MIDDLE CEREBRAL-ARTERY OCCLUSION IN THE RAT BY INTRALUMINAL SUTURE - NEUROLOGICAL AND PATHOLOGICAL EVALUATION OF AN IMPROVED MODEL

Background and Purpose The purpose of the present study was to evaluat e a modified method of intraluminal suture occlusion of the middle cer ebral artery (MCA) on the volume of brain infarction and on neurobehav ioral 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 afte r MCAo, brains were perfusion-fixed and infarct volumes were measured. Results In rats with 60-minute MCAo, only 3 of 7 animals with uncoate d sutures had infarcts, whereas in the group with poly-L-lysine-coated sutures, all rats (n=7) exhibited infarction (P=.009, Fisher's tract test). With 2 hours of MCAo, total infarct volume (corrected for brain edema) was significantly larger in rats with poly-L-lysine-coated sut ures than in the group with uncoated sutures (meant SEM, 122.1+/-4.8 v ersus 67.0+/-18.2 mm(3), respectively; P=.03; n=4 in each group). In t he 2-hour MCAo study, infarct volumes in the uncoated-suture group ten ded to be variable and inconsistent (coefficient of variation, 54%) co mpared with the group in which sutures were coated with poly-L-lysine, in which a highly consistent infarct was produced (coefficient of var iation of infarct volume, 8%). Conclusions Reversible MCAo in which a poly-L-lysine coated intraluminal suture was used proved to be a relia ble and effective modification of this technique, yielding consistentl y larger infarcts and greatly reduced interanimal variability.