Effects of cerebral ischemic postconditioning on expressions of Notch1,Cyclin D1 and CDK4 proteins in hippocampus of rats / 吉林大学学报(医学版)

ABSTRACT

Objective:To investigate the effects of cerebral ischemic postconditioning (CIP)on the expressions of Cyclin D1 and CDK4 proteins in hippocampal neurons of the rats with global cerebral ischemia and reperfusion (I/R)based on Notch1 signaling pathway,and to explore the mechanisms.Methods:A total of 128 healthy male SD rats were randomly divided into sham operation group,I/R group (modified Pulsinelli four vessel occlusion method), CIP group (repeated 3 times of reperfusion or blocking blood vessel before complete reperfusion)and DAPT group (intraperitoneal injection of 10 mg·kg-1 ·d-1 DAPT 3 h before CIP),and there were 32 rats in each group.HE staining was used to observe the morphology of the neurons at 6, 24, 48 and 72 h after ischemia;immunohistochemical staining was used to observe the expressions of Cyclin D1, CDK4 and Notch1 in the hippocampus of the rats;Western blotting method was used to observe the expression levels of Cyclin D1,CDK4 and Notch1 proteins in the hippocampus of the rats at different time points. Results:The HE staining results showed that compared with sham operation group,the structure of neurons in hippocampus area of the rats in I/R group was damaged and the survival rate of neurons was significantly decreased (P <0.05).Compared with I/R group,the survival rates of neurons in the hippocampus area of the rats in CIP group were significantly increased at the corresponding time (P <0.05).Compared with CIP group,the survival rates of neurons in hippocampus area of the rats in DAPT group at the corresponding time were significantly decreased (P < 0.05 ). The immunohistochemical staining results showed that compared with sham operation group,the number of cells with positive Notch1,Cyclin D1 and CDK4 in I/R group was increased (P < 0.05).Compared with I/R group,the number of Cyclin D1 and CDK4 positive cells in CIP group was decreased (P <0.05),and the number of Notch1 positive cells of was significantly increased (P <0.05).Compared with CIP group,the number of Cyclin D1 and CDK4 positive cells in DAPT group was increased (P < 0.05 ),and the number of Notch1 positive cells was significantly decreased (P < 0.05 ). The Western blotting results showed that compared with sham operation group,the expression levels of Notch1,Cyclin D1 and CDK4 proteins in the hippocampus of the rats in I/R group were increased (P <0.05);compared with I/R group,the expression levels of Cyclin D1 and CDK4 proteins in the hippocampus of the rats in CIP group were significantly decreased (P <0.05),and the expression level of Notch1 protein in the hippocanpus of the rats was significantly increased (P < 0.05 ); compared with CIP group,the expression levels of Cyclin D1 and CDK4 proteins in the hippocampus of the rats in DAPT group were increased (P <0.05),and the expression level of Notch1 protein was significantly decreased (P < 0.05).Conclusion:CIP may play an important role in protecting the neurons by increasing the activity of Notch1 and inhibiting the expressions of Cyclin D1 and CDK4.