This article describes a 3-year experience with focal neocortical ischemia in three rat strains. Multiple groups of adult Wistar (n = 50), Fisher 344 (n = 31), and spontaneously hypertensive (n = 72) rats were subjected to permanent occlusion of the distal middle cerebral (MCA) and ipsilateral common carotid arteries (CCA). Twenty-four hours later the animals were killed, and frozen brain sections were stained with hematoxylin and eosin to demarcate infarcted tissue. The infarct volume for each section was quantified with an image analyzer, and the total infarct volume was calculated with an iterative program that summed all interval volumes. Neocortical infarct volume was the largest and most reproducible in the spontaneously hypertensive rats (SHR). Statistical power analysis to project the numbers of animals necessary to detect a 25 or 50% change in infarct volume with alpha = 0.05 and beta = 0.2 revealed that only the SHR model was practical in terms of requisite animals: i.e., less than 10 animals per group. Tandem occlusion of the distal MCA and ipsilateral CCA in the SHR strain provides a surgically simple method for causing large neocortical infarcts with reproducible topography and volume. The interanimal variability in infarct volume that occurs even in the SHR strain dictates that randomized, concomitant controls are necessary in each study to ensure the accurate assessment of experimental manipulations or pharmacologic therapies.

Background and Purpose-Both the administration of growth factors and physical therapy such as forced arm use (FAU) are promising approaches to enhance recovery after stroke. We explored the effects of these therapies on behavioral recovery and molecular markers of regeneration after experimental ischemia. Methods-Rats were subjected to photothrombotic ischemia: sham (no ischemia), control (ischemia), brain-derived neurotrophic factor (BDNF; ischemia plus BDNF, 20 g), and FAU (ischemia plus FAU, 1-sleeve plaster cast ipsilateral limb). Animals survived 1 or 6 weeks and underwent behavioral testing (Rotarod, beam balance, adhesive removal, plantar test, neuroscore). After the rats were killed, brain sections were immunostained for semiquantitative analysis of MAP1B, MAP2, synaptophysin, GFAP expression, and quantification of infarct volumes. Results-Infarct volumes were not different between the groups 1 or 6 weeks after ischemia. BDNF-treated animals had better functional motor recovery (Rotarod, beam balance, neuroscore) compared with all other groups (PϽ0.05). There was no significant adverse effect of early FAU treatment on motor recovery, although sensorimotor function (adhesive removal test) was impaired (PϽ0.05). There were no differences between groups as measured by nociception of the left and right forepaw (plantar test). BDNF treatment transiently induced MAP1B expression in the ischemic border zone and synaptophysin expression within the contralateral cortex 6 weeks after ischemia (PϽ0.05

Background and Purpose-Pretreatment with intraventricular brain-derived neurotrophic factor (BDNF) reduces ischemic damage after focal cerebral ischemia. In this experiment we studied the effect of intravenous BDNF delivered after focal cerebral ischemia on neurological outcome, infarct size, and expression of proapoptotic and antiapoptotic proteins Bax and Bcl-2, respectively. Methods-With the use of the suture occlusion technique, the right middle cerebral artery in rats was temporarily occluded for 2 hours. Thirty minutes after vessel occlusion, BDNF (300 g/kg per hour in vehicle; nϭ12) or vehicle alone (nϭ13) was continuously infused intravenously for 3 hours. After 24 hours the animals were weighed and neurologically assessed on a 5-point scale. The animals were then killed, and brains underwent either 2,3,5-triphenyltetrazolium chloride staining for assessment of infarct volume or paraffin embedding for morphology and immunohistochemistry (Bax, Bcl-2). Results-Physiological parameters (mean arterial blood pressure, PO 2 , PCO 2 , pH, body temperature, glucose) and weight revealed no difference between groups. Neurological deficit was improved in BDNF-treated animals versus controls (PϽ0.05, unpaired, 2-tailed t test). MeanϮSD infarct volume was 229.7Ϯ97.7 mm 3 in controls and 121.3Ϯ80.2 mm

Regional cerebral protein synthesis was investigated in the Mongolian gerbil during recovery from forebrain ischemia produced by bilateral common carotid artery occlusion for 5 min. At various recirculation periods up to 72 h animals received a single dose of L-(3,5-3H)tyrosine and were killed 30 min later. Brains were processed for autoradiography using the stripping film technique. During the initial 30 min of recirculation autoradiographs revealed an almost complete inhibition of protein synthesis in all forebrain structures with the exception of the medio-dorsal thalamic nuclei. Between 30 min and 12 h of recirculation amino acid incorporation was completely restored in neurons of the cerebral cortex, basal ganglia, hippocampal CA3 and CA4 zones and the dentate gyrus. In CA1, early (90-min postischemia) and progressive recovery of a few irregularly dispersed neurons was observed, but the vast majority of pyramidal cells never regained their normal biosynthetic activity. Between 3 and 6 h of recirculation CA1 neurons showed faint labeling, followed by a secondary deterioration resulting in complete lack of incorporation within 12 h after restoration of blood flow. Autoradiographs at all subsequent time points exhibited persistent inhibition of protein synthesis in CA1 until neuronal necrosis occurred 2-3 days later. Thus, in contrast to ischemia-resistant cell populations with rapid progressive and complete restoration of protein synthesis, hippocampal neurons undergoing delayed necrosis are characterized by an early incomplete recovery immediately followed by a secondary persistent inhibition.