelial cells. METHODS:Human umbilical vein endothelial cells(HUVECs) were cultured in medium 199 containing normal concentration of glucose(5.5 mmol/L). For high glucose treatment, glucose solution was added to the final concentration of 25 mmol/L. Reactive oxygen species(ROS) were detected by flow cytometry and confocal microscopy. The activity of nicotinamide adenine dinucleotide phosphate(NADPH) oxidase was measured by lucigenin assay. Phosphorylated protein kinase C(PKC) and the expression levels of NADPH oxidase subunits Nox4 and Nox2/gp91^phox were determined by quantitative real-time PCR and immunoblotting. RESULTS:High glucose increased ROS production, NADPH oxidase activity and the expression of Nox4 and Nox2/gp91^phox subunits. Treatment of endothelial cells with atorvastatin resulted in significant inhibition(in a concentration-dependent manner) of high glucose-induced ROS production, NADPH oxidase activation and the expression of Nox4 and Nox2/gp91^phox subunits. PKC inhibitor showed a similar effect to that of atorvastatin on high glucose-induced oxidative stress. Furthermore, atorvastatin rapidly inhibited high glucose-induced activation of protein kinase C, an upstream activator of NADPH oxidase. CONCLUSION:PKC is involved in high glucose-induced oxidative stress in HUVECs. Atorvastatin inhibits high glucose-induced oxidative stress by depressing PKC activity in human endothelial cells.     

Effect of shikonin on high glucose-induced apoptosis and oxidative stress in vascular endothelial cells

AIM:To investigate the effect of shikonin on the apoptosis and oxidative stress induced by high concentration of glucose in vascular endothelial cells. METHODS:Rat thoracic aortic endothelial cells were randomly divided into 5 groups:normal control group (with glucose at concentration of 5.5 mmol/L in cell culture medium), high glucose group (with glucose at concentration of 33 mmol/L in cell culture medium), high glucose+low shikonin group (with glucose at concentration of 33 mmol/L and shikonin at concentration of 0.1 μmol/L in cell culture medium), high glucose+medium shikonin group (with glucose at concentration of 33 mmol/L and shikonin at concentration of 1 μmol/L in cell culture medium), and high glucose+high shikonin group (with glucose at concentration of 33 mmol/L and shikonin at concentration of 10 μmol/L in cell culture medium). After treatments, the cell viability was measured by CCK-8 assay and cell apoptotic rate was analyzed by flow cytometry. In addition, the status of oxidative stress was evaluated by determining the levels of malondialdehyde (MDA), reactive oxygen species (ROS), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). The activation of Nrf2/HO-1 signaling pathway was determined by Western blot. RESULTS:Compared with high glucose group, shikonin reversed high glucose-induced decrease in cell viability and increase in apoptosis in a concentration-dependent manner. High concentration of glucose induced high levels of MDA and ROS, while decreased the levels of SOD and GSH-Px. However, after treatment with shikonin, the contents of MDA and ROS were decreased, while the activities of SOD and GSH-Px were increased as compared with high glucose group. Furthermore, the high concentration of glucose up-regulated the protein levels of cleaved caspase-3, HO-1 and Nrf2 (nuclear). Compared with high glucose group, the protein levels of cleaved caspase-3, HO-1 and Nrf2 (nuclear) were partly decreased after treatment with shikonin. CONCLUSION:Shikonin alleviates high glucose-induced vascular endothelial cell apoptosis. Its mechanism may be related to activation of Nrf2/HO-1 signaling pathway and down-regulation of oxidative stress in vascular endothelial cells.     

