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 less than 0.001) characterized by sensorimotor dysfunctions and hemiplegia. Memory retention was significantly (p less than 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.