Advanced glycation end products induce apoptosis of human ovarian granulosa COV434 cells and up-regulate pro-inflammatory cytokine HMGB1 autocrine

AIM:To study whether advanced glycation end products (AGEs) induce the apoptosis of human ovarian granulosa COV434 cells, and to explore the possible mechanism. METHODS:Human ovarian granulosa COV434 cells were treated with AGEs at different concentrations. Flow cytometry was used to observe the apoptotic rate. The protein levels of caspase-3 and cleaved caspase-3 were determined by Western blot. The release of high mobility group box 1 protein (HMGB1) in the culture supernatant was measured by ELISA. RESULTS:Compared with control group, early apoptotic rate and late apoptotic rate in 100 mg/L AGEs group and 200 mg/L AGEs group were significantly increased (P<0.05). No obvious difference of caspase-3 protein level in each group was observed, while the protein levels of cleaved caspase-3 in 100 mg/L AGEs group and 200 mg/L AGEs group were significantly increased compared with control group (P<0.05). In addition, compared with control group, pro-inflammatory factor HMGB1 in the culture medium in 100 mg/L AGEs group and 200 mg/L AGEs group was significantly increased. CONCLUSION:The apoptosis of human ovarian granulosa COV434 cells induced by AGEs may be related to pro-inflammatory reaction.     

The signal transducers involved in the regulation of calcium sensitivity of vascular smooth muscle in hemorrhagic shock

AIM: To observe the regulatory effects of Rho-kinase, PKC and PKG on calcium sensitivity of vascular smooth muscle in hemorrhagic shock in rats. METHODS: The superior mesenteric artery (SMA) from hemorrhagic shock model of rat was adopted to assay the calcium sensitivity via observing the contraction initiated by Ca2+ under depolarizing conditions (120 mmol/L K+) with isolated organ perfusion system. Rho-kinase agonist Ang-Ⅱ and inhibitor fasudil, PKC agonist PMA and inhibitor staurosporine, PKG agonist 8Br-cGMP and inhibitor KT-5823 were used as tool agents to study the regulatory effect of Rho-kinase, PKC and PKG on the calcium sensitivity of SMA following shock. RESULTS: Ang-Ⅱ, PMA and KT-5823 improved the calcium sensitivity of SMA and made the cumulative dose-response curve of SMA to Ca2+ shift to the left, their Emax of Ca2+ (at 3×10-2 mol/L) was 0.630 g/mg, 0.595 g/mg and 0.624 g/mg, respectively, which were all higher than that in shock control (0.377 g/mg) (P<0.05, P<0.01). Fasudil, staurosporine and 8Br-cGMP delimitated the calcium sensitivity of SMA and made the cumulative dose-response curve of Ca2+ shift to the right, their Emax at 3×10-2 mol/L of Ca2+ was 0.242 g/mg, 0.230 g/mg and 0.256 g/mg, respectively, which were all lower than that in shock control (0.377 g/mg) (P<0.05, P<0.01). CONCLUSION: Rho-kinase, PKC, PKG play important roles in the regulation of calcium sensitivity of vascular smooth muscle in hemorrhagic shock.     

Histochemical changes of skin in diabetic rats

AIM: To explore the histochemical changes of diabetic skin and the pathogenesis of impaired wound healing in diabetes. METHODS: 54 male Sprague-Dawley (SD) rats weighing 200-220 g were randomized into control and STZ-induced diabetic groups. The shaved skin specimens from the back of rats were collected in 4, 8 and 12 weeks post STZ-induction, respectively. Hematoxylin-eosin dye was used for histological examination. Meanwhile, the skin glucose contents were measured by Beckman’s autoanalyzer. Skin AGEs concentrations were assessed by detecting total fluorescence in tissue collagen and immunohistochemistry assay. RESULTS: The skin thickness in diabetic animals was decreased, with the features of multilayer epithelium structure disappeared in epidermis and collagen fibers atrophied, swollen and degenerated in dermis; The inflammatory responses in the dermis of diabetic animals were increased obviously. The results also revealed that skin glucose contents in diabetic rats ［(2.64±1.03）mg/g skin］ were 2-3 times higher than those in the controls ［(0.74±0.33)mg/g skin］ (P<0.01). The collagen fluorescence and AGEs positive expressions in diabetic skin enhanced significantly when compared with age-matched controls over the whole experimental course (P<0.05). CONCLUSIONS: A histochemical changes had already been occurred in diabetic skin before injury, which may be result from the local biochemical factors such as high concentrations of glucose and AGEs. These might be an important mechanism in the pathogenesis of impaired wound healing in diabetes.     

