The Effect Of AQP4 And VEGF In The Brain Of The Rat With Sustained Threshold Controlled Hypotension At Different Time

Objective:At present,it is not completely clear about the length of time leading to cerebral edema with sustained threshold controlled hypotension.This research aims to make clear about the time limit for the continued safety of the threshold controlled hypotension and the molecular mechanism of leading to brain injury,with the support of observations of the tolerance of the rat brain after threshold controlled hypotension at different time.Methods:30 rats were randomly divided into 5 groups,each group with 6 rats: Group A(normal);Group B(lower blood pressure),Group B set four different points sustained controlled hypotension:0.5h,1h,2h,4h.So 4 groups:B1,B2,B3,B4.Use sodium nitoprusside(SNP) and esmolol(ESM) induce controlled hypotension.During the time of lowering blood pressure,recorded rats' vital signs and did blood gas analysis.24hours later,observed rats' neurobehavioral functions and survival rate after hypotension.Then took half of their brains to detect wet and dry weight to check water content of brain tissue and used immunohistochemistry to determine the expression of VEGF and AQP4.Result:(1) Assessment of the rats' neurobehavioral functions:there was statistic difference(p＜0.05) between B4 and A,and both the survival rates after 24 hours of Group A and Group B were100%.(2) There were marked differences between B4 and A about the water content of brain tissue;The HE staining can be seen a large number of cell vacuolar degeneration,cell arrange rarefaction and cellular sewlling of astrocyte in B4(3).Comparison of average optical density of AQP4 between Group A and Group B:B3 were higher than A(p＜0.05),B4 were more higher than A(p＜0.01);Comparison of average optical density of AQP4 in the same group:there are statistic difference(p＜0.05) in B4 and B3.(4) Comparison of average optical density of VEGF between Group A and Group B:B3 were higher than A(p＜0.05),B2 were higher than A(p＜0.05),B4 were higher than A(p＜0.01); Comparison of average optical density of VEGF in the same group:B4 were higher than over B3(p＜0.05).Conclusions:1.1.After 2h hypotension of MAP50mmHg induced by SNP and ESM,rats' neurobehavioral functions have no injuries.After 4h rats' neurobehavioral functions were declined. 2.After 2h hypotension of MAP50mmHg induced by SNP and ESM,AQP4 in brain hippocampus was weakly positive,brain tissue was mild edema;After 4h hypotension of MAP50mmHg induced by SNP and ESM,AQP4 in brain hippocampus was positive,and brain tissue was obvious edema.3.VEGF in brain hippocampus after 1h hypotension of MAP50nnHg induced by SNP and ESM were weakly positive,VEGF in brain hippocampus after4h hypotension of MAP50nnHg induced by SNP and ESM was strongly positive.