GABA receptors in Caenrohabditis elegans embryonic muscle cells

Abstract

GABA receptors mediate fast inhibitory neurotransmission in both vertebrates and invertebrates. They are targets of anxiolytic and antiepileptic drugs as well as of commonly used insecticides and antihelminthics. Here we investigated GABA receptors in the free-living nematode Caenorhabditis elegans, which is a model for the study of the nervous system as well as a model of parasitic nematodes. Nematode muscle contains, in addition to two types of nicotinic receptors, a GABA receptor. We used a primary culture to explore the functional properties of GABA receptors from L1 muscle cells at the macroscopic and single-channel levels. Rapid application of GABA to L1 muscle cells elicits inward currents that decay fast due to desensitization. In cell-attached patches, 1-10mM GABA activates channels of ~ 2.6 pA (membrane potential: +100mV) and a mean duration of about 0.22 ms. The frequency of channel openings increases as a function of GABA concentration. The analysis of single-channel properties shows a homogenous channel population, indicating the presence of a single GABA receptor subtype. Our study contributes to the understanding of muscle GABA receptor properties and, in turn, provides new avenues for exploration of anthelmintic therapies