51
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Garlapow ME, Huang W, Yarboro MT, Peterson KR, Mackay TFC. Quantitative Genetics of Food Intake in Drosophila melanogaster. PLoS One 2015; 10:e0138129. [PMID: 26375667 PMCID: PMC4574202 DOI: 10.1371/journal.pone.0138129] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 08/25/2015] [Indexed: 12/16/2022] Open
Abstract
Food intake is an essential animal activity, regulated by neural circuits that motivate food localization, evaluate nutritional content and acceptance or rejection responses through the gustatory system, and regulate neuroendocrine feedback loops that maintain energy homeostasis. Excess food consumption in people is associated with obesity and metabolic and cardiovascular disorders. However, little is known about the genetic basis of natural variation in food consumption. To gain insights in evolutionarily conserved genetic principles that regulate food intake, we took advantage of a model system, Drosophila melanogaster, in which food intake, environmental conditions and genetic background can be controlled precisely. We quantified variation in food intake among 182 inbred, sequenced lines of the Drosophila melanogaster Genetic Reference Panel (DGRP). We found significant genetic variation in the mean and within-line environmental variance of food consumption and observed sexual dimorphism and genetic variation in sexual dimorphism for both food intake traits (mean and variance). We performed genome wide association (GWA) analyses for mean food intake and environmental variance of food intake (using the coefficient of environmental variation, CVE, as the metric for environmental variance) and identified molecular polymorphisms associated with both traits. Validation experiments using RNAi-knockdown confirmed 24 of 31 (77%) candidate genes affecting food intake and/or variance of food intake, and a test cross between selected DGRP lines confirmed a SNP affecting mean food intake identified in the GWA analysis. The majority of the validated candidate genes were novel with respect to feeding behavior, and many had mammalian orthologs implicated in metabolic diseases.
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Affiliation(s)
- Megan E. Garlapow
- Program in Genetics, North Carolina State University, Raleigh, NC, 27695–7614, United States of America
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, 27695, United States of America
- W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, NC, 27695, United States of America
| | - Wen Huang
- Program in Genetics, North Carolina State University, Raleigh, NC, 27695–7614, United States of America
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, 27695, United States of America
- W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, NC, 27695, United States of America
| | - Michael T. Yarboro
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, 27695, United States of America
| | - Kara R. Peterson
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, 27695, United States of America
| | - Trudy F. C. Mackay
- Program in Genetics, North Carolina State University, Raleigh, NC, 27695–7614, United States of America
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, 27695, United States of America
- W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, NC, 27695, United States of America
- * E-mail:
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52
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Rohwedder A, Selcho M, Chassot B, Thum AS. Neuropeptide F neurons modulate sugar reward during associative olfactory learning ofDrosophilalarvae. J Comp Neurol 2015; 523:2637-64. [DOI: 10.1002/cne.23873] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Revised: 07/19/2015] [Accepted: 07/28/2015] [Indexed: 01/29/2023]
Affiliation(s)
- Astrid Rohwedder
- Department of Biology; University of Fribourg; Fribourg Switzerland
| | - Mareike Selcho
- Department of Neurobiology and Genetics, Theodor-Boveri-Institute, Biocenter; University of Würzburg; Würzburg Germany
| | - Bérénice Chassot
- Department of Biology; University of Fribourg; Fribourg Switzerland
| | - Andreas S. Thum
- Department of Biology; University of Fribourg; Fribourg Switzerland
- Department of Biology; University of Konstanz; Konstanz Germany
- Zukunftskolleg; University of Konstanz; Konstanz Germany
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53
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Lushchak OV, Carlsson MA, Nässel DR. Food odors trigger an endocrine response that affects food ingestion and metabolism. Cell Mol Life Sci 2015; 72:3143-55. [PMID: 25782410 PMCID: PMC11113394 DOI: 10.1007/s00018-015-1884-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 01/29/2015] [Accepted: 03/12/2015] [Indexed: 10/23/2022]
Abstract
Food odors stimulate appetite and innate food-seeking behavior in hungry animals. The smell of food also induces salivation and release of gastric acid and insulin. Conversely, sustained odor exposure may induce satiation. We demonstrate novel effects of food odors on food ingestion, metabolism and endocrine signaling in Drosophila melanogaster. Acute exposure to attractive vinegar odor triggers a rapid and transient increase in circulating glucose, and a rapid upregulation of genes encoding the glucagon-like hormone adipokinetic hormone (AKH), four insulin-like peptides (DILPs) and some target genes in peripheral tissues. Sustained exposure to food odors, however, decreases food intake. Hunger-induced strengthening of synaptic signaling from olfactory sensory neurons (OSNs) to brain neurons increases food-seeking behavior, and conversely fed flies display reduced food odor sensitivity and feeding. We show that increasing the strength of OSN signaling chronically by genetic manipulation of local peptide neuromodulation reduces feeding, elevates carbohydrates and diminishes lipids. Furthermore, constitutively strengthened odor sensitivity altered gene transcripts for AKH, DILPs and some of their targets. Thus, we show that food odor can induce a transient anticipatory endocrine response, and that boosted sensitivity to this odor affects food intake, as well as metabolism and hormonal signaling.
