rPer1 and rPer2 induction during phases of the circadian cycle critical for light resetting of the circadian clock

Photic resetting of a biological clock is one of the fundamental characteristics of circadian systems and allows living organisms to adjust to a particular environment. Nocturnal light induces the Per1 and Per2 genes, which leads to a resetting of the circadian clock in the suprachiasmatic nucleus (...

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Published in:Brain research 2009-09, Vol.1289, p.37-48
Main Authors: NAGANO, Mamoru, ADACHI, Akihito, MASUMOTO, Koh-Hei, MEYER-BERNSTEIN, Elizabeth, SHIGEYOSHI, Yasufumi
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Cell Cycle Proteins - genetics
Cell Cycle Proteins - metabolism
Chronobiology
Circadian Rhythm - genetics
Darkness
Fundamental and applied biological sciences. Psychology
In Situ Hybridization
Intracellular Signaling Peptides and Proteins - genetics
Intracellular Signaling Peptides and Proteins - metabolism
Male
Motor Activity - genetics
Nuclear Proteins - genetics
Nuclear Proteins - metabolism
Period Circadian Proteins
Rats
Rats, Wistar
RNA, Messenger - metabolism
Suprachiasmatic Nucleus - metabolism
Time Factors
Vertebrates: anatomy and physiology, studies on body, several organs or systems
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Summary:Photic resetting of a biological clock is one of the fundamental characteristics of circadian systems and allows living organisms to adjust to a particular environment. Nocturnal light induces the Per1 and Per2 genes, which leads to a resetting of the circadian clock in the suprachiasmatic nucleus (SCN), the mammalian circadian center. In our present study, we investigated whether light differentially induces the rat Per1 (rPer1) and Per2 (rPer2) genes to enable resetting of their circadian clocks. In a 24-hour LD cycle (12 h light:12 h dark), which is shorter than the normal free-running period for rats, Per1 alone showed strong induction in the ventrolateral region of the SCN (VLSCN) during the early day. In contrast, in a 25 hour LD cycle (12.5 h light:12.5 h dark), which is longer than the free running period for these animals, rPer2 alone was strongly induced in the VLSCN, at the end of the light phase and during the early dark periods. Our current findings therefore suggest that Per1 and Per2 are differentially regulated for daily entrainment to the LD cycle.
ISSN:0006-8993
1872-6240
DOI:10.1016/j.brainres.2009.06.051