Influence of photoperiod duration and light-dark transitions on entrainment of Per1 and Per2 gene and protein expression in subdivisions of the mouse suprachiasmatic nucleus
Language English Country France Media print-electronic
Document type Journal Article, Research Support, Non-U.S. Gov't
PubMed
19840112
DOI
10.1111/j.1460-9568.2009.06945.x
PII: EJN6945
Knihovny.cz E-resources
- MeSH
- Biological Clocks physiology MeSH
- Period Circadian Proteins * genetics metabolism MeSH
- Circadian Rhythm physiology MeSH
- Photoperiod * MeSH
- Mice, Inbred C57BL MeSH
- Mice MeSH
- Suprachiasmatic Nucleus * anatomy & histology metabolism MeSH
- Light MeSH
- Darkness MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Mice MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Period Circadian Proteins * MeSH
- Per1 protein, mouse MeSH Browser
- Per2 protein, mouse MeSH Browser
The circadian clock located within the suprachiasmatic nuclei (SCN) of the hypothalamus responds to changes in the duration of day length, i.e. photoperiod. Recently, changes in phase relationships among the SCN cell subpopulations, especially between the rostral and caudal region, were implicated in the SCN photoperiodic modulation. To date, the effect of abrupt, rectangular, light-to-dark transitions have been studied while in nature organisms experience gradual dawn and twilight transitions. The aim of this study was to compare the effect of a long (18 h of light) and a short (6 h of light) photoperiod with twilight relative to that with rectangular light-to-dark transition on the daily profiles of Per1 and Per2 mRNA (in situ hybridization) and PER1 and PER2 protein (immunohistochemistry) levels within the rostral, middle and caudal regions of the mouse SCN. Under the short but not under the long photoperiod, Per1, Per2 and PER1, PER2 profiles were significantly phase-advanced under the twilight relative to rectangular light-to-dark transition in all SCN regions examined. Under the photoperiods with rectangular light-to-dark transition, Per1 and Per2 mRNA profiles in the caudal SCN were phase-advanced as compared with those in the rostral SCN. The phase differences between the SCN regions were reduced under the long, or completely abolished under the short, photoperiods with twilight. The data indicate that the twilight photoperiod provides stronger synchronization among the individual SCN cell subpopulations than the rectangular one, and the effect is more pronounced under the short than under the long photoperiod.
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