Limited Therapeutic Time Windows of Mild-to-Moderate Hypothermia in a Focal Ischemia Model in Rat
Figure 1
(Revised from [16]). Intraischemic moderate hypothermia (30°C) reduces infarct size in a focal ischemia with partial reperfusion. Focal ischemia was induced by 1 h of bilateral CCA occlusion and permanent dMCAo. Body core temperature was lowered to 30°C 10 min before stroke onset by spraying 70% alcohol on the rat body. (a) The upper panel shows representative infarcts stained with cresyl violet from rats euthanized 2 d after stroke. The pale area with asterisks represents the infarct region. Normothermic ischemia damaged the cortex ipsilateral to the occluded MCA, whereas hypothermia spared all or most of the injured cortex. Only a small lesion was observed in the presented section from a hypothermic rat. The bar graphs represent statistical analysis of infarct size 2 d after stroke. Two-way ANOVA (two factors, temperature and brain section level) was used to compare the effect of temperature on the infarct size at each level (data not shown) and on the mean of all 4 levels. Hypothermia () reduced the mean infarct size by 80% compared with normothermia (; ). (b) The upper panel shows representative sections stained with cresyl violet from animals surviving 2 months after stroke. Most of the cortex in the infracted hemisphere was lost in normothermic but not hypothermic rats. The lower panel of bar graphs shows infarct size 60 d after stroke. Hypothermia () reduced infarct size 60 d after stroke compared with normothermia (; ). # versus 37°C, .