Effects of aminoguanidine intervention on lens cell damage induced by D-galactose in rat eyes

AIM: To investigate the effects of aminoguanidine intervention on lens cell damage induced by D-galactose in rat eyes and its mechanism of action. METHODS: D-galactose (400 mg/kg) was injected into rats intraperitoneally for 14 weeks to induce the animal model of glycosylation and lens cell damage. Aminoguanidine (75 mg/kg, 150 mg/kg) were administered for 12 weeks by intragastric administration beginning at 3rd week. All animals were killed and blood samples were taken to measure the activity of aldose reductase, the level of fructosamine, the amounts of glycohaemoglobin and advanced glycation end-products. The lenses of eyes were taken to detect the activities of AR, GR, SOD and SDH. The amounts of AGEs, GSH, MDA or outleakage of LDH were measured, respectively. The ultrastructure and apoptosis of lens epithelial cells were examined by transmission electron microscope and flow cytometry, respectively. RESULTS: Animals were treated with D-galactose for 14 weeks, the serum level of fructosamine, the amounts of glycohaemoglobin and AGEs, and activity of AR were significantly increased. The amount of AGEs and activity of AR in lens were increased, the activity of antioxidase was decreased and oxidative product was increased. The apoptosis, the damages of mitochondria and cell nucleus in lens cells were observed. After treated with aminoguanidine for 12 weeks, the activity of AR and the level of fructosamine in serum, and the amounts of glycohaemoglobin and AGEs were significantly decreased (P<0.01). The outleakage of LDH and amount of MDA were also decreased (P<0.05, P<0.01), the activities of GR, SDH and SOD were increased (P<0.05, P<0.01). The apoptotic rate of lens cells was reduced (P<0.05, P<0.01). The morphology of mitochondria and cell nucleus were improved. CONCLUSION: D-galactose induces the damage of cell nucleus, the mitochondria and apoptosis in lens cells by glycosylation and oxidative stress. Aminoguanidine may supply the protective action through inhibiting the glycosylation and oxidative stress.     

Effect of Xuefuzhuyu decoction on cardiomyopathy in type 2 diabetic rats

AIM: To observe the pathologic changes of cardiomyopathy in type 2 diabetic rats and the therapeutic effect of Xuefuzhuyu decoction.METHODS: The diabetic model was established by feeding the animals with high-fat diet and injecting a middle dose of streptozotocin (50 mg/kg) intraperitoneally in 42 Wistar male rats. After 8 weeks, the damage of the heart in the model animals was detected by electrocardiogram and echocardiography, and the serum level of glucose, total cholesterol and triglyceride were determined by the methods of clinical chemistry. The content of collagen was quantified by Masson staining. The apoptosis of cardiomyocytes was measured by TUNEL apoptosis kit. The structures of myocardial damage were observed under light and electronic microscopes.RESULTS: (1) Compared with normal group at the same time points, the contents of serum glucose, triglyceride and cholesterol in model group increased (P<0.05). At the 11th and 14th weeks, the thickness of LVDS was significantly increased (P<0.01), the structure of myocardial tissues was severely damaged and collagen fiber content increased obviously (P<0.01). The cell apoptosis was also increased. (2) Compared with control group at the same time points, the contents of serum glucose, cholesterol and triglyceride in Xuefuzhuyu decoction group significantly decreased (P<0.05). The thickness of LVDS at the 11th and 14th weeks was decreased (P<0.05) and LVM at the 14th week became significantly thinner (P<0.01). The damage of the myocardium and subcellular structure was slighter and the content of collagen was lower than that in control group (P<0.05). The cell apoptosis was also attenuated.CONCLUSION: The levels of blood glucose, total cholesterol and triglyceride and the content of collagen fibers increase when diabetic cardiomyopathy develops, with more cell apoptosis and severe damage in the cardiac structure. Xuefuzhuyu decoction decreases the level of blood lipid in diabetic cardiomyopathy, alleviates the pathological changes of myocardial fibrosis and delays the progression of diabetic cardiomyopathy.     

