Long-term functional end points following middle cerebral artery occlusionin the rat

The purpose of the present study was to assess the magnitude and stability of a number of functional deficits in rats subjected to occlusion of the mi ddle cerebral artery (MCAO). Three groups of rats, treated with 90-min, 120 -min, or sham occlusion were used in functional studies for 22 weeks follow ing surgery. The following tests were used: methamphetamine-induced rotatio n, the staircase test, acquisition of operant responding, running-wheel beh avior, and performance of operant differential reinforcement of a low-rate responding (DRL) schedule of reinforcement. Histology performed at 23 weeks following infarct showed on average modest damage of a 19% reduction in he mispheric volume. Of the behavioral tests conducted, rotation, the staircas e test, and the operant DRL were sensitive to ischemic damage, and were und er some circumstances related to lesion size. These data show that long-ter m functional deficits following MCAO are demonstrable, and hence, assessmen t of long-term neuroprotection is feasible. (C) 2000 Elsevier Science Inc.