Roles Of NF-κB And Toll-like Receptor4in Neuroprotection Induced By Noninvasive Limb Remote Ischemic Postconditioning In MCAO Rats

Objective:This study aims to investigate whether NF-κB and Toll-like receptor4involve in the cerebral protection induced by noninvasive remote ischemic postconditioning in middle cerebral artery occlusion model in rats.Methods:Adult male Sprague-Dawley rats weighing250-300g were randomly divided into three groups:Sham group, I/R group and NRIPoC group(each n=15). Rats in I/R group were underwent middle cerebral artery occlusion (MCAO) for90min referencing to Longa’s method. Rats in NRIPoC group received three cycles of5min ischemia/5min reperfusion on the right hind limb continuously after90min occlusion of middle cerebral artery. Rats in Sham group were underwent the same operation as I/R group without MCAO. Neurological defict score (NDS) and cerebral infarct size in the three groups were examined at24h after middle cerebral artery reperfusion. Neuronal cell morphology and survival of neurons in ischemic penumbra were observed respectively by HE staining The expression of NF-κB and Toll-like receptor4were measured via immunohistochemistry and Western blot analysis.Results:1.The cerebral infarct size at24h after middle cerebral artery reperfusion in NRIPoC group were significantly smaller than that in the I/R group(P<0.05).2. Normal morphological characteristics of neurons showed in Sham group by microscopic examination.:There were a large number of dying neurons in the core ischemic cortex and in the ischemic penumbra, ischemic penumbra and chromatin margination. And the amount of neurons were decreased significantly in both I/R group and NRIPoC group compared with that in Sham group (P<0.05). But the injury of neurons in NRIPoC was relieved compared with that in I/R group.3. The expression of NF-κB and Toll-like receptor4in both I/R group and NRIPoC group increased significantly than those in Sham group (P<0.05), but decreased significantly in NRIPoC group than those in I/R group (P<0.05).4. The NDS median in NRIPoC group decreased compared with that in I/R group at24h after cerebral ischemia reperfusion, but there was no significant difference in NDS between I/R group and NRIPoC group (P>0.05).Conclusions:The reason of the cerebral protection against transient focal cerebral I/R injury induced by noninvasive distal limb ischemic postconditioning may be the decreasing expression of NF-κB and TLR4,and the alleviating of the inflammatory reaction.