Icariin attenuates high glucose-induced insulin resistance in C2C12 myotubes

AIM: To observe the potential effects of icariin on high glucose-induced insulin resistance in C2C12 myotubes and to investigate its underlying mechanisms. METHODS: The insulin resistance model was induced by high glucose (25 mmol/L) in the C2C12 myotubes. The effects of icariin on Akt phosphorylation at T308, glucose transporter 4 (GLUT4) membrane translocation, and glucose uptake were investigated in high glucose-treated C2C12 myotubes. The protein levels of phosphorylated proteins were determined by Western blot. The glucose uptake was measured by colorimetric method. The small interfering RNA (siRNA) was used to knockdown the expression of p38 MAPK. RESULTS: Icariin significantly increased insulin-stimulated Akt T308 phosphorylation in C2C12 myotubes treated with high glucose. Treatment with icariin at 25, 50 and 75 μmol/L for 24 h increased Akt T308 phosphorylation in a dose-dependent manner (P<0.05 or P<0.01). Treatment with icariin at 50 μmol/L for 12, 24 and 36 h increased Akt T308 phosphorylation in a time-dependent manner (P<0.05 or P<0.01). In addition, treatment with icariin at 50 μmol/L for 24 h significantly enhanced the expression of GLUT4 on plasma membrane (P<0.01) and 2-deoxyglucose (2-DG) uptake (P<0.01). Treatment with icariin recovered high glucose-reduced p38 MAPK phosphorylation (P<0.01). Pharmacological or genetic inhibition of p38 MAPK abolished the protective impacts of icariin on insulin-stimulated Akt T308 phosphorylation (P<0.01), GLUT4 plasma membrane translocation (P<0.01), and 2-DG uptake under high glucose condition (P<0.05). CONCLUSION: Icariin attenuates high glucose-induced insulin resistance in C2C12 myotubes by activating p38 MAPK.     

High glucose induces H9c2 cardiomyocyte hypertrophy through Ca2+-CaN-NFAT3 signaling pathway

AIM: To study the morphological changes of cardiac H9c2 cells during the developmental process of fetal rat. METHODS: Embryonic rat heart-derived H9c2 cells were maintained in DMEM supplemented with 10% fetal bovine serum. The H9c2 cells were plated at a density of 6000 cells/cm and divided into 5 groups: H9c2 cells were treated with 5 mmol/L glucose, 25 mmol/L glucose, 50 mmol/L glucose, Norvasc (25 nmol/L)+25 mmol/L glucose, or Norvasc (25 nmol/L)+50 mmol/L glucose for 48 h. The morphology of H9c2 cells was observed. The cell surface area was measured by Image-Pro Plus 6.1 software. Fluorescence spectrophotometry was used to detect the concentration of intracellular calcium ion ([Ca²⁺]_i)in the cardiomyocytes. The concentration of CaN in the cell was measured by ELISA. The mRNA expression of CaNAβ, NFAT3 and β-MHC in the cells was detected by real-time PCR. The protein levels of CaNAβ, NFAT3 and β-MHC in cultural H9c2 cells were detected by Western blot. RESULTS: The mean area of the cells, the mean fluorescence value of [Ca²⁺]_i and the concentration of CaN in 25 mmol/L glucose group were higher than those in 5 mmol/L glucose group, and those were lower than those in 50 mmol/L glucose group. After treated with Norvasc, those results decreased significantly. The expression of CaNAβ, NFAT3 and β-MHC at mRNA and protein levels in 25 mmol/L glucose group was higher than those in 5 mmol/L glucose group, but was lower than those in 50 mmol/L glucose group. The expression of CaNAβ, NFAT3 and β-MHC at mRNA and protein levels decreased significantly in Norvasc treatment group. CONCLUSION: Ca²⁺-CaN-NFAT3 signaling pathway is perhaps involved in high glucose-induced H9c2 cardiomyocyte hypertrophy.     

Role of ATP-sensitive potassium channels in inhibitory effect of hydrogen sulfide on high glucose-induced injury in H9c2 cardiac cells

AIM: To investigate the roles of ATP-sensitive potassium (K_ATP) channels in high glucose-induced cardiac injury and the inhibitory effect of hydrogen sulfide (H₂S) on the cardiomyocyte injury. METHODS: The expression level of K_ATP channel protein was tested by Western blot. The cell viability was measured by CCK-8 assay. The number of apoptotic cells was observed by Hoechst 33258 nuclear staining. Mitochondrial membrane potential (MMP) was examined by JC-1 staining. RESULTS: After the H9c2 cells were treated with 35 mmol/L glucose (high glucose, HG) for 1~24 h, the protein level of K_ATP channel was significantly reduced at 6 h, 9 h, 12 h and 24 h, reaching the minimum level at 12 h and 24 h. Pretreatment of the cells with 400 μmol/L NaHS (a donor of H₂S) prior to exposure to HG for 12 h considerably blocked the down-regulation of K_ATP channels induced by HG. Pretreatment of the cells with 100 μmol/L mitochondrial K_ATP channel opener diazoxide, 50 μmol/L non-selective K_ATP channel opener pinacidil or NaHS obviously inhibited HG-induced injuries, leading to an increase in the cell viability, and decreases in the number of apoptotic cells and the MMP loss. Pretreatment with 100 μmol/L mitochondrial K_ATP channel antagonist 5-hydroxydecanoic acid or 1 mmol/L non-selective K_ATP channel antagonist glibenclamide attenuated the above cardioprotective effects of NaHS. CONCLUSION: K_ATP channels mediate the inhibitory effect of H₂S on HG-induced cardiac injury.     

