title: Effects of selective muscarinic antagonists, pirenzepine and AF-DX 116, on passive avoidance tasks in mice.
abstract: To clarify the physiological roles of muscarinic acetylcholine (mACh) receptor subtypes, M1 and M2, on learning and memory, we examined the effects of three antagonists, atropine (non-selective), pirenzepine (M1 selective) and 11-[[2-[(diethylamino)methyl]-1-piperidinyl]acetyl]-5, 11-dihydro-6H-pyrido[2,3-b][1,4]benzodiazepine-6-one, AF-DX 116 (M2 selective), on step-through passive avoidance tasks in mice. During acquisition tests, mice were trained repeatedly until they achieved criterion latency (300 s). In all experiments, drugs or vehicles were intracerebroventricularly administered. Pre-training (5 min before) administration of atropine (1-40 nmol) and pirenzepine (10 and 40 nmol) shortened the response latency in retention tests at 14 d after acquisition training. Pre-test (5 min before) and post-training (immediately after the acquisition training) administration of atropine slightly but not significantly impaired retention scores. The administration of AF-DX 116 did not apparently affect the scores in any of tests. Thus, the M1 receptor subtype coupling systems seem to be more important in the acquisition-consolidation process rather than in the retrieval process.
authors.affiliation: Department of Pharmacology, Faculty of Pharmaceutical Sciences, Hokkaido University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Ohnuki
authors.forename: Y
authors.initials: Y
authors.lastname: Nomura
mesh_terms: D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001362:Avoidance Learning / Q000187:drug effects*; D008297:Male; D051379:Mice; D018727:Muscarinic Antagonists / Q000494:pharmacology*; D010890:Pirenzepine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D043643:Receptor, Muscarinic M1; D043585:Receptor, Muscarinic M2; D011976:Receptors, Muscarinic / Q000502:physiology
chemical_list: D018727:Muscarinic Antagonists; D043643:Receptor, Muscarinic M1; D043585:Receptor, Muscarinic M2; D011976:Receptors, Muscarinic; D010890:Pirenzepine; D001285:Atropine; C048593:otenzepad