The Circadian system: Plasticity at many leves.

MURARO NI; PIREZ N; CERIANI MF

NEUROSCIENCE

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2013 vol. 247 p. 280 - 293

0306-4522

Over the years it has become crystal clear that avariety of processes encode time-of-day information, rangingfrom gene expression, protein stability, or subcellularlocalization of key proteins, to the fine tuning of networkproperties and modulation of input signals, ultimatelyensuring that physiology and behavior are properly synchronizedto a changing environment. The purpose of thisreview is to put forward examples (as opposed to generatea comprehensive revision of all the available literature) inwhich the circadian system displays a remarkable degreeof plasticity, from cell autonomous to circuit-based levels.In the literature, the term circadian plasticity has been usedto refer to different concepts. The obvious one, more literally,refers to any change that follows a circadian (circa = -around, diem= day) pattern, i.e. a daily change of a givenparameter. The discovery of daily remodeling of neuronalstructures will be referred herein as structural circadianplasticity, and represents an additional and novel phenomenonmodified daily. Finally, any plasticity that has to do witha circadian parameter would represent a type of circadianplasticity; as an example, adjustments that allow organismsto adapt their daily behavior to the annual changes in photoperiodis a form of circadian plasticity at a higher organizationallevel, which is an emergent property of the wholecircadian system. Throughout this work we will revisit thesetypes of changes by reviewing recent literature delvingaround circadian control of clock outputs, from the mostimmediate ones within pacemaker neurons to the circadianmodulation of rest?activity cycles.