Effects of Continuous Supply of Light or Carbachol to the SCN on the Rat Free-running Rhythm

Noboru MURAKAMI; Tadashi FURUKAWA; Takashi YOKAWA; Teiichi ETOH; Kiyohisa TAKAHASHI

doi:10.2170/jjphysiol.36.411

Noboru MURAKAMI, Tadashi FURUKAWA, Takashi YOKAWA, Teiichi ETOH, Kiyohisa TAKAHASHI

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Keywords: circadian rhythm, suprachiasmatic nucleus, acetylcholine

JOURNAL FREE ACCESS

1986 Volume 36 Issue 2 Pages 411-416

DOI https://doi.org/10.2170/jjphysiol.36.411

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Abstract

Exposure to continuous light (LL) results in elongation of the free-running period of the rat circadian rhythm. However, the LL may not always mean constant intensity of light for the suprachiasmatic nucleus (SCN), since rats may regulate contrast of illumination by their eyelids which are closed during sleep phase. The removal of eyelids caused shortening of the free-running period or arrhythmicity under LL. In addition, implantation of carbachol-acetylcholine agonist-near the SCN also resulted in similar effects.

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