title: Facilitatory effect of the intra-hippocampal pre-test administration of MT3 in the inhibitory avoidance task.
abstract: The cholinergic system plays a crucial role in learning and memory. Modulatory mechanisms of this system in the acquisition and consolidation processes have been extensively studied, but their participation in the memory retrieval process is still poorly understood. Conventional pharmacological agents are not highly selective for particular muscarinic acetylcholine receptor subtypes. Muscarinic toxins (MTs) that are highly selective for muscarinic receptors were extracted from the venom of the mamba snake, like the toxin MT3, selective for the M4 receptor subtype. These toxins are useful tools in studies of the specific functions of the M4 mediated transmission. The M4 receptor selective antagonist MT3, given into the dorsal hippocampus before the test, have enhanced the memory retrieval of an inhibitory avoidance task in rats. MT3 had no effect in the habituation to a new environment, including basic motor parameters, meaning that the effect in he inhibitory avoidance is purely cognitive. Our results suggest an endogenous negative modulation of the cholinergic muscarinic system upon the retrieval of previously consolidated aversive memories, hereby shown by the facilitatory effect of MT3.
authors.affiliation: Laboratório de Psicobiologia e Neurocomputação, Departamento de Biofísica, Instituto de Biociências, Universidade Federal do Rio Grande do Sul-Porto Alegre, RS, Brazil.
authors.forename: Felipe
authors.initials: F
authors.lastname: Diehl
authors.forename: Lucas
authors.initials: L
authors.lastname: Fürstenau de Oliveira
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Sánchez
authors.forename: Clarissa
authors.initials: C
authors.lastname: Camboim
authors.forename: Lucas
authors.initials: L
authors.lastname: de Oliveira Alvares
authors.forename: Vanusa Bispo
authors.initials: VB
authors.lastname: Lanziotti
authors.forename: Carlos
authors.initials: C
authors.lastname: Cerveñansky
authors.forename: Edgar
authors.initials: E
authors.lastname: Kornisiuk
authors.forename: Diana
authors.initials: D
authors.lastname: Jerusalinky
authors.forename: Jorge Alberto
authors.initials: JA
authors.lastname: Quillfeldt
mesh_terms: D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D001522:Behavior, Animal / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005106:Exploratory Behavior / Q000187:drug effects; D006624:Hippocampus / Q000187:drug effects* / Q000502:physiology; D007266:Inhibition, Psychological; D036341:Intercellular Signaling Peptides and Proteins; D008297:Male; D011939:Mental Recall / Q000187:drug effects; D018727:Muscarinic Antagonists / Q000008:administration & dosage*; D010455:Peptides / Q000008:administration & dosage*; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D018727:Muscarinic Antagonists; D010455:Peptides; C089528:muscarinic toxin 3