Light regulates expression of a Fos-related protein in rat suprachiasmatic nuclei

Neil Aronin, Stephen M. Sagar, Frank R Sharp, William J. Schwartz

Research output: Contribution to journalArticlepeer-review

285 Scopus citations


Mammalian circadian rhythmicity is endogenously generated by a pacemaker in the suprachiasmatic nuclei and precisely entrained to the 24-hr day/night cycle by periodic environmental light cues. We show that light alters the immunoreactive levels of a transcriptional regulatory protein, Fos, in the suprachiasmatic nuclei of albino rats. Photic regulation of Fos immunoreactivity does not occur in other retino-recipient brain areas except for the intergeniculate leaflet, which appears to be involved in mediating some of the complex effects of light on expressed circadian rhythms. Our results point to a promising new functional marker for the cellular effects of light and suggest that the expression of Fos or a related nuclear protein may be part of the mechanism for photic entrainment of the circadian clock to environmental light/dark cycles. (.

Original languageEnglish (US)
Pages (from-to)5959-5962
Number of pages4
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number15
StatePublished - 1990
Externally publishedYes


  • Circadian rhythm
  • Hypothalamus
  • Transcription factor

ASJC Scopus subject areas

  • Genetics
  • General


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