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

UMMS Affiliation

Department of Medicine, Division of Endocrinology and Metabolism; Department of Physiology; Department of Neurology

Publication Date


Document Type



Animals; Cell Nucleus; Circadian Rhythm; DNA-Binding Proteins; Darkness; Gene Expression; Hela Cells; Humans; Immune Sera; Immunohistochemistry; *Light; Male; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-fos; Rats; Rats, Inbred Strains; Suprachiasmatic Nucleus


Life Sciences | Medicine and Health Sciences


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.


Proc Natl Acad Sci U S A. 1990 Aug;87(15):5959-62.

Journal/Book/Conference Title

Proceedings of the National Academy of Sciences of the United States of America

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