Using DCE-MRI Technology And Methazolamide Load Experiment To Investigate The Changes Of Cerebral Blood Flow Reserve And Blood-brain Barrier In SD Rats Under Chronic High Altitude Environment

Objctive: To study the cerebral blood flow(CBF),cerebrovascular reserve(CVR)and Blood brain barrier(BBB)changes of SD rats under high altitude low pressure and hypoxia for a long time by using Dynamic Contrast-Enhanced Magnetic Resonance(DCE-MR)and methazolamide stress test.Methods: Forty 6-week-old Specific Pathogen Free(SPF)male SD rats were divided into plateau group and plain group,randomly.With 20 rats each.The rats in the plateau group and the plain group were placed in the animal laboratory of the People’s Hospital of Yushu Prefecture Tibetan Autonomous Region(about 3700 meters above sea level)and Chengdu.Raised by Dashuo Experimental Animal Company(approximately 500 meters above sea level),3 months later,the rats were scanned with a 7.0T magnetic resonance scanner for DCE-MR scanning,and then the rats were fed with methazolamide saline turbid solution.Two hours later,the head was performed DCE-MR scanning again,and finally the brain was perfused,and the tissue in the region of interest was pathologically examined.Subsequent post-processing of DCE data to obtain semi-quantitative parameters cerebral blood flow(CBF)and quantitative parameter volume transfer constant(Ktrans),substituting the CBF before and after methazolamide stimulation into the formula to obtain the cerebrovascular reserve(CVR).Results:(1)The gray matter and white matter regional cerebral blood flow(CBF)of rats in the plain group and the plateau group were not significantly different.And there was no statistical difference(p>0.05);(2)Before and after the metazolamide stress test,Cerebral blood flow(CBF)of the plateau group was significantly increased than that of the plain group in different regions of interest.And there is a statistical difference(p<0.05);(3)The cerebrovascular reserve(CVR)in the gray and white matter regions of rats in the plain group was lower than that in the plateau group.And there is a statistical difference(p<0.05);(4)The gray matter and white matter regional volume transfer constants(Ktrans)of rats in the plateau group and the plain group have no significantly difference.And there is no statistical difference(p>0.05).Conclusion: Under chronic high altitude environment,the blood-brain barrier(BBB)and cerebral blood flow(CBF)changes are not obvious,and the cerebrovascular reserve(CVR)increases.