Cytotoxicity of tributyltin in rat hippocampal slice cultures.

The neurotoxic effects of tributyltin (TBT), an endocrine-disrupting chemical, were evaluated in organotypic slice cultures of immature rat hippocampus. Confocal microscopy study with propidium iodide showed that TBT induced severe neuronal death in a concentration- and time-dependent manner with CA3 > CA1 > dentate gyrus ranking of vulnerability of the hippocampal subfields. Dead or damaged neurons exhibited chromatin condensation, which is one of the morphological characteristics of apoptosis, as revealed by acridine orange staining. TBT neurotoxicity was alleviated by application of free radical scavengers or antioxidants, such as catalase, superoxide dismutase, Trolox and alpha-tocopherol but not by ascorbic acid or N-acetyl-L-cysteine, which suggests an involvement of free radicals, particularly reactive oxygen species. Neurons displayed a long-lasting increase in intracellular Ca2+ concentrations after TBT treatment. Although neither N-methyl-D-aspartate (NMDA) receptor inhibitors nor voltage-sensitive Ca2+ channel blockers protected hippocampal neurons against TBT neurotoxicity, non-NMDA receptor antagonist completely prevented TBT-induced neurodegeneration. These data suggest that TBT provokes apoptosis-like neuronal cell death, which might be mediated by intracellular Ca2+ elevation and free radical generation via non-NMDA receptor activation.