INFLUENCE OF FETAL HIPPOCAMPAL GRAFTS ON LESIONS INDUCED BY INTRAVENTRICULAR INFUSION OF N-METHYL-D-ASPARTATE (NMDA) INTO RATS

Effects of fetal hippocampal transplants were evaluated following a pr olonged intraventricular excitotoxic lesion (1.0 mg of N-methyl-D-aspa rtate over two weeks infusion) in F344 rats. The septum and ipsilatera l hippocampus (CA1 and dentate regions) showed extensive cell loss, de creased acquisition of spatial memory was observed and a decrease in A ChE positive fiber innervation to the hippocampus was noted following the lesion. Fetal hippocampal transplants into the posterior lateral v entricle resulted in moderate graft survival and physiological analysi s of graft-host interconnection in vitro demonstrated evoked field pot entials. However, the transplants did not lead to significant improvem ent in behavior, possibly due to poor synaptic integration of the intr aventricular transplants into the host hippocampus. The prolonged intr aventricular NMDA lesion may be helpful to understand a mixed lesion m odel of both septal areas and hippocampus and also as a background les ion in which to assess the connectivity and development of various typ es of neural grafts.