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 (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.
Nagano
Mamoru
M
Department of Anatomy and Neurobiology, Kinki University School of Medicine 377-2 Ohno-Higashi, Osakasayama City, Osaka 589-8511, Japan.
Adachi
Akihito
A
Masumoto
Koh-hei
KH
Meyer-Bernstein
Elizabeth
E
Shigeyoshi
Yasufumi
Y
D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D002940:Circadian Rhythm / Q000235:genetics*; D003624:Darkness; D017403:In Situ Hybridization; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism; D008297:Male; D009043:Motor Activity / Q000235:genetics; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D056950:Period Circadian Proteins; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013493:Suprachiasmatic Nucleus / Q000378:metabolism*; D013997:Time Factors
D018797:Cell Cycle Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; C539024:Per1 protein, rat; C513311:Per2 protein, rat; D056950:Period Circadian Proteins; D012333:RNA, Messenger