title: Developmental trajectory of contextual learning and 24-h acetylcholine release in the hippocampus.
abstract: To determine the developmental trajectory of hippocampal function in rats, we examined 24-h changes in extracellular acetylcholine (ACh) levels and contextual learning performance. Extracellular ACh significantly correlated with spontaneous behavior, exhibiting a 24-h rhythm in juvenile (4-week-old), pubertal (6-week-old), and adult (9- to 12-week-old) rats. Although juveniles of both sexes exhibited low ACh levels, adult males had higher ACh levels than adult females. Moreover, juveniles exhibited much more spontaneous activity than adults when they showed equivalent ACh levels. Similarly, juveniles of both sexes exhibited relatively low contextual learning performance. Because contextual learning performance was significantly increased only in males, adult males exhibited better performance than adult females. We also observed a developmental relationship between contextual learning and ACh levels. Scopolamine pretreatment blocked contextual learning and interrupted the correlation. Since long-term scopolamine treatment after weaning impaired contextual learning in juveniles, the cholinergic input may participate in the development of hippocampus.
authors.affiliation: 1] Department of Physiology, Yokohama City University Graduate School of Medicine, 3-9 Fukuura Kanazawa-ku, Yokohama 236-0004, Japan [2] Department of Anatomy, Toho University School of Medicine, 5-21-16 Omori-Nishi Ota-ku, Tokyo 143-8540, Japan.
authors.forename: Kenkichi
authors.initials: K
authors.lastname: Takase
authors.affiliation: Department of Systems Neuroscience, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube 755-8505, Japan.
authors.forename: Yuya
authors.initials: Y
authors.lastname: Sakimoto
authors.affiliation: Department of Physiology, Yokohama City University Graduate School of Medicine, 3-9 Fukuura Kanazawa-ku, Yokohama 236-0004, Japan.
authors.forename: Fukuko
authors.initials: F
authors.lastname: Kimura
authors.affiliation: 1] Department of Physiology, Yokohama City University Graduate School of Medicine, 3-9 Fukuura Kanazawa-ku, Yokohama 236-0004, Japan [2] Department of Systems Neuroscience, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube 755-8505, Japan.
authors.forename: Dai
authors.initials: D
authors.lastname: Mitsushima
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D018680:Cholinergic Antagonists / Q000494:pharmacology; D005110:Extracellular Space / Q000378:metabolism; D005239:Fear; D005260:Female; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D007858:Learning / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009043:Motor Activity; D051381:Rats; D012601:Scopolamine / Q000494:pharmacology; D013997:Time Factors
chemical_list: D018680:Cholinergic Antagonists; D012601:Scopolamine; D000109:Acetylcholine