Potential interactions between toxicant-containing LC and motor neurons (see text for details). Toxicant uptake into the LC could reduce noradrenaline output, resulting in: (A) A dysfunctional blood-brain barrier, which becomes permeable to the same or other toxicants, or to inflammatory agents. (B) Decreased astrocytic function leading to increased synaptic glutamate. (C) Reduced trophic support to the neuron. (D) Microglial activation and inflammation. (E) Oligodendrocyte dysfunction causing impaired myelination.