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.

Calcium and phosphorus levels in serum and CSF in dementia.

Marked differences in CSF levels of both calcium and phosphorus were observed in patients with dementia and aged controls when compared with adult controls. A significant decrease in both Ca and P in CSF was observed in Alzheimer's type dementia (p less than 0.01) and multi-infarct dementia cases (p less than 0.01). The geriatric controls also showed a significant decrease in both Ca and P. A 60% decrease in diffusible Ca in CSF was noted both in patients and geriatric controls when compared to adult controls (p less than 0.001). Diffusible P was also decreased in all three groups (p less than 0.05). A marginal decrease in serum Ca and slight increase in P was observed in both patients and geriatric controls. The significant decrease in CSF Ca and P in both groups of patients compared with aged controls suggests this lowering of Ca and P is not due to solely to the aging process and indicates a role in the pathology of age-related disorders.

Regional distribution of dopamine beta-hydroxylase and monoamine oxidase in the brains of rats exposed to manganese.

The regional distribution of dopamine beta-hydroxylase (DBH) and monoamine oxidase (MAO) in rat brain was compared in control rats and rats given manganese in drinking-water (1 mg Mn/ml) for 30 days. In treated rats there was a significant accumulation of Mn in almost all regions of the brain except the hippocampus. Accumulation was highest in the hypothalamus, cortex and striatum. After Mn exposure, DBH activity was significantly decreased (in comparison with the controls) in the hypothalamus, striatum, mid-brain, cerebellum and cortex. A significant increase in MAO activity was found in the striatum, hypothalamus, mid-brain, hippocampus and medulla. The effects of Mn on these enzymes suggests the involvement of biogenic amines like dopamine, norepinephrine and serotonin during Mn toxicity. The effect of Mn is region specific and in certain regions the action of Mn on DBH differs from that on MAO. These different effects of Mn on DBH and MAO in different regions of the brain might explain the variable symptoms seen in Mn-induced neurotoxicity in humans.

Studies on down's syndrome and maternal age.

Details of clinical, genetic and karyotyping investigations carried out on thirty patients with Down's syndrome are described. All the patients showed Trisomy - 21,The information relating to the maternal age revealed that women in the age group of 15-35 also had cases of Down's syndrome which is in contrast to the findings made in western countries.