The Study Of The Expression Of IGF-1 And HSP70 On Cerebral Ischemia-reperfusion In Rats During Chronic Intermittent Hypoxia

Objective:To establish the rat model of chronic intermittent hypoxia(CIH) combining cerebral ischemia reperfusion(CIR) and explore the effect of obstructive sleep apnea syndrome(OSAS) on stroke by the expression of insulin-like growth factor-1(IGF-1) and heat shock protein 70(HSP70) after chronic intermittent hypoxia and cerebral ischemia reperfusion in rat. Methods:fifty eight Sprague-Dawley(SD) rats were chosen.Ten rats were carried out randomly to be monitored arterial blood oxygen saturation in hypoxic box.The remained forty eight rats were randomly assigned five experimental groups:unhandled control group(UC) (A group n=6),sham operation group(B group n=6),CIR group(C group n=12),CIH four weeks combining CIR group(D group n=12),CIH eight weeks combining CIR group(E group n=12). CIR group,CIH four weeks combining CIR group and CIH eight weeks combining CIR group were assigned the volume test group(C1 group,n=6;D1 group,n=6;E1 group,n=6)and the immunohistochemistry test group(C2 group,n=6;D2 group,n=6;E2 group,n=6). The CIH model established was made,and then the rats were exposed to the focal middle cerebral artery occlusion. The expression of IGF-1 and HSP70 were detected by immunohistochemistry . The effusion of polymorphonuclear leucocytes (PMNLs)in brain tissue was detected by HE staining. Infarct size was also investigated by TTC staining.Results: 1,The neurological functional deficit and the infarct volume in CIH eight weeks combining CIR group was more than that in CIR group and CIH four weeks combining CIR group(P<0.05),while the neurological functional deficit and the infarct volume in CIH four weeks combining CIR group was not significantly different from that in CIR group(P>0.05). 2,The expression of IGF-1 in CIH eight weeks combining CIR group was decreased Compared with that of CIR group and CIH four weeks combining CIR group(P<0.05).The expression of IGF-1 in CIH four weeks combining CIR group reduced Compared with that of CIR group(P<0.05).3,The expression of HSP70 in CIH eight weeks combining CIR group was decreased Compared with that in CIH four weeks combining CIR group(P<0.05),but not significantly different from that in CIR group(P>0.05). The expression of HSP70 in CIH four weeks combining CIR group was significant higher than that in CIR group(P<0.05).Conclusions: IGF-1 and HSP70 are protective factors in cerebral ischemia-reperfusion injury. CIH decreases the expression of IGF-1,which may be one of the mechanism of CIH enhancing cerebral ischemia reperfusion injury.