Effect of tea polyphenols on the contractile function of the papillary muscles of right ventricle in diabetic rats

AIM: To investigate the effect of tea polyphenols (TP) on the contractile function of the papillary muscles of right ventricle in the sixth and eighth week diabetic rats and the control rats. METHODS: Rats were induced to diabetic by an intravenous injection of alloxan. The papillary muscles of right ventricle in the sixth and eighth week diabetic rats were segregated and superfused with oxygenated Tyrode's solution. The contractile function and functional change under the electric stimulation state was recorded and compared between diabetic group and control group. RESULTS: 1/2 diastole interval elongation (P<0.05) and the depression of +dT/dtmax (P<0.01) and -dT/dtmax (P<0.05) of the papillary muscles of right ventricle were showed in the 6th week diabetic rats, while further damages, such as tension addition (P<0.01), 1/2 diastole interval elongation (P<0.01) and the depression of +dT/dtmax (P<0.01) and -dT/dtmax (P<0.01) in 8th week diabetic rats were also observed. TP at certain concentrations (15-120 mg/L) did not produce any effect on the 8th week diabetic rat's papillary muscle, but the positive muscle strength has been showed in the control rats and the sixth week diabetic rats. CONCLUSIONS: TP produces the positive muscle strength in the early diabetic cardiomyopathy, but has no beneficial effect on serious impaired diabetic myocardium.     

Expression of TGF-β1 and apoptosis in myocardium of diabetic rats

AIM: To study the pathophysiological mechanism of cardiomyopathy, the expression of TGF-β₁ and apoptosis in myocardium of diabetic rats were investigated. METHODS:The diabetes models were established by single intravenous injection of streptozotocin (50 mg/kg) in rats. By the method of immunochemistry, the expression of TGF-β₁ in the cardiomyocytes was detected as the index to evaluate the degree of fibrosis. The method of TUNEL was used to measure the cardiomyocyte apoptosis as the index to explore its importance in process of diabetic cardiomyopathy. RESULTS:① The weight of diabetic rats was apparently lower than that in the rats before the diabetic model was built (P<0.01), and the increase in weight in diabetic rats within three month was less than that in normal group. ② Compared with control group, the concentration of blood glucose was continually elevated during the experiment. ③ The expression of TGF-β₁ in the diabetic cardiac muscle was much more than that in normal group (P<0.01). ④ The apoptosis of myocardium measured by the method of TUNEL was apparent in the diabetic groups than that in normal one (P<0.01). However, no significance was detected in the different courses of diabetic groups. CONCLUSIONS:The apoptosis might play an important role in leading the diabetic cardiomyopathy to heart failure. The expression of TGF-β₁ in the myocardium of diabetic rats was more than that in normal and had an increasing trend in the procession of diabetic cardiomyopathy. TGF-β₁ might be a significant factor in diabetic myocardium fibrosis. Apoptosis might play an important role in the initial stage of diabetes, which promotes the diabetic cardiomyopathy to heart failure.     

Effect of advanced glycation end products on inflammation in cultured cardiomyocytes

AIM: To investigate the effect of advanced glycation end products on inflammation in cultured cardiomyocytes.METHODS: Primary cardiomyocytes were isolated from Sprague-Dawley neonatal (1 to 2 days old) rats ventricles.The insulin resistant cardiomyocyte model was established.Neonatal rat ventricular myocytes were exposed to AGEs for 24 hours.TNF-α mRNA and PPAR-γ mRNA expressions were determined by RT-PCR.Activation of NF-κB in the cells was examined by using immunocytochemistry.The ultrastructure of the cells was detected by transmission electron microscope.RESULTS: The exprssion of TNF-α mRNA and the activation of NF-κB increased,the expression of PPAR-γ mRNA decreased compared with control group (P<0.05).The differences among different AGE-BSA groups were significant (P<0.05).The numbers of chondriosome and smooth endoplasmic reticulum increased.CONCLUSION: AGEs significantly increase TNF-α mRNA expression and NF-κB activation,and restrain the expression of PPAR-γ mRNA.These data suggest that AGEs play an important role in the onset of diabetic cardiomyopathy.     

