Candidate Gustatory Interneurons Modulating Feeding Behavior in the Drosophila Brain

Feeding is a fundamental activity of all animals that can be regulated by internal energy status or external sensory signals. We have characterized a zinc finger transcription factor, klumpfuss(klu), which is required for food intake in Drosophila larvae. Microarray analysis indicates that expression of the neuropeptide gene hugin(hug) in the brain is altered in klu mutants and that hug itself is regulated by food signals. Neuroanatomical analysis demonstrates that hug-expressing neurons project axons to the pharyngeal muscles, to the central neuroendocrine organ, and to the higher brain centers, whereas hug dendrites are innervated by external gustatory receptor-expressing neurons, as well as by internal pharyngeal chemosensory organs. The use of tetanus toxin to block synaptic transmission of hug neurons results in alteration of food intake initiation, which is dependent on previous nutrient condition. Our results provide evidence that hug neurons function within a neural circuit that modulates taste-mediated feeding behavior.