A focal embolic model of cerebral ischemia in rats: introduction and evaluation

Cerebral thromboembolism is the most common type of acute stroke in the clinical setting. In the present study, we have described a focal embolic model of cerebral ischemia in rat. Cerebral ischemic injury in two different sizes was induced by injection of two different volumes of pre-formed clots into the middle cerebral artery (MCA). Neurological deficits were assessed at 1 and 24 h, respectively, after the MCA embolization. The brain infarction was evaluated with 2,3.5-triphenyltetrazolium chloride (TTC) staining at 72 h following embolic stroke. The incidence of gross hemorrhage was also identified on the TTC-stained brain sections. This study consisted of two groups. In the first group 10 mul of pre-formed clot was injected into MCA (n=10), and in the second group 5 mul of clot was injected (n=10), Embolizing a pre-formed clot resulted in an infarction in the territory irrigated by the MCA. Embolization with the different volume of clots resulted in different sizes of brain infarction, 32.1 +/-2.9% (mean +/-S.E.) in the 10-mul group versus 23 +/-4.5% (mean +/-S.E.) in the 5-mul group (P <0.05). The infarction size as well as neurological deficits correlated well with the volume of the clot injected. These results thus show that with the procedure described here a reliable and reproducible ischemic injury is produced in the brain. The model is relevant to thromboembolic ischemia in patients, and may offer a useful tool to investigate mechanisms underlying ischemic brain injury. It may also be used to test thrombolytic agents in ischemic brain injury. (C) 2001 Elsevier Science B.V. All rights reserved.