Dissecting the Dopaminergic Circuitry Underlying Feeding Behavior in Drosophila. Lay Kodama¹, Qili Liu¹, Mark Wu^1,2. 1) Department of Neurology, Johns Hopkins University, Baltimore, MD; 2) Department of Neuroscience, Johns Hopkins University, Baltimore, MD.

   Obesity is a major problem in modern society, and there is great interest in understanding the mechanisms mediating hunger and appetite. In animals, these hunger signals are essential for food seeking behaviors and can be modulated by various neural circuits. Dopamine (DA) is a key neuromodulator that has been shown to regulate a wide variety of behaviors in mammals, including feeding. In Drosophila, recent studies have suggested that DA increases the probability of the proboscis extension response (PER) by modulating the sensitivity of gustatory neurons to sucrose. Here, we investigated the role of DA and specific DA circuits in regulating feeding. To identify DA neurons involved in feeding, we activated distinct subsets of DA neurons and measured food intake after a mild-starvation protocol. These data suggest that a specific subset of DA neurons, distinct from those that promote arousal, is involved in promoting feeding. Using the PER assay, we also found that activation of these DA neurons promotes an increase in sensitivity to sweet-tasting substances, caloric (but tasteless) substances, and water, suggesting a general enhancement of appetitive responses. Using various intersectional approaches, we are further dissecting the specific DA neurons involved in these processes. In addition, we are working to identify the specific DA receptor and downstream target cells required for these behaviors.