title: Clock mutant mice with Jcl/ICR background shows an impaired learning ability in water maze, but not in passive avoidance, at the beginning of dark phase.
abstract: We observed the learning ability in Clock mutant mice with Jcl/ICR background (Clockj), a mice model of evening-type individuals, in the early part of dark phase. In order to estimate the learning ability, Morris water maze (WM) and passive avoidance (PA) test were performed. Release of acetylcholine, 5 hydroxytryptophan (5-HT) and dopamine (DA) in hippocampus was measured by in vivo microdialysis method. Clockj showed the impaired learning ability in the WM, but not in PA test. Hippocampal acetylcholine release was significantly attenuated in the Clockj in comparison to the wild-type mice. Neither 5-HT nor DA in the hippocampus was affected by the Clock mutation. Clock, an essential gene controlling circadian rhythm, may have an important role on the spatial learning and hippocampal cholinergic function, at least, at the beginning of the dark phase.
authors.affiliation: Department of Integrative Physiology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan. sei@basic.med.tokushima-u.ac.jp
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Sei
authors.forename: Katsutaka
authors.initials: K
authors.lastname: Oishi
authors.forename: Atsuko
authors.initials: A
authors.lastname: Sano
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Seno
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Ohmori
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Morita
authors.forename: Norio
authors.initials: N
authors.lastname: Ishida
mesh_terms: D006916:5-Hydroxytryptophan / Q000494:pharmacology; D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001522:Behavior, Animal; D056926:CLOCK Proteins; D002940:Circadian Rhythm; D004298:Dopamine / Q000494:pharmacology; D006624:Hippocampus / Q000378:metabolism; D008297:Male; D018782:Maze Learning; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008813:Mice, Inbred ICR; D009154:Mutation; D018377:Neurotransmitter Agents / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics*
chemical_list: D018377:Neurotransmitter Agents; D015534:Trans-Activators; D006916:5-Hydroxytryptophan; D056926:CLOCK Proteins; C538944:Clock protein, mouse; D000109:Acetylcholine; D004298:Dopamine