Reversible middle cerebral artery occlusion without craniectomy in rats.

TLDR

The study aimed to develop a simple, noninvasive rat model of reversible middle cerebral artery ischemia using extracranial vascular occlusion. The authors induced MCA occlusion in anesthetized rats by inserting a 4‑0 nylon suture into the cervical internal carotid artery and advancing it intracranially, while interrupting external carotid and extracranial internal carotid branches to reduce collateral flow, and they monitored physiological parameters, neurologic deficits, mortality, and performed histologic and electrophysiologic assessments. India ink perfusion confirmed MCA blockage in 14 of 20 rats and restoration of flow in six after suture removal, and permanent occlusion produced resolving moderate neurologic deficits in 7 of 8 rats with unilateral infarcts averaging 37.6 % of the coronal sectional area at 72 h. Abstract truncated at 250 words.

Abstract

To develop a simple, relatively noninvasive small-animal model of reversible regional cerebral ischemia, we tested various methods of inducing infarction in the territory of the right middle cerebral artery (MCA) by extracranial vascular occlusion in rats. In preliminary studies, 60 rats were anesthetized with ketamine and different combinations of vessels were occluded; blood pressure and arterial blood gases were monitored. Neurologic deficit, mortality rate, gross pathology, and in some instances, electroencephalogram and histochemical staining results were evaluated in all surviving rats. The principal procedure consisted of introducing a 4-0 nylon intraluminal suture into the cervical internal carotid artery (ICA) and advancing it intracranially to block blood flow into the MCA; collateral blood flow was reduced by interrupting all branches of the external carotid artery (ECA) and all extracranial branches of the ICA. In some groups of rats, bilateral vertebral or contralateral carotid artery occlusion was also performed. India ink perfusion studies in 20 rats documented blockage of MCA blood flow in 14 rats subjected to permanent occlusion and the restoration of blood flow to the MCA territory in six rats after withdrawal of the suture from the ICA. The best method of MCA occlusion was then selected for further confirmatory studies, including histologic examination, in five additional groups of rats anesthetized with halothane. Seven of eight rats that underwent permanent occlusion of the MCA had resolving moderately severe neurologic deficits (Grade 2 of 4) and unilateral infarcts averaging 37.6 +/- 5.5% of the coronal sectional area at 72 hours after the onset of occlusion. (ABSTRACT TRUNCATED AT 250 WORDS)