The aim of the present work was to test the hypothesis that early ischemic preconditioning provides effective protection of the brain against ischemic damage via effects on cerebral blood flow. Experiments were performed using male Wistar rats anesthetized with thiopental using two methods to produce ischemia: 1) ligation of the left common carotid and left middle cerebral arteries; 2) endovascular occlusion of the middle cerebral artery for 30 and 60 min. Preconditioning was modeled using two 5-min episodes of bilateral occlusion of the common carotid arteries with 5-min reperfusion periods. Infarct size was assessed by staining with triphenyltetrazolium chloride; major vessel blood flow was measured by Doppler ultrasonography, and ischemic zones were measured by staining with Evans blue. Preconditioning led to significant decreases in infarct size after ischemia for 30 and 60 min and after ischemia without reperfusion. Preconditioning had no effect on measures of major vessel blood flow in the middle cerebral artery, as indicated by Doppler ultrasonography data. The ischemic preconditioning group showed no decreases in ischemic zone size 5 min after occlusion of the left middle cerebral artery, while 30–40 min after the onset of ischemia there was a reduction in the ischemic zone in the preconditioning groups. Along with cytoprotective effects, ischemic preconditioning decreased ischemic zone size and had marked additional infarct-limiting effects in focal transient and permanent cerebral ischemia in rats.
Neuroscience and Behavioral Physiology: V.42, Issue 6 (2012), P. 643-650.