| Background and PurposeBrain edema is a life-threatening complication of Acute cerebral ischemia. The molecular cascade initiated by cerebral ischemia includes the loss of membrane ionic pumps and cell swelling. Secondary formationof free radicals and proteases disrupts brain-cell membranes, causing irreversible damage. Since aquaporins(Water channel protein, WCP) found byAgre in 1993, a large number of basic and clinical research to establish its important role in the function of transport the water across the cell membrane.Theoretical basis of the traditional MRI-DWI is the Brownian motion of water molecules in organize and cell Brownian. Conventional wisdom is that this is mainly affect on the free diffusion of water movement by tissue membranes, interstitial cells.As well as, due to the exchange of macromolecules with cells or tissue gap in the course of the water molecules campaign. It has a wealth of different subtypes of aquaporin in the membrane. The speed of Water molecules free diffusion in the cell its obvious differences with the water through the AQPs in cell membrane. The theory of Aquaporin presents a challenge to otraditional DWI imaging mechanism, but also let people to rediscover MRI-DWI technology from the perspective of molecular biology, molecular medicine and molecular imaging,This study is watch the temporal evolution of parameters from multi-b diffusion weighted imaging in an Experimental MCAO model,and to discuss the Effect of butylphthalide on expression of aquaporin-4. Materials and Methods1?125 healthy SD rats were randomly divided into 3 groups: MCAO group(55 MCAO rats), butylphthalide group(55 MCAO rats with butylphthalide), sham operation group(15 rats). The experimental group would be further divided into 6 groups(1h, 3h,6h, 12 h,24h), 10 model was ensure success in each group.2?Using the U.S company GE MR 750 3.0T magnetic resonance instrument and special coil rats, The experimental group and the experimental group rats were scanned axial T2-weighted imaging(T2WI), T1-weighted imaging(T1WI), T2 WI FLAIR, axial DWI(b=1000 s/mm2)and multi-b DWI( b=0,50,100,150,200,300,500,800,1000,1 300,1 500,1700,2000, 2500,3 000,3500,4 000,4500 s/mm2).3?After the scan complete, 5 rats of 3h in each groups were choosed for dry-wet weight and evaluation of neurological function, and 10 rats semi-quantitative immunohistochemical analysis of AQP-4 and PKC at each time point.4?Standard ADC(ADCst) maps were calculated from standard b-values, while maps of pure diffusion coefficients(D), pseudo-diffusion coefficients(D~*), and ultra-high ADCs(ADCuh) were calculated from the 18 b-values using a tri-component model. In this model, D and D~* values were quantified with a bi-exponential equation using b-values less than 2,000 s/mm2, while ADCuh was quantified by fitting the signals at ultra-high b-values(2,000–4,500 s/mm2) to the mono-exponential equation. ADCst, ADCuh, D, and D~* of the basal ganglia were compared between each group.5?All data are analyzed by SPSS17.0 statistical software, and the quantitative data was expressed as mean ± standard deviation. The score of neurological function between the different groups was analyzed by rank test. Two of the three groups were compared with each other using LSD-t test. When P<0.05, the two samples were considered statistically significant. Results1?The the difference of the score of neurological function between the MCAO groups and butylphthalide group was statistically significant(Z=-2.01,P=0.044). The BWC of the MCAO?butylphthalide groups increased significantly compared with the control group after 3h, the difference was statistically significant(P1=0.00,P2=0.01). And the difference between MCA and butylphthalide group was statistically significant(P3=0.01).2?The ADCst in MCAO and butylphthalide group in rapid decline after 1h, 12 h fell to the lowest, then slightly increased, and the difference between them was statistically significant(P1<0.05). D~*?D?ADCuh in MCAO fell to the lowest at 6h, but at 12 h fell to the lowest in butylphthalide. In 1-6h the difference between MCAO and butylphthalide group was statistically significant(P1<0.05). The difference between MCAO and sham?butylphthalide and sham was statistically significant(P2<0.05?P3<0.05). In 1-6h after MCAO, the ADCuh has the most obvious changes.3?AQP-4 and PKC expression was seen in MCAO group and butylphthalide group after 1h, and 24 h reached the peak. And the difference between MCAO and sham?butylphthalide and sham was statistically significant(P2?P3<0.05). In 1-6h the difference between MCAO and butylphthalide group was statistically significant(P1<0.05). In 1-6h after MCAO, the AQP4 and PKC has the most obvious expression. Conclusion1? D~* may provide useful information with the microvasculature perfusion, and may reflect the microcirculation change of acute brain ischemia in vivo.2? ADCuh could be more valuable than ADCst, D and D~*. ADCuh may provide some information of aquaporin molecular.3? Butylphthalide improves ischemic cerebral edema regulating AQP-4 and PKC expression. Butylphthalide may through PKC pathway regulate AQP-4 need be further studied. |
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