Glycinergic transmission in the circadian network. A time-of-day dependent switch

FRENKEL L; MARÍA FERNANDA CERIANI

Sao Paulo

Simposio; XIII Latin American Symposium on Chronobiology; 2015

LASC

GLYCINERGIC TRANSMISSION IN THE CIRCADIAN NETWORK: A TIME-OF-DAY DEPENDENT SWITCH The small ventral Lateral Neurons (sLNvs) constitute a central pacemaker for the ≈150 units that comprise the circadian network in the Drosophila brain. They rely on the release of the neuropeptide Pigment Dispersing Factor (PDF) for coordinating the action of the remaining neurons required for network synchronization and a proper organization of the daily locomotor activity. Despite extensive efforts, fast communication among circadian clusters remains obscure. We sought to identify classical neurotransmitters released by sLNvs through disruption of their re-uptake. By means of RNAi-mediated downregulation, we found that glycine transporter and synthesis in these neurons increased period length by nearly an hour without affecting rhythmicity of locomotor activity. We also found that glycine stops action potential firing in circadian neurons. Moreover, downregulation of glycine receptor subunits in sLNv targets impaired rhythmicity. Interestingly, disruption of glycinergic transmission onto constant circadian targets triggers a subtle increase in period length. In contrast, the same treatment in the dynamic targets slightly shortens the period of locomotor activity. In brief, sLNv could operate as a time-of-day switch that rapidly turns off specific targets to keep the circadian network synchronized.