Expermental Study On Magnetic Resonance Diffusion Weighted Imaging, Apoptosis And AQP-4 After Acute Cerebral Ischemia And Reperfusion In Rabbits

Objective To disclose the relationship between cell apoptosis, AQP-4 and DWI byanalyzing the detection of Magenetic Resonance Diffusion Imaging of actue cerebral ischemiaand reperfusion in rabbits. Methods Fifty-eight Newzeland white rabbits were divided intopermanent ischemia group(A group, n=30)which were subdivided into ischemic 1h, 3h, 6h, 12h,24h, 48h groups(n=5 each grpup) and reperfusion group after 1h cerebral ischemia(n=28)which were subdivided into 2h (n=5), 5h (n=5), 11h(n=4), 23h (n=5), 47h (n=5) groups.All rabbit brains were cut out to make histologic section immediate after each time point MRIexamination. Toluidine blue stain, apoptosis and AQP-4 detection were carried out respectivelyunder microscope. Results The hyperintensity area in MRI-DWI tend to enlarge gradually inpermanent ischemia groups. The average ADC value decrease at frist and then increasegradually. In reperfusion groups, the ADC value increase at 2h point with hypertension areashrinkage and decrease at 5h point.After that, the ADC value is increase again with DWIhypertension area enlarge gradually. The number of positive apoptosis cells was graduallygrowth after ischemia and reached a peak at 12h point. In reperfusion group, the extent of changof positive apoptosis cells is smaller than that in permanent ischemia groups. AQP-4 positvecells decrease within 6h, and then increased after that in permanent ischemia groups. There wasa close relationship between ADC value and AQP-4 positive cells(r=0.829, P=0.042). Inreperfusion groups there was a steady chang within 6h about AQP-4 positive cells. After that,the number of positive cells go up. Conclusion 1. This study certified again that 6h isimportant time window for acute cerebral ischemia. At 6h point, many physiological andbiochemical indicator happened to chang. 2. We can estimate the degree of tissue damage according to the decline of ADC value. The ADC value of upper limit of 95 percent confidenceinterval in ischemia central area is 58.75×10^-5 mm²/s. 3. The number of apoptosis positivecells is relate to the degree and duration of cerebral ischemia, there is no relationship betweenthe number of apoptosis positive cells and ADC value. 4. In permanent ischemia groups, there isa close relationship between the chang pattern of rADC and the expression of AQP-4.