Puskar Mishra1,2, Shany E Yang1, Austin B Montgomery1, Addison R Reed1, Aylin R Rodan1,3,4,5, Adrian Rothenfluh6,7,8,9. 1. Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA. 2. Department of Bioengineering, University of Utah, Salt Lake City, UT, USA. 3. Department of Internal Medicine, Division of Nephrology & Hypertension, University of Utah, Salt Lake City, UT, USA. 4. Department of Human Genetics, University of Utah, Salt Lake City, UT, USA. 5. Medical Service, Veterans Affairs Salt Lake City Health Care System, University of Utah, Salt Lake City, UT, USA. 6. Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA. Adrian.Rothenfluh@hsc.utah.edu. 7. Department of Human Genetics, University of Utah, Salt Lake City, UT, USA. Adrian.Rothenfluh@hsc.utah.edu. 8. Department of Psychiatry, University of Utah, Salt Lake City, UT, USA. Adrian.Rothenfluh@hsc.utah.edu. 9. Department of Neurobiology, University of Utah, Salt Lake City, UT, USA. Adrian.Rothenfluh@hsc.utah.edu.
Abstract
BACKGROUND: Proper regulation of feeding is important for an organism's well-being and survival and involves a motivational component directing the search for food. Dissecting the molecular and neural mechanisms of motivated feeding behavior requires assays that allow quantification of both motivation and food intake. Measurements of motivated behavior usually involve assessing physical effort or overcoming an aversive stimulus. Food intake in Drosophila can be determined in a number of ways, including by measuring the time a fly's proboscis interacts with a food source associated with an electrical current in the fly liquid-food interaction counter (FLIC). Here, we show that electrical current flowing through flies during this interaction is aversive, and we describe a modified assay to measure motivation in Drosophila. RESULTS: Food intake is reduced during the interaction with FLIC when the electrical current is turned on, which provides a confounding variable in studies of motivated behavior. Based on the FLIC, we engineer a novel assay, the fly liquid-food electroshock assay (FLEA), which allows for current adjustments for each feeding well. Using the FLEA, we show that both external incentives and internal motivational state can serve as drivers for flies to overcome higher current (electric shock) to obtain superior food. Unlike similar assays in which bitterness is the aversive stimulus for the fly to overcome, we show that current perception is not discounted as flies become more food-deprived. Finally, we use genetically manipulated flies to show that neuropeptide F, an orthologue of mammalian NPY previously implicated in regulation of feeding motivation, is required for sensory processing of electrical current. CONCLUSION: The FLEA is therefore a novel assay to accurately measure incentive motivation in Drosophila. Using the FLEA, we also show that neuropeptide F is required for proper perception or processing of an electroshock, a novel function for this neuropeptide involved in the processing of external and internal stimuli.
BACKGROUND: Proper regulation of feeding is important for an organism's well-being and survival and involves a motivational component directing the search for food. Dissecting the molecular and neural mechanisms of motivated feeding behavior requires assays that allow quantification of both motivation and food intake. Measurements of motivated behavior usually involve assessing physical effort or overcoming an aversive stimulus. Food intake in Drosophila can be determined in a number of ways, including by measuring the time a fly's proboscis interacts with a food source associated with an electrical current in the fly liquid-food interaction counter (FLIC). Here, we show that electrical current flowing through flies during this interaction is aversive, and we describe a modified assay to measure motivation in Drosophila. RESULTS: Food intake is reduced during the interaction with FLIC when the electrical current is turned on, which provides a confounding variable in studies of motivated behavior. Based on the FLIC, we engineer a novel assay, the fly liquid-food electroshock assay (FLEA), which allows for current adjustments for each feeding well. Using the FLEA, we show that both external incentives and internal motivational state can serve as drivers for flies to overcome higher current (electric shock) to obtain superior food. Unlike similar assays in which bitterness is the aversive stimulus for the fly to overcome, we show that current perception is not discounted as flies become more food-deprived. Finally, we use genetically manipulated flies to show that neuropeptide F, an orthologue of mammalian NPY previously implicated in regulation of feeding motivation, is required for sensory processing of electrical current. CONCLUSION: The FLEA is therefore a novel assay to accurately measure incentive motivation in Drosophila. Using the FLEA, we also show that neuropeptide F is required for proper perception or processing of an electroshock, a novel function for this neuropeptide involved in the processing of external and internal stimuli.
Authors: Amber L Alhadeff; Zhenwei Su; Elen Hernandez; Michelle L Klima; Sophie Z Phillips; Ruby A Holland; Caiying Guo; Adam W Hantman; Bart C De Jonghe; J Nicholas Betley Journal: Cell Date: 2018-03-22 Impact factor: 41.582
Authors: William W Ja; Gil B Carvalho; Elizabeth M Mak; Noelle N de la Rosa; Annie Y Fang; Jonathan C Liong; Ted Brummel; Seymour Benzer Journal: Proc Natl Acad Sci U S A Date: 2007-05-09 Impact factor: 11.205
Authors: Raniero L Peru Y Colón de Portugal; Shamsideen A Ojelade; Pranav S Penninti; Rachel J Dove; Matthew J Nye; Summer F Acevedo; Antonio Lopez; Aylin R Rodan; Adrian Rothenfluh Journal: Addict Biol Date: 2013-10-29 Impact factor: 4.280
Authors: Pavel M Itskov; José-Maria Moreira; Ekaterina Vinnik; Gonçalo Lopes; Steve Safarik; Michael H Dickinson; Carlos Ribeiro Journal: Nat Commun Date: 2014-08-04 Impact factor: 14.919