The Role And Mechanism Of Notch Signal Pathway In Sevoflurane Improving Hypoxic-ischemic Brain Injury In Neonatal Rats

Objective: Hypoxic-ischemic brain injury(HIBI),as a serious central nervous system disease,has a high mortality and disability rate.At present,there are many studies on the brain protection of sevoflurane,but there are still many unknowns about its role and mechanism in the developing brain.Evidence shows that Notch classical signal pathway plays an important role in the growth and development of cerebral vessels.In this experiment,we established the HIBI model of newborn rats to study whether sevoflurane plays a protective role in brain by regulating angiogenesis through Notch signal pathway and its possible mechanism.Methods: 1.Experimental grouping and model preparation: 125 7-day-old rats weighing12-17 g were randomly divided into 5 groups(n=25,Male to female ratio 1:1):Control group,HIBI group,HIBI+sevoflurane treatment group(HIBI+SEV),HIBI+Notch inhibitor group(HIBI+D),HIBI+sevoflurane+inhibitor group(HIBI+SEV+D).The control group was only operated to separate the left carotid artery,while the HIBI model was prepared by separating and ligating the left carotid artery of rats and hypoxia in 8%hypoxia environment for 2 hours;The sevoflurane group needs to inhale sevoflurane for30 minutes 2.4% after HIBI modeling;In the inhibitor group,DAPT 0.03 mg /kg was injected into the left ventricle 30 minutes before modeling.Other groups were injected with the same volume of normal saline.2.Brain injury observation: seven days after modeling,extract protein from rat brain tissue and make frozen sections.Use Western Blot to detect the protein level of Notch1,Hes1,CD31,Vegf A,GAPDH and β-actin,and then the number of brain neuron damage was detected by nissl staining.3.Behavioral observation after HIBI: Barnes maze test,rod rotation test,open field test,and elevated cross maze test were performed 28 days after the model was established to evaluate the spatial learning and memory,movement,and anxiety-like behavior of rats.Results:1.After statistical analysis of WB experimental results,it was found that compared with the control group,the expression of CD31,the downstream transcription factor Hes1 of Vegf A and Notch signaling pathway in each group of rats after HIBI decreased,and sevoflurane could increase the expression of protein.2.In Nissl staining,the number of cells per unit area in each group was statistically analyzed.The number of cells in the four treatment groups decreased,the HIBI+D group decreased the most significantly,the HIBI+SEV group decreased the least,and the number of cells in the HIBI+SEV+D group increased compared with the HIBI+D group.3.In Barnes maze experiment,the waiting time to find the target hole was used as an index to measure the spatial learning and memory ability of rats.Compared with HIBI+SEV group,the waiting time of HIBI+D group increased,and then the waiting time of HIBI+SEV+D group decreased.Open field test and elevated cross maze can evaluate the motor and anxiety-like behavior of rats.Rats in HIBI+D group showed obvious anxiety tendency.There was no significant statistical difference in the indicators of exercise and endurance of rats in the rotating rod test.Conclusion:Sevoflurane promotes angiogenesis after HIBI in newborn rats by activating Notch signal pathway,thus increasing the number of neurons after HIBI,playing a role in brain protection,and improving the recovery of HIBI memory ability and anxiety-like behavior in rats.