Glucagon-like peptide-1 protects against cardiac microvascular injury in diabetic rats via Keap1-Nrf2 signaling pathway

AIM: To investigate the protective effects of glucagan-like peptide-1 (GLP-1) on cardiac microvascular injury in diabetic rats and the underlying mechanism. METHODS: Diabetic rats were induced by intraperitoneal injection of streptozocin, and then randomized to 3 months of vehicle or exenatide (a GLP-1 analogue) treatment. Before and after the treatment, body weight, blood glucose and blood pressure were measured. Cardiac microvascular permeability was detected by transmission electron microscopy. Cardiac microvascular endothelial cells (CMECs) were isolated and cultured in normal glucose (5.5 mmol/L), high glucose (25 mmol/L), and high glucose plus GLP-1 (10^-8 mol/L). The production of reactive oxygen species (ROS) was examined by superoxide assay kit and dihydroethidium staining. The protein expression of GLP-1 receptor (GLP-1R), Kelch-like epichlorohydrin-associated protein 1 (Keap1), nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) was determined by Western blot. RESULTS: Exenatide treatment for 3 months improved the cardiac microvascular permeability in the diabetic rats. The GLP-1R was expressed in CMECs. GLP-1 inhibited high glucose-induced ROS production (P<0.05). Compared with high glucose group, the protein expression of Keap1 was decreased, and Nrf2 and HO-1 were increased significantly (P<0.05). CONCLUSION: GLP-1 inhibits oxidative stress in high glucose-induced CMECs, and improves the cardiac microvascular permeability in diabetic rats. The protective effects of GLP-1 may be related to Keap1-Nrf2 signaling pathway.     

Protective effect of anti-aging Klotho protein on human umbilical vein endothelial cells treated with high glucose

AIM: To study the protective effect of anti-aging Klotho protein on human umbilical vein endothelial cells (HUVECs) treated with high glucose (HG).METHODS: HUVECs were cultured in vitro, and divided into PBS control group, 5.5 mmol/L glucose group, 33.3 mmol/L glucose group, 0.1 μmol/L Klotho+33.3 mmol/L glucose group, 1 μmol/L Klotho+33.3 mmol/L glucose group, and 10 μmol/L Klotho+33.3 mmol/L glucose group. The viability of the HUVECs was measured by MTT assay. The content of malondialdehyde (MDA), and the activities of lactate dehydrogenase (LDH), superoxide dismutase (SOD) and glutathione (GSH) in cell culture supernatants were observed. The production of reactive oxygen species (ROS) in HUVECs was analyzed by flow cytometry. The levels of nitric oxide (NO), endothelin (ET-1), intercellular adhesion molecule-1 (ICAM-1) in HUVEC culture medium were detected by ELISA. The protein expression of nuclear factor-kappa B (NF-κB) in the HUVECs was determined by Western blot. RESULTS: Compared with PBS control group, 33.3 mmol/L glucose significantly decreased the HUVEC viability, increased ROS, LDH and MDA levels, reduced the activities of SOD and GSH, decreased the NO secretion, and induced the ET-1 and ICAM-1 secretion and the protein expression of NF-κB in HUVECs. When HUVECs were treated with Klotho protein at different concentrations combined with 33.3 mmol/L glucose, the cell viability was increased significantly, the ROS, LDH and MDA levels were decreased significantly, the antioxidant SOD and GSH activities were significantly increased, the secretion of NO was increased, but ET-1 and ICAM-1 releases and protein expression of NF-κB were significantly reduced.CONCLUSION: Anti-aging Klotho protein promotes the viability of HUVECs treated with HG, reduces the oxidative damage and ROS production, and restores the normal secretory function of HUVECs, thus playing a protective role in vascular endothelial cells through reducing the protein expression of NF-κB.     

