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Neurotoxicology. 2004 Jun;25(4):599-604.

Presynaptic disruption of transmitter release by lead.

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Department of Cellular and Molecular Physiology, College of Medicine, University of Cincinnati, P.O. Box 670576, Cincinnati, OH 45267-0576, USA.


Low concentrations of inorganic lead ions (Pb2+) disrupt transmitter release by causing aberrant augmentation of spontaneous and suppression of evoked release. These effects result from high affinity interactions of Pb2+ with the voltage-gated calcium channels (VGCC) as well as Ca2+ binding proteins which regulate the synaptic vesicle mobilization, docking, and exocytosis processes. Augmentation of spontaneous release may involve stimulation of vesicle mobilization consequent to Pb2+ activation of CaMKII-dependent phosphorylation of synapsin I and/or stimulation of asynchronous exocytosis via direct Pb2+ activation of the putative exocytotic Ca2+-sensor protein synaptotagmin I. In addition, synergistic stimulation of PLC and DAG/Pb2+-dependent activation of PKC may enhance the secretagogue effects of Pb2+ by increasing metal sensitivity of exocytosis and/or modulating calcium channel activity. In contrast to intracellularly-mediated actions of Pb2+ resulting in augmentation of spontaneous release, the inhibition of evoked transmitter release by Pb2+ is largely attributable to extracellular block of the voltage-gated calcium channels.

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