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Affiliation(s)
- Oleh V. Lushchak
- Department of Zoology, Stockholm University, 10691 Stockholm, Sweden
- Present Address: Department of Biochemistry and Biotechnology, Vasyl Stefanyk Precarpathian National University, Ivano-Frankivsk, Ukraine
| | | | - Dick R. Nässel
- Department of Zoology, Stockholm University, 10691 Stockholm, Sweden
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54
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Lewis L, Siju K, Aso Y, Friedrich A, Bulteel A, Rubin G, Grunwald Kadow I. A Higher Brain Circuit for Immediate Integration of Conflicting Sensory Information in Drosophila. Curr Biol 2015; 25:2203-14. [DOI: 10.1016/j.cub.2015.07.015] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 06/18/2015] [Accepted: 07/06/2015] [Indexed: 10/23/2022]
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55
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Ko KI, Root CM, Lindsay SA, Zaninovich OA, Shepherd AK, Wasserman SA, Kim SM, Wang JW. Starvation promotes concerted modulation of appetitive olfactory behavior via parallel neuromodulatory circuits. eLife 2015; 4:e08298. [PMID: 26208339 PMCID: PMC4531282 DOI: 10.7554/elife.08298] [Citation(s) in RCA: 126] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 07/24/2015] [Indexed: 12/19/2022] Open
Abstract
The internal state of an organism influences its perception of attractive or aversive stimuli and thus promotes adaptive behaviors that increase its likelihood of survival. The mechanisms underlying these perceptual shifts are critical to our understanding of how neural circuits support animal cognition and behavior. Starved flies exhibit enhanced sensitivity to attractive odors and reduced sensitivity to aversive odors. Here, we show that a functional remodeling of the olfactory map is mediated by two parallel neuromodulatory systems that act in opposing directions on olfactory attraction and aversion at the level of the first synapse. Short neuropeptide F sensitizes an antennal lobe glomerulus wired for attraction, while tachykinin (DTK) suppresses activity of a glomerulus wired for aversion. Thus we show parallel neuromodulatory systems functionally reconfigure early olfactory processing to optimize detection of nutrients at the risk of ignoring potentially toxic food resources.
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Affiliation(s)
- Kang I Ko
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Cory M Root
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Scott A Lindsay
- Cell and Developmental Biology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Orel A Zaninovich
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Andrew K Shepherd
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Steven A Wasserman
- Cell and Developmental Biology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Susy M Kim
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Jing W Wang
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
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56
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McNeill MS, Robinson GE. Voxel-based analysis of the immediate early gene, c-jun, in the honey bee brain after a sucrose stimulus. INSECT MOLECULAR BIOLOGY 2015; 24:377-390. [PMID: 25773289 DOI: 10.1111/imb.12165] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Immediate early genes (IEGs) have served as useful markers of brain neuronal activity in mammals, and more recently in insects. The mammalian canonical IEG, c-jun, is part of regulatory pathways conserved in insects and has been shown to be responsive to alarm pheromone in honey bees. We tested whether c-jun was responsive in honey bees to another behaviourally relevant stimulus, sucrose, in order to further identify the brain regions involved in sucrose processing. To identify responsive regions, we developed a new method of voxel-based analysis of c-jun mRNA expression. We found that c-jun is expressed in somata throughout the brain. It was rapidly induced in response to sucrose stimuli, and it responded in somata near the antennal and mechanosensory motor centre, mushroom body calices and lateral protocerebrum, which are known to be involved in sucrose processing. c-jun also responded to sucrose in somata near the lateral suboesophageal ganglion, dorsal optic lobe, ventral optic lobe and dorsal posterior protocerebrum, which had not been previously identified by other methods. These results demonstrate the utility of voxel-based analysis of mRNA expression in the insect brain.
