A scanning electron-microscopic study of the effects of methylmercury on the neuronal cytoskeleton

Cultured mouse neuroblastoma cells, Neuro-2a (c1300), were exposed to 2.5 and 5.0 microM methylmercury (MeHg) with or without the concomitant administration of 10 mM glutathione for 24 h. Treated cells viewed by scanning electron microscopy (SEM) appeared sponge-like and were surrounded by fragments of cytoplasmic processes. SEM cytoskeletal preparations of treated cells showed a collapsed matrix containing globular bodies. Microtubules were not seen in treated cells, but intermediate and microfilaments were observed. SDS-PAGE analysis of cytoskeletal extracts revealed bands ranging in size from 90 to 27 kDa in all treatment groups except in the 5.0 microM-MeHg-treated group. This group showed a single band co-migrating with actin. Cells exposed to glutathione alone or concomitantly with MeHg appeared similar to control cells under all experimental conditions. These observations suggest that MeHg may predominantly affect microtubules to form a condensation product.