FETAL GRAFTS FROM HIPPOCAMPAL REGIO SUPERIOR ALLEVIATE ISCHEMIC-INDUCED BEHAVIORAL DEFICITS

Transitory global cerebral ischaemia produced in rats by four vessel o cclusion for 15 min produced substantial loss of CA1 cells in dorsal h ippocampus and minimal other intra- and extra-hippocampal damage. Isch aemic rats showed a long-lasting impairment in spatial navigation in t he water maze, and such impairment was sensitive to task difficulty. G roups of ischaemic animals were implanted with foetal tissue dissected from hippocampal regio superior (SUP-containing CA1 field), regio inf erior (INF-containing dentate gyrus), and basal forebrain, with grafts sited in the alveus above the damaged CA1 region, Behavioral testing in the water maze (acquisition, retention and a working memory task) w as conducted over a period of 4 to 12 weeks after grafting. Only rats receiving the SUP graft showed consistent improvement in water maze pe rformance, relative to ischaemic controls, when tested in retention an d working memory. Although the selective effect of CA1-containing graf ts suggests repairing of the damaged host circuit, functional recovery may have been related to the greater ability of SUP grafts to survive and grow in the host ischaemic hippocampus.