Effect of gap junction on permeability of blood-brain barrier in rats after cerebral ischemia- reperfusion

Objective To investigate the possible mechanism of the gap junctional influence on the change in permeability of the blood-brain barrier(BBB)after reperfusion subsequent to cerebral ischemia.Methods In the test laser scanning confocal microscope(LSCM)was used to investigate the change of Cx43 levels and distribution.The MCAO/R model was induced using intraluminal suture technique first described by Longa with a little modification.A total of 60 Wistar rats were divided into 4 groups:the sham-operation group,control group,octanol-treatment group and DMSO vehicle control group. Control group were further divided into seven subgroups at different time points of reperfusion after middle cerebral artery occlusion.To observe the change in permeability of BBB,Evans blue(EB)in the brain tissue was surveyed by the means of EB fluorescent quantitation.Octanol-treatment group and DMSO vehicle control group were done at the point of the peak of permeability of BBB.Octanol,the specific blocker for gap junctions(GJ)was used in an intervention study.To compare the amount of EB with the same point of groups,the influence of octanol on BBB permeability was investigated.Results At 3 h of reperfusion after cerebral ischemia for 2 h,the permeability of BBB began to increase,reached the peak at 24 h of reperfusion and was still elevated at 72 h.The Cx43 expression formed into bigger plague and remained linear disposition in the penumbra after reperfusion subsequent to cerebral ischemia.Octanol group was done at 24 h of reperfusion after cerebral ischemia.The amount of EB of octanol group((4.924±0.296)μg/g)was significantly lower than that of corresponding operation control group(5.543±0.506)μg/g.Conclusions (1)Cx43 expression is concentrated around vessels in brain.The Cx43 forms into bigger plague and the function maybe strengthens after reperfusion.Gap junction might aggravate the disruption of BBB.(2) Octanol,the specific blocker of gap junctions,could effectively prevent the permeability of BBB from increasing and has a protective effect on BBB.