Takase Kenkichi, Sakimoto Yuya, Kimura Fukuko, Mitsushima Dai
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.
Department of Systems Neuroscience, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube 755-8505, Japan.
Sci Rep. 2014 Jan 17;4:3738. doi: 10.1038/srep03738.
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.
为了确定大鼠海马功能的发育轨迹，我们检测了细胞外乙酰胆碱（ACh）水平的24小时变化以及情境学习表现。细胞外ACh与自发行为显著相关，在幼年（4周龄）、青春期（6周龄）和成年（9至12周龄）大鼠中呈现出24小时节律。虽然两性幼年大鼠的ACh水平都较低，但成年雄性大鼠的ACh水平高于成年雌性大鼠。此外，当幼年大鼠和成年大鼠的ACh水平相当时，幼年大鼠的自发活动比成年大鼠多得多。同样，两性幼年大鼠的情境学习表现相对较低。由于情境学习表现仅在雄性大鼠中显著提高，成年雄性大鼠的表现优于成年雌性大鼠。我们还观察到情境学习与ACh水平之间的发育关系。东莨菪碱预处理会阻断情境学习并中断这种相关性。由于断奶后长期给予东莨菪碱会损害幼年大鼠的情境学习，胆碱能输入可能参与海马的发育。
