Effect of methylmercury exposure on different neurotransmitter systems in rat brain.

The effect of methylmercury (4.0 mg/kg/day, for 50 days) exposure was studied on various neurotransmitter systems in hypothalamus, pons-medulla, brain-stem, and striatum of rats. Although methylmercury exposure resulted in marked increases in dopamine (DA) content of various brain regions and in the brain-stem or striatal norepinephrine (NE) level, the level of metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) was markedly decreased in the same regions. On the other hand, concentrations of 5-hydroxyindoleacetic acid (5-HIAA) in various brain regions were considerably decreased in methylmercury-exposed rats. Similarly, the 5-hydroxytryptamine (5-HT) level was markedly decreased in the hypothalamus, brain-stem, and striatum.