The Protective Effect Of Blood-letting Puncture On Well Point By Mitophagy Mediated By HIF-1?/BNIP3 Pathway On Acute High Altitude Brain Injury In Rats

Objective:To study the protective effect of mitophagy mediated by HIF-1?/BNIP3 pathway on acute high altitude brain injury in rats and explore the biological mechanism of the blood-letting puncture on well point in acute high altitude hypoxia initially,so as to provide new ideas for clinical prevention and treatment of acute high altitude hypoxic brain injury.Methods:Adult male SD rats were randomly divided into normal control(A)group,12 h,24h,48 h and 72 h of hypobaric hypoxia(B)group,12 h,24h,48 h and 72 h of well point blood-letting intervention(C)group.The rats in Group C were treated with blood-letting puncture on well point of hand once a day for 7 days,and the bleeding amount was 10 ul per point.At the same time,the rats in group A were fed normally outside and grabbed once a day in the same way as the rats in group B and C,on the eighth day,the rats in group A were taken.And the rats in group B and C were placed in the simulated hypobaric oxygen chamber(5000m above sea level)to establish the model of acute high altitude brain injury.After exposure to the corresponding time in the cabin,the rats were taken out of the cabin and anesthetized immediately,abdominal aortic blood,brains were taken.HE staining was used to observe the histopathological changes of rat hippocampus.Elisa was used to detect the serum levels of S100 B,GFAP,HIF-1?,VEGF in peripheral blood.Real time PCR was used to detect the expression of HIF-1?,BNIP3 m RNA in the rat hippocampus.Western-Blot was used to detect the expression of Beclin-1,LC3 protein in the rat hippocampus.Results:1.HE staining:Compared with Group A,there were different degrees of damage in the hippocampal CA1 region in Group B at each time point,which was related to the time of hypoxia,and the degree of injury was serious at 72 hours.At the same time,the injury in Group C were milder than that in Group B.2.Elisa:Compared with Group A,the serum levels of S100 B,GFAP,HIF-1? and VEGF increased obviously in Group B at each time point(P<0.01).Compared with Group B at the same time,the levels of S100 B,GFAP decreased in Group C(P<0.05 or P<0.01),the levels of HIF-1?,VEGF increased in Group C(P<0.05 or P<0.01).3.Real time PCR:Compared with Group A,the expression of HIF-1?,BNIP3 m RNA in rat hippocampus increased obviously in Group B at each time point(P<0.05).Compared with Group B at the same time,at 12 and 24 hours,the expression of HIF-1? and BNIP3 m RNA in rat hippocampus increased obviously in Group C(P<0.05),at 48 and 72 hours,there was no significant difference(P>0.05).4.Western-blot:Compared with Group A,at 24 hours,the expression of Beclin-1protein in Group B increased obviously(P<0.01),at 12,48,72 hours,there was no significant difference(P>0.05).The expression of LC3 II protein in the hippocampus of rats increased obviously in Group B at each time point(P<0.01 or P<0.05).Compared with Group B at the same time,at 24 hours,the expression of Beclin-1 protein increased obviously in Group C(P<0.01),at 12,48,72 hours,there was no significant difference(P>0.05).At 24,48,72 hours,the expression of LC3 II protein increased obviously in Group C(P<0.01),at 12 hours,there was no significant difference(P>0.05).Conclusion:The serum levels of S100 B and GFAP can be used as evaluation indexes for the degree of acute hypoxic brain injury in plateau.The intervention of well point bloodletting can improve the degree of brain injury in rats with acute high altitude hypoxia and protect brain.The mechanism may be related to affecting the mitophagy levels mediated by HIF-1?/BNIP3 signaling pathway.