Activity and state dependent modulation of salt taste behavior in Drosophila melanogaster

Abstract

AbstractSodium present in NaCl is a fundamental nutrient required for many physiological processes. In animals including Drosophila low-salt concentrations induce attraction and high-salt concentrations evoke aversive behavior. Although high salt detection pathways have been studied in great details but mechanisms that regulate high salt consumption in animals are largely undetermined. We looked into the neural mechanisms of high NaCl consumption in adult Drosophila by which flies modify their acceptance of high salt as a function of diet where a long-term high-salt exposure increases taste sensitivity of pharyngeal LSO neurons and enhance high salt intake. Exposing flies to high NaCl diet for three days show decline in high salt aversion under starvation. Additionally, genetic suppression of LSO pharyngeal neurons in high NaCl fed flies inhibit excessive salt intake. We observed this modulation requires functional LSO neurons and a starvation state or dopamine. Multiple independent taste receptor neurons and pathways are involved in such a modulation. Silencing any one of multiple LSO neuronal types inhibits excessive salt intake. Our study suggests flies can adapt to the amount of salt ingested over several days, indicating the presence of a critical mechanism to reset the salt appetite and related neural circuits.