ABSTRACT
BACKGROUND: Nickel ions (Ni2+) are a heavy metal with wide industrial uses. Environmental and occupational exposures to Ni are potential risk factors for brain dysfunction and behavioral and neurological symptoms in humans. METHODS: We reviewed the current evidence about neurochemical and behavioral alterations associated with Ni exposure in laboratory animals and humans. RESULTS: Ni2+ exposure can alter (both inhibition and stimulation) dopamine release and inhibit glutamate NMDA receptors. Few reports claim an effect of Ni2+ at the level of GBA and serotonin neurotransmission. At behavioral levels, exposure to Ni2+ in rodents alters motor activity, learning and memory as well as anxiety and depressive-like symptoms. However, no analysis of the dose-dependent relationship has been carried out regarding these effects and the levels of the Ni2+ in the brain, in blood or urine. CONCLUSION: Further research is needed to correlate the concentration of Ni2+ in biological fluids with specific symptoms/deficits. Future studies addressing the impact of Ni2+ under environmental or occupational exposure should consider the administration protocols to find Ni2+ levels similar in the general population or occupationally exposed workers.
