Effects of manganese on the nervous system.

The acute effect of manganese on the synaptosomal sodium-dependent choline uptake was studied. Manganese (Mn) revealed a mixed competitive-noncompetitive inhibition of the choline uptake, at Mn concentrations in the mM range. We do not believe that lack of choline for transmitter synthesis is of importance in Mn poisoning. Manganese chloride intubation of neonatal rats resulted in reduced homovanillic acid content in the striatum and hypothalamus. No other alteration in the dopamine or serotonin metabolism was revealed. A mechanism of cytotoxic action of manganese is discussed in terms of its transition metal properties and interaction with reactive oxygen compounds which result in the production of substances that alkylate or oxidize the cellular thiols.