Chronic oral administration of methylcyclopentadienyl manganese tricarbonyl altered brain biogenic amines in the mouse: comparison with inorganic manganese.

This study was conducted to investigate the effects associated with high dose administration of organic manganese to mice and to compare these effects with those of inorganic manganese. The disposition and toxicity of methylcyclopentadienyl manganese tricarbonyl (MMT; a potential substitute for lead in gasoline) in the brains of ddY mice was studied after 12-months administration (at 0.5 g/kg of MMT) in food. Mice exposed to inorganic manganese received 2.0 g/kg of MnCl2 in food for the same period. There was no significant difference in food intake between the control mice and the MMT-exposed mice or MnCl2-exposed mice. Normetanephrine level in the cerebellum of the MMT-exposed group was significantly increased compared with the control, and correlated with the manganese concentration. The manganese concentration was significantly increased in the cerebellum of the MMT-exposed group compared with the control and MnCl2-exposed groups. On the whole, methoxylation from the 3-hydroxyl of catecholamine tended to be promoted by manganese.