Background: Clinical relevance is an essential requirement for animal models of acute cerebrovascular disease. Middle cerebral artery embolic occlusion (eMCAo) in rats closely resembles human ischemic stroke. But this model is technically intricate and/or require more than a day of preparation before surgery.

Aims: Our aim was to elaborate straightforward thrombotic focal cerebral ischemia rat model, which would reproduce key components of human thromboembolic stroke.

Methods: Male Wistar rats (300–400g) were subjected to eMCAo by administration of an autologous blood clot in the following way. Under anesthesia (6% chloral hydrate, 300 mg/kg i.p.) left common carotid, external carotid and pterygopalatine arteries were ligated. The thrombus formed within 20 minutes in a syringe  (100 μl blood mixed with thromboplastin and CaCl₂) was introduced into the left internal carotid artery. Control animals (n=5) were injected with saline. The incision was sutured 10 minutes after catheter removal. Neurological status was assessed two hours before euthanasia using 20-point scale. After 6 hours (n=4), 1 (n=3), 3 (n=6) and 6 (n=5) days, rat’s brain was removed, fixed and embedded in paraffin. Histological evaluation of neuronal damage was performed on hematoxylin-eosin stained coronal sections of brain.

Results: The overall mortality rate was 22% (during surgery – 5%, first day – 16%). Motor dysfunctions were found in rats after 1, 3, and 6 days (p<0.05) (Figure 1). Histological analysis 6 hours after surgery revealed foci of necrosis in striatum and cortex of ipsilateral hemisphere (ILH) in one rat, 3 days after – in four. On days 1 and 6, all rats had necrotic zones in ILH cortex, hippocampus, and subcortical regions. Quantitative analysis revealed a decrease in hippocampal pyramidal neurons density (p <0.05) (Table 2).

Neurological status assessment of eMCAo surged rats (20-point scale; * – p<0.05, Mann-Whitney test vs Control group)

Pyramidal neurons density in hippocampus of eMCAo surged rats (number of neurons per 1mm of laier length, ob. 20x; * – p<0.05, Mann-Whitney test vs Control group)

Conclusions: Presented thromboembolic stroke model doesn’t require microsurgery, long-term preparation, one surgery takes approximately 45 min and leads to reproducible manifested morpho-functional brain alterations.

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/new-thromboplastin-based-modification-of-thromboembolic-ischemic-stroke-model-in-rats/