Behavior-based discovery of small-molecule modulators of neurochemical signaling pathways that underlie addiction

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PROJECT SUMMARY Addiction is a complex pathology of neural circuits that function in reward-processing, impulse control, and goal-directed behaviors. Small molecules targeting neuromodulator signaling pathways that function in these circuits are important therapeutics for the treatment of addiction. There is an urgent need to improve the pharmacology used to treat addiction. To address this need, we have developed methods that uses behavior- based screens to interrogate a novel source of natural products for effects on neuromodulator signaling in the nervous system of a microscopic animal - the nematode C. elegans. The natural products that we will screen are microbial metabolites that have eluded detection because they are not expressed under basal conditions but can only be elicited by environmental triggers. This microbial 'dark metabolome' contains small molecules with a wide variety of biological activities. These compounds have not yet been assayed for effects on the animal nervous system, and they constitute a rich and untapped resource for novel psychopharmacology. Through screens designed to demonstrate proof-of-concept, we have already identified compounds that strongly and specifically act on a circuit that uses neuropeptides and serotonin to generate behavior. We have also designed behavior-based screens for novel modulators of dopamine signaling. In addition to providing the opportunity to perform high-throughput behavior-based screens, the powerful genetics of the C. elegans model allows assignment of neuroactive compounds to specific neuromodulator signaling pathways. Successful completion of the aims of this project will generate enhanced and expanded libraries of novel natural products never before assayed for effects on the nervous system, identify novel small-molecule regulators of neural circuits, and match those compounds to specific neuromodulator signaling systems integral to the pathology of addiction.