Atropine, an anticholinergic drug, impairs memory retrieval of a high consolidated avoidance response in mice.
Immediate post-training intraperitoneal administration of the centrally acting anticholinesterase physostigmine (70.0, or 150.0 microg/kg) enhanced retention of male CF-1 mice tested 48 h after training in a one-trial step-through inhibitory avoidance task (0.8 mA, 50 Hz, 1 s footshock). The effect was observed in mice that received saline 30 min before the retention test; on the contrary, the pre-test administration of the centrally active muscarinic cholinergic antagonist, atropine (1.0 mg/kg, i.p.), but not methylatropine (1.0 mg/kg, i.p.), instead of saline, prevents the enhancement of retention induced by both doses of the anticholinesterase when given immediately after training. The high retention performance caused by post-training physostigmine was recovered following a second administration of the same doses of the drug, 10 min after the pre-test injections of atropine. Since, physostigmine do not influence memory retrieval when given prior to the retention test, and its post-training effects are not due to the induction of state-dependency, the recover of the high retention performance was probably due to a classical interaction between a muscarinic competitive antagonist and an indirect cholinergic agonist. Further, atropine probably does not modify the memory trace by erasing it, but by producing a poor retrieval.
Boccia
Mariano M
MM
Laboratorio de Neurofarmacología de Procesos de la Memoria, Cátedra de Farmacología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, 5 Piso (C1113AAD), Buenos Aires, Argentina.
Blake
Mariano G
MG
Acosta
Gabriela B
GB
Baratti
Carlos M
CM
D000818:Animals; D001285:Atropine / Q000009:adverse effects*; D001362:Avoidance Learning / Q000187:drug effects*; D001522:Behavior, Animal / Q000187:drug effects; D002800:Cholinesterase Inhibitors / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D008297:Male; D008569:Memory Disorders / Q000139:chemically induced* / Q000523:psychology; D051379:Mice; D018727:Muscarinic Antagonists / Q000009:adverse effects*; D010830:Physostigmine / Q000494:pharmacology; D011930:Reaction Time / Q000187:drug effects
D002800:Cholinesterase Inhibitors; D018727:Muscarinic Antagonists; D001285:Atropine; D010830:Physostigmine