Actin-dependent regulation of neurotransmitter release at central synapses

Depolymerization of actin by latrunculin A transiently promotes neurotransm itter release. The mean rate of mEPSCs increases by a Ca2+-independent proc ess, without a concomitant change in the mean amplitude. The readily releas able vesicle pool size and the rate of refilling of the readily releasable pool remain unaltered by latrunculin treatment. Evoked neurotransmitter rel ease also increases in a manner consistent with an increase in vesicle rele ase probability. The observed enhancement of neurotransmitter release is sp ecific to actin depolymerization mediated by latrunculin A and is not cause d by cytochalasin D. Our findings indicate that actin participates in a reg ulatory mechanism that restrains fusion of synaptic vesicles at the active zone.