Brain manganese accumulation following systemic administration of different forms

Area of Science:

• Neuroscience
• Toxicology
• Environmental Health

Background:

• Manganese is an essential element, but excessive exposure can lead to neurotoxicity.
• Different forms of manganese may have varying toxicokinetic profiles.
• Understanding manganese retention in the brain is crucial for assessing neurotoxic risk.

Purpose of the Study:

• To compare the content and retention of manganese in the blood and brain of mice after exposure to different manganese forms.
• To investigate the time course of manganese accumulation and persistence in the brain and blood.

Main Methods:

• Mice received acute subcutaneous injections of manganese chloride, manganese oxide (Mn3O4), or methylcyclopentadienyl manganese tricarbonyl (MMT).
• Brain and blood manganese concentrations were measured at various time points post-injection.
• The effects of single versus repeated injections were assessed.

Main Results:

• A single injection of manganese markedly elevated brain manganese within 1 day, with levels sustained for at least 21 days.
• Repeated injections further increased manganese in both brain and blood.
• Manganese chloride resulted in higher brain manganese concentrations compared to manganese oxide and MMT.
• Brain manganese levels showed persistent high concentrations for extended periods.

Conclusions:

• Manganese exposure leads to significant and persistent accumulation in the mouse brain.
• The chloride form of manganese appears to be more efficiently retained in the brain.
• Persistent retention of manganese in brain tissue is a potential mechanism for slow-developing neurotoxicity.