Antagonism of muscarinic M1 receptors by dicyclomine inhibits the consolidation of morphine-associated contextual memory.

Full Abstract

M1 muscarinic receptor has been shown to be involved in cognitive functions of the brain. Conditioned place preference (CPP) paradigm involves memory for the association between environmental stimuli and the rewarding properties produced by a treatment. Using a balanced CPP design, we studied the possible involvement of M1 muscarinic receptors on the acquisition, expression and consolidation of morphine place conditioning in male mice. Subcutaneous administration of morphine sulphate-induced CPP in a dose-dependent manner. Using a 6-day schedule of conditioning, it was found that dicyclomine, an M1 muscarinic antagonist, significantly reduced the time spent by mice in the morphine compartment when given immediately, but not 6h, after each conditioning session (consolidation). It had no effect when administered 30 min before each conditioning session during CPP training period (acquisition) or 30 min before testing for place preference in the absence of morphine (expression). It is concluded that M1 muscarinic receptors may play a time-dependent role in the consolidation of reward-related memory of morphine.

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Author information

Author/s: Esmaeili, Behnaz (B); Basseda, Zahra (Z); Dehpour, Ahmad Reza (AR);

Affiliation: Department of Pharmacology, School of Medicine, Medical Sciences/University of Tehran, Iran.

Journal and publication information

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

Journal: Brain research bulletin (Brain Res Bull), published in United States. (Language: eng)

Reference: 2008-Jul; vol 76 (issue 4) : pp 380-7

Dates: Created 2008/05/26; Completed 2008/07/16;

PMID: 18502314, status: MEDLINE (last retrieval date: 11/6/2008)

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Animals
Brain - drug effects; metabolism
Conditioning (Psychology) - drug effects; physiology
Dicyclomine - pharmacology
Dose-Response Relationship, Drug
Drug Interactions - physiology
Learning - drug effects; physiology
Male
Memory - drug effects; physiology

Memory - drug effects; physiology
Mice
Morphine - pharmacology
Morphine Dependence - drug therapy; metabolism
Muscarinic Antagonists - pharmacology
Narcotics - pharmacology
Receptor, Muscarinic M1 - antagonists & inhibitors; metabolism
Reward
Time Factors

Associated Chemicals: Muscarinic Antagonists (0) ; Narcotics (0) ; Receptor, Muscarinic M1 (0) ; Morphine (57-27-2) ; Dicyclomine (77-19-0)

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