TIME-RELATED EFFECTS OF STRESS ON CHOLINERGIC SENSITIVITY

The effect of the administration of the muscarinic cholinergic agonist oxotremorine on locomotor activity was investigated in DBA/2 mice sub jected to chronic restraint stress of different durations (120 min dai ly for 10, 14 or 18 days). Oxotremorine induced a depressant effect on locomotion, which was reduced after 10 and 14 days of restraint, but not after a 18-day restraint stress. Acetylcholine (ACh) content was s ignificantly reduced in prefrontal cortex after 10 and 14 days of stre ss but returned to control values after 18 days of restraint. No chang es in ACh content were observed in nucleus accumbens and striatum. The se results are discussed in terms of possible changes in muscarinic re ceptor sensitivity.