Middle cerebral artery occlusion of rats: Pathological and neurological evaluation of the model

Abstract

Eighty seven Sprague-Dawley rats were used to study the anatomy of the horizontal segment of middle cerebral artery (MCA) and infarction after occlusion of this vessel. We investigated the size and location of the lesion produced, and found a correlation between infarct size and neurological deficit. Fourty rats were used to determine the anatomical variations of MCA after intracardiac carbon black injection. Five major patterns of MCA were defined and two of them were major and constituted 88% of rats. In the experimental group (n:20) through a subtemporal burrhole MCA was exposed and after defining the anatomical variations of the artery according to our classification, MCA was coagulated 3-4 mm length from the origin of the lateral striate arteries to the inferior cerebral vein and divided. Control rats (n:20) underwent identical surgical procedures except for occlusion. Twenty-four hours after MCA occlusion, all animals were neurologically evaluated. In the experimental group, one rat scored 1, five rats scored 2, nine rats scored 3, five rats scored 4. On the third day after occlusion the brains were removed and stained with 2% 2,3,5 triphenyltetrazolium chloride (TTC). In each animal, the area of infarction was assessed and graded using computer analysis method. There were no rats grade I infarcts, 4 with grade II, 10 with grade III, 6 with grade IV. This study show that once the anatomical variations of the MCA and its branches in our strain of rats was determined, it was possible to achieve 80% grade III and IV infarcts.