IMPROVEMENT OF PASSIVE-AVOIDANCE TASK AFTER GRAFTING OF FETAL STRIATAL CELL-SUSPENSIONS IN ISCHEMIC STRIATUM IN THE RAT

Behavioral recovery and cell survival/growth after grafting of fetal s triatal cell suspensions in the ischemic striatum of rats were investi gated. Ischemia was induced by one hour intraluminal occlusion of the right middle cerebral artery under halothane anesthesia. During the is chemia rats usually manifested signs of hemiparesis and sometimes rota tions. Behavioral function was measured by a passive avoidance task an d radial arm maze test at 1-2 weeks and 6-7 weeks after ischemia. The size of the ischemic lesions depended on each animal, but the ischemic animals showed deficits in both passive avoidance task and radial maz e test. Two weeks after ischemia, fetal striatal cells, marked with Di I, were transplanted into the ischemic striatum. The transplantation i mproved the ischemia-induced deficit in the passive avoidance task but not in radial maze test. Although there were variations in the size o f the grafts, many DiI-positive cells with dendritic outgrowth were de tected under fluorescent microscopy. Immunohistochemical study reveale d that many choline acetyltransferase (ChAT) positive cells and GABA-p ositive cells survived in the grafts. However, striosome-matrix compar tments were not evident inside the grafts. Thus, partial recoveries in both cytoarchitectural and behavioral aspects were obtained by striat al cell grafts, suggesting that neural transplantation could be a usef ul approach in reconstructing ischemic brain function.