Pharmacological evidence of muscarinic-cholinergic sensitization following chronic stress.

RATIONALE

Although much evidence supports a major role of brain cholinergic transmission in memory consolidation processes, little is known about cholinergic functioning under environmental pressure.

OBJECTIVES

The present experiments were aimed at investigating possible functional adaptation of muscarinic receptors promoted by a chronic stressful procedure in an inbred strain of mice highly susceptible to stress.

METHODS

We tested the effects of post-trial administration of a cholinergic agonist and a muscarinic antagonist on the retention of a passive avoidance task in control animals and compared these effects with those observed following food restriction.

RESULTS

Food restriction enhanced the facilitatory effects of oxotremorine and reduced the impairing effects of atropine on memory consolidation.

CONCLUSION

Our results support the view that chronic sensitization of muscarinic receptors occurs following chronic stress.