Nociceptin/orphanin FQ and nocistatin on learning and memory impairment induced by scopolamine in mice.
1. Nociceptin, also known as orphanin FQ, is an endogenous ligand for the orphan opioid receptor-like receptor 1 (ORL1) and involves in various functions in the central nervous system (CNS). On the other hand, nocistatin is recently isolated from the same precursor as nociceptin and blocks nociceptin-induced allodynia and hyperalgesia. 2. Although ORL1 receptors which display a high degree of sequence homology with classical opioid receptors are abundant in the hippocampus, little is known regarding their role in learning and memory. 3. The present study was designed to investigate whether nociceptin/orphanin FQ and nocistatin could modulate impairment of learning and memory induced by scopolamine, a muscarinic cholinergic receptor antagonist, using spontaneous alternation of Y-maze and step-down type passive avoidance tasks in mice. 4. While nocistatin (0.5-5.0 nmol mouse-1, i.c.v.) administered 30 min before spontaneous alternation performance or the training session of the passive avoidance task, had no effect on spontaneous alternation or passive avoidance behaviours, a lower per cent alternation and shorter median step-down latency in the retention test were obtained in nociceptin (1.5 and/or 5.0 nmol mouse-1, i.c.v.)-treated normal mice. 5. Administration of nocistatin (1.5 and/or 5.0 nmol mouse-1, i.c.v.) 30 min before spontaneous alternation performance or the training session of the passive avoidance task, attenuated the scopolamine-induced impairment of spontaneous alternation and passive avoidance behaviours. 6. These results indicated that nocistatin, a new biologically active peptide, ameliorates impairments of spontaneous alternation and passive avoidance induced by scopolamine, and suggested that these peptides play opposite roles in learning and memory.
Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Meijo University, Nagoya, Japan. mhiramt@meijo-u.ac.jp
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Hiramatsu
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Inoue
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects; D001522:Behavior, Animal / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D007837:Latency Period, Psychological; D007858:Learning / Q000187:drug effects*; D007859:Learning Disabilities / Q000139:chemically induced / Q000188:drug therapy; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D008568:Memory / Q000187:drug effects*; D008569:Memory Disorders / Q000139:chemically induced / Q000188:drug therapy; D051379:Mice; D018727:Muscarinic Antagonists / Q000633:toxicity*; D018847:Opioid Peptides / Q000494:pharmacology*; D012601:Scopolamine / Q000037:antagonists & inhibitors / Q000633:toxicity*; D000097629:Nociceptin
D018727:Muscarinic Antagonists; D018847:Opioid Peptides; D012601:Scopolamine; D000097629:Nociceptin; C111148:nocistatin