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Affiliation(s)
- M S McNeill
- Department of Entomology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA; Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA; Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
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57
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Camilleri M. Peripheral mechanisms in appetite regulation. Gastroenterology 2015; 148:1219-33. [PMID: 25241326 PMCID: PMC4369188 DOI: 10.1053/j.gastro.2014.09.016] [Citation(s) in RCA: 142] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 09/09/2014] [Accepted: 09/15/2014] [Indexed: 12/13/2022]
Abstract
Peripheral mechanisms in appetite regulation include the motor functions of the stomach, such as the rate of emptying and accommodation, which convey symptoms of satiation to the brain. The rich repertoire of peripherally released peptides and hormones provides feedback from the arrival of nutrients in different regions of the gut from where they are released to exert effects on satiation, or regulate metabolism through their incretin effects. Ultimately, these peripheral factors provide input to the highly organized hypothalamic circuitry and vagal complex of nuclei to determine cessation of energy intake during meal ingestion, and the return of appetite and hunger after fasting. Understanding these mechanisms is key to the physiological control of feeding and the derangements that occur in obesity and their restoration with treatment (as shown by the effects of bariatric surgery).
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Affiliation(s)
- Michael Camilleri
- Clinical Enteric Neuroscience Translational and Epidemiological Research, Mayo Clinic College of Medicine, Rochester, Minnesota.
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58
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Bose C, Basu S, Das N, Khurana S. Chemosensory apparatus of Drosophila larvae. Bioinformation 2015; 11:185-8. [PMID: 26124558 PMCID: PMC4479052 DOI: 10.6026/97320630011185] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 02/26/2015] [Indexed: 02/08/2023] Open
Abstract
Many insects, including Drosophila melanogaster, have a rich repertoire of olfactory behavior. Combination of robust behavioral assays, physiological and molecular tools render D. melanogaster as highly suitable system for olfactory studies. The small number of neurons in the olfactory system of fruit flies, especially the number of sensory neurons in the larval stage, makes the exploration of sensory coding at all stages of its nervous system a potentially tractable goal, which is not possible in the foreseeable future in any mammalian preparation. Advances in physiological recordings, olfactory signaling and detailed analysis of behavior, can place larvae in a position to ask previously unanswerable questions.
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Affiliation(s)
| | | | - Nabajit Das
- Indian Institute of Science Education and Research Kolkata (IISER-K), Mohanpur, West Bengal – 741246, India
- Authors equally contributed
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59
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Abstract
Genetic manipulations of neuronal activity are a cornerstone of studies aimed to identify the functional impact of defined neurons for animal behavior. With its small nervous system, rapid life cycle, and genetic amenability, the fruit fly Drosophila melanogaster provides an attractive model system to study neuronal circuit function. In the past two decades, a large repertoire of elegant genetic tools has been developed to manipulate and study neural circuits in the fruit fly. Current techniques allow genetic ablation, constitutive silencing, or hyperactivation of neuronal activity and also include conditional thermogenetic or optogenetic activation or inhibition. As for all genetic techniques, the choice of the proper transgenic tool is essential for behavioral studies. Potency and impact of effectors may vary in distinct neuron types or distinct types of behavior. We here systematically test genetic effectors for their potency to alter the behavior of Drosophila larvae, using two distinct behavioral paradigms: general locomotor activity and directed, visually guided navigation. Our results show largely similar but not equal effects with different effector lines in both assays. Interestingly, differences in the magnitude of induced behavioral alterations between different effector lines remain largely consistent between the two behavioral assays. The observed potencies of the effector lines in aminergic and cholinergic neurons assessed here may help researchers to choose the best-suited genetic tools to dissect neuronal networks underlying the behavior of larval fruit flies.
