Time-dependent effects of global cerebral ischemia on anxiety, locomotion, and habituation in rats.

Although changes in emotionality represent common features of post-ischemic recovery in humans, little is known about the effects of global cerebral ischemia on standard behavioral measures of emotionality in rodents. The present study investigated anxiety, locomotor activity, and habituation in test-naïve ischemic (subjected to 10 min global ischemia) and sham-operated rats tested 1, 5, 15, and 30 days post-reperfusion in the elevated plus-maze and the open-field. Although rats tested on day 1 post-reperfusion showed increased anxiety relative to sham-operated controls, they demonstrated decreased anxiety on day 5. Anxiety levels were normal on days 15 and 30 following ischemia. Similarly, time-dependent changes in locomotor activity were observed with ischemic rats showing increased activity level on days 1, 5, and 30 post-reperfusion. Surprisingly, locomotor activity was suppressed at day 15. Habituation deficits in the open-field were apparent only on day 1 despite the lack of CA1 neuronal degeneration at this time interval. These findings suggest that both the nature and extent of the effects of global ischemia on behavioral measures of emotionality, locomotion, and habituation in rats are time-dependent.