ABSTRACT
Objective To investigate the changes in the expression of phosphatidylinositol 3?kinase(PI3?K),mammalian target of rapamycin (mTOR)and Beclin?1 in the hippocampus of normal rats and intermittent hypoxia rats with cerebral ischemia/reperfusion ,so as to explore the role of PI3K/mTOR/autophagy pathway in global cerebral ischemia/reperfusion injury aggravated by intermittent hypoxia. Methods A total of 80 healthy male Wistar rats were randomly divided into sham operation group(SO group,n=20),merely ischemia/reperfusion group(I/R group,n=20),intermittent hypoxia for 7?day ischemia/reperfusion group(IH7+I/R group,n=20),and intermittent hypoxia for 21?day ischemia/reperfusion group(IH21+I/R group,n=20). IH7+I/R group and IH21+I/R group were respectively given intermittent hypoxia for 7 days and 21 days before ischemia/reperfusion. The cerebral ischemia/reperfusion model was established by modified Pulsinelli four?vessel occlusion method. The morpholog?ical changes of nerve cells in hippocampal CA1 region were observed by HE staining and electron microscope. The protein expressions of PI3?K, mTOR and Beclin?1 of nerve cells in hippocampal CA1 region were detected by immunohistochemical staining and RT?PCR. The learning memory capacity of rats were assessed by the Morris water maze test. Results Compared with SO group,I/R group increased the never cells morphology damages,reduced the number of survival neurons,and declined the ability of learning and memory(P<0.05). Immunohistochemistry showed that the number of PI3?K immunoreactive cell,mTOR immunoreactive cell and Beclin?1 immunoreactive cell increased in I/R group compared with S0 group(P<0.05). RT?PCR showed that the expressions of PI3?K,mTOR and Beclin?1 increased in I/R group compared with S0 group(P<0.05). Compared with I/R group,intermittent hypoxia groups increased the never cells morphology damages,decreased the number of survival neu?rons,and declined the ability of learning and memory(P<0.05). Immunohistochemistry showed that the number of PI3?K immunoreactive cell, mTOR immunoreactive cell and Beclin?1 immunoreactive cell increased in IH7+I/R and IH21+I/R groups compared with I/R group(P<0.05). RT?PCR showed that the expressions of PI3?K,mTOR and Beclin?1 increased in IH7+I/R and IH21+I/R groups compared with I/R group(P<0.05),and the changes were more significant in IH21+I/R group(P<0.05). Conclusion Intermittent hypoxia can aggravate neurological injury after ischemia,which is related to PI3K/mTOR/autophagy pathway activation.
ABSTRACT
Objective:To study the effect of endothelin receptor antagonist BQ-123 on the nerve function damage after subarachnoid hemorrhage (SAH)in the rats,and to explore the mechanisms.Methods:Total 120 male SD rats were divided into sham group,SAH group,low dose of BQ-123 group (50 μg· kg-1 )and high dose of BQ-123 group (75 μg·kg-1 ).The SAH rat models were established by injecting the autologous blood into cisterna magna twice.The morphological changes of hippocampus nerve cells of rat brain tissue were detected with HE staining, and the expressions of mTOR, Beclin-1 and LC3-Ⅱ in the hippocampus of rats were detected with immunohistochemistry and RT-PCR;the shuttle-box experiment was used to evaluate the abilities of learning and memory,and the holding power evaluation was used to evaluate the forelimb pulling force of the rats in various groups at each time point.Results:Compared with sham group,the morphological damages of neurons of the rats in SAH group were increased,the survival rate of neurons of the rats in SAH group was decreased (P <0.05),the expression levels of mTOR mRNA,Beclin-1 mRNA and LC3-Ⅱ mRNA in hippocampus tissue of the rats were increased (P < 0.05),and the abtilities of learning and memory and the values of holding power were decreased (P <0.05).Compared with SAH group,the morphological damages of neurons of the rats in BQ-123 groups were decreased,the survival rates of neurons of the rats in BQ-123 groups were increased (P < 0.05),the expression levels of mTOR mRNA of rats were decreased (P <0.05),the expression levels of Beclin-1 mRNA and LC3-ⅡmRNA in hippocampus tissue were increased (P <0.05),and the abilities of learning and memory and the values of holding power were increased (P < 0.05 ). The changes were more significant in high dose of BQ-123 group compared with low dose of BQ-123 group (P <0.05).Conclusion:BQ-123 can improve the nerve function damage after SAH in the rats,its mechanism may be related to regulating the mTOR/autophagy signaling pathway.