Expression of SR-A II and CD36 in white blood cells correlate with plasma AGEs levels and diabetic complications

AIM: To investigate the correlation of the expression of scavenger receptors SR-A II and CD36 in white blood cells (WBCs) with the plasma levels of advanced glycosylation end products (AGEs) and different diabetic complications.METHODS: Blood samples were collected from 78 patients with diabetic complications. The levels of plasma AGEs were determined by using spectrofluorimetry. RNA in WBCs was extracted with Trizol reagent and the mRNA levels of SR-A II and CD36 were determined by RT-PCR. RESULTS: In the patients tested, the mRNA level of SR-A Ⅱ was found to be the highest in those with diabetic nephropathy, and lowest in those with fatty liver. The expression of CD36 was found to be the highest in diabetic patients with fatty liver and lowest in those with coronary heart disease. The expression of both receptors in WBCs showed significantly higher levels in diabetic patients with hypertension, and lower in those with cataract. The plasma levels of AGEs negatively correlated with mRNA levels of CD36 (r=-0.89,P<0.01), while positively correlated with SR-A II mRNA levels (r=-0.82, P< 0.05).CONCLUSION: The increased plasma levels of AGEs may stimulate the expression of SR-A II in WBCs, and higher expression of SR-A Ⅱ and CD36 was significantly related to diabetic complications, nephropathy and fatty liver, respectively. However, low expression of CD36 in some diabetic patients with complications might be important causes for their high plasma AGEs levels.     

Apoptosis in diabetic foot ulcers and human fibroblast cells treated with AGEs

AIM：To investigate cell apoptosis in diabetic foot ulcers and the effect of advanced glycosylation end products (AGEs) on apoptosis in human fibroblast cells. METHODS：Diabetic foot patients (n=18) and 18 age-matched non-diabetic controls were recruited. The clinical and biochemical features were compared by statistics methods. Skin biopsies were obtained from foot. Cleaved caspase-3 was measured by immunohistochemistry using the technique of streptavidin-biotin complex (SABC) staining. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) technique was used to detect apoptosis of the skin tissues. Human primary foreskin fibroblasts were isolated and cultured in the presence of 5.6 mmo/L glucose, 25 mmo/L glucose, fluctuant glucose (changing the glucose from 5.6 mmo/L to 25 mmo/L every 8 h) or AGEs (150 mg/L, containing 5.6 mmo/L glucose). After 72 h treatment, Western blotting was used to determine the levels of the apoptotic protein cleaved-caspase-3. Other cells were trypsinized, washed with cold PBS and incubated with PI and Annexin V-FITC, then analyzed by flow cytometry to detect cell apoptosis. RESULTS：Diabetic patients had higher levels of fasting blood glucose (FBG), 2-hour postprandial blood glucose (2 h PBG) and glycosylated hemoglobin A1c (HbA1c), and longer wound duration. The protein level of cleaved caspase-3 was significantly higher in diabetic group, suggesting that apoptosis was increased in diabetic skin tissues. TUNEL analysis showed that apoptotic index was higher in diabetic group compared with that in non-diabetic group (8.4%±1.5% vs 3.8%±08%), which further confirmed that cell apoptosis was increased in diabetic foot tissues. In human fibroblasts, the levels of cleaved caspase-3 in normal group, sustained high glucose group, fluctuant high glucose group and AGEs group were 080±0.13, 1.22±0.18, 1.46±0.32 and 1.83±0.25, respectively. The apoptotic rates detected by flow cytometry were 2.43%±0.19%, 2.89%±0.51%, 3.99%±0.24% and 6.83%±0.36%, respectively. Both the level of cleaved caspase-3 and the apoptotic rate in AGEs group were higher than those in normal glucose group and sustained high glucose group. CONCLUSION：Increased apoptosis in diabetic foot ulcers is one of the most important reasons for impaired wound healing. As compared to sustained high glucose and glucose fluctuations, AGEs induce greater apoptosis in human fibroblast cells.     

