Hippocampal lesions induced by trimethyltin in the neonatal rat brain

The neuropathology of trimethyltin (TMT) chloride on neonatal rat hippocampus was investigated. It was found that the development of pathological lesions in the developing hippocampus is age-dependent and the most vulnerable age period was between postnatal days (PND) 9 and 15. TMT-treated animals appeared to be significantly stunned in growth. Brains of these animals were also markedly smaller than those of age-matched controls. Histopathology and electron microscopy examination of the hippocampus on PND 15, 21 and 24 from animals exposed to 6.0 mg TMT-Cl/kg b.w. on PND 11 revealed rapid destructions of the Ammon's horn. The granule cells of fascia dentata, despite some non-specific pathological changes (swelling, lysosomal accumulation), showed only minimal necrotic activity. Pyramidal neurons of the Ammon's horn, however, displayed extensive damage. Extensive neuronal edema, accumulation of lysosomes and myelinoid membranous bodies and cellular necrosis were observed as early as 4 days (PND 15) after exposure. By PND 24, total abolishment of the Ammon's horn occurred with extensive dystrophic calcification and astrocytic gliosis of the area.