Effects of edaravone on high glucose-induced apoptosis in SH-SY5Y cells via regulating microRNA-25

AIM: To observe the effects of edaravone on high glucose-induced apoptosis of SH-SY5Y cells and its potential mechanism. METHODS: The SH-SY5Y cells were cultured in the DMEM medium with 100 mmol/L glucose and 100 μmol/L edaravone for 24 h. The viability of the SH-SY5Y cells was detected by MTT assay. The levels of ROS in the cells were determined by DCFH-DA fluorescent probing. The apoptotic rates of the cells were analyzed by flow cytometry. The protein expression of Bax and Bcl-2 in the cells were detected by Western blot. The expression levels of micro-RNA-25 (miR-25) were determined by real-time PCR. To further clarify the target sites of edaravone on inhibiting apoptosis induced by high glucose, miR-25 inhibitor was applied to the SH-SY5Y cells and the activity of caspase-3 was measured.RESULTS: Compared with control group, the cell viability was decreased significantly in model group, and the ROS level was increased significantly. The protein expression of Bax was up-regulated significantly, while the expression levels of Bcl-2 and miR-25 were significantly down-regulated. Compared with model group, the cell viability was increased significantly in edaravone group. The ROS level was decreased significantly. Meanwhile, the expression of Bax was down-regulated, while the expression of Bcl-2 and miR-25 was up-regulated with statistical significance. The caspase-3 activity of the cells incubated with 100 mmol/L glucose and miR-25 inhibitor was increased. However, no alteration of caspase-3 activity with edaravone added simultaneously was observed. CONCLUSION: Edaravone inhibits the apoptosis of SH-SY5Y cells induced by high glucose with the potential target site of miR-25.     

Effect of insulin on the SGK1 expression and extracellular matrix synthesis in human mesangial cells cultured in high glucose

AIM:To study the effect of insulin on the serum and glucocorticoid-inducible kinase 1 (SGK1) expression and extracellular matrix synthesis in human glomerular mesangial cells (HMC) cultured in high glucose. METHODS:The HMCs were cultured in the presence of 5.5 or 25 mmol/L glucose with or without 100 nmol/L insulin (i.e. NG, HG, NI and HI groups). 4 h latter, expressions of SGK1, insulin receptor substrate-1 (IRS1) and IRS2 in corresponding groups were detected by immunofluorescence or examined by Western blotting. The phosphorylation of IRS1 and IRS2 was measured by immunoprecipitation. 24 h latter, connective tissue growth factor(CTGF) and fibronectin (FN) were also examined by RT-PCR and ELISA, respectively. RESULTS:Compared with NG, the SGK1 protein expression in HG, NI and HI groups was significantly higher (P<0.01). High glucose mainly caused IRS2 protein and its phosphorylation level increase (P<0.01). When treated with 100 nmol/L insulin, IRS1 protein and its phosphorylation in HI group apparently elevated while slight inhibition of IRS2 protein expression and its phosphorylation were observed (HI vs HG, P<0.05). High glucose enhanced the expression of CTGF and FN, and insulin strengthened this effect.CONCLUSION:Insulin and high glucose up-regulate the expression of SGK1 in mesangial cells through different target molecular pathways and ultimately enhance ECM synthesis. The effect of insulin is highly associated with IRS1 signaling cascades.     

Ubiquitin-dependent degradation of SnoN/Ski protein in glomerular mesangial cells induced by high glucose

AIM: To observe the protein expression of SnoN/Ski and ubiqutin ligase Arkadia in rat glomerular mesangial cells (GMCs) exposed to the high glucose. METHODS: Cultured rat glomerular mesangial HBZY-1 cells were divided into control group, 20 mmol/L glucose group, 30 mmol/L glucose group, 30 mmol/L glucose+MG132 group (culture medium containing 30 mmol/L glucose and 0.5 μmol/L specific proteasome inhibitor MG132), and mannitol group. The expression levels of SnoN, Ski and Arkadia were measured by Western blotting analysis, immunofluorescence and laser scanning confocal microscopy. RESULTS: In control GMCs, the expression of SnoN/Ski was rich and Arkadia was weak. After stimulated with high glucose, the expression of SnoN/Ski was decreased and Arkadia was gradually increased (P<0.05). Compared with high glucose group, the levels of SnoN/Ski and Arkadia were mostly reverted by adding the proteasome inhibitor MG132 at concentration of 0.5 μmol/L (P<0.01). The expression levels of SnoN/Ski and Arkadia were not significantly changed in mannitol group in comparison with control group (P>0.05). CONCLUSION: High glucose decreases the expression of SnoN/Ski through ubiquitin-dependent degradation of SnoN/Ski. The degradation of SnoN/Ski mediated by Arkadia may play an important role in the pathogenesis of diabetic nephropathy.     