Effects of advanced glycation end products on protein and mRNA expression of macrophage inflammatory protein-1α in cultured human umbilical vein endothelial cells

AIM: To investigate the effects of advanced glycation end products (AGEs) on protein and mRNA expression of macrophage inflammatory protein-1α (MIP-1α) in cultured human umbilical vein endothelial cells(HUVECs). METHODS: HUVECs were cultured with AGEs at different concentrations for 24 h and at a concentration of 400 mg/L for different time.The levels of mRNA and protein expression of MIP-1α in cultured HUVEC were detected by in situ hybridization and Western blot, respectively. RESULTS: In situ hybridization showed that after exposure of HUVECs to AGEs at different concentrations (100 mg/L, 200 mg/L, 400 mg/L) for 24 h, the average integrated optical density values (18.76±3.17, 26.58±1.61, 34.23±2.25) of MIP-1α mRNA expression in HUVECs were higher than that in control group (13.83±1.24, P0.05). After exposure of HUVECs to AGEs at a concentration of 400 mg/L for 12 h, 24 h and 36 h, the average integrated optical density values of MIP-1α mRNA expression in HUVECs were 22.67±1.46, 34.23±2.25 and 42.28±3.14, higher than that in 0 h group (12.56±1.24, P0.05). Western Blot showed that exposure of HUVECs to AGEs at different concentrations(100 mg/L, 200 mg/L, 400 mg/L) for 24 h resulted in a 1.34-fold, 1.87-fold and 2.46-fold increase in the expression of MIP-1α protein in HUVECs compared with BSA control group (P<0.05). Meanwhile, exposure of HUVECs to AGEs at a concentration of 400 mg/L for 12 h, 24 h and 36 h resulted in a 1.82-fold, 2.71-fold and 3.34-fold increase in MIP-1α protein expression in HUVECs compared with 0 h group (P<0.05). CONCLUSION:These data suggest that AGEs could induce a high expression of MIP-1αmRNA and protein in cultured HUVECs in a dose-dependent and time-dependent manner.     

Expression of FBXW7 in diabetic cardiomyopathy

AIM:To investigate the expression of F-box/WD repeat-containing protein 7 (FBXW7) in the myocardium of type 1 diabetic rats and to clarify its role in the development of diabetic cardiomyopathy. METHODS:All rats were randomly divided into non-diabetic (ND) group, 4-week diabetes mellitus (DM) model group, 8-week DM mo-del group and 12-week DM model group. The DM model was prepared by intraperitoneal injection of streptozotocin (60 mg/kg). The change of myocardial pathological structure was investigated by HE staining. The FBXW7 expression level in the myocardium was determined by Western blot and immunohistochemistry methods. RESULTS:DM induced cardiomyocyte degeneration and necrosis as shown by cardiac histological analysis. Both Western blot and immunohistochemistry results showed that the expression level of FBXW7 was significantly increased in 4-week, 8-week and 12-week DM groups compared with control group (P<0.01). However, The FBXW7 expression level in 12-week DM group was decreased compared with 4-week and 8-week DM groups. CONCLUSION:With the development of diabetes, the expression of FBXW7 in the myocardium of the rats with diabetic cardiomyopathy shows a tendency to increase first and then decrease, suggesting that it plays some roles in the development of diabetic cardiomyopathy.     

Effects of pentoxifylline on ventricular remodeling and cardiac function of dilated cardiomyopathy rats

AIM: To explore the effects of pentoxifylline (PTX) on ventricular remodeling and cardiac function in dilated cardiomyopathy (DCM) rats.METHODS: Lewis rats were randomly allocated to a myocin-induced dilated cardiomyopathy (DCM) group receiving saline (n=10), a DCM group receiving PTX (PTX group; 25 mg·kg^-1·d^-1, ip, for 30 days, n=10) or healthy control group (n=10). The levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and IL-10 in the blood plasma were analyzed by ELISA. The extent of fibrosis was estimated using Massons staining and immunohistochemistry analyses. Cardiac structure and function were measured by echocardiography.RESULTS: PTX decreased plasma levels of TNF-α and IL-6, and increased IL-10 level in DCM animals compared with DCM group ［TNF-α: (7.21±0.24) μg/L vs (19.30±1.31) μg/L, P<0.01; IL-6: (119.60±36.58) ng/L vs (189.50±13.25) ng/L, P<0.05; IL-10: (41.26±3.27) μg/L vs (32.45±4.32) μg/L, P<0.05］. Collagen volume fraction (CVF), perivascular collagen area (PVCA) and collagen Ⅰ/Ⅲ ratio were lower in PTX group than those in DCM group ［CVF: (16.45±3.01)% vs (23.33±4.43)%, P<0.05; PVCA: 4.58±2.10 vs 13.74±4.29, P<0.05; Ⅰ/Ⅲ ratio: 2.84±0.67 vs 4.22±0.54, P<0.01］. Left ventricular end-diastolic dimension reduced ［(6.11±0.51) mm vs (6.46±0.28) mm, P<0.05］ and left ventricular ejection fraction elevated ［(77.29±5.20)% vs (62.73±10.11)%, P<0.01］ by PTX compared with DCM.CONCLUSION: PTX modulates plasma levels of inflammatory cytokines, delays the ventricle remodeling and improves the heart function in DCM rats.     

