title: Octopamine-mediated circuit mechanism underlying controlled appetite for palatable food in Drosophila.
abstract: The easy accessibility of energy-rich palatable food makes it difficult to resist food temptation. Drosophila larvae are surrounded by sugar-rich food most of their lives, raising the question of how these animals modulate food-seeking behaviors in tune with physiological needs. Here we describe a circuit mechanism defined by neurons expressing tdc2-Gal4 (a tyrosine decarboxylase 2 promoter-directed driver) that selectively drives a distinct foraging strategy in food-deprived larvae. Stimulation of this otherwise functionally latent circuit in tdc2-Gal4 neurons was sufficient to induce exuberant feeding of liquid food in fed animals, whereas targeted lesions in a small subset of tdc2-Gal4 neurons in the subesophageal ganglion blocked hunger-driven increases in the feeding response. Furthermore, regulation of feeding rate enhancement by tdc2-Gal4 neurons requires a novel signaling mechanism involving the VEGF2-like receptor, octopamine, and its receptor. Our findings provide fresh insight for the neurobiology and evolution of appetitive motivation.
authors.affiliation: Department of Cellular Biology and Biomedical and Health Sciences Institute, University of Georgia, Athens, GA 30602.
authors.forename: Ting
authors.initials: T
authors.lastname: Zhang
authors.forename: Audrey
authors.initials: A
authors.lastname: Branch
authors.forename: Ping
authors.initials: P
authors.lastname: Shen
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001069:Appetite Regulation / Q000502:physiology*; D001070:Appetitive Behavior / Q000502:physiology*; D005075:Biological Evolution; D004330:Drosophila / Q000502:physiology*; D029721:Drosophila Proteins / Q000378:metabolism; D007150:Immunohistochemistry; D007814:Larva / Q000502:physiology; D009474:Neurons / Q000378:metabolism*; D009478:Neuropeptide Y / Q000378:metabolism; D009655:Octopamine / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D040262:Receptors, Vascular Endothelial Growth Factor / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism; D014445:Tyrosine Decarboxylase / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; C557617:GAL4 protein, Drosophila; D009478:Neuropeptide Y; C503412:Octbeta3R protein, Drosophila; D043562:Receptors, G-Protein-Coupled; D014157:Transcription Factors; D009655:Octopamine; D040262:Receptors, Vascular Endothelial Growth Factor; C500802:Tdc2 protein, Drosophila; D014445:Tyrosine Decarboxylase
keywords: PDGF/VEGF receptor (Pvr); Ras; downstream of receptor kinase (Drk); feeding behavior