title: Circadian variations of melatonin binding sites in the goldfish brain.
abstract: Daily and circadian variations in melatonin binding sites in the brain of goldfish (Carassius auratus) were examined by radioreceptor assay. Under light-dark cycles of 12:12 h, the density (B(max)) of melatonin binding sites in the brain exhibited daily variations with a peak and a trough seen around the light offset and 2 h before light onset, respectively. The affinity (K(d)) exhibited no variation. The rhythm in the B(max) persisted even under constant darkness with higher levels during the late subjective-day. These results indicate that the density of melatonin binding sites in the goldfish brain is regulated by the circadian clock.
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: Kiyoshi
authors.initials: K
authors.lastname: Furukawa
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Tabata
authors.forename: Katsumi
authors.initials: K
authors.lastname: Aida
mesh_terms: D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000378:metabolism*; D002940:Circadian Rhythm; D003624:Darkness; D005260:Female; D006054:Goldfish; D008027:Light; D008297:Male; D008550:Melatonin / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D044094:Receptors, Melatonin
chemical_list: D011956:Receptors, Cell Surface; D018160:Receptors, Cytoplasmic and Nuclear; D044094:Receptors, Melatonin; D008550:Melatonin