TY - JOUR
T1 - Dopamine signaling in wake-promoting clock neurons is not required for the normal regulation of sleep in drosophila
AU - Fernandez-Chiappe, Florencia
AU - Hermann-Luibl, Christiane
AU - Peteranderl, Alina
AU - Reinhard, Nils
AU - Senthilan, Pingkalai R.
AU - Hieke, Marie
AU - Selcho, Mareike
AU - Yoshii, Taishi
AU - Shafer, Orie T.
AU - Muraro, Nara I.
AU - Helfrich-Förster, Charlotte
N1 - Funding Information:
This study was supported by German Research Foundation Grants Fo207/14-1 and PA3241/2-1 to C.H. F. and M.S., respectively; Agencia Nacional de Promoción de la Investigación, el Desarrollo Tecnológico y la Innovación Grant PICT-2015-2557 to N.I.M.; and FOCEM-Mercosur Grant COF 03/11 to the Biomedicine Research Institute of Buenos Aires; and by National Institutes of Health/National Institute of Neurological Disorders and Stroke Grant R01-NS-077933 and an National Science Foundation IOS (Integrative Organismal Systems) Grant 1354046 to O.T.S. We thank Serge Birman for providing the TH-Gal4 line and for profound discussions on dopamine effects; Jan Marek Ache for valuable discussion and editing of the manuscript; Indra Hering for help with the sleep experiments; and Barbara Mühlbauer for general excellent assistance. M. Selcho’s present address: Department of Animal Physiology, Institute of Biology, Carl-Ludwig-Institute for Physiology, Leipzig University, 04103 Leipzig, Germany. pF.F.-C. and C.H.-L. contributed equally to this work. The authors declare no competing financial interests. Correspondence should be addressed to Charlotte Helfrich-Förster at charlotte.foerster@biozentrum.uni-wuerzburg.de or Nara I. Muraro at nmuraro@ibioba-mpsp-conicet.gov.ar. https://doi.org/10.1523/JNEUROSCI.1488-20.2020 Copyright © 2020 the authors
Publisher Copyright:
© 2020 the authors
PY - 2020/12/9
Y1 - 2020/12/9
N2 - Dopamine is a wake-promoting neuromodulator in mammals and fruit flies. In Drosophila melanogaster, the network of clock neurons that drives sleep/activity cycles comprises both wake-promoting and sleep-promoting cell types. The large ventrolateral neurons (l-LNvs) and small ventrolateral neurons (s-LNvs) have been identified as wake-promoting neurons within the clock neuron network. The l-LNvs are innervated by dopaminergic neurons, and earlier work proposed that dopamine signaling raises cAMP levels in the l-LNvs and thus induces excitatory electrical activity (action potential firing), which results in wakefulness and inhibits sleep. Here, we test this hypothesis by combining cAMP imaging and patch-clamp recordings in isolated brains. We find that dopamine application indeed increases cAMP levels and depolarizes the l-LNvs, but, surprisingly, it does not result in increased firing rates. Downregulation of the excitatory D1-like dopamine receptor (Dop1R1) in the l-LNvs and s-LNvs, but not of Dop1R2, abolished the depolarization of l-LNvs in response to dopamine. This indicates that dopamine signals via Dop1R1 to the l-LNvs. Downregulation of Dop1R1 or Dop1R2 in the l-LNvs and s-LNvs does not affect sleep in males. Unexpectedly, we find a moderate decrease of daytime sleep with downregulation of Dop1R1 and of nighttime sleep with downregulation of Dop1R2. Since the l-LNvs do not use Dop1R2 receptors and the s-LNvs also respond to dopamine, we conclude that the s-LNvs are responsible for the observed decrease in nighttime sleep. In summary, dopamine signaling in the wake-promoting LNvs is not required for daytime arousal, but likely promotes nighttime sleep via the s-LNvs.
AB - Dopamine is a wake-promoting neuromodulator in mammals and fruit flies. In Drosophila melanogaster, the network of clock neurons that drives sleep/activity cycles comprises both wake-promoting and sleep-promoting cell types. The large ventrolateral neurons (l-LNvs) and small ventrolateral neurons (s-LNvs) have been identified as wake-promoting neurons within the clock neuron network. The l-LNvs are innervated by dopaminergic neurons, and earlier work proposed that dopamine signaling raises cAMP levels in the l-LNvs and thus induces excitatory electrical activity (action potential firing), which results in wakefulness and inhibits sleep. Here, we test this hypothesis by combining cAMP imaging and patch-clamp recordings in isolated brains. We find that dopamine application indeed increases cAMP levels and depolarizes the l-LNvs, but, surprisingly, it does not result in increased firing rates. Downregulation of the excitatory D1-like dopamine receptor (Dop1R1) in the l-LNvs and s-LNvs, but not of Dop1R2, abolished the depolarization of l-LNvs in response to dopamine. This indicates that dopamine signals via Dop1R1 to the l-LNvs. Downregulation of Dop1R1 or Dop1R2 in the l-LNvs and s-LNvs does not affect sleep in males. Unexpectedly, we find a moderate decrease of daytime sleep with downregulation of Dop1R1 and of nighttime sleep with downregulation of Dop1R2. Since the l-LNvs do not use Dop1R2 receptors and the s-LNvs also respond to dopamine, we conclude that the s-LNvs are responsible for the observed decrease in nighttime sleep. In summary, dopamine signaling in the wake-promoting LNvs is not required for daytime arousal, but likely promotes nighttime sleep via the s-LNvs.
KW - CAMP
KW - Clock neurons
KW - Dopamine
KW - Patch-clamp recording
KW - Sleep
KW - Wakefulness
UR - http://www.scopus.com/inward/record.url?scp=85097967751&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85097967751&partnerID=8YFLogxK
U2 - 10.1523/JNEUROSCI.1488-20.2020
DO - 10.1523/JNEUROSCI.1488-20.2020
M3 - Article
C2 - 33172977
AN - SCOPUS:85097967751
VL - 40
SP - 9617
EP - 9633
JO - Journal of Neuroscience
JF - Journal of Neuroscience
SN - 0270-6474
IS - 50
ER -