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Role of dopamine in manganese neurotoxicity
M Parenti1, L Rusconi, V Cappabianca
1Department of Pharmacology Emilio Trabucchi, University of Milan, Italy.
Abstract:
Manganese chloride increased cell mortality when added to human fibroblast cultures. The toxicity of the metal was greatly enhanced by dopamine; this effect was antagonized by the presence in the culture medium of catalase and superoxide dismutase enzymes. Manganese chloride also caused a marked decrease of striatal dopamine concentrations when infused into rat substantia nigra. Manganese neurotoxicity was lowered by pretreating the animals with drugs that reduced striatal dopamine turnover rate. Administration of an antioxidant, such as vitamin E, also partially prevented striatal dopamine decline induced by intranigral manganese infusion. Therefore, the decreased availability or autoxidation of dopamine attenuated manganese neurotoxicity. These findings are in agreement with previous observations suggesting that manganese increases toxic products originating from dopamine catabolism.
Insights
Manganese chloride is toxic to human cells and brain tissue, with dopamine significantly increasing its harmful effects. Antioxidants and enzymes that reduce dopamine levels or its oxidation can protect against manganese neurotoxicity.
Area of Science:
- Neuroscience
- Toxicology
- Cell Biology
Background:
- Manganese is an essential trace element, but excessive exposure can lead to neurotoxicity.
- Dopamine, a key neurotransmitter, has been implicated in the mechanisms of metal-induced neurodegeneration.
- Understanding the interaction between manganese and dopamine is crucial for neuroprotection strategies.
Purpose of the Study:
- To investigate the role of dopamine in manganese-induced cell mortality and neurotoxicity.
- To explore the protective effects of antioxidants and enzymes against manganese toxicity.
- To elucidate the mechanisms underlying manganese neurotoxicity in relation to dopamine metabolism.
Main Methods:
- In vitro studies using human fibroblast cultures exposed to manganese chloride and dopamine.
- In vivo studies involving intranigral infusion of manganese chloride in rat substantia nigra.
- Assessment of cell mortality, dopamine concentrations, and the effects of catalase, superoxide dismutase, and vitamin E.
Main Results:
- Manganese chloride increased cell mortality, an effect potentiated by dopamine.
- Catalase and superoxide dismutase antagonized manganese-dopamine toxicity in vitro.
- Manganese infusion decreased striatal dopamine concentrations in rats, an effect mitigated by drugs reducing dopamine turnover and by vitamin E.
- Reduced dopamine availability or autoxidation attenuated manganese neurotoxicity.
Conclusions:
- Dopamine significantly enhances manganese neurotoxicity, likely through increased toxic dopamine catabolism products.
- Antioxidants and enzymes that manage dopamine levels or its oxidative stress offer potential protective mechanisms against manganese neurotoxicity.
- These findings highlight the critical role of dopamine metabolism in manganese-induced cellular damage and neurodegeneration.