Curcumin ameliorates high glucose-induced dysfunction of vasoconstriction via heme oxygenase-1 and GC pathway

AIM: To explore the protective effect of curcumin on high glucose-induced decrease in contraction of isolated rat aortic rings, and to elucidate its underlying mechanism. METHODS: The thoracic aortic rings with endothelium of male Sprague-Dawley rats were mounted on a bath system. Isometric contractions of aortic rings were measured. HO activity was also evaluated. RESULTS: (1)Four hours after incubated with 44 mmol/L of glucose (high glucose), the vascular contraction responses to phenylephrine (PE) decreased compared to control group (containing 11 mmol/L of glucose). (2)Coincubation with curcumin (3×10-11-3×10-10 mol/L) and high glucose, the high glucose-induced decrease in contraction responses to PE of arteries was partly inhibited. (3)Four hours after incubation with curcumin, the HO activity in thoracic aorta increased. ZnPP, an inhibitor of HO-1, completely abrogated the protection effect of curcumin. (4)Methylene blue, an inhibitor of guanylate cyclase (GC), partly abolished the protective effect of curcumin. CONCLUSION: Curcumin prevents the high glucose-induced decrease in contraction responses to PE in intact aortic rings. The mechanism might be mainly involved in the activation of HO-1 and GC.     

Naringin protects human umbilical vein endothelial cells against injury induced by high glucose through PI3K/AKT/eNOS pathway

AIM: To investigate the protective effect of naringin (Nar) on the injury of human umbilical vein endothelial cells (HUVECs) induced by 33 mmol/L high glucose (HG) and to explore its possible mechanisms.METHODS: The injury model was established by treating HUVECs with HG medium for the indicated time (6, 12, 24, 48 and 72 h), and then the levels of NO, eNOS and p-eNOS were detected, respectively. The effects of Nar on high glucose-induced endothelial cell injury were observed. HUVECs were treated with Nar at concentrations of 5, 10, 25, 50 and 100 mg/L for 6 h, 12 h, 24 h, 36 h and 48 h. The levels of NO in the supernatants were measured. The effects of Nar on HG-injured HUVECs were explored by treating the cells with 10 μmol/L of LY294002, a PI3K inhibitor, or 0.5 μmol/L of AKT inhibitor Ⅳ, an AKT inhibitor, and then the levels of NO, PI3K, AKT, eNOS and their phosphorylated proteins were determined by Western blot.RESULTS: Nar at concentration of 50 mg/L significantly attenuated the injury of endothelial cells induced by high glucose (P<0.01), and the protective effects of Nar were abolished by pretreating with the inhibitor of PI3K or AKT (P<0.01).CONCLUSION: Nar protects endothelial cells against the injury induced by high glucose through PI3K/AKT/eNOS pathway.     

Hydrogen sulfide attenuates human umbilical vein endothelial cell senescence via modulation of Sirt1/eNOS pathway

AIM: To explore the role of Sirt1/eNOS signalling pathway in the protective effect of hydrogen sulphide (H₂S) against endothelial cell senescence induced by high glucose.METHODS: High glucose (33 mmol/L) was applied to induce senescence in primary human umbilical vein endothelial cells (HUVECs). The cell viability, the proportion of senescence-associated β-galactosidase (SA-β-Gal) positive cells and the plasminogen activator inhibitor 1 (PAI-1) expression were detected to assess the senescence model. Mean while, Sirt1 siRNA was used to examine the effect of Sirt1 on eNOS expression and the senescence-related parameters.RESULTS: Treatment of HUVECs with high glucose decreased the cell viability slowly with a larger proportion of the cells stained with SA-β-Gal, and the protein expression of PAI-1 was dramatically increased. The increased cell viability, reduced SA-β-Gal positive cells and decreased protein expression of PAI-1 were detected after sodium hydrosulfide (NaHS, 100 μmol/L) treatment. Furthermore, NaHS treatment upregulated the protein expression of Sirt1 and eNOS, and eventually increased the production of nitric oxide (NO).CONCLUSION: Exogenous H₂S modulates Sirt1/eNOS/NO pathway to prevent HUVECs against high glucose-induced senescence.     

