Basic Research On Microcirculation Changes And Neuroprotection Of Cang-Ai Volatile Oil After Cerebral Ischemia-Reperfusion Injury Based On 7T-MRI

OBJECTIVE: The MRI diffusion tensor imaging technique and perfusion imaging technique were used to study the effect of nasal inhalation of Cang-Ai volatile oil on the cerebral and ischemic reperfusion injury(MCAO)model.Methods:Experiment 1: 32 healthy adult male SD rats were divided into sham operation group,model(MCAO)group,Cang-Ai volatile oil(CAVO)group and positive control group according to the random allocation principle.The rats in the CAVO group were given a 20-minute CAVO atomization intervention 2 hours after the model was made,followed by a daily atomization intervention for 20 minutes and continuous atomization for 7 days.Then,by using 7.0T magnetic resonance imaging,4 groups of rats were scanned by coronary DSC 3 hours,3 days,and 7 days after successful modeling.The cerebral blood flow(CBF)and cerebral blood volume in thestriatum of the largest infarct level(CBV)and mean transit time(MTT)were measured and then calculated the relative cerebral blood flow(rCBF),relative cerebral blood volume(rCBV)and relative mean transit time(rMTT),observed 4groups of rats 3h,3d,7d brain microcirculation changes.Experiment 2: 24 healthy adult male SD rats were divided into sham-operated group,middle artery occlusion reperfusion(MCAO)group and volatile oil(CAVO)group according to the principle of random allocation.The Zea Longa score was used to evaluate the degree of neurological damage of rats in each group immediately after modeling and on day 7after modeling.Coronal diffusion tensor imaging(DTI)scans were performed at 3 h,3 d,and 7 d after the successful modeling of the three groups of rats using 7.0T magnetic resonance imaging.The apparent diffusion coefficient(ADC)and anisotropy score(FA)are measured,and then the relative apparent diffusion coefficient(rADC)and relative anisotropy score(rFA)are calculated.Seven days later,the volume of cerebral infarction in each group was evaluated by TTC staining,and the correlation between rFA,rADC and neurological score was analyzed.Results:Experiment 1: After the 7T-MRI scan,it was found that the rCBF and rCBV of the MCAO group rats were significantly lower than that of the sham operation group at 3h,3d,and 7d after modeling,and rMTT was higher than the sham operation group at 3h.No statistically significant difference;rCBF in the CAVO group and the positive control group was significantly higher than that in the MCAO group at 3h,3d,and 7d after modeling,the difference was statistically significant(P <0.05);the most obvious was day 3(P <0.01).On the 3rd and 7th days after administration of the model,the striatal rCBV in the CAVO group and the positive control group were significantly higher than the MCAO group,and the results were significantly different(P> 0.05).Obvious(P <0.01),the positive control group was most obvious on the 7th day(P <0.01).Three hours after administration,the rMTT value of the striatum of the MCAO group was higher than that of the CAVO group,and the difference was statistically significant(P <0.05).Three hours after the administration of the model,the rMTT value of the striatum of the MCAO group was significantly higher than that of the positive control group,and the difference was statistically significant(P <0.01).At 3 and 7 days after modeling,the rMTT value of the striatum of the MCAO group was slightly higher than that of the CAVO group and the positive control group,the difference was not statistically significant(P> 0.05).Experiment 2: There was no neurological deficit after awakening in the sham-operated group.The MCAO group and the CAVO group had different degrees of neurological deficit.On the 7th day,the neurological score of the CAVO group was less than the MCAO group(P <0.05).DTI scan results showed that the striatum rADC value of the CAVO group was higher than that of the MCAO group at 3 h and 3 d after modeling(P <0.05),and there was no significant difference between the three groups at 7 d(P> 0.05).The rADC value of the motor cortex in the CAVO group was higher than that of the MCAO group 3 hours after modeling(P <0.01),and there was no statistically significant difference at 3 and7 days.The rFA value of striatum in CAVO group was higher than that in MCAO group at 3 and 7 days after modeling(P <0.05).There was no statistically significant difference in the rFA values of the motor cortex between the MCAO group and the CAVO group at three time points.TTC staining results showed that there was no infarct area in the sham operation group,and the cerebral infarction volume in the CAVO group was smaller than that in the MCAO group(P <0.05).Correlation analysis showed that the rFA value of the striatum(r =-0.847),the rADC value of the motor cortex(r =-0.647),the rFA value of the motor cortex(r =-0.660)and the scores of neurological deficit in the MCAO and CAVO groups There was a significant correlation(P <0.05).Conclusion: For the first time,CAVO can regulate the microcirculation in the infarcted area after cerebral ischemia-reperfusion,improve the prognosis and effectively protect the neurological function of MCAO rats by reducing the toxic edema of cells in the ischemic area and accelerating the recovery of nerve fiber bundles.