Comparison of the lesion produced by permanent focal cerebral ischaemia in three animal models using magnetic resonance imaging

Introduction. Animal models of brain ischemia are essential to reveal the full aspects of cerebrovascular pathologies. The perfect animal model that reflects every aspect of stroke pathophysiology does not exist, hence there is a need for a proper selection of the animal model in order to interpret properly the results from experimental research. Aim. To characterize and compare the temporal evolution of three common models of focal brain ischemia using magnetic resonance imaging (MRI) techniques. Materials and methods. Thirty Sprague-Dawley rats were distributed into three groups, each of them submitted to one of the following surgery procedures: middle cerebral artery (MCA) intracranial suture, MCA electrocoagulation, and MCA intraluminal suture. Each rat was subjected to an MRI study at days 1, 2, 3, 4, 7 and 14 post-surgery. T-2 weighted images were obtained in order to calculate both lesion volumes and edema. Results. Infarct volume and edema were maximal for the intraluminal model (peaks of mean 297 +/- 163 mm(3) and mean 17 +/- 9%, respectively) compared to intracranial suture (178 +/- 62 mm(3) and 9 +/- 6%, respectively) and electrocoagulation (181 45 mm(3) and 9 6%, respectively) models. Discussion. The intraluminal occlusion of the MCA model, although yields in the highest mortality rate (28%), it is the more suitable for long term studies, mainly because of the absence of craniotomy. In the electrocoagulation model a non ischemic lesion region is observed which leads to an abnormal lesion evolution as compared with the other two models.