Abstract
Photic information entrains a circadian pacemaker located in the suprachiasmatic nucleus (SCN) of the mammalian hypothalamus to environmental light/dark cycles. To determine whether light regulates c-fos gene expression in the SCN, we have measured c-fos mRNA levels in the SCN of the golden hamster. We report that, during the subjective night, light causes a rapid increase in levels of c-fos mRNA in the SCN. Light pulses of 5 min duration are sufficient to induce c-fos mRNA, and the highest mRNA levels occur 30 min following the onset of light. The minimum level of illumination required to induce an increase in c-fos mRNA is indistinguishable from the minimum irradiance that produces a phase shift in the hamster's circadian rhythm of activity. In addition, the induction of c-fos mRNA in the SCN by light is itself under circadian regulation. Light induction of c-fos mRNA occurs only during the subjective night, at circadian times when photic phase shifting of activity occurs. Taken together, these data suggest that c-fos may be a molecular component of the photic pathway for entrainment of mammalian circadian rhythms.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 127-134 |
| Number of pages | 8 |
| Journal | Neuron |
| Volume | 5 |
| Issue number | 2 |
| DOIs | |
| State | Published - Aug 1990 |
Funding
We thank Dr. Lester Lau for providing the c-fos cDNA clone, John Mcrdacq and Jason Rahal for their advice and assistance, and Dr. Daniel Linzer for critical reading of this manuscript. This work wassupported bygrantsfrom the NIH, NSF,and NIMH (to). S.T.) and from the NIH, NSF, and the McKnight Foundation (to K. E. M.).
ASJC Scopus subject areas
- General Neuroscience