Early treatment with aminoguanidine on level of plasma and renal AngⅡ in diabetic rats

AIM: To investigate the effect of aminoguanidine (AG) on plasma and renal levels of angiogenesis Ⅱ (AngⅡ), and to identify the relationship of AGEs with AngⅡ in STZ-induced diabetic rats. METHODS: Wistar rats were randomly assigned to three groups. Diabetes was induced, rats were then received AG in treatment group. At the end of 12th week, urine albumin excretion rate (UAER) and calculate creatinine clearance (Ccr) were detected. Periodic acid-Schiff reagent was used to evaluate renal pathology. Plasma and renal AngⅡ were analyzed by radioimmunoassay and immunohistochemistry, respectively. RESULTS: AG treatment significantly prevented the increase in UAER (P<0.01), renal pathology (P<0.01), and level of renal AngⅡ (P<0.01). However, plasma concentration of AngⅡ was higher than that in diabetic rats without AG treatment (P<0.01). CONCLUSION: AG down-regulates renal Ang Ⅱ level, probably by reducing the formation of AGEs, which may be one of the renoprotective factors in diabetic nephropathy. More proofs are needed to identify the result that plasma AngⅡ concentration increases in DMA group.     

Effects of PAR-2 agonist peptide on proliferation and cytosolic calcium level in hepatoma cells

AIM: To investigate the effects of PAR-2 agonist peptide on the proliferation and cytosolic calcium concentration (［Ca2+］c) in human hepatoma cells HepG2. METHODS: Human hepatoma cell line HepG2 was cultured. The cells were treated with PAR-2 agonist peptide SLIGKV-NH2 and the reverse PAR-2 agonist peptide VKGILS-NH2, respectively. The ［Ca2+］c of hepatoma cells were measured by microfluorimetric techniques based on calcium indicator fura-2/AM. The influences on proliferation of hepatoma cells were determined by MTT method. The changes of cell cycle were evaluated by flow cytometry, and the changes of cyclin D1 mRNA expression were detected by RT-PCR. RESULTS: After treated with 50 μmol/L SLIGKV-NH2, a rapid rise of ［Ca2+］c in HepG2 cells was induced (P<0.01), percent S phase, G2/M phase and proliferation index (PI) of HepG2 cells were elevated (P<0.01), and cyclin D1 mRNA expression was significantly upregulated (P<0.01). The proliferation rates of HepG2 cells treated with 1-50 μmol/L SLIGKV-NH2 were significantly increased, and the effect was in a dose-dependent manner (P<0.01 or P<0.05). No statistical significance of the difference between VKGILS-NH2 and control group was observed (P>0.05). CONCLUSION: PAR-2 agonist peptide induces the rise of ［Ca2+］c in HepG2 cells, upregulates the expression of cyclin D1 mRNA, accelerates the progress of cell cycle, promotes the synthesis of DNA and the proliferation of hepatoma cells via activating PAR-2 in vitro.     

Effects of Tribulus terrestris L. saponin on apoptosis and changes in cytosolic calcium induced by hypoxia/reoxygenation in rat cortical neurons

AIM: To study the effect of Tribulus terrestris L. saponin (TTLS) on apoptosis and changes in cytosolic calcium concentration induced by hypoxia/re-oxygenation in rat cortical neurons. METHODS: Rat cortical neurons in primary culture were used, and a apoptosis model was induced by hypoxia/reoxygenation. LDH releasing rate was detected by spectrophotometry. The apoptosis rate of cortical neurons was analyzed quantitatively by flow cytometry with Annexin V-FITC and PI staining. Intracellular free Ca2+(［Ca2+］i) was observed with a confocal laser-scanning microscope and determined by mean fluorescent value with Fluo-3 fluometry. RESULTS: Compared to control group, three hours of hypoxia and twelve hours of reoxygenation group induced cortical neuronal apoptosis and significantly increased the intracellular free Ca2+ concentration（P<0.01). Compared with model group, TTLS decreased the percentage of neuronal apoptosis and reduced neuronal ［Ca2+］i（P<0.01).CONCLUSION: TTLS could obviously reduce hypoxia/reoxygenation-induced apoptosis and alleviate the damage degree of rat cortical neurons.The mechanism might be related to inhibiting the calcium overload induced by hypoxia/reoxygenation in rat cortical neurons.     

