Methylmercury neurotoxicity: Why are some cells more vulnerable than others?

Methylmercury (MeHg) is a ubiquitous environmental contaminant which produces well-defined neuropathologic alterations in the central nervous system. The cerebellum and visual cortex are the two primary targets of MeHg-induced neurotoxicity in both humans and mammals, and these targets are also reflected in the clinical symptoms. In the cerebellum, granule cells are extremely sensitive to MeHg-induced neurotoxicity, whereas neighboring Purkinje cells are spared, although they accumulate as much or more MeHg as compared to the cerebellar granule cells. The current review discusses several innate characteristics of each of these two cell types which may contribute to the differential selectivity of MeHg.