INFLUENCE OF AN ENRICHED ENVIRONMENT AND CORTICAL GRAFTING ON FUNCTIONAL OUTCOME IN BRAIN INFARCTS OF ADULT-RATS

The purpose of this work was to study if enriched housing conditions a nd fetal neocortical transplantation could enhance the functional outc ome after focal brain ischemia in adult rats. The right middle cerebra l artery (MCA) was ligated in 34 inbred, spontaneously hypertensive ma le rats, which were then randomly divided into three groups. Groups A and B were transferred to an enriched environment, i.e., a large cage with opportunities for various activities but not forcing the rats to do any particular tasks; group C was kept in standard laboratory cages . Three weeks after the MCA occlusion blocks of fetal neocortical tiss ue (Embryonic Day 17) were transplanted to the infarct cavity in group s B and C. Rats in group A (n = 11) and group B (n = 11) performed equ ally well and significantly better than rats in group C (n = 10) when placed on an inclined plane and when traversing a rotating pole 6 and 9 weeks after the MCA occlusion and in a leg placement test at 9, but not 6 and 12 weeks. Skilled forelimb function did not differ between t he groups. Infarct size and thalamic atrophy did not differ between th e groups and graft size was similar in group B and C. There was no cor relation between infarct size and motor function in any of the tests i n rats housed in an enriched environment. Since the environment can si gnificantly alter functional outcome without reducing infarct size we suggest that more attention should be given to the role of the laborat ory environment and to long term behavioral outcome in experimental st roke. (C) 1995 Academic Press, Inc.