A Novel Thromboplastin-Based Rat Model of Ischemic Stroke

Abstract

The thromboembolic ischemia model is one of the most applicable for studying ischemic stroke in humans. The aim of this study was to develop a novel thromboembolic stroke model, allowing, by affordable tools, to reproduce cerebral infarction in rats. In the experimental group, the left common carotid artery, external carotid artery, and pterygopalatine branch of maxillary artery were ligated. A blood clot that was previously formed (during a 20 min period, in a catheter and syringe, by mixing with a thromboplastin solution and CaCl₂) was injected into the left internal carotid artery. After 10 min, the catheter was removed, and the incision was sutured. The neurological status of the animals was evaluated using a 20-point scale. Histological examination of brain tissue was performed 6, 24, 72 h, and 6 days post-stroke. All groups showed motor and behavioral disturbances 24 h after surgery, which persisted throughout the study period. A histological examination revealed necrotic foci of varying severity in the cortex and subcortical regions of the ipsilateral hemisphere, for all experimental groups. A decrease in the density of hippocampal pyramidal neurons was revealed. Compared with existing models, the proposed ischemic stroke model significantly reduces surgical time, does not require an expensive operating microscope, and consistently reproduces brain infarction in the area of the middle cerebral artery supply.

Keywords: brain injury; embolic stroke; hippocampus; rat model; thromboplastin.

Figure 1

Scheme of thromboembolic occlusion of the MCA. CCA—common carotid artery, MCA—middle cerebral artery, ICA—internal carotid artery, PPA—pterygopalatine artery, BA—basilar artery, ECA—external carotid artery, ACA—anterior cerebral artery, PCA—posterior cerebral artery.

Figure 2

Neurological assessment of animal status 24 h after embolic MCAO; 20-point scale, *—significant difference vs control (p ≤ 0.05, Mann-Whitney U-criterion). The data is presented as mean with standard deviation.

Figure 3

Decrease in neurological status in post stroke period persisted for 5 days after MCAO. The 20-point scale, *—significant difference vs. control (p ≤ 0.05. Wilcoxon W-criterion). The data are presented as mean with standard deviation.

Figure 4

Frontal slices of rat brain, hematoxylin-eosin staining. Ischemic lesions in the territory of the left hemisphere supplied by MCA: striatum, cortex, hippocampus. (a,b) Sham control, no areas of damage in the ipsilateral and contralateral cerebral hemispheres. (c,d) A total of 24 h after embolization, infarct areas in the striatum and cortex are pale-stained. (e,f) A total of 72 h after embolization, infarct areas in the striatum and hippocampus. (g,h) A total of 6 days after embolization, infarct areas in the striatum, cortex, hippocampus, and thalamus.