056 | Glycinergic inhibition shapes circadian oscillation in membrane potential of Drosophila clock neurons


Author: Christian Mauricio Carpio Romero | Email: ccarpio@leloir.org.ar

Christian Mauricio Carpio Romero , Jose Manuel Duhart , Lia Frenkel , María Fernanda Ceriani

1° Laboratorio de genética del comportamiento – Fundación Instituto Leloir – Instituto de Investigaciones Bioquímicas de Buenos Aires (CONICET)
2° Laboratorio de Neurociencias del tiempo – IB3 – Facultad de Ciencias Exactas y Naturales – Universidad de Buenos Aires (CONICET)

In Drosophila, the central circadian clock comprises 150 neurons distributed in different clusters, which receive inputs from the environment, process the information and organize the animal pattern of daily activity. The interaction among these clusters through neuropeptides has extensively been studied. However, only recently the impact of communication through classical neurotransmitters and their role in the temporal organization of daily activities has been uncovered. Thus, the impact of glycinergic neurotransmission in the adult fly brain are not entirely clear.
We had previously shown that LNvs are glycinergic and that downregulation of glycine receptor subunits in putative sLNv targets impairs rhythmicity. Employing a technique for anterograde transsynaptic circuit tracing, we now found evidence of connectivity among the sLNvs Interestingly, sLNvs express the glycine receptor subunit GRD, whose knock down triggered behavioral phenotypes reminiscent of GlyT knock down (period lengthening under DD). GRD localization to the sLNvs was further confirmed by immunohistochemistry. Finally, employing a genetic encoded sensor, we uncovered a role of glycine in setting the sLNv membrane potential, which appears to change between day and night. Thus, we propose that in addition to a direct clock-control, the sLNvs recruit non cell-autonomous extrinsic signals (i.e., glycine) to shape their own excitability and hence coherence within the central pacemaker.