title: In vitro photic entrainment of the circadian rhythm in melatonin release from the pineal organ of a teleost, ayu (Plecoglossus altivelis) in flow-through culture.
abstract: The effects of light on the circadian rhythm in melatonin release from the pineal organ of a teleost, ayu (Plecoglossus altivelis) were investigated in flow-through culture. Under the reversed light-dark (LD) cycle, the melatonin rhythm phase shifted as compared with those under the normal LD cycle. This phase shift persisted even under constant darkness (DD). Single 6-h light pulses starting at six different circadian phases under DD acutely suppressed melatonin release. Phase-dependent phase shifts in the circadian rhythm of melatonin release were also observed. The phase response curve to light pulses in the ayu pineal organ is typical of that found in many circadian systems. Thus, the ayu pineal organ should provide a useful model for analyzing the physiological and molecular basis of the entrainment mechanism of vertebrate circadian system.
authors.affiliation: Department of Anatomy, St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae, Kawasaki 216-8511, Japan. iigo@cc.utsunomiya-u.ac.jp
authors.forename: Masayuki
authors.initials: M
authors.lastname: Iigo
authors.forename: Kanta
authors.initials: K
authors.lastname: Mizusawa
authors.forename: Makoto
authors.initials: M
authors.lastname: Yokosuka
authors.forename: Masayuki
authors.initials: M
authors.lastname: Hara
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Ohtani-Kaneko
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Tabata
authors.forename: Katsumi
authors.initials: K
authors.lastname: Aida
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Hirata
mesh_terms: D000818:Animals; D002940:Circadian Rhythm / Q000528:radiation effects*; D003624:Darkness; D005399:Fishes / Q000502:physiology*; D008027:Light; D008550:Melatonin / Q000378:metabolism*; D009924:Organ Culture Techniques; D017440:Photoperiod; D010870:Pineal Gland / Q000378:metabolism*
chemical_list: D008550:Melatonin