Neural grafting to ischemic and excitotoxic, hippocampal lesions in the adult rat.

Results of neural grafting to excitotoxic and ischemic lesions of the adult rat hippocampus is reviewed with particular emphasis on the exchange of host-transplant nerve connections. Based on observations obtained by a variety of tracing techniques about 6 weeks after--(i) grafting of pieces of neonatal fascia dentata to one week old ibotenic acid lesions of the adult rat fascia dentata, (ii) grafting of suspensions of late fetal CA3 cells to one week old ibotenic acid lesions of the adult rat CA3--and (iii) grafting of suspensions of late fetal CA1 cells to one week old ischemic lesions of the adult rat CA1, we conclude that axon-sparing lesions of the mentioned types enhance the growth of adult host brain axons of the so called point-to-point type into neural grafts. We interpret these findings as the result of an improved capability of adult host brain axons to participate in the graft host interaxonal competition for synaptic sites in the developing neural grafts. At the same time an extensive growth of graft CA3 and CA1 axons into the host brain was demonstrated.