The Evaluation and Quantification of Cerebral Infarction Following a Middle Cerebral Artery Occlusion in Rats

Kim, In Soo; Yim, Man Bin; Lee, Chang Chull; Son, Eun Ik; Kim, Dong Won; Kim, In Hong; Kwon, Kun Young

Abstract

In order to find out the accuracy of the quantification of the infarction area by using triphenyltetrazolium chloride(TTC) staining and to evaluate the change of the infarction size according to the duration after the ischemic insult, in a series of 33 adult rats, a surgical occlusion of the middle cerebral artery(MCA) was carried out through a small subtemporal craniotomy. 11 animals at 6 hour, 12 animals at 24 hour and 10 animals at 48 hour following the surgical occlusion of the MCA, rats were sacrificed and brain slices were obtained and stained with TTC, and hematoxyline and eosin(H & E). The size of the infraction area stained by each method was quantified by a computer image analysis system. The average percent of the infarction size(+/-standard error) was larger in the 24 and 48 hour groups than that of the 6 hour group(determined by TTC:9.94+/-0.97 vs. 9.98+/-1.08 vs. 6.83+/-0.82%, respectively:6 hour vs. 24 & 48 hour groups;one-way ANOVA test p<0.05 determined by H & E:10.02+/-0.94 vs. 10.02+/-1.06 vs. 7.73+/-0.85%, respectively). However, there was no significant difference in the size of the infarction between the 24 and 48 hour groups. The size of the infarction area determined by either method was not significantly different in any group(TTC vs. H & E:paired t-test p>0.05), and linear regression analysis showed a significant correlation existed between the two methods in all groups. However, the degree of correlation was more prominent in the 24 and the 48 hour groups than 6 hour group(6 hour group:r=0.76, slope=0.78, y intercept=0.55;24 hour group:r=0.97, slope=1.03, y intercept=-0.78;48 hour group:r=0.98, slope=0.94, y intercept=0.42). From this study it is concluded that: 1) the evolution of the infarction size continues up to 24 hours following the arterial occlusion, and thereafter, the change of the infarction size is minimal in the rat. This data suggests that it is sufficient to evaluate the change of the infarction size up to 24 hours following the ischemic insult in the experimental study of ischemia in the rat. 2) the detection and the quantification of the cerebral infarction by using TTC staining is a reliable method after 24 hours following the ischemic insult. However, in the earlier period than 24 hours following the ischemic insult, staining with TTC coupled with histopathological H & E staining will add to the accuracy in the obtainin the quantity of the cerebral infarction in the rat.