Altered presynaptic vesicle release and cycling during mGluR-dependent LTD.
The site of modification of synaptic transmission during long-term plasticity in the mammalian hippocampus remains controversial. Here we used a fluorescent marker of presynaptic activity, FM 1-43, to directly image presynaptic function during metabotropic glutamate receptor-dependent long-term depression (mGluR-LTD) at CA3-CA1 excitatory synapses in acute hippocampal slices. We found a significant decrease in the rate of FM 1-43 release in response to synaptic stimulation following induction of mGluR-LTD, providing direct evidence for altered presynaptic function. Moreover, we found that mGluR-LTD causes several changes in FM dye release properties that are consistent with a change in the mode of vesicle cycling, possibly involving a switch from a full fusion mode of release to a "kiss-and-run" mode of release through the transient opening of a fusion pore.
D000818:Animals; D000831:Animals, Newborn; D004558:Electric Stimulation; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D005089:Exocytosis / Q000502:physiology; D006624:Hippocampus / Q000378:metabolism* / Q000648:ultrastructure; D007473:Ion Channels / Q000378:metabolism; D051379:Mice; D009433:Neural Inhibition / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D017729:Presynaptic Terminals / Q000378:metabolism* / Q000648:ultrastructure; D021381:Protein Transport / Q000502:physiology; D018094:Receptors, Metabotropic Glutamate / Q000378:metabolism*; D013570:Synaptic Membranes / Q000378:metabolism* / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000502:physiology; D013572:Synaptic Vesicles / Q000378:metabolism* / Q000648:ultrastructure
D007473:Ion Channels; D018094:Receptors, Metabotropic Glutamate