ERIC Number: EJ768104
Record Type: Journal
Publication Date: 2005-Jul
Reference Count: 51
Calcium-Activated Proteases Are Critical for Refilling Depleted Vesicle Stores in Cultured Sensory-Motor Synapses of "Aplysia"
Khoutorsky, Arkady; Spira, Micha E.
Learning & Memory, v12 n4 p414-422 Jul 2005
"Aplysia" motoneurons cocultured with a presynaptic sensory neuron exhibit homosynaptic depression when stimulated at low frequencies. A single bath application of serotonin (5HT) leads within seconds to facilitation of the depressed synapse. The facilitation is attributed to mobilization of neurotransmitter-containing vesicles from a feeding vesicle store to the depleted, readily releasable pool by protein kinase C (PKC). Here, we demonstrate that the calpain inhibitors, calpeptin, MG132, and ALLN, but not the proteasome inhibitors, lactacystin and "clasto"-lactacystin [beta]-lactone, block 5HT-induced facilitation of depressed synapses. Likewise the 5HT-induced enhancement of spontaneous miniature potentials (mEPSPs) frequency of depressed synapses is significantly reduced by calpeptin. In contrast, neither the facilitation of nondepressed synapses nor the enhancement of their mEPSPs frequency is affected by the inhibitor. The data suggest that action potentials-induced calcium influx activate calpains. These, in turn, play a role in the refilling processes of the depleted, releasable vesicle store. (Contains 5 figures.)
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Publication Type: Journal Articles; Reports - Research
Education Level: N/A
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