Résumé
Fuel additive methylcyclopentadienyl manganese tricarbonyl (MMT) is counted as an organic manganese (Mn)-derived compound. The toxic effects of Mn (alone and complexed) on dopaminergic (DA) neurotransmission have been investigated in both cellular and animal models. However, the impact of environmentally relevant Mn exposure on DA neurodevelopment is rather poorly understood. In the present study, the MMT dose of 100 μM (about 5 mg Mn/L) caused up-regulation of DA-related genes in association with cell body swelling and increase in the number of DA neurons of the ventral diencephalon subpopulation DC2. Furthermore, our analysis identified significant brain Mn bioaccumulation and enhancement of total dopamine levels in association with locomotor hyperactivity. Although DA levels were restored at adulthood, we observed a deficit in the acquisition and consolidation of memory. Collectively, these findings suggest that developmental exposure to low-level MMT-derived Mn is responsible for the selective alteration of diencephalic DA neurons and with long-lasting effects on fish explorative behaviour in adulthood.
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•Developmental exposure to low-dose MMT induces brain Mn bioaccumulation.•Dopaminergic system dysfunction due to low-dose MMT-derived Mn.•Selective vulnerability of DA neurons controlling locomotor and sensory activity.•Long-term health risks from embryo exposure to environmentally relevant Mn.
Main findingsSelective vulnerability of dopaminergic neuron progenitors to low-dose MMT-derived manganese exposure and long-term neurological outcomes.