Mechanosensory Inputs Influence Caenorhabditis elegans Pharyngeal Activity via Ivermectin Sensitivity Genes

Mechanical stimulation induces opposite behavioral responses in the adult and dauer pharynx. Tail tap of adults inhibits pharyngeal pumping via a pathway involving the innexin gene unc-7 and components of the glutamatergic pathway encoded by the genes avr-14 and avr-15. Tail tap of dauers stimulates pumping through a mechanism involving G(alpha)o and G(alpha)q. The nematocidal drug ivermectin is believed to kill worms by opening a glutamate-gated chloride channel (AVR-15) on pharyngeal muscle, causing complete pumping inhibition. However, ivermectin can also inhibit pumping in the absence of this channel. We propose that one of the ways ivermectin could prevent pumping, in the absence of the AVR-15 ivermectin-binding channel on pharynx muscle, is to target AVR-14 and AVR-15, which are expressed in the inhibitory pathway linking mechanosensation and pumping activity.