Age-dependent susceptibility to manganese-induced neurological dysfunction

Area of Science:

• Neuroscience
• Toxicology
• Developmental Biology

Background:

• Chronic manganese (Mn) exposure causes neurodegenerative deficits similar to Parkinson's disease.
• Effects of Mn on adult brains are known, but impacts on the developing brain are less understood.

Purpose of the Study:

• To investigate the behavioral and neurochemical effects of Mn exposure in the developing brain.
• To compare Mn toxicity in juvenile versus adult mice, and assess the impact of combined juvenile and adult exposure.

Main Methods:

• C57Bl/6 mice were exposed to Mn via intragastric gavage at juvenile, adult, or both stages.
• Behavioral changes (locomotor activity, novelty-seeking) and neurochemical alterations (dopamine, Mn, Fe, Cu levels) were assessed.
• Tissue analysis used inductively coupled plasma-mass spectrometry (ICP-MS).

Main Results:

• Juvenile male mice showed heightened sensitivity to Mn, with increased novelty-seeking and hyperactivity.
• Adult male mice pre-exposed as juveniles exhibited reduced movement and novelty-seeking.
• Mn accumulated most in the striatum, substantia nigra (SN), and cortex of juvenile mice.

Conclusions:

• The developing brain is more vulnerable to Mn toxicity than the adult brain.
• Juvenile Mn exposure exacerbates neurochemical and behavioral dysfunction, especially when followed by adult exposure.
• Sex- and age-dependent differences in Mn vulnerability were observed.