Mechanism of Sos2 inhibiting NFATc1-mediated podocyte injury in diabetic nephropathy

AIM: To observe the effect of high glucose (HG) stimulation on the expression of guanine nucleotide exchange factor Sos2 (Son of Sevenless homolog 2) in mouse podocytes, and to explore the role of Sos2 in HG-induced podocyte damage and its possible molecular mechanisms. METHODS: The expression of Sos2 in the podocytes of diabetic nephropathy patients was observed by immunofluorescence staining and laser confocal microscopy. In vitro, the Sos2 expression at mRNA and protein levels in immortalized podocytes with HG (30 mmol/L glucose) stimulation for 48 h was determined by the methods of RT-PCR, Western blot and immunofluorescence. Using Western blot, immunofluorescence and wound-healing assay, the expression of podocin, the translocation of NFATc1 into the nucleus and the podocyte migration with or without Sos2 silencing or overexpression were analyzed. The expression of downstream target genes for NFATc1 was detected by RT-PCR. RESULTS: The expression of Sos2 was significantly decreased in the podocytes of diabetic nephropathy patients and in vitro cultured podocytes with HG stimulation (P<0.05). When Sos2 was silenced, the expression of podocin was significantly decreased, the migration ability of podocytes was increased, and the translocation of NFATc1 into the nucleus was increased (P<0.05). In contrast, after overexpression of Sos2 in the podocytes with HG stimulation, the podocin expression level was obviously higher, and the podocyte migration ability and the translocation of NFATc1 into the nucleus were decreased (P<0.05).CONCLUSION: Sos2 may attenuate the diabetic nephropathy-induced podocyte injury by inhibiting NFATc1.     

Puerarin protects high glucose-induced injury of vascular relaxation by activation of heme oxygenase-1

AIM: To investigate the effect of puerarin on acute high glucose-induced attenuation of ACh relaxation in isolated rat aortic rings, and to elucidate its underlying mechanism. METHODS: The thoracic aortic rings with endothelium of male Sprague-Dawley rats were mounted on a bath system. Isometric relaxation of aortic rings was measured. RESULTS: ① After incubation with high concentration of glucose (44 mmol/L), the vascular relaxation responses to ACh decreased. ② After coincubation with puerarin (10-10-10-8 mol/L) and high glucose, the high glucose-induced attenuation of ACh relaxation responses of artery was partly inhibited in a dose-dependent manner. ③ After incubation with puerarin for 2 h, the HO-1 activity of thoracic aorta increased. ZnPPIX (an inhibitor of heme oxygenase-1) abrogated the protective effect of puerarin. CONCLUSION: Puerarin prevents the acute high glucose-induced attenuation of endothelium-dependent relaxation in aortic rings. The mechanism might be involved in the activation of heme oxygenase-1.     

Inhibitory effect of oxymatrine on high glucose-induced rat renal tubular epithelial-mesenchymal transition

AIM:To investigate the inhibitory effect of oxymatrine (OM) on high glucose-induced rat renal tubular epithelial-mesenchymal transition (EMT). METHODS:The rat renal tubular epithelial NRK52E cells were cultured in vitro. The cells were divided into control group, high glucose group, high glucose+different concentrations of OM groups and high glucose+0.50 g/L OM dynamic observation group. The expression of TGF-β1, Smad7, α-SMA and E-cadherin at mRNA and protein levels was detected by real-time PCR and Western blotting. The viability of NRK52E cells was determined by MTT assay. RESULTS:(1) Compared with control group, the expression of TGF-β1 and α-SMA at mRNA and protein levels in high glucose group gradually increased, and Smad7 protein and E-cadherin mRNA and protein gradually reduced, but the mRNA expression of Smad7 gradually increased. (2) Compared with high glucose group, as increases in OM doses, the expression of TGF-β1 and α-SMA at mRNA and protein levels in high glucose+different concentrations of OM groups gradually reduced, and Smad7 protein and E-cadherin mRNA and protein gradually increased, but the mRNA expression of Smad7 had no significant change. (3) Compared with high glucose group, the expression of TGF-β1 and α-SMA at mRNA and protein levels was significantly reduced, the expression of E-cadherin at mRNA and protein levels significantly increased, and the protein expression of Smad7 significantly increased, but the mRNA expression of Smad7 had no significant change in high glucose+0.50 g/L OM dynamic observation group. CONCLUSION: In NRK52E cells, oxymatrine inhibits high glucose induced EMT by down-regulating TGF-β1 and up-regulating Smad7, thus preventing the fibrosis effect of TGF-β1/Smads signaling.     

