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The effect of manganese inhalation on basal ganglia dopamine concentrations in rhesus monkey
Abstract:
Manganese (Mn) may produce neurotoxicity in man through inhalation of Mn dust. Animals exposed to excessive Mn develop neurological abnormalities, and neuropathological lesions in the brain mainly in the globus pallidus with decreased concentrations of the neurotransmitter, dopamine (DA), in the brain. Monkeys exposed to Mn by inhalation did not produce any abnormal movements. After two years, the animals were sacrificed and certain brain areas were compared to controls. There were significant decreases in DA concentration in caudate and globus pallidus, and there was a 60-80% increase in Mn concentration in the basal ganglia of the brain. The DA system in the basal ganglia is vulnerable to the effects of Mn, but the amount of Mn inhaled and the period of exposure would appear to determine whether abnormal neurological signs develop.
Insights
Inhaled manganese (Mn) dust can cause neurotoxicity. Studies show Mn exposure damages the dopamine system in the brain, particularly the basal ganglia, even without visible neurological signs.
Area of Science:
- Neuroscience
- Toxicology
- Environmental Health
Background:
- Manganese (Mn) exposure, primarily through inhalation of dust, is a known risk factor for neurotoxicity in humans.
- Animal studies demonstrate that excessive Mn exposure leads to neurological abnormalities and specific neuropathological lesions in the brain, notably in the globus pallidus.
Purpose of the Study:
- To investigate the neuropathological and neurochemical effects of chronic manganese inhalation in a primate model.
- To assess the impact of manganese exposure on dopamine concentrations and brain tissue in specific areas.
Main Methods:
- Monkeys were exposed to manganese dust via inhalation for an extended period (two years).
- Following exposure, animals were sacrificed, and specific brain regions, including the basal ganglia (caudate and globus pallidus), were analyzed.
- Concentrations of manganese and dopamine were measured and compared to control groups.
Main Results:
- Despite no observable abnormal movements during exposure, significant neurochemical changes were detected in the exposed monkeys.
- A notable decrease in dopamine (DA) concentration was observed in the caudate nucleus and globus pallidus.
- Manganese levels in the basal ganglia significantly increased by 60-80% compared to control subjects.
Conclusions:
- The dopamine (DA) system within the basal ganglia is particularly vulnerable to the neurotoxic effects of inhaled manganese.
- The development of overt neurological signs appears to be dependent on the cumulative dose of manganese inhaled and the duration of exposure.