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Aim To investigate the effect of p38 MAPK AS-ODNs on the expression of GLT-1 during the induction of brain ischemic tolerance induced by cerebral ischemic preconditioning (CIP).Methods Eighty healthy male Wistar rats with permanent occlusion of the bilateral vertebral arteries were randomly divided into 6 groups: ①Sham group (n=10);②CIP group (n=10);③ischemic insult (Ⅱ) group (n=10);④CIP+Ⅱ group (n=10);⑤p38 MAPK AS-ODNs+CIP+Ⅱ group (n=30);⑥p38 MAPK S-ODNs+CIP+Ⅱ group (n=10).Group ⑤ was divided into 5 nmol, 10 nmol and 15 nmol subgroups according to the dose of p38 MAPK AS-ODNs (n=10).The dose of p38 MAPK S-ODNs was 15 nmol.All the rats were sacrificed 6 h and 2 d after the sham operation or the last time of global brain ischemia reperfusion.Western blot and immunohistochemistry analysis were used for detecting the expression of p-p38 MAPK and GLT-1 protein.Results CIP moderately up-regulated the expression of p-p38 MAPK and significantly up-regulated the expression of GLT-1 protein, inhibited the excessively up-regulation of p-p38 MAPK and the down-regulation of GLT-1 induced by ischemic insult.p38 MAPK AS-ODNs significantly inhibited the up-regulation of p-p38 MAPK and GLT-1 protein in a dose-dependent manner during the induction of brain ischemic tolerance by CIP.Conclusion p38 MAPK AS-ODNs inhibit the up-regulation of GLT-1 during the induction of brain ischemic tolerance induced by CIP.
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Objective Cerebral ischemic tolerance induced by cerebral ischemic preconditioning has become a hotspot in the researches of ischemic cerebrovascular disease, and its specific mechanism remains to be clarified.This study was to explore the brain protection mechanisms of cerebral ischemic preconditioning by observing the expressions of HIF-1αand VEGF in the cortex area sur-rounding the infarct locus in rats with focal cerebral ischemia /reperfusion ( I/R) after cerebral ischemic preconditioning. Methods A total of 130 male SD rats were randomly divided into three groups:sham operation, middle cerebral artery occlusion, and cerebral is-chemic preconditioning, the animals in the latter two groups subjected to 2, 6, 12, 24, 48 and 72 h of I/R.The expressions of HIF-1α and VEGF at different time points were detected by immunohistochemistry and Western blot. Results In the middle cerebral artery occlusion group, the expressions of HIF-1αand VEGF positive cells and proteins increased at 2 h after I/R, reached the peak at 24 h, and then gradually decreased to and at 72 h, but still higher than in the sham operation group (P<0.05).The expressions of HIF-1αand VEGF positive cells were significantly higher in the cerebral ischemic preconditioning than in the middle cerebral artery occlusion group (all P<0.05), so were the expressions of HIF-1αand VEGF positive proteins in the former group than in the latter (all P<0.05).The sham operation group showed only a little in-crease in the expressions of HIF-1αand VEGF positive cells and proteins. Conclusion Cerebral ischemia reperfusion injury induces the expressions of HIF-1αand VEGF, which can be further upregulated by brain ischemic preconditioning.
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This study was aimed to explore the function of c-Jun N-terminal kinase (JNK) signaling pathway in the induction of brain ischemic tolerance, and observe the function of Shu-Xue Tong-Mai (SXTM) capsule pretreatment. Ischemic preconditioning was performed for 3 min on rats to induce cerebral ischemic tolerance. Rat model of cere-bral ischemia reperfusion (the ischemia pretreatment group, I/R group) was established 24 h later. Western blot was used to detect the protein expression of JNK and phosphorylation of c-Jun N-terminal kinase (P-JNK), comparing to the expression with the sham operation group, I/R group and SXTM capsule group. Tunel method was applied to de-tect the apoptosis of neurons. Relationship between expression of JNK, P-JNK and apoptosis of neurons was also studied. The results showed that compared with the model group, expressions of P-JNK in ischemia preconditioning group and SXTM group were declined significantly (P < 0.05); and the apoptosis of neurons quantity was also de-clined (P< 0.05). It was concluded that ischemia preconditioning can decrease the apoptosis of neurons in cerebral ischemia reperfusion, and improve neurologic function. Its mechanism related to the inhibition of JNK signaling path-way. SXTM capsule pretreatment can protect the cerebral by inhibiting the JNK signaling pathway.
