CO-TRANSMISSION IN THE CIRCADIAN NETWORK

MILDINER SEBASTIAN; SOFÍA POLCOWÑUK; FRENKEL L; M FERNANDA CERIANI

Valparaíso

Simposio; XIV Latin American Symposium on Chronobiology 2017 - LASC 2017; 2017

Centro Interdisciplinario de Neurociencia de Valparaíso

Co-transmission in the circadian network: temporalsegregation of neurotransmitters as a means of daily rewiring? The central circadian oscillator of Drosophilamelanogaster is composed of about 150 neurons. Among them, the 8 small lateral ventral neurons (sLNvs) are fundamental in various aspects of temporal organization, but by far the most studied one is in the fly daily locomotor activity. sLNvs release PDF, the neuropeptide that synchronizes circadian oscillators. While the relevance of neuropeptidergic transmission is well established, uncovering the role of fast neurotransmission is booming.After a screen aimed at unveiling sLNv neurotransmitter identity, we established that sLNvs release glycine. Glycinergic transmission inhibits sLNv post-synaptic targets. Notwithstanding, our results also suggest that sLNvs recruit excitatory cholinergic transmission for communication. Unexpectedly, acetylcholine depletion in these neurons by downregulating its synthesis, recycling or synaptic vesicle refilling, leads to a lengthening in the period of locomotor activity, as it is the case with glycinergic transmission, suggesting that period lengthening is the result of altering the hierarchical relationship among clusters The "one neuron, one neurotransmitter" dogma has repeatedly been questioned by findings within the mammalian brain, where co-transmission seems to be the rule. In addition, it has been proposed that co-transmission would play a role in plasticity. Since reorganization of synaptic circuits by neurotransmitter switching can occur in response to changes in the environment or nutritional state, we propose that temporal segregating the synaptic vesicular content contributes to the functional rewiring of the circadian network in Drosophila.