Facilitatory effect of the intra-hippocampal pre-test administration of MT3 in the inhibitory avoidance task.
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.
Diehl
Felipe
F
Laboratório de Psicobiologia e Neurocomputação, Departamento de Biofísica, Instituto de Biociências, Universidade Federal do Rio Grande do Sul-Porto Alegre, RS, Brazil.
Fürstenau de Oliveira
Lucas
L
Sánchez
Gonzalo
G
Camboim
Clarissa
C
de Oliveira Alvares
Lucas
L
Lanziotti
Vanusa Bispo
VB
Cerveñansky
Carlos
C
Kornisiuk
Edgar
E
Jerusalinky
Diana
D
Quillfeldt
Jorge Alberto
JA
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
D036341:Intercellular Signaling Peptides and Proteins; D018727:Muscarinic Antagonists; D010455:Peptides; C089528:muscarinic toxin 3