Middle Cerebral Artery Occlusion in the Rat by Intraluminal Suture: Neurological and Pathological Evaluation of an Improved Model

Abstract

Background and Purpose The purpose of the present study was to evaluate a modified method of intraluminal suture occlusion of the middle cerebral artery (MCA) on the volume of brain infarction and on neurobehavioral function in rats subjected to a temporary focal ischemic insult. Methods Male Sprague-Dawley rats were anesthetized with halothane and subjected to 60 minutes or 2 hours of temporary MCA occlusion (MCAo) by an intraluminal thread. In one group of rats, the suture was coated with poly- l -lysine, while in a second group, a conventional uncoated suture was used. Behavioral function was evaluated at 50 to 60 minutes after occlusion and during a 3-day period after MCAo. Three days after MCAo, brains were perfusion-fixed and infarct volumes were measured. Results In rats with 60-minute MCAo, only 3 of 7 animals with uncoated sutures had infarcts, whereas in the group with poly- l -lysine–coated sutures, all rats (n=7) exhibited infarction ( P =.009, Fisher's exact test). With 2 hours of MCAo, total infarct volume (corrected for brain edema) was significantly larger in rats with poly- l -lysine–coated sutures than in the group with uncoated sutures (mean±SEM, 122.1±4.8 versus 67.0±18.2 mm 3 , respectively; P =.03; n=4 in each group). In the 2-hour MCAo study, infarct volumes in the uncoated-suture group tended to be variable and inconsistent (coefficient of variation, 54%) compared with the group in which sutures were coated with poly- l -lysine, in which a highly consistent infarct was produced (coefficient of variation of infarct volume, 8%). Conclusions Reversible MCAo in which a poly- l -lysine–coated intraluminal suture was used proved to be a reliable and effective modification of this technique, yielding consistently larger infarcts and greatly reduced interanimal variability.