RT Journal Article
SR Electronic
T1 Entrainment of circadian rhythms depends on firing rates and neuropeptide release of VIP SCN neurons
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 322339
DO 10.1101/322339
A1 Cristina Mazuski
A1 John H. Abel
A1 Samantha P. Chen
A1 Tracey O. Hermanstyne
A1 Jeff R. Jones
A1 Tatiana Simon
A1 Francis J. Doyle III
A1 Erik D. Herzog
YR 2018
UL http://biorxiv.org/content/early/2018/05/16/322339.abstract
AB The mammalian suprachiasmatic nucleus (SCN) functions as a master circadian pacemaker, integrating environmental input to align physiological and behavioral rhythms to local time cues. Approximately 10% of SCN neurons express vasoactive intestinal polypeptide (VIP); however, it is unknown how firing activity of VIP neurons releases VIP to entrain circadian rhythms. To identify physiologically relevant firing patterns, we optically tagged VIP neurons and characterized spontaneous firing over three days. VIP neurons had circadian rhythms in firing rate and exhibited two classes of instantaneous firing activity. We next tested whether physiologically relevant firing affected circadian rhythms through VIP release. We found that VIP neuron stimulation with high, but not low, frequencies shifted gene expression rhythms in vitro through VIP signaling. In vivo, high frequency VIP neuron activation rapidly entrained circadian locomotor rhythms. Thus, increases in VIP neuronal firing frequency release VIP and entrain molecular and behavioral circadian rhythms.HighlightsMazuski et al. identified three classes of circadian SCN neurons based on their distinct firing patterns consistent over multiple daysThere are two distinct classes (tonic and irregular firing) of VIP SCN neurons.Stimulation of VIP SCN neurons at physiologically relevant frequencies phase shifts whole-SCN circadian rhythms in gene expression through VIP release. These effects are blocked with VIP antagonists.Firing of VIP SCN neurons entrains circadian rhythms in locomotor behavior in a frequency and time-of-day dependent manner.