Role of muscarinic M1 receptors in inhibitory avoidance and contextual fear conditioning.

Full Abstract

The objective of the present study was to observe the effects of pre-training or post-training administration of dicyclomine, a M1 muscarinic antagonist, on inhibitory avoidance (IA) and contextual fear conditioning (CFC) and to investigate if the effects observed with the pre-training administration of dicyclomine are state-dependent. For each behavioral procedure (IA and CFC) groups of Wistar male rats were treated with saline or dicyclomine either 30 min before training (pre-training), immediately after training or 30 min before training/30 min before test (pre-training/pre-test). The animals were tested 24 h after training. The acquisition of IA and CFC was impaired by pre-training administration of dicyclomine. The consolidation of both tasks was not affected by dicyclomine given immediately after training. Pre-training/pre-test administration of dicyclomine impaired both tasks, an effect similar to that observed in the group which only received pre-training administration. Pre-test treatment induced dissociation between both tasks, impairing CFC retrieval, without interfering with the animals avoidance response. These results show that the dicyclomine did not affect IA and CFC consolidation, suggesting specific involvement of M1 muscarinic receptor only in acquisition these tasks, and these effects was not state-dependent. However, it is possible that the retrieval of these tasks may be mediated, at least in part, by different neurochemical mechanisms and may be dissociated by dicyclomine.

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Author information

Author/s: Soares, Juliana Carlota Kramer (JC); Fornari, Raquel Vecchio (RV); Oliveira, Maria Gabriela Menezes (MG);

Affiliation: Departamento de Psicobiologia, Universidade Federal de São Paulo, Rua Napoleão de Barros, 925, 04024-002, São Paulo, SP, Brazil. ju(-atsign-)psicobio.epm.br

Journal and publication information

Publication Type: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't

Journal: Neurobiology of learning and memory (Neurobiol Learn Mem), published in United States. (Language: eng)

Reference: 2006-Sep; vol 86 (issue 2) : pp 188-96

Dates: Created 2006/08/29; Completed 2006/11/28; Revised 2007/10/17;

PMID: 16647280, status: MEDLINE (last retrieval date: 12/26/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Animals
Avoidance Learning - drug effects; physiology
Behavior, Animal - drug effects; physiology
Conditioning, Classical - drug effects; physiology
Dicyclomine - administration & dosage
Drug Administration Schedule
Environment

Fear - drug effects; physiology
Inhibition (Psychology)
Male
Muscarinic Antagonists - administration & dosage
Rats
Rats, Wistar
Receptor, Muscarinic M1 - drug effects; physiology

Associated Chemicals: Muscarinic Antagonists (0) ; Receptor, Muscarinic M1 (0) ; Dicyclomine (77-19-0)

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