Light regulates expression of a Fos-related protein in rat suprachiasmatic nuclei.
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.
Aronin
N
N
Department of Medicine, University of Massachusetts Medical School, Worcester 01655.
Sagar
S M
SM
Sharp
F R
FR
Schwartz
W J
WJ
D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D002940:Circadian Rhythm; D004268:DNA-Binding Proteins / Q000235:genetics*; D003624:Darkness; D015870:Gene Expression / Q000528:radiation effects; D006367:HeLa Cells / Q000378:metabolism; D006801:Humans; D007106:Immune Sera; D007150:Immunohistochemistry; D008027:Light; D008297:Male; D011518:Proto-Oncogene Proteins / Q000032:analysis / Q000235:genetics*; D016760:Proto-Oncogene Proteins c-fos; D051381:Rats; D011919:Rats, Inbred Strains; D013493:Suprachiasmatic Nucleus / Q000502:physiology* / Q000528:radiation effects
D004268:DNA-Binding Proteins; D007106:Immune Sera; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos