Neurotransmitters and Behavioral Alterations Induced by Nickel Exposure

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.