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60
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Yamamoto S, Seto ES. Dopamine dynamics and signaling in Drosophila: an overview of genes, drugs and behavioral paradigms. Exp Anim 2014; 63:107-19. [PMID: 24770636 PMCID: PMC4160991 DOI: 10.1538/expanim.63.107] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Changes in dopamine (DA) signaling have been implicated in a number of human neurologic
and psychiatric disorders. Similarly, defects in DA signaling in the fruit fly,
Drosophila melanogaster, have also been associated with several
behavioral defects. As most genes involved in DA synthesis, transport, secretion, and
signaling are conserved between species, Drosophila is a powerful genetic
model organism to study the regulation of DA signaling in vivo. In this
review, we will provide an overview of the genes and drugs that regulate DA biology in
Drosophila. Furthermore, we will discuss the behavioral paradigms that
are regulated by DA signaling in flies. By analyzing the genes and neuronal circuits that
govern such behaviors using sophisticated genetic, pharmacologic, electrophysiologic, and
imaging approaches in Drosophila, we will likely gain a better
understanding about how this neuromodulator regulates motor tasks and cognition in
humans.
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Affiliation(s)
- Shinya Yamamoto
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston,TX77030, USA
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61
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Williams MJ, Goergen P, Rajendran J, Zheleznyakova G, Hägglund MG, Perland E, Bagchi S, Kalogeropoulou A, Khan Z, Fredriksson R, Schiöth HB. Obesity-linked homologues TfAP-2 and Twz establish meal frequency in Drosophila melanogaster. PLoS Genet 2014; 10:e1004499. [PMID: 25187989 PMCID: PMC4154645 DOI: 10.1371/journal.pgen.1004499] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 05/27/2014] [Indexed: 12/21/2022] Open
Abstract
In all animals managing the size of individual meals and frequency of feeding is crucial for metabolic homeostasis. In the current study we demonstrate that the noradrenalin analogue octopamine and the cholecystokinin (CCK) homologue Drosulfakinin (Dsk) function downstream of TfAP-2 and Tiwaz (Twz) to control the number of meals in adult flies. Loss of TfAP-2 or Twz in octopaminergic neurons increased the size of individual meals, while overexpression of TfAP-2 significantly decreased meal size and increased feeding frequency. Of note, our study reveals that TfAP-2 and Twz regulate octopamine signaling to initiate feeding; then octopamine, in a negative feedback loop, induces expression of Dsk to inhibit consummatory behavior. Intriguingly, we found that the mouse TfAP-2 and Twz homologues, AP-2β and Kctd15, co-localize in areas of the brain known to regulate feeding behavior and reward, and a proximity ligation assay (PLA) demonstrated that AP-2β and Kctd15 interact directly in a mouse hypothalamus-derived cell line. Finally, we show that in this mouse hypothalamic cell line AP-2β and Kctd15 directly interact with Ube2i, a mouse sumoylation enzyme, and that AP-2β may itself be sumoylated. Our study reveals how two obesity-linked homologues regulate metabolic homeostasis by modulating consummatory behavior. The size of individual meals and feeding frequency are important for homeostatic control. Due to the complex neuroendocrine system regulating human food intake it is difficult to uncover the mechanisms underlying eating disorders. The genetically tractable model system Drosophila melanogaster has a comparatively simple brain; yet, similar to humans, its eating behavior can adapt to respond to nutritional needs. Our study describes how the obesity-linked homologues TfAP-2 (human TFAP2B) and Tiwaz (human KCTD15) regulate a unique feedback system involving noradrenalin-like octopamine and the CCK homolog Dsk, that exert positive and negative effects on Drosophila feeding behavior. Our findings provide insight into how two conserved obesity-linked genes regulate feeding behavior in order to maintain metabolic balance.
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Affiliation(s)
- Michael J. Williams
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
- * E-mail:
| | - Philip Goergen
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Jayasimman Rajendran
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Galina Zheleznyakova
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Maria G. Hägglund
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Emelie Perland
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Sonchita Bagchi
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Argyro Kalogeropoulou
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Zaid Khan
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Robert Fredriksson
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Helgi B. Schiöth
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
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Su CY, Wang JW. Modulation of neural circuits: how stimulus context shapes innate behavior in Drosophila. Curr Opin Neurobiol 2014; 29:9-16. [PMID: 24801064 DOI: 10.1016/j.conb.2014.04.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 04/03/2014] [Accepted: 04/10/2014] [Indexed: 11/25/2022]
Abstract
Remarkable advances have been made in recent years in our understanding of innate behavior and the underlying neural circuits. In particular, a wealth of neuromodulatory mechanisms have been uncovered that can alter the input-output relationship of a hereditary neural circuit. It is now clear that this inbuilt flexibility allows animals to modify their behavioral responses according to environmental cues, metabolic demands and physiological states. Here, we discuss recent insights into how modulation of neural circuits impacts innate behavior, with a special focus on how environmental cues and internal physiological states shape different aspects of feeding behavior in Drosophila.
