Referenced in: none

Automatically associated channels: Kv12.1 , Slo1

Title: Circadian and photic regulation of phosphorylation of ERK1/2 and Elk-1 in the suprachiasmatic nuclei of the Syrian hamster.

Authors: Andrew N Coogan, Hugh D Piggins

Journal, date & volume: J. Neurosci., 2003 Apr 1 , 23, 3085-93

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/12684495

Abstract
In this study we investigated the circadian and photic regulation of phosphorylation of the extracellular signal-related kinase (ERK) 1/2, and the transcription factor Elk-1 in the suprachiasmatic nuclei of the Syrian hamster. We report that levels of phosphorylated ERK (P-ERK) are rhythmic, peaking during the mid subjective day, whereas phosphorylated Elk-1 (P-Elk-1) shows no distinct rhythm. Light pulses during the subjective night rapidly, but transiently, induce P-ERK, whereas P-Elk-1 is also induced, albeit with a slower time course. Application of the ERK pathway inhibitor U0126 attenuates photic induction of both P-ERK and P-Elk-1 and phase advances of wheel-running behavior. The NMDA receptor channel blocker, MK-801, also significantly attenuates photic induction of P-ERK and P-Elk-1. Taken together, these results indicate a role of the ERK cascade in the regulation of free-running circadian rhythms and of photic-resetting of these rhythms and suggest that in the mammalian suprachiasmatic nuclei, Elk-1 represents a novel molecular component of the photic-induction pathway.