TY - JOUR
T1 - Nonphotic entrainment by 5-HT(1a/7) receptor agonists accompanied by reduced Per1 and Per2 mRNA levels in the suprachiasmatic nuclei
AU - Horikawa, Kazumasa
AU - Yokota, Shin Ichi
AU - Fuji, Kazuyuki
AU - Akiyama, Masashi
AU - Moriya, Takahiro
AU - Okamura, Hitoshi
AU - Shibata, Shigenobu
PY - 2000/8/1
Y1 - 2000/8/1
N2 - In mammals, the environmental light/dark cycle strongly synchronizes the circadian clock within the suprachiasmatic nuclei (SCN) to 24 hr. It is well known that not only photic but also nonphotic stimuli can entrain the SCN clock. Actually, many studies have shown that a daytime injection of 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH DPAT), a serotonin 1A/7 receptor agonist, as a nonphotic stimulus induces phase advances in hamster behavioral circadian rhythms in vivo, as well as the neuron activity rhythm of the SCN in vitro. Recent reports suggest that mammalian homologs of the Drosophila clock gene, Period (Per), are involved in photic entrainment. Therefore, we examined whether phase advances elicited by 8-OH DPAT were associated with a change of Period mRNA levels in the SCN. In this experiment, we cloned partial cDNAs encoding hamster Per1, Per2, and Per3 and observed both circadian oscillation and the light responsiveness of Period. Furthermore, we found that the inhibitory effect of 8-OH DPAT on hamster Per1 and Per2 mRNA levels in the SCN occurred only during the hamster's mid-subjective day, but not during the early subjective day or subjective night. The present findings demonstrate that the acute and circadian time-dependent reduction of Per1 and/or Per2 mRNA in the hamster SCN by 8-OH DPAT is strongly correlated with the phase resetting in response to 8-OH DPAT.
AB - In mammals, the environmental light/dark cycle strongly synchronizes the circadian clock within the suprachiasmatic nuclei (SCN) to 24 hr. It is well known that not only photic but also nonphotic stimuli can entrain the SCN clock. Actually, many studies have shown that a daytime injection of 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH DPAT), a serotonin 1A/7 receptor agonist, as a nonphotic stimulus induces phase advances in hamster behavioral circadian rhythms in vivo, as well as the neuron activity rhythm of the SCN in vitro. Recent reports suggest that mammalian homologs of the Drosophila clock gene, Period (Per), are involved in photic entrainment. Therefore, we examined whether phase advances elicited by 8-OH DPAT were associated with a change of Period mRNA levels in the SCN. In this experiment, we cloned partial cDNAs encoding hamster Per1, Per2, and Per3 and observed both circadian oscillation and the light responsiveness of Period. Furthermore, we found that the inhibitory effect of 8-OH DPAT on hamster Per1 and Per2 mRNA levels in the SCN occurred only during the hamster's mid-subjective day, but not during the early subjective day or subjective night. The present findings demonstrate that the acute and circadian time-dependent reduction of Per1 and/or Per2 mRNA in the hamster SCN by 8-OH DPAT is strongly correlated with the phase resetting in response to 8-OH DPAT.
KW - 5-HT(1A/7) receptor
KW - 8-OH DPAT
KW - Circadian rhythm
KW - Hamster
KW - NIH Image
KW - Per mRNA
KW - Suprachiasmatic nucleus
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U2 - 10.1523/jneurosci.20-15-05867.2000
DO - 10.1523/jneurosci.20-15-05867.2000
M3 - Article
C2 - 10908630
AN - SCOPUS:0034255045
VL - 20
SP - 5867
EP - 5873
JO - Journal of Neuroscience
JF - Journal of Neuroscience
SN - 0270-6474
IS - 15
ER -