| Objective To investigate the effects of Remote ischemic post-conditioning on the expression of aquaporin-4(AQP4)and blood-brain barrier permeability in rats brain tissue after focal cerebral ischemia-reperfusion.Methods A middle cerebral artery embolization-reperfusion(MCAO/R)model was established using the wire embolization method.Seventy-five male SD rats were randomly and equally divided into 3 groups: Sham-operated group(Sham group),ischemia-reperfusion group(I/R group),and remote ischemic post-conditioning(RIPC group).The neurological function of each rat was scored 24 h after reperfusion;the water content of brain tissue was measured by wet and dry weight method;the morphological and pathological changes of neuronal damage in the hippocampal region were examined by hematoxylin-eosin(HE)staining under light microscopy;the volume of cerebral infarction was measured by TTC staining;the permeability of the blood-brain barrier was assessed by Evan’s blue(EB)exudation measurement;the Western Blot The expression of water channel protein-4 was evaluated by Western Blot method.Results1.rats in the Sham group showed no neurological deficits;in contrast,rats in the I/R group showed severe signs of neurological deficits and significantly higher neurological scores(p<0.001);compared with the I/R group,rats in the RIPC group showed a slight decrease in neurological scores,but not statistically significant.2.By hematoxylin-eosin(HE)staining of brain tissues,the following pathological changes were observed under light microscopy: the histocyte morphology of the hippocampal CA1 area on the ischemic side of the Sham group was normal,and no abnormalities such as edema and necrosis were observed;the hippocampal CA1 area on the ischemic side of the I/R group showed obvious pathological changes,including interstitial laxity,edema,widening of pericellular gaps,disorganized cell arrangement,and The nerve cell volume was reduced;while the nerve cell concentration and interstitial swelling in the CA1 area of the hippocampus on the ischemic side of the RIPC group were significantly reduced,and the arrangement was more regular.3.The water content of brain tissue was measured by wet and dry weight ratio: compared with the Sham group,the edema of brain tissue in the I/R group was significantly higher and the water content was significantly higher(p<0.001);compared with the I/R group,the water content of brain tissue in the RIPC group was significantly lower(p<0.001).4.TTC staining method was used to determine the volume of brain infarction in rats: all brain tissues in the Sham group were red and no infarct foci were seen;the ischemic side of brain tissues in the I/R group was white and the infarct range was larger,while the volume of brain infarct foci in the RIPC group was reduced compared with the I/R group(p<0.001).5.Evans blue(EB)exudation was measured to determine the permeability of the bloodbrain barrier: no Evans blue staining exudation was observed in the brain tissue of rats in the Sham group with the naked eye,while significant staining exudation was seen in the brain tissue of the ischemic side of rats in the I/R and RIPC groups.Compared with the Sham group,the content of Evans blue in the brain tissue on the ischemic side of the rats in the I/R group was significantly higher(p<0.001),and compared with the I/R group,the content of Evans blue in the brain tissue on the ischemic side of the rats in the RIPC group was significantly lower(p =0.013).6.Western Blot method to assess the expression of aquaporin 4: the expression of AQP4 was significantly higher in the I/R group than in the Sham group,while the expression of AQP4 was significantly lower in the RIPC group compared with the I/R group.Conclusion1.RIPC can improve neurological dysfunction after MCAO/R,reduce brain edema,decrease infarct volume,reduce blood-brain barrier permeability,and produce cerebral protection.2.RIPC can reduce ischemia-reperfusion injury,decrease the permeability of the bloodbrain barrier,reduce brain edema,and decrease infarct volume by downregulating AQP4 expression.3.The use of the lower limbs of SD rats as an organ for remote ischemic post-conditioning is safe and feasible,and deserves further clinical exploration and application. |
