PMID- 1613544
OWN - NLM
STAT- MEDLINE
DCOM- 19920730
LR  - 20191101
IS  - 0270-6474 (Print)
IS  - 1529-2401 (Electronic)
IS  - 0270-6474 (Linking)
VI  - 12
IP  - 7
DP  - 1992 Jul
TI  - A nonphotic stimulus causes instantaneous phase advances of the light-entrainable 
      circadian oscillator of the Syrian hamster but does not induce the expression of 
      c-fos in the suprachiasmatic nuclei.
PG  - 2516-22
AB  - The study investigated whether nonphotic cues that alter the phase of overt 
      circadian rhythms do so by causing instantaneous shifts in the underlying, 
      light-sensitive clock. Wheel-running activity in Syrian hamsters was studied 
      under free-running conditions of constant dim red light as an overt marker of 
      circadian phase, the daily onset of activity being defined as circadian time 12 
      (CT 12). Exposure to a 15 min pulse of bright light at CT 12.20 caused a phase 
      delay in activity onset, whereas pulses delivered at CT 11.20 had no effect upon 
      the overt rhythm. Correlated with their effect on behavior, light pulses 
      delivered at CT 12.20 induced expression of c-fos-like immunoreactivity in the 
      retinorecipient regions of the suprachiasmatic nuclei of the hypothalamus (SCN), 
      whereas pulses delivered at CT 11.20 had no effect upon the expression of c-fos. 
      Expression of this immediate-early gene therefore provided a second marker of 
      circadian phase, because its induction by light is closely correlated with the 
      onset of subjective night (CT 12). To establish a suitable protocol for nonphotic 
      shifts of the activity rhythm, animals were handled and received a subcutaneous 
      injection of saline at different circadian phases. Injections at CT 8 or CT10 
      caused an immediate bout of wheel-running activity, and a consequent phase 
      advance in the activity rhythm as assessed by the earlier onsets of activity in 
      successive days. Handling and injections at other circadian phases were without 
      effect. Despite shifting the overt rhythm, these procedures at CT 10 did not lead 
      to the expression of c-fos in the SCN.(ABSTRACT TRUNCATED AT 250 WORDS)
FAU - Mead, S
AU  - Mead S
AD  - Department of Anatomy, University of Cambridge, United Kingdom.
FAU - Ebling, F J
AU  - Ebling FJ
FAU - Maywood, E S
AU  - Maywood ES
FAU - Humby, T
AU  - Humby T
FAU - Herbert, J
AU  - Herbert J
FAU - Hastings, M H
AU  - Hastings MH
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - J Neurosci
JT  - The Journal of neuroscience : the official journal of the Society for 
      Neuroscience
JID - 8102140
SB  - IM
GS  - c-fos
MH  - Animals
MH  - *Circadian Rhythm
MH  - Cricetinae
MH  - Darkness
MH  - Gene Expression
MH  - *Genes, fos
MH  - Light
MH  - Male
MH  - Mesocricetus/*physiology
MH  - Motor Activity
MH  - Photic Stimulation
MH  - Suprachiasmatic Nucleus/*physiology
PMC - PMC6575841
EDAT- 1992/07/01 00:00
MHDA- 1992/07/01 00:01
PMCR- 1993/01/01
CRDT- 1992/07/01 00:00
PHST- 1992/07/01 00:00 [pubmed]
PHST- 1992/07/01 00:01 [medline]
PHST- 1992/07/01 00:00 [entrez]
PHST- 1993/01/01 00:00 [pmc-release]
AID - 10.1523/JNEUROSCI.12-07-02516.1992 [doi]
PST - ppublish
SO  - J Neurosci. 1992 Jul;12(7):2516-22. doi: 10.1523/JNEUROSCI.12-07-02516.1992.