Protection of hepatocyte growth factor on neurons subjected to oxygen-glucose deprivation/reperfusion / 生理学报

The present study was conducted to investigate the effect of hepatocyte growth factor (HGF) on cortical neurons exposed to oxygen-glucose deprivation/reperfusion (OGD/R). Primary cultured cerebral cortical neurons were prepared from Sprague-Dawley rats. The cells were used for experiments after culture for 12 d in vitro. To initiate OGD/R, the culture medium was replaced by glucose-free medium, and cells were transferred to a humidified incubation chamber flushed by a gas mixture of 95% N(2) and 5% CO(2) at 37 °C for 2 h. Following this treatment, neurons were fed with glucose-supplemented (25 mmol/L) medium, and returned to the incubator under normoxic condition for 0-24 h. The cell viability was assessed by MTT assay, and cell injury was evaluated by lactate dehydrogenase (LDH) leakage rate. The percentage of apoptotic cells was analyzed by flow cytometry and Hoechst 33258 staining. The expressions of c-Met mRNA and protein were detected by RT-PCR and Western blot analysis, respectively. Oxygen-glucose deprivation for 2 h decreased the cell viability and increased LDH leakage rate in cultured cerebral cortical neurons. The cell viability declined and LDH leakage rate increased with the reperfusion time going on (0-24 h). To explore the influence of HGF on neurons under oxygen-glucose deprivation for 2 h/reperfusion for 24 h (OGD(2)/R(24)) condition, the cultures were pretreated with HGF at different concentrations (5-120 ng/mL) 2 h prior to OGD(2)/R(24). The results showed that OGD(2)/R(24) treatment significantly decreased the cell viability, increased LDH leakage rate and the percentage of apopototic cells. Pretreatment with HGF at 5 ng/mL and 10 ng/mL did not affect the decrease in cell viability resulting from OGD(2)/R(24). In the presence of 20 ng/mL HGF, the increase in cell viability in cortical neurons exposed to OGD(2)/R(24) began to appear, and 80 ng/mL of HGF exhibited the maximal effect. HGF at 5, 10 and 20 ng/mL did not affect the increase in LDH leakage rate in cortical neurons exposed to OGD(2)/R(24). In the presence of 40 ng/mL HGF, the decrease in LDH leakage rate in cortical neurons subjected to OGD(2)/R(24) began to appear, and 80 ng/mL of HGF displayed the maximal effect. In addition, HGF at 80 ng/mL significantly attenuated cell apoptosis resulting from OGD(2)/R(24). As detected by semi-quantitative RT-PCR and Western blot analysis, c-Met mRNA and protein were expressed in cerebral cortical neurons cultured for 12 d in vitro. c-Met mRNA and protein expressions in cortical neurons exposed to OGD(2)/R(24) were significantly upregulated and were not affected by pretreatment of HGF at 80 ng/mL. Treatment with c-Met inhibitor SU11274 (5 μmol/L) completely eliminated HGF-mediated protection of cortical neurons subjected to OGD(2)/R(24). The results suggest that HGF directly protects cortical neurons against OGD/R-induced cell injury in a dose-dependent manner, and HGF has a potent anti-apoptotic action on neurons exposed to OGD/R.

Effect of thrombin on cultured rat cerebral astrocyte injured by hypoxia/reoxygenation and its relationship with iNOS / 中南大学学报(医学版)

OBJECTIVE@#To observe the effect of thrombin on the cytotoxicity of astrocytes injured by hypoxia/reoxygenation(H/R) and to explore its relationship with inducible nitric oxide synthase (iNOS).@*METHODS@#Primary astrocytes were cultured in DMEM with 10% approximately 15% calf serum and divided into 6 groups: a control group, a Tm control group, an H/R group, a Tm+H/R group, a hirudin (HR) control group, and a Tm+HR+ H/R group. The cell damage and viability were detected by the 3-(4, 5-di-methyl-thazol-2-yl)-2, 5 diphenyl-tetrazol-iumbromide (MTT) conversion method. The NO level in the cultured cell supernatant was assayed by Griess reagent. The flow cytometry was performed to evaluate the apoptosis rate of astrocytes. The iNOS mRNA was examined by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). Immunocytochemistry was used to observe the expression of iNOS protein.@*RESULTS@#The cell viability injured by H/R was lower than that of the control group, the NO production and apoptosis rate in the cell of H/R group were higher than those of the control group. Incubation of H/R cell with 10kU/L Tm enhanced the cytotoxicity of H/R stimulation compared with the cells injured by H/R. Hirudin can reverse the effect of thrombin. RT-PCR and immunocytochemistry analysis demonstrated that the levels of iNOS mRNA and iNOS protein increased in the cells treated by H/R. Tm enhanced the expression of iNOS mRNA and iNOS protein in the cells treated by H/R. Hirudin blocked the effect of Tm.@*CONCLUSION@#Increasing the level of iNOS and enhancing the production of NO may be the mechanism of thrombin cytotoxicity in astrocytes injured by H/R.

Protective effect of thrombin precondition on astrocytes insulted by oxygen-glucose deprivation / 中南大学学报(医学版)

OBJECTIVE@#To explore the effect of thrombin precondition (TPC) on the rat cerebral astrocytes(As) cultured in oxygen-glucose deprivation (OGD).@*METHODS@#Astrocytes were pretreated with thrombin (TB) at various concentrations (0.005 approximately 5.000 kU/L), and then insulted by OGD. The cell damage and viability were evaluated by the lactate dehydrogenase (LDH) effusion rate and the 3-(4,5-dimethylthazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) conversion method. Detection of apoptotic cells was determined by the flow cytometry technique. The glutamate uptake of astrocytes was studied with [3H]-glutamate incorporation.@*RESULTS@#OGD increased the LDH, decreased the cell viability, increased the number of apoptotic astrocytes, and decreased the glutamate uptake (P<0.01). While preconditioned with thrombin at the same condition, the LDH decreased, the cell viability increased, the percentage of apoptotic cells decreased, and the glutamate uptake increased (P<0.05). The maximum protective effect of thrombin was observed at 0.1 kU/L.@*CONCLUSION@#Low concentration of thrombin precondition (TPC) can protect the astrocytes from oxygen-glucose deprived injury, and attenuate its apoptosis in a dose-dependent manner.