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AIM:To explore the roles of Akt ( also called protein kinase B ) and active caspase-3 in the leptin-mediated chronic morphine antinociceptive tolerance in rats .METHODS: A model of chronic morphine antinociceptive tolerance was established in the SD rats .The protein levels of spinal Akt and cleaved caspase-3 were tested by Western blotting.The technique of immunohistochemical staining was used to detect the immunoreactivity positive cells of phospho -rylated ( p)-Akt and cleaved caspase-3 in the spinal cord .Double staining of immunohistochemistry was used to examine the cellular location of the p-Akt and cleaved caspase-3 positive cells.RESULTS: The chronic intrathecal injection of morphine (15 μg) for 7 d markedly upregulated the spinal protein levels of p-Akt and cleaved caspase-3 in the rats.Thirty min before injection of morphine , intrathecal injection of leptin antagonist (3μg) for 7 d significantly attenuated the upreg-ulation of the protein levels of p-Akt and cleaved caspase-3 induced by chronic morphine treatment .The p-Akt was exclu-sively observed in the spinal neurons .The cleaved caspase-3 was only localized with the spinal astrocytes .Intrathecal injec-ting the inhibitors of leptin , Akt and caspase-3 ameliorated the chronic antinociceptive tolerance .CONCLUSION: The spinal Akt pathway and active caspase-3 are involved in the leptin-mediated chronic morphine antinociceptive tolerance in rats.
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AIM:Tostudywhe ther theangiotens in-(1-7)[Ang-(1-7)]/Mas receptor axis protects cardio-myocytes against high glucose (HG)-induced injury by inhibiting nuclear factor-κB (NF-κB) pathway.METHODS:The cell viability was measured by CCK-8 assay.The intracellular levels of reactive oxygen species ( ROS) were detected by DCFH-DA staining .The number of apoptotic cells was tested by Hoechst 33258 nuclear staining .Mitochondrial membrane potential ( MMP) was examined by JC-1 staining.The levels of NF-κB p65 subunit and cleaved caspase-3 protein were de-termined by Western blotting.RESULTS: Treatment of H9c2 cardiac cells with 35 mmol/L glucose (HG) for 30, 60, 90, 120 and 150 min significantly enhanced the levels of phosphorated ( p) NF-κB p65, peaking at 60 min.Co-treatment of the cells with 1 μmol/L Ang-(1-7) and HG for 60 min attenuated the up-regulation of p-NF-κB p65 induced by HG. Co-treatment of the cells with Ang-(1-7) at concentrations of 0.1~30μmol/L and HG for 24 h inhibited HG-induced cy-totoxicity, evidenced by an increase in cell viability .On the other hand, 1 μmol/L Ang-(1-7) ameliorated HG-induced apoptosis, oxidative stress and mitochondrial damage , indicated by decreases in the number of apoptotic cells , cleaved caspase-3 level, ROS generation and MMP loss .However, the above cardioprotective effects of Ang-(1-7) were markedly blocked by A-779, an antagonist of Ang-(1-7) receptor (Mas receptor).Similarly, co-treatment of H9c2 cardiac cells with 100 μmol/L PDTC ( an inhibitor of NF-κB) and HG for 24 h also obviously reduced the above injuries induced by HG.CONCLUSION:Ang-(1-7)/Mas receptor axis prevents the cardiomyocytes from the HG-induced injury by inhibiting NF-κB pathway .
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AIM:To investigate the roles of ATP-sensitive potassium ( KATP ) channels in high glucose-induced cardiac injury and the inhibitory effect of hydrogen sulfide ( H2 S) on the cardiomyocyte injury.METHODS:The expres-sion level of KATP 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 exam-ined 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 KATP 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 400μmol/L NaHS ( a donor of H2 S) prior to exposure to HG for 12 h con-siderably blocked the down-regulation of KATP channels induced by HG.Pretreatment of the cells with 100 μmol/L mito-chondrial KATP channel opener diazoxide, 50μmol/L non-selective KATP channel opener pinacidil or NaHS obviously inhibi-ted 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 100μmol/L mitochondrial KATP channel antagonist 5-hydroxydecanoic acid or 1 mmol/L non-selective KATP channel antagonist glibenclamide attenuated the above cardioprotective effects of NaHS.CONCLUSION:KATP channels mediate the inhibitory effect of H2 S on HG-induced cardiac injury.
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Objective To investigate the different responses of diaphragm and peripheral muscles to cisatracurium in rabbits.Methods 8 male New zealand rabbits were anaesthetized with pentobarbital,and then the diaphragm,tibialis anterior,soleus muscles,phrenic nerves,tibial nerve,and peroneal nerve were gently freeded.The muscles were secured to force displacement transducers,and the nerves were directly stimulated by electrodes with supramaximal square waves.The isometric force of twitch tention of each muscle was recorded.The cumulative dose-response technique was separately used for obtaining the ED50and ED95 values of the cisatracurium in each muscle.Results The muscle-relaxing of cisatracurium on the three muscles in were observed in a dose-dependent manner.The ED50 values and ED95 values were: diaphragm(39.3 ± 2.5)μg/kg and(75.7 ± 4.2)μg/kg,tibialis anterior(80.6 ± 7.5)μg/kg and(123.3 ±9.3)μg/kg,soleus(80.0 ± 7.1)μg/kg and(126.9 ± 9.4)μg/kg,respectively.It had significant difference between diaphragm vs tibialis or soleus,P ＜ 0.05.Conclusions The muscle relaxant effects of cisatracurium on diaphragm and peripheral muscles were different,and diaphragm was more sensitive than peripheral muscles.
