Motor performance in rats exposed to severe forebrain ischemia: effect of fasting and 1,3-butanediol

Functional assessment of animals following experimental cerebral ischemia is often difficult due to the passive nature of many neurologic exams. We attempted to increase the objectivity of motor function evaluation by adapting quantifiable behavioral tests and actively testing rats' motor capability following a cerebral ischemic insult. It was hypothesized that active testing would reveal motor deficits which were not readily apparent upon casual observation and that such testing would provide a more sensitive means of experimental neurologic assessment. Wistar rats were exposed to reversible severe forebrain ischemia using the four-vessel occlusion technique. Motor function was evaluated using the total motor score (sum of scores for screen test, balance beam test, and prehensile-traction test) over the 48 hours which followed 20 minutes of cerebral ischemia. To manipulate neurologic outcome, rats were fed or fasted the day prior to ischemia and then pretreated with either 1,3-butanediol or saline. Fasted saline-treated animals demonstrated improved total motor performance compared with fed animals by 48 hours after ischemia. There was no improvement in motor performance by fasted vs. fed rats from among the butanediol-treated animals. Pretreatment with butanediol resulted in significantly better total motor performance among fasted rats 24 hours after ischemia; however, by 48 hours postischemia, no difference was detectable. This is the first demonstration of motor deficits produced by four-vessel occlusion in rats. The motor tests devised appear to be adequately sensitive to detect changes in motor function that are not apparent with passive observation in this model.