NEUROLOGICAL AND BEHAVIORAL OUTCOMES OF FOCAL CEREBRAL-ISCHEMIA IN RATS

Background and Purpose: The aim of this study was to investigate the neurobehavioral consequences of focal ischemia in rats. Methods: We induced permanent occlusion of the left middle cerebral artery in 14 Sprague-Dawley rats, and used 13 sham-operated rats as controls. During surgery, brain temperature and body temperature were kept at normothermia. Neurobehavioral studies (neurological examination, passive avoidance task, Y maze test, and modified open-field test) were carried out 4 days after ischemia before killing the rats to evaluate histological damage. Results: Ischemia induced large infarcts in the cortex (138.6 +/- 8.5 mm3) and caudate-putamen (48.8 +/- 2.6 mm3) and, compared with sham-operated rats, produced a dramatic neurological deficit (p < 0.001) characterized by sensorimotor dysfunctions and hemiplegia. Memory retention was significantly (p < 0.05) impaired in the passive avoidance task, but neither vigilance and exploratory behavior measured in the modified open-field test nor working memory evaluated in the Y maze test were disturbed. Infarct size was not correlated with the neurological or behavioral deficits. Conclusions: This lack of correlation indicates the necessity of carrying out parallel histological, neurological, and behavioral studies in any assays of new drugs using this model of focal ischemia.