Effects of middle cerebral artery occlusion on spontaneous activity and cognitive function in rats

The middle cerebral artery occlusion (MCAO) in the rat is a commonly used model to evaluate new therapeutic strategies for the treatment of ischemic stroke. However, many such studies rely on short-term neurological examination and infarct volume as endpoint measures while neglecting more long-term functional assessments. In this study, we examined whether there were changes in passive avoidance behavior, spontaneous behavioral patterns across the light-dark cycle, and motor coordination as measured on the rotorod test 1 month after Sprague-Dawley rats had undergone MCAO. Compared to age-matched controls, fewer animals in the MCAO group remained on the platform during the passive avoidance retention test (p < .03). Significant differences between the groups were observed in the spontaneous activity during the initial portions of both the light and dark testing periods, when the test situation was new (p < .01 to .05, depending on the variable examined). Any differences on the rotorod test failed to gain statistical significance. These results suggest that at least the passive avoidance test and measures of spontaneous activity are sensitive to ischemia-induced damage over a more prolonged survival period and therefore may be appropriate measures for long-term effectiveness of new treatments.