The crude extract of glands appended to the jaws of the polychaete annelid Glycera convoluta induces an important increase in the spontaneous quantal transmitter release on frog and crayfish neuromuscular junctions and on Torpedo nerve-electroplaque junctions. The venom similarly triggers acetylcholine (ACh) release from synaptosomes purified from Torpedo electric organ. At the frog neuromuscular junction, the reproducibility, the reversibility and the dose-dependence of the venom action permit a quantitative evaluation of the effect. The crude venom extract has been fractionated by gel-filtration. The effect on transmitter release has been found in a high molecular weight fraction distinct from those which contain the protease and phospholipase activities.
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Molecular Dynamics of Synaptic Function Laboratory, Queensland Brain Institute and School of Biomedical Sciences, The University of Queensland, Brisbane, QLD 4072, Australia.
Glycerotoxin (GLTx), a large neurotoxin isolated from the venom of the sea worm Glycera convoluta, promotes a long-lasting increase in spontaneous neurotransmitter release at the peripheral and central synapses by selective activation of Ca(v)2.2 channels. We found that GLTx stimulates the very high frequency, long-lasting (more than 10 hours) spontaneous release of acetylcholine by promoting nerve terminal Ca(2+) oscillations sensitive to the inhibitor omega-conotoxin GVIA at the amphibian neuromuscular junction.
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Unité des Venins, Institut Pasteur, 28, rue du Dr Roux, 75015 Paris, France.
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