Glycinergic transmission in the circadian network: a time-of-day dependent switch

LIA FRENKEL; NARA I MURARO; ANDREA N BELTRÁN GONZALEZ; DANIEL J. CALVO; M. FERNANDA CERIANI

Buenos Aires

Congreso; 2nd FALAN (Federation of Latin-American and Caribbean Societies for Neuroscience) Congress; 2016

Federation of Latin-American and Caribbean Societies for Neuroscience

The small ventral Lateral Neurons (sLNvs)constitute a central pacemaker for the ≈150 units that comprise the circadiannetwork in the Drosophila brain. Theyrely on the release of the neuropeptide Pigment Dispersing Factor (PDF) forcoordinating the action of the remaining clock neurons required for a properorganization of the daily locomotor activity. In addition, we have shown thatsynapse remodeling of clock neuronal terminals takes place on daily basis and,furthermore, that it led to differential contacts across the day. Despiteextensive efforts to uncover their neurotransmitter identity, fastcommunication among circadian clusters remains obscure. We sought to identifyclassical neurotransmitters released by sLNvs through disruption of theirre-uptake. By means of RNAi-mediated downregulation, we found that glycinetransporter and synthesis in these neurons increased period length by nearly anhour without affecting rhythmicity of locomotor activity. We also found thatglycine stops action potential firing in circadian neurons. Moreover,downregulation of putative glycine receptor subunits in sLNv targets impairedrhythmicity. Interestingly, disruption of glycinergictransmission specifically onto plastic (=time of day dependent) or constanttargets triggers opposite phenotypes in circadian period. In sum, sLNv couldoperate as a time-of-day switch that rapidly turns off specific targets to keepthe circadian network synchronized.