Effect of interaction of Mn2+ with Zn2+, Hg2+ and Cd2+ on some neurochemicals in rats.

Manganese chloride was administered alone or in combination with zinc chloride, mercuric chloride and cadmium chloride i.p. to rats daily for 30 days to investigate the effect of interaction of these elements on the contents of aromatic amino acids, biogenic amines and 5-hydroxyindole acetic acid (5-HIAA) in the brain. Combined manganese (Mn) and zinc (Zn) administration had an antagonistic effect on the contents of aromatic amino acids, but no effect on dopamine (DA) and produced a significant decrease in the content of 5-hydroxytryptamine (5-HT). Combination of Mn with mercury (Hg) or cadmium (Cd) produced pronounced changes in these neurochemicals indicating a more serious effect on the brain compared with a single treatment with either metal.