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Affiliation(s)
- Chih-Ying Su
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, United States
| | - Jing W Wang
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, United States.
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63
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Bjordal M, Arquier N, Kniazeff J, Pin JP, Léopold P. Sensing of amino acids in a dopaminergic circuitry promotes rejection of an incomplete diet in Drosophila. Cell 2014; 156:510-21. [PMID: 24485457 DOI: 10.1016/j.cell.2013.12.024] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 08/07/2013] [Accepted: 11/15/2013] [Indexed: 01/18/2023]
Abstract
The brain is the central organizer of food intake, matching the quality and quantity of the food sources with organismal needs. To ensure appropriate amino acid balance, many species reject a diet lacking one or several essential amino acids (EAAs) and seek out a better food source. Here, we show that, in Drosophila larvae, this behavior relies on innate sensing of amino acids in dopaminergic (DA) neurons of the brain. We demonstrate that the amino acid sensor GCN2 acts upstream of GABA signaling in DA neurons to promote avoidance of the EAA-deficient diet. Using real-time calcium imaging in larval brains, we show that amino acid imbalance induces a rapid and reversible activation of three DA neurons that are necessary and sufficient for food rejection. Taken together, these data identify a central amino-acid-sensing mechanism operating in specific DA neurons and controlling food intake.
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Affiliation(s)
- Marianne Bjordal
- University of Nice-Sophia Antipolis, Institute of Biology Valrose, Parc Valrose, 06108 Nice, France; CNRS, Institute of Biology Valrose, Parc Valrose, 06108 Nice, France; INSERM, Institute of Biology Valrose, Parc Valrose, 06108 Nice, France
| | - Nathalie Arquier
- University of Nice-Sophia Antipolis, Institute of Biology Valrose, Parc Valrose, 06108 Nice, France; CNRS, Institute of Biology Valrose, Parc Valrose, 06108 Nice, France; INSERM, Institute of Biology Valrose, Parc Valrose, 06108 Nice, France
| | - Julie Kniazeff
- Institut de Génomique Fonctionnelle, CNRS UMR5203, INSERM U661, Université Montpellier 1 & 2, 34094 Montpellier, France
| | - Jean Philippe Pin
- Institut de Génomique Fonctionnelle, CNRS UMR5203, INSERM U661, Université Montpellier 1 & 2, 34094 Montpellier, France
| | - Pierre Léopold
- University of Nice-Sophia Antipolis, Institute of Biology Valrose, Parc Valrose, 06108 Nice, France; CNRS, Institute of Biology Valrose, Parc Valrose, 06108 Nice, France; INSERM, Institute of Biology Valrose, Parc Valrose, 06108 Nice, France.
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64
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Abstract
Odors are highly evocative, yet how and where in the brain odors derive meaning remains unknown. Our analysis of the Drosophila brain extends the role of a small number of hunger-sensing neurons to include food-odor value representation. In vivo two-photon calcium imaging shows the amplitude of food odor-evoked activity in neurons expressing Drosophila neuropeptide F (dNPF), the neuropeptide Y homolog, strongly correlates with food-odor attractiveness. Hunger elevates neural and behavioral responses to food odors only, although food odors that elicit attraction in the fed state also evoke heightened dNPF activity in fed flies. Inactivation of a subset of dNPF-expressing neurons or silencing dNPF receptors abolishes food-odor attractiveness, whereas genetically enhanced dNPF activity not only increases food-odor attractiveness but promotes attraction to aversive odors. Varying the amount of presented odor produces matching graded neural and behavioral curves, which can function to predict preference between odors. We thus demonstrate a possible motivationally scaled neural "value signal" accessible from uniquely identifiable cells.
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65
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Octopamine-mediated circuit mechanism underlying controlled appetite for palatable food in Drosophila. Proc Natl Acad Sci U S A 2013; 110:15431-6. [PMID: 24003139 DOI: 10.1073/pnas.1308816110] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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.
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