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Objective To explore whether the phosphorylation of NF-κB P65 subunit is involved in the cytotoxicity to and inflammation in an immortal human keratinocyte cell line HaCaT during cobalt chloride (CoCl2-induced chemical hypoxia. Methods HaCaT cells were treated with CoCl2 of 2 mmol/L to set up a chemical hypoxia-induced cell model of injury. Then, RNA interference was used to down-regulate the expression of P65 in CoCl2-induced HaCaT cells. After additional culture, cell viability was tested by cell counting kit8 (CCK-8), the levels of interleukin 6 (IL-6) and interleukin 8 (IL-8) were detected by ELISA kits, phosphorylated and total P65 protein was measured by Western blot. Results The exposure of HaCaT cells to 2 mmol/L CoCl2 for 0 to 4 hours enhanced the phosphorylation of P65, which began at 0.5 hour, peaked at 1.5 hours, and restored to the normal level at 4 hours, and the level of P65 phosphorylation was about 6.6 times that in the untreated control group. The CoCl2 of 2 mmol/L decreased the cell viability of HaCaT cells in a time dependent manner, and a significant difference was observed in the viability of HaCaT cells between CoCl2-treated and untreated HaCaT cells at 2, 4, and 6 hours (P ＜ 0.05, 0.01, 0.01 ). The release of IL-6 and IL-8 from HaCaT cells was also promoted by CoCl2 treatment. The knockdown of P65 expression with siRNA markedly suppressed the CoCl2-induced cytotoxicity to and increase in the release of IL-6 and IL-8 from HaCaT cells,despite of an increment in cell viability by about 11%. Conclusion The phosphorylated P65 subunit mediates CoCl2-induced cytotoxicity and inflammatory injury to HaCaT cells.
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Aim To explore the effect of survivin in PC12 cells against injuries induced by cobalt chloride(CoCl_2).Methods PC12 cells were exposed to CoCl_2 at different doses in different time to set up the chemical hypoxia induced PC12 cells injuries model.Cell viability was tested by using cell counter kit-8.Dose-effect(200～1 000 μmol·L~(-1))and time-effect(0～48 h)relationship between hypoxia induced by CoCl_2 and the expression of survivin was evaluated by western blot.Results PC12 cells viability was inhibited significantly by CoCl_2 in a dose and time dependent manners;At the concentrations from 200 to 600 μmol·L~(-1) CoCl_2 for 24 h,survivin expression was upregulated in a dose dependent manner,peaking at 600 μmol·L~(-1) CoCl_2 treatment,exceeding this concentration of CoCl_2,with dose increasing,survivin expression decreased.At the dose of CoCl_2 up to 1 000 μmol·L~(-1),survivin did not express basically;Treatment with 600 μmol·L~(-1) CoCl_2 in different time,within the range of 0～36 h,the expression of survivin enhanced in time dependent manner.But with the extension of time,survivin expression was declining; 17-allylamino-17-demethoxygeldanamycin (2 μmol·L~(-1)),an inhibitor of Hsp90,not only decreased survivin overexpression but also obviously enhanced the injuries of PC12 cells induced by CoCl_2,which didn't damage PC12 cells alone.Conclusion Upregulation of survivin expression may be one of the endogenous defense mechanisms for PC12 cells against chemical hypoxia.
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Objective To evaluate the effects of propofol pretreatment on blood-brain barrier disruption caused by intracarotid injection of hyperosmolar mannitol. Methods Twenty-four male SD rats aged 5-6 months, weighing 300-350 g were randomly divided into 3 groups (n = 8 each) :Ⅰ control group; Ⅱ small-dose propofol group and Ⅲ large dose propofol group. The animals were anesthetized with isoflurane, tracheostomized and mechanically ventilated (VT = 10-15 ml2kg-1, RR = 45-55 bpm) . PETCO2 was maintained at 35-45 mm Hg. Right femoral artery and vein were cannulated for BP and HR monitoring, blood sampling and drug administration. Right internal and external carotid arteries were exposed. External carotid artery was ligated and internal carotid artery was cannulated for mannitol administration. In the two propofol groups propofol 20 mg?kg-1 or 40 mg2kg-1 was injected slowly over 20 min. Ten minutes after propofol injection was started, 20% mannitol was infused at 0.25 ml?kg-1?s-1 for 30 seconds. Two minutes after intracarotid mannitol injection 20 uCi 14 C-AIB was injected via femoral vein in all three groups. Five minutes after 14C-AIB injection, 20 uCi 3H-Dextran was injected via femoral vein. Arterial blood samples were taken within 10 min after 14C-AIB injection every 20 seconds for 2 min then after an interval of 2 min every min. Altogether 14 blood samples were taken. The animals were then decapitated and cerebral cortex, cerebellum, pons and basal ganglia were separated. The radioactivity of plasma and brain specimens was counted with a liquid scintillation counter. The blood-brain Ki for 14C-AIB was calculated. Results The Ki of the ipsilateral cortex where mannitol was injected was 4.9 times as much as that of the contralateral cortex in control group, 3-5 times in small dose propofol group and 2.5 times in large dose propofol group respectively (P