We describe an electrophysiological preparation of the neuromuscular junction of the nematode C. elegans, which adds to its considerable genetic and genomic resources. Mutant analysis, pharmacology and patch-clamp recording showed that the body wall muscles of wild-type animals expressed a GABA receptor and two acetylcholine receptors. The muscle GABA response was abolished in animals lacking the GABA receptor gene unc-49. One acetylcholine receptor was activated by the nematocide levamisole. This response was eliminated in mutants lacking either the unc-38 or unc-29 genes, which encode alpha and non-alpha acetylcholine receptor subunits, respectively. The second, previously undescribed, acetylcholine receptor was activated by nicotine, desensitized rapidly and was selectively blocked by dihydro-β-erythroidine, thus explaining the residual motility of unc-38 and unc-29 mutants. By recording spontaneous endogenous currents and selectively eliminating each of these receptors, we demonstrated that all three receptor types function at neuromuscular synapses.
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The authors thank K. Broadie, T. Fergestad and D.E. Featherstone for technical assistance, L. Avery and A.V. Maricq for discussions, M. Hammarlund for providing the F21D12.3-GFP strain, K. Knobel for confocal images and K. Broadie and D.E. Featherstone for reading the manuscript. This work was supported by NIH grant RO3 MHS9820-01 (J.E.R.) and the Damon Runyon Fund (E.M.J.).
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Richmond, J., Jorgensen, E. One GABA and two acetylcholine receptors function at the C. elegans neuromuscular junction. Nat Neurosci 2, 791–797 (1999). https://doi.org/10.1038/12160
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