Metabolic Modulation of Taste Sensitivity: Investigating the Role of Dopamine and Insulin Receptor Signaling in Drosophila melanogaster
Earle, Lindsey
Earle, Lindsey
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Abstract
Internal state consists of a variety of factors and metabolic pathways which are responsible for modulating feeding behavior. Hunger is an essential cue in animals to trigger this behavior, and dopamine has previously been established to increase sweet taste sensitivity in a fasted state in the fruit fly, Drosophila melanogaster. This data has been replicated and further expanded upon to include amino acid taste sensitivity in sweet gustatory receptor neurons (GRNs). Drosophila insulin like peptides (DILPs) are ligands to the tyrosine kinase insulin receptor (InR), which is a conserved insulin receptor with humans. DILP levels fluctuate depending on satiation, and their exact role at the primary sensory level is unknown. We use the Gal4-UAS system to express RNAi directed against the dopamine receptor (DopEcR) or express a dominant negative form of the InR in the primary sweet taste GRNs, using a Gr64f-Gal4 driver. Using the proboscis extension response (PER), where a fly is mounted in place and the GRNs stimulated with a solution, we show that dopamine is responsible for increase sensitivity to both sugar and amino acids whereas insulin is more involved in suppressing sugar sensitivity. To examine nutrient consumption in freely- behaving flies, we used the Fly Liquid-Food Interaction Counter (FLIC). FLIC data shows that expressing InR[DN] leads to an increased number of feeding events for amino acids, but interestingly, a decrease in the length of consumption. Conversely, for sucrose solutions the number of feeding events is not impacted, but expressing InR[DN] leads to an increase in feeding bout duration. FLIC data for DopEcR RNAi lines is complementary to PER, showing a suppression in food interactions and number of feeding events across nutrients while increasing length of feeding bouts. This data suggests that dopamine is essential for eliciting feeding behavior for amino acids and sucrose in Drosophila, while insulin receptors have a nutrient-dependent role.
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Date
1/1/2026
Student Status
Senior (Graduating in 2026)
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Oral Presentation
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Neuroscience
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College of Arts and Sciences
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Life Science