Release of endogenous Zn2+ from brain tissue during activity

Abstract

The role of divalent transition metal ions in neural function is poorly understood. In excess, these ions are associated with neurological disorders such as Wilson's disease¹, Pick's disease² and epileptic seizures^3,4. We suggest that zinc ions, which are contained in nerve terminals, are extruded into the extracellular space during neuronal activity. Excessive levels of zinc may be released during intense neuronal activation, and contribute to the paroxysm and toxic damage observed. Zinc ions are contained in high concentrations in mossy fibres of the hippocampal formation⁵, and it is the postsynaptic neurones of these fibres which are most susceptible to the toxic effects of kainic acid⁶, a potent convulsant, or to chronic exposure to organometallic compounds⁷. Here we demonstrate for the first time that Zn²⁺ is released into the extracellular space during excitation of hippocampal slices.