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Recent studies have shown that astrocytes play important roles in ATP degradation and adenosine (a well known analgesic molecule) generation, which are closely related to pain signaling pathway. The aim of this study was to investigate whether morphine, a well known analgesic drug, could affect the speeds of ATP enzymolysis and adenosine generation in rat astrocytes. Intracellular calcium concentration ([Ca(2+)](i)) of astrocyte was measured by flow cytometry, and the time points that morphine exerted notable effects were determined for subsequent experiments. Cultured astrocytes were pre-incubated with morphine (1 μmol/L) and then were incubated with substrates, ATP and AMP, for 30 min. The speeds of ATP enzymolysis and adenosine generation were measured by high performance liquid chromatography (HPLC). The results showed that both 1.5 and 48 h of morphine pre-incubation induced maximal ATP enzymolysis speed in astrocytes among all the time points, and there was no statistical difference of ATP enzymolysis speed between morphine treatments for 1.5 and 48 h. As to adenosine, morphine pre-incubation for 1.5 h statistically increased adenosine generation, which was degraded from AMP, in cultured astrocytes compared with control group. However, no difference of adenosine generation was observed after 48 h of morphine pre-incubation. These results indicate that treatment of morphine in vitro dynamically changes the concentrations of ATP and adenosine in extracellular milieu of astrocytic cells. In addition, astrocyte can be regarded as at least one of the target cells of morphine to induce changes of ATP and adenosine levels in central nervous system.

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Objective To explore the effect of hydrogen sulfide (H2S) on the expression of survivin in PC12 cells and the neuroprotective function of H2S on PC12 cells.Methods Different concentrations of sodium hydrosulfide (NaHS) were used to treat the PC12 cells at different times.Dose-effect (50-800 μmol/L) and time-effect (0-180 min) on the expression of survivin were evaluated by Western blotting.Cell viability was tested by using cell counter kit-8.Results NariS treatment at the concentrations from 50 to 200 μmol/L for 30 min could up-regulate the expression of survivin in a dose dependent manner,however,when the concentration of NariS was above that,the expression of survivin decreased gradually;when the concentration of NariS reached 800 μmoi/L,the expression level of survivin was lower than the normal level.Treatment with 400 μmol/L NariS within the range of 0-60 min could promote the expression of survivin in a time dependent manner,but with the extension of time,the expression of survivin was declined.On the other hand,400 μmol/L NaHS preconditioning could enhance the expression of survivin promoted by CoCl2 and reduce the injuries of PC12 cells induced by CoCl2 to increase the cell viability.Conclusion H2S increases the expression ofsurvivin in a dose and time dependent manners at certain degree,which may be related to the protection of PC12 cells against chemical hypoxic damage.

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<p><b>OBJECTIVE</b>To explore the effect of extracellular signal regulated kinase 1/2 (ERK1/2) on edaravone (EDA)-triggered protection against myocardial toxicity induced by isoprenaline (ISO) in H9c2 myocardial cells (H9c2 cells).</p><p><b>METHODS</b>H9c2 cells were exposed to ISO at different concentrations to establish a cardiac toxicity model induced by persistent excitation of β1 receptor. EDA was added before ISO as a pretreatment. PD-98059, an ERK1/2 inhibitor, was administered 1 h prior to EDA to inhibit the phosphorylation of ERK1/2. Cell viability was measured using cell counter kit (CCK-8). The expressions of p-ERK1/2 and t-ERK1/2 were tested by Western blotting. Mitochondrial membrane potential (MMP) was detected by Rhodamine123 (Rh123) staining and photofluorography.</p><p><b>RESULTS</b>Exposure of H9c2 cells to 80 µmol/L ISO for 24 h down-regulated ERK1/2 phosphorylation and repressed MMP. Pretreatment with 10-40 µmol/L EDA for 1 h inhibited ISO-induced myocardial toxicity and pretreatment of 40 µmol/L EDA partially rescued ERK1/2 phosphorylation and MMP level. PD-98059 abolished cardiac protection of EDA, leading to myocardial toxicity and MMP loss.</p><p><b>CONCLUSION</b>EDA can protect H9c2 cells against myocardial injury induced by ISO by suppressing ISO-triggered inhibition of ERK1/2 activation.</p>

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<p><b>OBJECTIVE</b>To investigate the protective effect of reactive oxygen species (ROS) scavenger, N-acetyl-L-cysteine (NAC), against H9c2 cardiomyocytes from injuries induced by chemical hypoxia.</p><p><b>METHODS</b>H9c2 cells were treated with cobalt chloride (CoCl2), a chemical hypoxia-mimetic agent, to establish the chemical hypoxia-induced cardiomyocyte injury model. NAC was added into the cell medium 60 min prior to CoCl2 exposure. The cell viability was evaluated using cell counter kit (CCK-8), and the intercellular ROS level was measured by 2', 7'- dichlorfluorescein-diacetate (DCFH-DA) staining and photofluorography. Mitochondrial membrane potential (MMP) of the cells was observed by Rhodamine123 (Rh123) staining and photofluorography, and the ratio of GSSG/ (GSSG+GSH) was calculated according to detection results of the GSSG kit.</p><p><b>RESULTS</b>Exposure of H9c2 cardiomyocytes to 600 micromol/L CoCl2 for 36 h resulted in significantly reduced cell viability. Pretreatment with NAC at the concentrations ranging from 500 to 2000 micromol/L 60 min before CoCl2 exposure dose-dependently inhibited CoCl2-induced H9c2 cell injuries, and obviously increased the cell viability. NAC at 2000 micromol/L obviously inhibited the oxidative stress induced by CoCl2, decreased the ratio of GSSG/(GSSG+GSH), increased ROS level, and antagonized CoCl2-induced inhibition on MMP.</p><p><b>CONCLUSION</b>NAC offers obvious protective effect on H9c2 cardiomyocytes against injuries induced by chemical hypoxia by decreasing in the ratio of GSSG/(GSSG+GSH) and ROS level and ameliorating MMP.</p>

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