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  • Poster presentation
  • Open Access

Influence of cholinergic system modulators on morphine state-dependent memory of passive avoidance in mice

  • 1,
  • 2 and
  • 3
Annals of General Psychiatry20065 (Suppl 1) :S163

  • Published:


  • Morphine
  • Locomotor Activity
  • Atropine
  • System Modulator
  • Passive Avoidance


In the step-down passive avoidance task and 24 hours after the pre-training administration of morphine, the memory is impaired. The administration of the same dose of morphine as pre-test treatment restored the memory. Since cholinergic system has been reported to be involved in several actions of morphine (e.g.: modulation of memory and analgesia).

Materials and methods

We have investigated the part played by the cholinergic modulator drugs, on the memory recall in mice. The locomotor activity of the animals was studied as well.


The administration of atropine alone (as a peripheral/central muscarinc antagonist) showed no intrinsic activity. When the drug was co-administered with morphine, it prevented significantly the morphine-induced memory recall. Hexamethonium (as a peripheral nicotinic antagonist), showed neither intrinsic activity nor a significant change in the morphine-induced memory recall. Mecamylamine (as a peripheral/central nicotinic antagonist) did not show a significant effect when it was used alone, but when co-administered with morphine it prevented significantly the morphine-induced memory recall. The results with neostigmine (as a peripheral anticholinestrase) were similar to that of hexamethonium. Physostigmine (as a peripheral/central anticholinestrase), induced memory recall by itself. The memory recall of the step-down passive avoidance task was not related to the locomotor activity of the animals.


It has been concluded that morphine-induced memory recall might be influenced by the central cholinergic activity.

Authors’ Affiliations

Department of Physiology and Pharmacology, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran
Department of Pharmacology, School of Medicine, Tehran, Iran
University of Medical Sciences, Tehran, Iran


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© The Author(s) 2006