Endothelin receptor antagonist BQ123 inhibits calcification in vascular smooth muscle cells induced by β-glycerophosphate

AIM:To observe the effect of endothelin receptor antagonist (BQ123) on calcification in rat vascular smooth muscle cells (VSMCs) in vitro. METHODS:Calcification of cultured rat VSMCs was produced by incubation with β-glycerophosphate. Calcium content, Ca2+ deposition and alkaline phosphatase activity were analyzed to estimate the extent of calcification. The DNA synthesis was detected by ［3H］ -TdR and ［3H］-Leu incorporation. Osteopontin (OPN) mRNA was measured by competitive quantitative RT-PCR. Content of ET was measured by radioimmunoassay (RIA). RESULTS:The results showed that compared with the control, the content of calcium, ［45Ca2+］ uptake and alkaline phosphatases activities in calcified VSMCs increased by 118%, 174% and 7-fold (all P<0.01), respectively. The expression of OPN mRNA in calcified VSMCs was up-regulated by 86% (P<0.01). The calcified VSMCs grew rapidly, in which ［3H］-TdR and ［3H］-Leu were elevated by 71% and 35%. The content of ET in calcified VSMCs medium was increased by 35% as compared with control. Furthermore, calcified VSMCs plus BQ123 groups obviously relieved degree of calcification, of which calcium content, Ca2+ deposition and alkaline phosphatase activities were 33%, 37%, 40% lower than those in calcified VSMCs (P<0.01), respectively. The expression of OPN mRNA was down-regulated by 25% (P<0.01) and significantly inhibited VSMCs proliferation. CONCLUSION:BQ123 reduces VSMCs calcification, suggesting that ET promotes calcification in VSMCs mainly by ET/ ETA receptor pathway.     

Effects of panax notoginseng saponins on content of triglyceride and the mRNA expression of LXRα in steatotic hepatocyte L02

AIM: To study the effects of panax notoginseng saponins (PNS) on the content of triglyceride (TG) and the mRNA expression of liver X receptor α (LXRα) in steatotic hepatocyte L02.METHODS: The cells of hepatocyte L02 were cultured with 50% bovine calf serum for 48 h and a model of steatosis of hepatocytes was established. The appropriate concentrations of PNS on steatotic hepatocytes were detected by MTT assay. The cells were divided into 5 groups: normal control group, model group, spontaneous recovery group, low concentration of PNS group (10 mg/L) and high concentration of PNS group (50 mg/L). Meanwhile, hepatocytes in model group were continuously cultured by RPMI-1640 medium containing 50% bovine calf serum while others were cultured by RPMI-1640 medium containing 10% bovine calf serum. After 24 h, the lipid droplets in the cells stained with oil red O were observed under microscope, the intracellular TG levels were determined by automatic biochemical analyzer and the mRNA expression of LXRα in hepatocytes was examined by RT-PCR. RESULTS: Compared to normal control group, Oil red O staining presented numerous orange-red or red lipid droplets in the cytoplasm of human L02 hepatocytes in model group. The content of TG in model group were significantly increased (P<0.01). After treated with PNS for 24 h, the content of TG in PNS treatment groups was significant decreased than that in spontaneous recovery group (P<0.05), especially in low concentration of PNS group (P<0.01). The accumulation of lipid droplets in low concentration of PNS group was decreased significantly. Compared to normal control group, the mRNA expression of LXRα in model group was significantly up-regulated (P<0.01). Compared to spontaneous recovery group, the mRNA expression of LXRα in PNS treatment groups declined in different levels, especially in low concentration group (P<0.05).CONCLUSION: The deposition of lipid in hepatocytes might be related to the high expression of LXRα mRNA. PNS decreases the content of TG in steatotic hepatocytes and promotes the recovery of hepatocyte steatosis by downregulating the mRNA level of LXRα.