GLYCINERGIC TRANSMISSION IN THE CIRCADIAN NETWORK: A TIME-OF-DAY DEPENDENT SWITCH

BELTRÁN GONZALEZ A; MURARO, NI; CERIANI, MF; FRENKEL, L; CALVO, DJ

C.A.B.A.

Congreso; 2nd FALAN Congress; 2016

FALAN (Federation of Latin-American and Caribbean Societies for Neurosciences)

GLYCINERGIC TRANSMISSION IN THE CIRCADIAN NETWORK: A TIME-OF-DAY DEPENDENT SWITCHL Frenkel1, NI Muraro1,3, A Beltrán Gonzalez2, DJ Calvo3 & MF Ceriani21 Laboratorio de Genética del Comportamiento- Fundación Instituto Leloir- IIBBA- CONICET, Argentina.2 Laboratorio de Neurobiología Celular y Molecular- INGEBI- CONICET- Universidad de Buenos Aires, Argentina.3 Present address: IBioBA- MPSP- CONICET, Argentina.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 clock neurons required for a proper organization of the daily locomotor activity. In addition, we have shown that synapse remodeling of clock neuronal terminals takes place on daily basis and, furthermore, that it led to differential contacts across the day. Despite extensive efforts to uncover their neurotransmitter identity, 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 putative glycine receptor subunits in sLNv targets impaired rhythmicity. Interestingly, disruption of glycinergic transmission specifically onto plastic (=time of day dependent) or constant targets triggers opposite phenotypes in circadian period. In sum, sLNv could operate as a time-of-day switch that rapidly turns off specific targets to keep the circadian network synchronized.