Effects of the monitoring of cerebral blood flow in the preparation of cerebral ischemia model in rats / 中国脑血管病杂志

ABSTRACT

Objective To investigate whether the monitoring of cerebral blood flow can be used to evaluate the successful preparation of rat models with focal cerebral ischemia.Methods With the line plug inserted into the left internal cerebral artery of 30 SPF Wistar Han rats at (16.0±0.5) mm,(18.0±0.5) mm and (20.0±0.5) mm respectively,three kinds of focal cerebral ischemia models (10 each) were prepared.All the rats were divided into incomplete occlusion group,complete occlusion group and deep occlusion group according to whether the blood clots were found in skull base and the infarction was appeared in the middle cerebral artery territory after the whole brain was stained with 2,3,5-triphenyl tetrazolium chloride.The cerebral blood flow in the middle cerebral artery territory of each animal was monitored by laser Doppler at the time of before and after blocking with the line plug inserted and reperfusion with the line plug pulled out and recorded for statistical analysis.The cerebral blood flow was expressed as the relative flow unit (perfusion unit,PU);The changes of the cerebral blood flow after occlusion and reperfusion were expressed as a percentage of that blood flow and those before occlusion.Results During the process of modeling,1 rats died,and the other in the incomplete occlusion group (n=9),in the complete occlusion group (n=15),and in the deep occlusion group (n=5).The depths of inserting of 8 rats in the incomplete occlusion group were about (16±0.5) mm,and the blood flow from the anterior cerebral artery to middle cerebral artery could not be prevented completely,the Longa score was evaluated 6 h after ischemia and ranged from 0 to 1,there were no blood clots in skull base and no infarction after TTC staining.The depths of inserting of 9 rats in the complete occlusion group were about (18±0.5) mm,and the anterior cerebral artery blood flow was completely blocked,the neurological dysfunction was significant after 6 h ischemia and the Longa score was ranged from 2 to 3,the blood clots in skull base were absent and the infarctions in middle cerebral artery territory were obvious after TTC staining.The depth of inserting of 5 rats in the deep occlusion group were about (20±0.5) mm,and the anterior cerebral artery blood flow was also completely blocked,the neurological dysfunction was serious after 6 h ischemia and the Longa score was ranged from 3 to 4,there existed blood clots in skull base and obvious infarctions in middle cerebral artery territory after TTC staining.The cerebral blood flows after the line plug inserted compared with those before occlusion in the incomplete occlusion group,complete occlusion group and deep occlusion group were all decreased (94±17 vs.256±36,43±9 vs.286±44,44±6 vs.294±46,respectively,all P0.05);The percentages of cerebral blood flow after occlusion and before were (36.93±0.06)%,(15.09±0.02)%,(15.52±0.04)% respectively,and the difference between groups was statistically significant (F=39.14,P<0.01).The cerebral blood flow after reperfusion were 213±31,147±17,96±14,respectively,and the difference was also statistically significant (F=50.05,P<0.01),and the cerebral blood flow in deep occlusion group was less than that in complete occlusion group(P<0.05);The percentages of cerebral blood flow after reperfusion and before occlusion were (83.10±0.02)%,(51.83±0.05)%,(33.49±0.09)% respectively,and the difference was also statistically significant (F=93.23,P<0.01).Conclusion The cerebral blood flow monitored by laser Doppler can be used as a real-time,convenient,micro invasive,objective and reliable standard to evaluate the successful preparation of rat MCAO models with line plug method.