Activity and State-Dependent Modulation of Salt Taste Behavior Via Pharyngeal Neurons in Drosophila melanogaster

Abstract

Sodium, which is present in NaCl (Sodium Chloride), is a vital nutrient required for numerous physiological processes. In animals, including Drosophila, low-salt concentrations induce attraction and high-salt concentrations trigger aversive behavior. Although the analysis of low and high salt concentrations in Drosophila has been described at the cellular level, the mechanisms governing high salt consumption and taste modulation remain unclear. Our study examined the neural basis of high NaCl consumption in adult Drosophila, focusing on how dietary adaptation influences salt acceptance. Our findings suggest that prolonged exposure to high salt alters the taste sensitivity of the pharyngeal labral sense organ (LSO) neurons, promoting increased salt intake, particularly under starvation conditions. This modulation requires active LSO neurons, as genetic suppression of their activity in high-salt-fed flies prevents excessive salt consumption under starvation or dopamine-supplemented feeding. Furthermore, multiple independent taste receptor neurons and pathways within the LSO contribute to this response. Silencing any one of these LSO neuron types can prevent excessive salt intake. In conclusion, our study suggests that Drosophila undergoes dietary salt adaptation over time, revealing a key mechanism for resetting salt appetite and related neural circuits.