Effect of Co-administration of Morphine and Cholinergic Antagonists on Y-maze Spatial Recognition Memory Retrieval and Locomotor Activity in Mice

The interaction of morphine and cholinergic system was shown in previous studies. In the present study, we investigated whether morphine would interact with the cholinergic antagonists, scopolamine and atropine in a Y-maze spatial recognition memory. Pre-test treatments of morphine (5, 1.5, 0.5 mg/kg), scopolamine (1, 0.1 mg/kg), atropine (0.5, 0.1 mg/kg) were used in the experiments, relatively high or low doses were paired respectively as co-administration measures. The results showed that co-administration of morphine 0.5 mg/kg + scopolamine 0.1 mg/kg and morphine 0.5 mg/kg + atropine 0.1 mg/kg disturbed the inspective exploratory behavior (percent of arm duration) but not the inquisitive behavior (percent of arm visits) of the spatial memory retrieval, while the drugs didn’t cause amnesia when single administered of the concerned low doses. Distinct interaction was found between scopolamine and morphine on increasing locomotor activity.