An abrupt shift in the day/night cycle causes desynchrony in the mammalian circadian center.
The suprachiasmatic nucleus (SCN) is the neuroanatomical locus of the mammalian circadian pacemaker. Here we demonstrate that an abrupt shift in the light/dark (LD) cycle disrupts the synchronous oscillation of circadian components in the rat SCN. The phases of the RNA cycles of the period genes Per1 and Per2 and the cryptochrome gene Cry1 shifted rapidly in the ventrolateral, photoreceptive region of the SCN, but were relatively slow to shift in the dorsomedial region. During the period of desynchrony, the animals displayed increased nighttime rest, the timing of which was inversely correlated with the expression of Per1 mRNA in the dorsomedial SCN. Molecular resynchrony required approximately 6 d after a 10 hr delay and 9 approximately 13 d after a 6 hr advance of the LD cycle and was accompanied by the reemergence of normal rest-activity patterns. This dissociation and slow resynchronization of endogenous oscillators within the SCN after an LD cycle shift suggests a mechanism for the physiological symptoms that constitute jet lag.
Nagano
Mamoru
M
Department of Anatomy and Neurobiology, Kinki University School of Medicine, Osakasayama City, Osaka 589-8511, Japan.
Adachi
Akihito
A
Nakahama
Ken-ichi
K
Nakamura
Toru
T
Tamada
Masako
M
Meyer-Bernstein
Elizabeth
E
Sehgal
Amita
A
Shigeyoshi
Yasufumi
Y
D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D001683:Biological Clocks; D018797:Cell Cycle Proteins; D021081:Chronobiology Disorders / Q000209:etiology*; D002940:Circadian Rhythm / Q000502:physiology; D056931:Cryptochromes; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D009043:Motor Activity / Q000502:physiology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D056950:Period Circadian Proteins; D010775:Photic Stimulation / Q000379:methods; D017440:Photoperiod; D017956:Photoreceptor Cells, Invertebrate; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D043562:Receptors, G-Protein-Coupled; D013493:Suprachiasmatic Nucleus / Q000378:metabolism / Q000502:physiology; D013997:Time Factors; D014157:Transcription Factors
D018797:Cell Cycle Proteins; C538964:Cry1 protein, mouse; C538965:Cry1 protein, rat; D056931:Cryptochromes; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins; D009687:Nuclear Proteins; C539023:Per1 protein, mouse; C539024:Per1 protein, rat; C513312:Per2 protein, mouse; C513311:Per2 protein, rat; D056950:Period Circadian Proteins; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; D014157:Transcription Factors; C119828:cry protein, Drosophila