Septotemporal gradients of trimethyltin-induced hippocampal lesions.

Rats were administered 6 mg/kg trimethyltin (TMT) PO, and sacrificed at various time points (up to 60 days) for pathological evaluation. Studies along the full extent of the septotemporal axis revealed region-specific and cell field-specific damage. Dentate granule cells were most affected at the temporal pole and were only minimally affected at the septal pole. CA3c pyramidal neurons were affected along the full extent of the septotemporal axis. CA3a and CA3b pyramidal cells were most affected in the septal pole, and virtually unaffected in the temporal pole. It is suggested that CA3a and CA3b pyramidal cell damage may be dependent upon functionally intact granule cells.