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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Behavior, Animal
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Butadienes / pharmacology
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Circadian Rhythm*
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Cricetinae
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DNA-Binding Proteins*
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Dizocilpine Maleate / pharmacology
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Enzyme Inhibitors / pharmacology
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Light*
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MAP Kinase Signaling System
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Male
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Mesocricetus
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Mitogen-Activated Protein Kinase 1 / metabolism
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Mitogen-Activated Protein Kinase 3
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Mitogen-Activated Protein Kinase Kinases / antagonists & inhibitors
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Mitogen-Activated Protein Kinases / metabolism*
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Nitriles / pharmacology
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Phosphorylation / radiation effects
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Proto-Oncogene Proteins / metabolism*
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Proto-Oncogene Proteins c-fos / metabolism
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Receptors, N-Methyl-D-Aspartate / antagonists & inhibitors
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Suprachiasmatic Nucleus / enzymology
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Suprachiasmatic Nucleus / metabolism*
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Suprachiasmatic Nucleus / radiation effects
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Transcription Factors*
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ets-Domain Protein Elk-1
Substances
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Butadienes
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DNA-Binding Proteins
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Enzyme Inhibitors
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Nitriles
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Proto-Oncogene Proteins
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Proto-Oncogene Proteins c-fos
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Receptors, N-Methyl-D-Aspartate
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Transcription Factors
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U 0126
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ets-Domain Protein Elk-1
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Dizocilpine Maleate
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Mitogen-Activated Protein Kinase 1
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Mitogen-Activated Protein Kinase 3
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Mitogen-Activated Protein Kinases
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Mitogen-Activated Protein Kinase Kinases