| Objectives T Focal cerebral ischemia-reperfusion injury in SD rats.To investigate whether distal limb ischemic postconditioning has neuroprotective effects on focal cerebral ischemia and reperfusion injury in rats and to analyze its possible protective mechanisms.And to explore the reliable time window of distal limb ischemic postconditioning.Methods 75 healthy male SD rats were randomly divided into three groups:(Sham group,n=15),ischemia/reperfusion group(I/R group,n=15),remote limb ischemic postconditioning group(RIPost C group,n=45).RIPost C group according to the different processing time is divided into RIPost C 0h,RIPost C 2h,RIPost C 4h three subgroups.Routine anesthesia rats in each group,supine position fixed,disinfection.Sham group: From the middle of the neck incision,blunt separation of the right sternocleidomastoid muscle and anterior cervical muscle group,Exposure to the right common carotid artery(CCA),Internal carotid artery(ICA),External carotid artery(ECA).Only separate the blood vessels,No line bolt insertion and ischemic postconditioning,And then suture the muscles and skin layer by layer.I/Rgroup: In addition to the above operations,Ligation ECA far end,With microarterial clip clip CCA and ICA near the heart,In the ECA near the end of a small cut,insert the bolt,successfully blocked the right middle cerebral artery blood flow after the fixed line bolt,suture the skin.continued to block 90 minutes after the pull out the bolt,restore blood flow.RIPost C group: In the same way as I/R group operation.The rats in each subgroup were subjected to ischemic postconditioning operation at 2h,2h and 4h after pulling out the bolt,Ischemic postconditioning method for the rubber band placed in the lower limb root fastening 5min / relaxation 5min,cycle 4 times.Cerebral ischemia and reperfusion for 24 hours.The neurological score was scored by Zea-Longa's neurological score method;Determination of brain tissue water content by dry-wet weight ratio method;The infarct volume was measured by TTC staining and the percentage of infarct volume was calculated;Evaluation of ischemic penumbra cell apoptosis by TUNEL method;The expression of Bcl-2 and Bax protein positive cells in ischemic penumbra was determined by immunohistochemistry.Results 1 Neurological function score:Sham rats did not show neurological deficits;I/R group and RIPost C group were different degrees of limb paralysis,the score was higher than the Sham group,the difference was statistically significant(P<0.05);The score of RIPost C group was lower than that of I/R group(P<0.05).Subsequent treatment time delay,RIPost C subgroup scores showed an upward trend,but the difference was not statistically significant.2 Brain tissue water content:The water content of brain tissue in I/R group and RIPost C group was higher than that in Sham group,the difference was statistically significant(P<0.05).RIPost C group was lower than I/R group,the difference was statistically significant(P<0.05);The water content of the brain tissue of RIPost C subgroup was increased,but there was no significant difference among the subgroups.3 Cerebral infarct volume determination: Sham group brain tissue stained red,no white infarction;There were obvious infarcts in RIPost C group and I/R group.Followed by treatment time delay,RIPost C group cerebral infarction volume showed an increasing trend,The size of cerebral infarction in RIPost C 0h group and RIPost C 2h group was significantly different(P<0.05).4 Apoptosis:Sham group had no obvious apoptotic cells,The number of apoptotic cells in I/R group and RIPost C group was significantly higher than that in Sham group(P<0.05).Subsequent processing time is delayed,The number of apoptotic cells in RIPost C subgroups increased gradually,but they were lower than those in I/R group(P<0.05).The number of apoptotic cells in RIPost C 2h group was higher than that in RIPostC 0h group,but the difference was not statistically significant.The number of apoptotic cells in RIPost C 2h group was significantly higher than that in RIPost C 0h group and RIPost C 2h group(P<0.05).5 Bcl-2 and Bax protein positive cells:Sham group only a small amount of Bcl-2 and Bax protein positive cells.Compared with Sham group,the expression of Bcl-2 and Bax protein positive cells in I/R group and RIPost C group was significantly higher than that in Sham group(P<0.05).Compared with I / R group,the expression of Bcl-2 protein positive cells in RIPost C group increased,The expression of Bax protein positive cells was decreased,the difference was statistically significant(P <0.05).Subsequent processing time is delayed,The expression of Bcl-2 protein positive cells in RIPost C group showed a decreasing trend,and the expression of Bax protein positive cells was increasing,but there was no significant difference between RIPost C 2h group and RIPost C 0h group.In contrast,RIPost 4h group was statistically significant(P<0.05)compared with RIPost C 0h.In the Bcl-2/Bax ratio comparison,Compared with Sham group,the ratio of Bcl-2/Bax in I/R group decreased,the difference was statistically significant(P<0.05).The ratio of Bcl-2/Bax in RIPost C group increased,the difference was statistically significant(P<0.05).Subsequent processing time is delayed,The ratio of Bcl-2/Bax in RIPost C group was decreased,but there was no significant difference between RIPost C 2h group and RIPost C 0h group.However,RIPost C 4h group than the RIPost C0 h group was statistically significant(P<0.05).Conclusions 1 Remote limb ischemic postconditioning has protective effect on focal cerebral ischemia and reperfusion injury in rats.2 The mechanism may be to regulate the expression of Bcl-2 and Bax proteins in different degrees,so as to reduce the neuronal apoptosis.3 The postoperative treatment time was delayed and the neuroprotective effect of distal limb ischemic postconditioning was decreased.The more reliable post-treatment time window was performed immediately after reperfusion to 2 hours. |
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