Hippocampal but not astrocyte transplants enhance recovery on a forced choice alternation task after kainate lesions.

In rats, intrahippocampal injections of kainate produced selective lesions of the CA3 pyramidal cells and a performance deficit on a forced-choice alternation task. Transplants of embryonic hippocampus significantly facilitated recovery on the alternation task whereas hippocampal transplants taken from adult donors showed a similar but non-significant trend in recovery. Previous data have shown that after frontal cortex ablation transplants of cultured astrocytes facilitated behavioral recovery. After hippocampal lesions however transplants of cultured astrocytes, either before or after kainate injections, did not facilitate recovery on the alternation task. Trophic activity produced by astrocytes did not appear to be sufficient to enhance the rate of recovery. Replacement of damaged neurons may be required for the observed enhanced behavioral recovery.