Presentation of a Standard Model of Focal Cerebral Ischemia Induction for Evaluating of Sequelas Brain Edema in Mice

Stroke remains one of main causes of death and disability in human. Animal models of the brain ischemia provide important roles for studying of the pathophysiological mechanisms and evaluating of the efficacy of neuroprotective agents. The aim of this study is introducing a new model of the focal cerebral ischemia with increased success and low mortality rate. Fifteen six C57/BL6 male mice were anesthetized with isofolorane and mixture of O2/N2O divided in four groups. Focal cerebral ischemia was induced by intraluminal filament method. A silicon coated nylon filament was used for middle cerebral artery occlusion. Regional cerebral blood flow was monitored by laser Doppler flowmetery for leading of filament in vascular pathway. In the 24 hours following ischemia (60minutes), animals were assessed for neurological outcome, infarct volume and brain edema induction. A new and reformed neurological test was used for evaluation of neurological deficits. 10 µm coronal sections were collected from 12 levels of the brain and stained, digitized and quantified by using an image analysis system. Ischemic brain edema was investigated by brain water content detection. When sham operated mice had no motor deficit and infarction, induction of ischemia in ischemic group, seriously caused impairment of motor functions (neurological deficit score 3.36±0.25). Mean total infarct volume of left (ischemic) hemisphere was 85.2±4.9 mm3 and 47 percent of infarction occurred in subcortical regions of the brain. Induction of focal cerebral ischemia in the left (ischemic) hemisphere of the brain significantly increased water content (83.1±0.29 percent) compared to both hemispheres of sham group and right hemisphere of the same group. Success rate of ischemia induction was 97.6 percent and mortality rate was 4.21 percent. These findings indicate, this can be used for brain ischemia studies with high success rate, low mortality rate and narrow variety of the size and location of infarct volume. This model provides controlled and standard conditions to study ischemic brain injury and edema formation and introduce new therapeutic strategies.