HIPPOCAMPAL AMINO-ACID-CONCENTRATIONS AFTER RAPHE AND OR SEPTAL CELL-SUSPENSION GRAFTS IN RATS WITH FIMBRIA-FORNIX LESIONS/

Two weeks after infracallosal electrolytic fimbria-fornix lesions, Lon g-Evans female rats received intrahippocampal suspension grafts of eit her fetal septal or mesencephalic raphe tissue, or a mixture of both. Ten months after lesion surgery, the concentrations of alanine, aspart ate, GABA, glutamate, glutamine, glycine, serine and taurine were dete rmined in a dorsal, a ''middle'' and a ventral region of the hippocamp us. We found neither the lesions nor the grafts to have significantly modified the concentration of these amino acids which, in all groups, presented a regional heterogeneity in their hippocampal distribution. GABA, glutamate and glutamine were highest in the ventral hippocampus, whereas the other amino acids were highest in the dorsal region. Our results (i) show that fimbria-fornix lesions do not result in lasting effects on hippocampal concentrations of the assessed amino acids, (ii ) confirm the regional heterogeneity in the distribution of these amin o acids in the hippocampus and (iii) demonstrate that cell suspension grafts of fetal septal or mesencephalic raphe tissue, as well as graft s of a mixture of both of these tissues, do not exert a non-specific e ffect on either of the amino acid concentrations measured.These data c omplete those of the preceeding paper [Kiss et al. (1990) Neuroscience 36, 61-72] concerning the effects of the same grafts on hippocampal c holinergic, serotonergic and noradrenergic markers, as well as on seve ral behavioural variables.