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Objective To investigate the effect and significance of microglia/macrophage activation prior to cerebral ischemic preconditioning (CIP) in regulating toll-like receptors 2 (TLR2)/nuclear factor-kappa B (NF-κB) inflammatory signaling pathway in early stage after ischemic brain injury in rats.Methods Thirty healthy male SD rats were selected and divided into normal control group,sham operation group,ischemia group,intervention group and treatment group according to random number table,with six rats per group.A rat model of focal permanent cerebral infarct was established by occlusion of middle cerebral artery (MCAO).CIP was performed by local ischemia-reperfusion.Minocycline was used to inhibit microglia/macrophage activation after CIP.Features of microglia/macrophage activation after CIP were detected by immunofluorescence; mRNA expressions of predominant factors (NF-κB inhibitor α,IκB-α;tumor necrosis factor α,TNF-α) of TLR2/NF-κB inflammatory signaling pathway in parietal cerebral cortex by in situ hybridization method; death rate by Kaplan-meier survival curves; neurological deficits by a 5-point neurological scale; brain infarct size by triphenyl tetrazolium chloride (TTC) staining.Results Microglia/macrophage started activation at one hour after cerebral ischemic injury in preconditioning group and presented a significant increase at 12 hours.Speed and range of activation were higher in preconditioning group than in ischemic group.IκB-α mRNA in preconditioning group started expression at one hour.TNF-α mRNA in preconditioning group remained a low expression in 12 hours and had a significantly lower peak value as compared with that in ischemic group (P ＜ 0.05).CIP increased rat survival rate significantly,improved nerve function and reduced infarction size when compared with the ischemia group (P ＜ 0.05).Minocycline inhibited nerve protection by CIP significantly (P ＜0.05).Conclusion CIP induces rapid activation of microglia/macrophage in early period of rat cerebral ischemic injury and provides brain protection probably via inhibition of TLR2/NF-κB activity and inflammatory overreaction to cerebral ischemia.
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@#Objective To explore initially the roles of the 3 major signaling pathways of mitogen activated protein kinases (MAPK) in cerebral ischemia preconditioning. Methods Healthy adult SD rats were randomly divided into 3 groups: normal control group; sham-operated group and ischemic preconditioning or ischemic tolerance group (n=6). SDS-PAGE, Western blot and Gel Doc imagine systems were applied to determine the phosphorylation and protein expression of ERK, JNK and p38 in somatosensory cortex of rat. Results The phosphorylation level of ERK1 and JNK46KD in somatosensory cortex increased significantly (P<0.05) after ischemia preconditioning. Conclusion The increased ERK1 and JNK46KD phosphorylation in somatosensory cortex may be involved in the development of cerebral ischemia preconditioning and can not be ruled out in which the role of p38.
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@#Objective To explore initially the role of c-Jun N-terminal protein kinases (JNK) in cerebral ischemia preconditioning.Methods Healthy adult SD rats were randomly divided into 5 groups: control group, sham-operated group, ischemic preconditioning or ischemic tolerance group, bee venom group, peripheral noxious tolerance group. SDS-PAGE, Western blot and Gel Doc imagine systems were applied to determine the JNK phosphorylation and protein expression in somatosensory cortex and hippocampus. Results The phosphorylation level of JNK46KD but not JNK54KD in somatosensory cortex increased significantly (P<0.05) after ischemia preconditioning, while no significant changes had been observed in that of JNK46KD and JNK54KD in hippocampus. In addition, the protein expression level of JNK46KD but not JNK54KD fell on control level in somatosensory cortex after ischemic preconditioning, while no significant changes in JNK46KD and JNK54KD protein expression were found in hippocampus. Conclusion The increased JNK46KD phosphorylation and fallen JNK46KD protein expression in somatosensory cortex may be involved in the development of cerebral ischemia preconditioning.
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@#Objective To explore initially the role of extracellular signal-regulated kinase (ERK1/2) in cerebral ischemic preconditioning. Methods Healthy adult SD rats were randomly divided into 5 groups: normal control group; sham group; ischemic preconditioning or ischemia tolerance group; bee venom group; peripheral noxious tolerance group. SDS-PAGE, Western blot and Gel Doc imagine systems were applied to determine the ERK1/2 phosphorylation and protein expression in somatosensory cortex and hippocampus of rats. Results The phosphorylation level of ERK1 in somatosensory cortex increased significantly (P<0.05) after ischemic preconditioning, while no significant changes in ERK2 and that of ERK1/2 in hippocampus. No significant changes in ERK1/2 protein expression were found both in somatosensory cortex and hippocampus after ischemic preconditioning. Conclusion The increased ERK1 phosphorylation level in somatosensory cortex may be involved in cerebral ischemic preconditioning.
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AIM: To explore the role of NO in the induction of brain ischemic tolerance (BIT) by observing changes of NOS activity and NO_2-/NO_3- content following a transient cerebral ischemia. METHODS: The rat 4-vessel occluding brain ischemic model was used. 140 male Wistar rats were divided into sham, cerebral ischemic preconditioning (CIP), ischemic insult and CIP+ischemic insult groups. An occlusion of the 4 vessels for 3 min was normally used as CIP, and a relative long one for 10 min was used as ischemic insult. When CIP was followed by ischemic insult, the interval between them was 3 d. The CA1 region of the hippocampus of rats was dissected out at 0 h, 2 h, 16 h, 24 h, 36 h, 72 h and 7 d after the last time of ischemia to assay its NOS activity and NO_2-/NO_3- content. RESULTS: The NOS activity and NO_2-/NO_3- content began to increase at 16 h, peaked at 24 h and decreased to basal level at 36 h of reperfusion after CIP. The duration of the up-regulation of NOS activity and NO_2-/NO_3- content was much shorter than that of BIT, which usually takes place 1-7 d after CIP. The pattern of upregulation of the NOS activity and NO_2-/NO_3- content was similar to the CIP group, but the maximum (24 h) was much more than that in CIP group (P