[Function and toxicity of trace metals in the central nervous system]

Trace metals such as zinc, manganese and iron usually serve the function of metalloproteins in neurons and glial cells, while a portion of trace metals exists in the presynaptic vesicles, and may be released with neurotransmitters. Zinc released into the synaptic cleft may serve as an inhibitory neuromodulator of glutamate release in the hippocampus, while neuromodulation by other trace metals such as manganese and copper might mean both functional and toxic aspects in the synapse. Dietary zinc deficiency affects zinc homeostasis in the brain, followed by an enhanced susceptibility to excitotoxicity of glutamate in the hippocampus. The homeostasis of trace metals in the brain is important for brain function and also prevention of brain diseases.