A cholinergic input determines the firing mode of a subset of clock neurons of Drosophila melanogaster

MURARO NI; CERIANI MF

Huerta Grande

Congreso; XXVII Congreso Anual de la Sociedad Argentina de Investigación en Neurociencia; 2012

Sociedad Argentina de Neurociencias

The rotation of our planet generates cyclic environmental conditions to which organisms have adapted by developing an endogenous clock. This allows them to anticipate the daily changes in light and temperature to adjust their physiology and behaviors accordingly. These circadian rhythms have been extensively studied in the fruit fly where many clock genes that interlock through negative feedback loops and generate daily oscillations have been described. Clock genes are expressed in approximately 150 clock neurons in the brain, of which a particular subset, the pigment dispersing factor-expressing lateral neurons (LNvs) have been found to play a central role.    Acetylcholine (ACh) has been previously described to act as an excitatory neurotransmitter on large-LNvs, however, no specific role has been suggested. Here we propose a role for ACh on determining the firing mode of large-LNvs because the addition of curare produces a shift from bursting, the more prevalent daytime firing mode, to tonic, which is normally found at nighttime. Additionally, the finding of TTX-resistant slow rhythmic depolarisations of alternating size led us to hypothesize that the large-LNvs could be not only pacemaker cells in the circadian sense but could also present endogenous rhythmic activity similar to cardiac pacemakers.