اثر وابستگي مورفين به يادگاري و حافظه فضايي در موش صحرايي نر

The effect of morphine dependency on spatial learning and memory in male rat

The effect of morphine dependency on learning and memory is controversial. In the present study, the male rats were used to evaluate the effects of morphine dependency on spatial learning and memory. Dependent animals received morphine sulfate in drinking water for 20-30 days. Experiments were performed in two parts using Morris Water Maze (MWM). In part one, the effect of morphine dependency in normal and cold water was considered. In this part, animals were divided into four groups in simple randomized manner. The first two groups (control and dependent), were studied in normal water (20± 2 ʹC), and two another groups, were studied in cold water (10-12ʹ C). Animals were studied in MWM from day 21. In part two, rats were divided into two groups (withdrawal-normal and withdrawal-cold) to evaluate the effect of withdrawal of morphine. The condition was similar to the first part of experiments, but application of morphine was stopped from day 21. 48 h later, experiments in MWM was begun. In each group of animals, the parameters of spatial learning and memory were analyzed. Data were subjected to t-test and ANOVA. The results showed: 1- Morphine dependency facilitated spatial learning and memory in MWM. 2- Cold water reduced swim speed but facilitated the formation of spatial memory. 3-Cold water abolished the effect of morphine on spatial learning but facilitated the effect on formation of spatial memory. 4- Withdrawal syndrome reversed the effects of morphine dependency. The mechanism(s) underling the phenomenon remains to be elucidated.