Dynamic Changes Of The Blood-brain Barrier's Permeability In The Early Stages Of Traumatic Shock And The Protective Mechanism Of Penehyclidine Hydrochloride In Rats

BackgroundBrain damage after traumatic shock(TS)is universal,but to date,no study concerning the dynamic changes of blood-brain barrier's permeability after TS is reported.NF-?B is a critical regulator of the inflammatory signaling pathway.The protective mechanism of penehyclidine hydrochloride(PHC),a new highly selective cholinergic receptor blocker,on cerebral ischemia-reperfusion injury is unclear.On the basis of our previous studies,the aim of this study is to explore the dynamic changes of BBB permeability after TS,the role NF-?B signaling pathway,and the protective effect and molecular mechanism of PHC on the permeability of BBB in the early stages of TS.Chapter 1 Dynamic Changes of Blood-brain Barrier's Permeability in the Early Stages of Traumatic ShockObjectiveTo investigate the dynamic changes of BBB permeability in rats in the early stages of traumatic shockMethodsThe rat model of traumatic shock was reproduced.Rats were divided randomly into five groups:Con,Shock,LRlh,LR2h and LR6h group.The water content and sodium fluorescein content of brain tissue were measured,and the ultrastructural changes were observed by electron microscopy.The mRNA and protein expressions of NKCC1,VEGF,Occludin,Claudin-5 and NF-?B p65 were detected by qPCR and Western blot,respectively.Results1.Compared with Con group,both the water content and the content of sodium fluorescein in brain tissues increased significantly,the ultrastructure of blood-brain barrier was damaged,the expressions of NKCC1,VEGF and p65 increased significantly,while the expressions of occludin and claudin-5 protein decreased in Shock group.2.Within 6 hours after routine resuscitation with Lactated Ringer's solution after traumatic shock,both brain water content and the content of fluorescein sodium increased with the prolongation of time,blood-brain barrier ultrastructural pathological damage exacerbated,expressions of NKCC1 andp65 increased,while the mRNA and protein expressions of occludin and claudin-5 protein decreased progressively with time.3.The peak value of the expression of VEGF after routine resuscitation with Lactate Ringer's solution in rats with traumatic shock was not synchronized with the dynamic trend of BBB permeability damage.4.The expressions of NF-?B p65 protein increased with the time within 6 hours after resuscitation,which are coincided with the dynamic changes of BBB permeability.ConclusionWithin 6 hours after traumatic shock and routine resuscitation,BBB permeability tends to aggravate with time,both transcellular and paracellular pathways were impaired,and VEGF and NF-?B might both be involved in the pathophysiological dynamic damage of BBB permeability.Chapter 2 The Regulatory Role of NF-?B Signaling Pathway in the Changes of Blood-brain Barrier's Permeability after Traumatic ShockObjectiveTo explore the regulatory role of NF-?B signaling pathway in the changes of BBB permeability after traumatic shockMethodsRats were divided into four groups:Con group,Shock group,LR6h group and PDTC6h group.The other methods are the same as Chapter 1.ResultsCompared with LR6h group,the brain water content and the content of fluorescein sodium decreased significantly,the expressions of NKCC1,VEGF and p65 decreased significantly,while the expressions of occludin and claudin-5 increased significantly in PDTC6h group.ConclusionNF-?B directly participates in the pathological process of BBB permeability damage after traumatic shock by regulating both paracellular and transcellular pathways.Chapter 3 Protective effect and possible mechanism of Penehyclidine Hydrochloride(PHC)on Blood-Brain Barrier after Traumatic ShockObjectiveTo explore the protective effect of PHC on BBB after traumatic shock and the possible underlying mechanism.MethodsRats were divided into four groups:Con group,Shock group,LR6h group and PHC6h group.The other methods are the same as Chapter 1.ResultsCompared with LR6h group,the brain water content and fluorescein sodium content decreased significantly,the expressions of NKCC1,VEGF and NF-?B p65 decreased significantly,while the expressions of occludin and claudin-5 increased in PHC6h group.ConclusionPHC can significantly alleviate BBB damage after traumatic shock,involving transcellular and paracellular pathways.The underlying mechanism not only lies in inhibiting the expression of VEGF,but also depends on inhibiting the activation of NF-?B.