The Neuroprotection Of Remote Ischemic Postconditioning And Its Effects On Expression Of Akt And GSK-3β In Rats

Objective Recently, many researehers have diseovered that ischemic postconditioning(PC) was a neuroprotective factor on cerebral ischemia/reperfusion injury, which could acted many mechanisms.However, there were few studies on remote ischemic postconditioning'(RPC).so, our research's purpose is going to prove whether RPC has neuroprotective effect by establishing the modle of Middle cerebral artery occlusion (MCAO) in rats and whether the expression of the phosphorylation Akt,GSK-3βinvolve in the neuroprotective effect.Method:There are two parts of this experiment.Part one:We established the steady model of MCAO in rats to proved the protective effects of RPC for brain tissue.24 male healthy SD Rats were randomly divided into three groups,8 rats per group:(1)control:rats' Middle cerebral arteries were occluded for 2h and reperfusioned for 24h.(2) Remote ischemic postconditioning at beginning of ischemia(I-RPC):double limb ischemic postconditioning was administrated at beginning of ischemia.(3) Remote ischemic postconditioning at beginning of reperfusion(R-RPC):double limb ischemic postconditioning was administrated at beginning of reperfusion. We made femoral artery ischemia/reperfusion 10min/10min for three cycles by bulldog clamp,namely RPC. Rats were sacrificed at 24h after reperfusion,then infarct size and functional neurological outcome were measuerd. Part two:To investigate the protective mechanism of RPC and its effect on the expression of the phosphorylation p-Akt, p-GSK-3β.24 male healthy SD rats were randomly divided into four groups,six rats per group:sham; control; I-RPC and R-RPC. Rats were sacrificed at 24h after reperfusion,then the paraffin-embedded tissue specimens were taken. We measured the infarct size by HE stain again and the degree of the Akt activation and GSK-3βinactivation were measured by immunofluorescence.Another 16 male healthy SD rats were randomly divided into four groups according to the same way. the degree of the Akt and GSK-3βactivation were detemined by Western blot.Results:(1)The Infarct volumes of I-RPC and R-RPC group measured by TTC and HE stain were significantly smaller than the control group (p<0.05).(2) The neurologieal deficis seore were tested at 24 hours after reperfusion.The score of group I-RPC and R-RPC were lower than control. But there was no significantly differents among the three groups(P>0.05),though the functional neurological outcome were improved by remote ischemic postconditioning groups.(3) Immunofluorescence and Western blot explained that the phosphorylation of Akt and GSK-3βin R-RPC group were higher both in contex and basal ganglia than control signifieantly(P<0.05). the phosphorylation of Akt and GSK-3βin I-RPC group were higher than control, but there was no significantly differents between them(P>0.05).Conclusions:We established the steady model of MCAO in rats to proved the protective effects of RPC for brain tissue.and the increasement of the phosphorylation of the Akt and GSK-3βmay be one of the neuroprotective mechanisms.