Cell Reports
Volume 19, Issue 1, 4 April 2017, Pages 72-85
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Article
Organization of Circadian Behavior Relies on Glycinergic Transmission

https://doi.org/10.1016/j.celrep.2017.03.034Get rights and content
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Highlights

  • LNvs are glycinergic neurons

  • Glycine is an inhibitory neurotransmitter in the adult fly brain

  • Glycine depletion renders the circadian network susceptible to environmental changes

  • Glycine provides coherence to the circadian network

Summary

The small ventral lateral neurons (sLNvs) constitute a central circadian pacemaker in the Drosophila brain. They organize daily locomotor activity, partly through the release of the neuropeptide pigment-dispersing factor (PDF), coordinating the action of the remaining clusters required for network synchronization. Despite extensive efforts, the basic principles underlying communication among circadian clusters remain obscure. We identified classical neurotransmitters released by sLNvs through disruption of specific transporters. Adult-specific RNAi-mediated downregulation of the glycine transporter or impairment of glycine synthesis in LNv neurons increased period length by nearly an hour without affecting rhythmicity of locomotor activity. Electrophysiological recordings showed that glycine reduces spiking frequency in circadian neurons. Interestingly, downregulation of glycine receptor subunits in specific sLNv targets impaired rhythmicity, revealing involvement of glycine in information processing within the network. These data identify glycinergic inhibition of specific targets as a cue that contributes to the synchronization of the circadian network.

Keywords

Drosophila
circadian rhythms
sleep-wake cycles
glycine
inhibitory neurotransmission
glycine transporter
glycine receptor subunit

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Present address: Biomedicine Research Institute of Buenos Aires (IBioBA) MPSP-CONICET, C1425FQD Buenos Aires, Argentina

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