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AIM: To examined the effects of hypoxic preconditioning ( HPC) on oxygen-glucose deprivation ( OGD)-induced PC12 cells, and to investigate its possible mechanisms of autophagy .METHODS: Cultured PC12 cells were randomly divided into control group , HPC group, 3-methyladenine (3-MA) group, HPC+OGD group, 3-MA+HPC+OGD group and OGD group .CCK-8 assay was used to detect the cell viability .The caspase-3 activity was also tested . TUNEL staining and flow cytometry were used to detect the cell apoptosis .The protein levels of apoptosis-related protein caspase-3 and autophagy-marked protein LC3-2 and beclin-1 were determined by Western blot .RESULTS:Compared with control group, the viability of PC12 cells was significantly reduced , and the activity of caspase-3 was significantly increased in OGD group.Compared with 3-MA+HPC+OGD group and OGD group , the viability of PC12 cells was significantly in-creased, and the activity of caspase-3 was significantly reduced in HPC +OGD group (P<0.05).The PC12 cell injury was apparent after OGD with a great increase in the apoptotic rate (P<0.05).Compared with OGD group, the apoptotic rate significantly decreased in HPC +OGD group ( P<0.05 ) .Compared with control group , the protein level of cleaved caspase-3 was significantly increased in OGD group ( P<0.05) .Compared with OGD group , the protein level of cleaved caspase-3 was significantly decreased , and the levels of LC3-2 and beclin-1 were significantly increased in HPC +OGD group (P<0.05).CONCLUSION:OGD decreases cell survival and induces apoptosis .Activation of cell autophagy may be the mechanism by which hypoxic preconditioning protects the PC 12 cells from OGD induced injury .
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AIM:To investigate the formation of membrane pore in PC 12 cells induced by exogenous adenosine triphosphate ( ATP) and to identify the key molecular targets .METHODS:PC12 cells were treated with different concen-trations of ATP to establish the injury model .The morphological change was observed under an inverted phase -contrast mi-croscope.The viability of the PC12 cells was measured by CCK-8 assay.Fluorescent dye YO-PRO-1 was used to detect the membrane permeability.The expression of P2X7 receptor and pannexin 1 (Panx1) at mRNA and protein levels was as-sessed by real-time PCR and Western blotting .RESULTS:After exposed to ATP (1 mmol/L, 3 mmol/L and 5 mmol/L) for 3 h, the PC12 cells became edematous , and the number of adherent cells decreased gradually in a dose-dependent man-ner .The cell viabilities in 3 mmol/L ATP group and 5 mmol/L ATP group were significantly decreased compared with con-trol group (P0. 05).The expression of P2X7 receptor at mRNA and protein levels was significantly increased (P0.05) when PC12 cells were exposed to ATP for 3 h.CONCLUSION:Extracellular ATP at high concentration may induce membrane pore formation with the expression and activation of P 2X7 receptor in PC12 cells.
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[ABSTRACT]AIM:ToexaminetheeffectsofhighconcentrationofextracellularATPonhumanneuroblastoma SH-SY5Y cell injury.METHODS: Cultured SH-SY5Y cells were grouped according to the concentrations of ATP and treatment time.The cell viability was detected by CCK-8 assay.The variation of autophagic vacuoles was observed with monodansylcadaverine staining .The cell apoptosis was analyzed by Hoechst 33258 staining.Meanwhile, apoptotic rate was detected by flow cytometry .The levels of caspase-3 and microtubule-associated protein 1 light chain 3-Ⅱ ( LC3-Ⅱ) were determined by Western blotting .RESULTS:Compared with control group , the survival rate of SH-SY5Y cells was signifi-cantly reduced by ATP at different concentrations (3, 6, 9, 12 and 15 mmol/L for 3 h) and different treatment time (1, 2, 3 and 6 h with 6 mmol/L ATP, peaking at 3 h).The autophagic vacuoles of SH-SY5Y cells were significantly increased at 1 h with ATP treatment , trended to decrease over time and returned to control level at 6 h.The protein expression of LC3-Ⅱwas significantly increased at 1 h with ATP treatment , which was consistent with the time points of increasing auto-phagic vacuoles .LC3-Ⅱexpression level gradually decreased at 2~3 h with ATP treatment , and returned to control level at 6 h.Compared with control group , the apoptotic rate and the expression level of caspase-3 were enhanced synchronously . The peak of apoptotic rate occurred at 3 h, and kept until 6 h.The level of cleaved caspase-3 expression peaked at 6 h. CONCLUSION:High concentration of extracellular ATP induces the autophagy and apoptosis of SH -SY5Y cells.The in-creased autophagy shows up , followed by the climax of apoptosis until 6 h.With the prolonged duration of ATP , apoptosis is the main process in the cells .
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Aim To investigate the protective effects of hydrogen sulfide ( H2 S) on focal cerebral ischemia/reperfusion injury in rats and the possible mechanisms. Methods Male Sprague Dawley rats were divided into three groups randomly: sham-operated group, cerebral ischemia/ reperfusion ( I/R) group and sodium hydro-sulfide ( NaHS ) + I/R group. The left temporary middle cerebral artery occlusion ( MCAO ) model was established by the line-embolism method. After rats were suffered 2h/24h ischemia/reperfusion stress, the mortality rate was evaluated, and the nervous function-al defect degree was evaluated by Longe scoring, the volumes of cerebral infarction was evaluated by 2 ,3 ,5-triphenyltetrazolium chloride ( TTC) staining, and the expression of P2X7 receptor protein in brain tissue was detected by the immunofluorescence method. Results The mortality rate in NaHS + I/R rats ( 29.41%) was obviously lower than those of I/R group ( 42 . 86%) . The nervous defect scores in NaHS + I/R rats were significant lower than those of I/R group ( P <0.05 ) . The volumes of cerebral infarction in NaHS +I/R group (21.88% ±3.53%) were significant lower than those of I/R group ( 36.71% ±3.73%) ( P <0.01 ) . The results of immunofluorescence showed that the positive expression cells of P2X7 receptor protein in cerebral cortex and hippocampal CA1 area of I/R group were significantly higher than those of sham-op-erated group(P<0. 01). However, compared with I/R group, the positive expression cells of P2X7 receptor protein in cerebral cortex and hippocampal CA1 area of NaHS + I/R group were significantly decreased ( P<0. 01). Conclusions H2S exerts the neuroprotective effect on focal cerebral ischemia/reperfusion injury in rats, and the protective mechanism might be associated with down-regulating the expression of P2X7 receptor protein in brain tissue.
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Objective To research the effect of exogenous estradiol(E-2) on transcriptional activity of regenerating hepatocytes in rats. Methods The E-2 levels in serum were measured using RIA and the numbers of argyrophil nucleolar organizer regions(AgNORs) were investigated. Results Rat serum E-2 level gradually declined after ovariectomy,and no E-2 could be measured after the 15th day.Exogenous E-2 could promote transcriptional activity of regenerating rat hepatocytes,particularly during the first 24h after PH,there was a dose-dependent increase in numbers of AgNORs 24-36h after PH,the exogenous E-2 cause a dose-dependent decrease in numbers of AgNORs,but all of the values were higher than that of control group.Conclusion E-2 can regulate the transcriptional activity of regenerating hepatocytes in rats.