Ethanol stimulates locomotion via a G α s-signalling pathway in IL 2 neurons in C . elegans

Alcohol is a potent pharmacological agent when cons umed acutely at sufficient quantities and repeated overuse can lead to addiction and deleteri ous effects on health. Alcohol is thought to modulate neuronal function through low affinity interactions with proteins, in particular with membrane channels and receptors. Paradoxicall y, alcohol acts as both a stimulant and a sedative. The exact molecular mechanisms for the a cute effects of ethanol on neurons, as either a stimulant or a sedative, however remain un clear. We investigated the role that the heat shock transcription factor, HSF-1, played in d etermining a stimulatory phenotype of Caenorhabditis elegans in response to physiologically relevant concentrat ions of ethanol (17 mM; 0.1% v/v). Using genetic techniques we demonst rate that either RNAi of hsf-1 or use of an hsf-1(sy441) mutant lacked the enhancement of locomotion in res pon e to acute ethanol exposure evident in wild-type animals. We identify hat the requirement for HSF-1 in this phenotype was IL2-neuron specific and required the downstream expression of the αcrystallin orthologue HSP-16.48. Using a combinati on of pharmacology, optogenetics and phenotypic analyses we determine that ethanol activ ates a Gαs – cAMP – protein kinase A signalling pathway in IL2 neurons to stimulate nema tode locomotion. We further implicate the phosphorylation of a specific serine residue (S er322) on the synaptic protein UNC-18 as an end-point for the G αs-dependent signalling pathway. These findings esta bli h and characterise a distinct neurosensory cell signallin g pathway that determines the stimulatory action of ethanol and identifies HSP-16.48 and HSF1 as novel regulators of this pathway.