Improvement of a rat thromboembolic stroke model for thromboly sis study

Abstract

Objective To establish and validate a modified rat thromboembolic stroke model. Methods After taking femoral arterial blood and mixing it with thrombin, they were injected into PE-50 catheter for preparing in vitro thrombosis in 60 Sprague-Dawley rats. A thromboembolic cerebral ischemia model induced by catheterization of the risht enternal carotid artery and the small blood clot emboli were injected into the internal carotid arteries. Thirty rats were randomly divided into a large number of emboli group （n = 10 with 12 emboli）, a median number of emboli group （n = 10 with 10 emboli） and a small number of emboli group （n = 10 with 8 emboli）. Two hours after embolus injection, the neurological deficit score was performed and the success rate of the model was compared in all groups. Twenty-four hours after embolus injection, the rats were sacrificed and the brains were removed for 2, 3, 5-triphenyltetrazolium chloride staining. The hemorrhage, infarct volume, bleeding incidence and mortality after cerebral infarction were evaluated. The high success rates of the modeling in the emboli groups were selected and they were randomly divided into either a normal saline group （n = 12） or a recombinant tissue-type plasminogen activator （rtPA） group （n = 12）. The rats were given normal saline and rtPA at 3 hours after embolus injection. Before embolus injection and 2, 6, 12 and 24 hours after embolus injection, the neurological scores were performed respectively; 24 hours after embolus injection, the rats were sacrificed and the brains were removed for 2,3,5-triphenyltetrazolium chloride staining. The hemorrhage rate, infarction size, degree of cerebral edema, and blood-brain barrier permeability were evaluated. Results Only 40% of rats had neurological deficits in the small number of emboli group, and the infarct volume was only 10.54 ±2. 82%. The success rates in the median and large number of emboli groups were 80% and 100% respectively. They were all significantly higher than those in the small number of emboli group （P = 0. 011 ）. The infarct volume was also significantly greater than that in the small number of emboli group （F = 40. 897, P = 0. 000）. After administration of rtPA, the mean survival time of the rats in the large number of emboli group was less than 24 hours, so the median number of emboli group was selected to study the thrombolytic effect of rtPA. The infarct volume and neurological function score in the rtPA group were improved significantly compared to the normal saline group （t = 7. 728, P = 0. 000）, while there were no significant differences in the hemorrhage rate, degree of brain edema and blood-brain barrier permeability between the 2 groups. Conclusions The stability and reproducibility were good in the modified thromboembolic cerebral ischemia model injected with 10 emboli, the neurological fimction was improved significantly after thrombolysis, and it was applicable to the experimental study of pathophysiology of cerebral ischemia and thrombolytic therapy. Key words: Disease Models, Animal; Thromboembolism; Brain lschemia; Cerebral Hemorrhage; TissuePlasminogen Activator; Rats