Neurobiology of Zinc

— This review presents the results of research concerning the role of zinc in neuronal membranes and synaptic processes. The development of views on zinc as an essential trace element is analyzed, from the demonstration of its catalytic, metabolic, and structural function to the elucidation of its regulatory role in intra- and inter-neuronal interactions. The body of information accumulated over recent decades on the significance of zinc for neuronal activity, in particular, for the regulation of excitation or inhibition, as well as for certain fine-tuned processes in the nerve cell membrane, is evaluated. The involvement of zinc in the functioning of the mediator brain systems, primarily, the glutamatergic system, is discussed. The available data on zinc vesiculation in neurons and its potential-dependent release into the synaptic cleft are analyzed. The processes in pre- or postsynaptic neuronal membranes involving zinc are described. Theories and hypotheses that expand views on zinc as a signal molecule are assessed. Attention is drawn to a number of controversial ideas and unsolved problems. For the specific case of the striatal nuclei, a hypothesis is developed about the involvement of vesicular zinc in the regulation of balance between the direct and indirect pathways, the two efferent systems of this subcortical formation, which is important for normal locomotor behavior and the prevention of neuromotor dysfunction.