Effect of manganese on biogenic amine metabolism in regions of the rat brain.
The effect of prolonged exposure to low-level manganese (Mn) on regional levels of biogenic amines in the rat brain was studied. Rats were given Mn in drinking-water for 90 days, which resulted in a two- to three-fold accumulation of Mn in all regions of the brain. After exposure, dopamine beta-hydroxylase (DBH), monoamine oxidase (MAO), dopamine (DA) and serotonin (5-HT) were measured in regions of the brain. There was a significant inhibition of DBH in the striatum (P less than 0.01), hypothalamus (P less than 0.01), mid-brain (P less than 0.001) and cortex (P less than 0.01). MAO was also decreased significantly in the cerebellum and cortex (both P less than 0.01). The striatum showed a decrease in DA content, but this was not significant. However, the hippocampus showed a significant decrease (P less than 0.01) and the mid-brain showed a significant increase (P less than 0.01) in DA levels. No significant changes were observed in 5-HT levels in any region, except for an increase in the cortex (P less than 0.01). It was observed that prolonged exposure of rats to low-level Mn affects both DBH and MAO, and that this effect is region-specific. However, the effect of Mn on biogenic amines seems to be variable, and this might explain the variable signs and symptoms observed in the various phases of Mn toxicity in humans.
Subhash
M N
MN
Department of Neurochemistry, National Institute of Mental Health and Neuro Sciences, Bangalore, India.
Padmashree
T S
TS
D000284:Administration, Oral; D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000201:enzymology; D001923:Brain Chemistry / Q000187:drug effects; D004298:Dopamine / Q000378:metabolism*; D004299:Dopamine beta-Hydroxylase / Q000378:metabolism; D008297:Male; D020149:Manganese Poisoning; D008995:Monoamine Oxidase / Q000378:metabolism; D051381:Rats; D012701:Serotonin / Q000378:metabolism*
D012701:Serotonin; D004299:Dopamine beta-Hydroxylase; D008995:Monoamine Oxidase; D004298:Dopamine