Roles Of P-Akt And Caspase-3in Cerebral Protection Induced By Remote Preconditioning Of Trauma In MCAO Rats

Objective:To observe the protective effects of remote preconditioning of trauma against ischemia/reperfusion injury, and then to investigate whether p-Akt and caspase-3involve in the cerebral protection induced by remote preconditioning of trauma using Transient MACO model in rats.Methods:Firstly, seventy healthy adult male Sprague-Dawley rats weighing250-300g were randomly divided into seven groups (n=10each group):Sham group, I/R group, RPCT0.5h group, RPCT1h group, RPCT2h group, RPCT4h group and RPCT24h group. The seven group rats were used to measure cerebral infarct volume and evaluate neurological defict. Secondly, the same forty rats as above were randomly divided into four groups (n=10each group):Sham group, I/R group,RPCT1h group and RPCT24h group. The four group rats were used to observe histological morphology, immunohistochemistry and Western blot analysis. The Sham group rats were only isolated the vessels and didn’t receive middle cerebral artery occlusion. The rats in I/R and RPCT groups were received right MCAO for90min according to Longa’s method, then perform a reperfusion for24hours. The rats in RPCT groups were accepted a2cm transverse abdominal incision via the abdominal midline,which extended through the skin, muscle and into the peritoneum before ischemia, then the incision was immediately closed. Neurological defict score (NDS) of the rats in all groups were evaluated by methods of Longa’s and Garcia after reperfusion24h. TTC staining was used to measure cerebral infarct volume. HE staining was used to observe the pathological changes of ischemic brain, while the survival of neurons in penumbra were observed by Nissl staining. The expression of Akt and p-Akt and caspase-3in the ischemic penumbra were measured by immunohistochemical and Western blot analysis.Results:1. TTC staining:The sham group had no infarction. Compared with the I/R group, the cerebral infarction volume in RPCT1h group, RPCT2h group, RPCT4h group and RPCT24h group decreased significantly (P<0.05), While there was no significant difference between I/R group and RPCT0.5h group.2. Neurological defict score (NDS):The scores of Garcia in RPCT1h group, RPCT2h group, RPCT4h group and RPCT24h group was higher than I/R group(P<0.05), while there was no significant difference between I/R group and RPCT0.5h group. There was no significant difference among the six groups measured by Zea-Longa method (P>0.05).3. HE staining:Normal morphological characteristics of neurons was showed in Sham group; Compared with I/R group, the neurons of ischemic penumbra in RPCT1h group and RPCT24h group were more integrated, while the quantity of neurons was more and the celebral interstitial edema was alleviative in ischemic penumbra comparing with I/R group. Furthermore, the number of survival neurons of core area in I/R group, RPCT1h group and RPCT24h group were fewer and the tissues were loose.4. Nissl staining:the number of survival neurons of ischemic penumbra in RPCT1h group and RPCT24h group increased significantly Comparing with I/R group (P<0.05).5. Immunohistochemical and Western blot analysis:the expression of Akt had no significant difference in all of the group ((P>0.05); The expression of caspase-3and p-Akt in the ischemic penumbra in I/R group, RPCT1h group and RPCT24h group increased significantly versus Sham group(P<0.05). Compared with I/R group, the expression of p-Akt in RPCT1h group and RPCT24h group were up-regulated (P<0.05), while the expression of caspase-3decreased significantly(P<0.05).Conclusion:Remote preconditioning of trauma may have protective effects against cerebral ischemia/reperfusion injury, which may contribute to activating Akt and inhibiting activity of caspase-3.