This animal study injected rats once with a low intravenous dose of manganese chloride and analyzed the brain four days later. Total brain manganese rose by about a fifth, with the largest increases in low molecular mass fractions including a citrate-sized fraction. Metabolomic analysis showed changes in amino acid, fatty acid, glutathione, glucose and nucleotide metabolism.
Key numbers
- Total brain manganese: 429.1 ± 15.9 ng/g after injection versus 360.1 ± 18.0 ng/g in controls (+19%, p < 0.001) (Table 1, p. 3).
- Aqueous brain extract manganese: 165.1 ± 18.0 versus 108.6 ± 4.8 ng/g (p < 0.001) (Table 1).
- Fold increases by size fraction: citrate-sized and amino-acid-sized fractions 1.8-fold (p < 0.001), transferrin-sized fraction 1.5-fold, largest and inorganic fractions 1.4-fold (Results, p. 4; n = 15 per group).
- Dose: 1.5 mg manganese/kg body weight, single intravenous injection (Introduction, p. 2).
Methods (brief)
Brains were extracted and manganese species separated by size-exclusion chromatography coupled to ICP-MS; methanolic extracts were profiled by ESI-ICR/FT-MS. Feces were collected for four days to follow excretion.
Evidence fitness
The paper supports mechanistic statements that manganese entering the brain shifts toward low molecular mass carriers and alters several brain metabolic pathways. Intravenous dosing bypasses gut and liver regulation, so it does not inform dietary exposure.
Limitations
A single low dose and one time point. Size fractions are assigned by retention time, not confirmed molecular identity, as the authors note. Results apply to rats.
Related evidence
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