title: Effects of muscarinic receptor antagonism in the basolateral amygdala on two-way active avoidance.
abstract: The aim of the present study was to investigate whether the blockade of muscarinic receptors (mRs) in the basolateral amygdala (BLA), which receives important cholinergic inputs related to avoidance learning, affects the consolidation of two-way active avoidance (TWAA). In Experiment 1, adult male Wistar rats were bilaterally infused with scopolamine (SCOP, 20 μg/site) or PBS (VEH) in the BLA immediately after a single 30-trial acquisition session. Twenty-four hours later, avoidance retention was tested in an identical session. Results indicated that scopolamine in the BLA did not affect TWAA performance measured by the number of avoidance responses. Experiment 2 was conducted to test whether such a negative outcome might be due to the occurrence of overtraining during acquisition, which may indeed have a protective effect against scopolamine-induced memory deficits. In this experiment, rats were infused with scopolamine in the BLA immediately after a brief 10-trial acquisition session and tested 24 h later in a 30-trial retention session. The SCOP group showed significantly more avoidances and inter-trial crossings in the retention session than the VEH rats. Together, these results reveal that mRs blockade in the BLA does not disrupt TWAA consolidation and may even enhance avoidance performance when infused after a low number of acquisition trials. Performance factors, such as locomotor activity in the shuttle-box, may account, at least in part, for the facilitative effects of muscarinic antagonism in the BLA.
authors.affiliation: Department de Psicobiologia i Metodologia de Ciències de Salut, Institut de Neurociències, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
authors.forename: Anna
authors.initials: A
authors.lastname: Carballo-Márquez
authors.forename: Pere
authors.initials: P
authors.lastname: Boadas-Vaello
authors.forename: Irene
authors.initials: I
authors.lastname: Villarejo-Rodríguez
authors.forename: Gemma
authors.initials: G
authors.lastname: Guillazo-Blanch
authors.forename: Margarita
authors.initials: M
authors.lastname: Martí-Nicolovius
authors.forename: Anna
authors.initials: A
authors.lastname: Vale-Martínez
mesh_terms: D000679:Amygdala / Q000187:drug effects*; D000704:Analysis of Variance; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D001522:Behavior, Animal / Q000187:drug effects; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D018727:Muscarinic Antagonists / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012601:Scopolamine / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D018727:Muscarinic Antagonists; D012601:Scopolamine