Reverse effect of protein kinase C inhibitor Ro-31-8220 on the hypertrophy of cardiomyocytes of neonatal rats induced by high glucose levels

AIM: To study the effect of protein kinase C (PKC) inhibitor Ro-31-8220 on the hypertrophy of cardiomyocytes of neonatal rats induced by high glucose levels, and to investigate the role of PKC and its downstream signal transduction pathway. METHODS: Using cultured neonatal cardiac myocytes as a model, the cells were divided into: (1) control group (glucose 5.5 mmol/L); (2) different high glucose level (10 mmol/L,15 mmol/L, 20 mmol/L, 25.5 mmol/L); (3) high glucose level (25.5 mmol/L) + PKC inhibitor Ro-31-8220 (50 nmol/L); (4) high glucose level (25.5mmol/L) + NF-κB inhibitor (BAY11-7082, 5 mmol/L). The cellular diameters and protein level were measured and the expression of PKC-α, PKC-β2, p-PKC-α, p-PKC-β2, NF-κB and c-Fos were determined by Western blotting. RESULTS: Neonatal cardiomyocytes cultured in high glucose concentration showed increased cellular diameters, protein level and higher expressions of PKC-α, PKC-β2, p-PKC-α, p-PKC-β2, NF-κB and c-Fos, which was consistent with the increased glucose levels and had statistical significance compared to control group (P<0.01). PKC inhibitor Ro-31-8220 reversed these changes induced by high glucose concentration as showed by decreased cellular diameters, protein level and expression of PKC-α, PKC-β2, p-PKC-α, p-PKC-β2, NF-κB and c-Fos, which had statistical significance compared to high glucose groups (P<0.01). CONCLUSION: High glucose levels induce hypertrophy of cardiomyocytes. PKC inhibitor Ro-31-8220 reverses the effect of high glucose on the cardiac myocytes, which may be via PKC/NF-κB/c-Fos pathway.     

Mitochondrial mechanism of hyperglycemia-induced apoptosis in primary mouse hepatocytes with steatosis

AIM: To investigate the role of high glucose in primary hepatocytes of mice fed with a high fat diet.METHODS: Male C57BL/6J mice were fed a high fat (45% of calories) diet ad libitum for 6 weeks to induce hepatic steatosis. Primary hepatocytes were isolated from the mouse liver by the 2 step collagenase perfusion method. The cells were incubated in low glucose (5 mmol/L), low glucose plus mannitol (30 mmol/L), or high glucose (35 mmol/L) DMEM medium for 12 h. The cell viability, apoptosis, mitochondrial membrane potential, and caspase enzymatic activities were measured. Furthermore, proteins related to the stress-sensitive signaling pathway of regulating high glucose-induced apoptosis in primary hepatocytes were determined by Western blotting.RESULTS: Incubation with 35 mmol/L glucose resulted in a significant decrease in cell viability and an increase in apoptosis, whereas mannitol had no significant effect on the cell viability or apoptosis. A progressive depolarization of the mitochondria, an increase in cytosol cytochrome C and a dramatic decrease in mitochondrial cytochrome C in high-glucose stressed hepatocytes were observed. The enzymatic activities of caspase-9 and caspase-3, but not caspase-8, were significantly increased in high glucose-stressed hepatocytes (P<0.05). High glucose treatment suppressed the expression of Bcl-2 and Bcl-xL, while it increased the expression of the pro-apoptotic factor Bax.CONCLUSION: High glucose stress reduces mitochondrial membrane potential, initiates mitochondria-mediated apoptotic pathways and promotes apoptosis of hepatocytes with steatosis. This may be an important pathological mechanism of hyperglycemia-induced progression of nonalcoholic fatty liver disease.