Facilitating effects of morphine dependence on spatial learning and memory in rat

Abstract

The effect of morphine on spatial learning and memory is controversial. In the present study, the male rats were used to evaluate the effect of morphine dependence and cold water swimming on spatial learning and memory. Dependent animals received morphine sulfate in drinking water for 25 days. Animals were divided into four groups in simple randomized manner. The first control and dependent groups, were studied in normal water (20± 2 ^◦C), and the second control and dependent groups were studied in cold water (10-12^◦ C). Morris Water Maze (MWM) experimentations were begun from 21st to 25th days of morphine administration. In each group of animals, spatial learning and memory parameters were analyzed. The results showed that morphine dependence may facilitates spatial learning and memory in MWM, and cold water reduces swimming speed but facilitating the formation of spatial memory. On the other hand, cold water swimming abolished the effects of morphine on spatial learning but facilitated its effect on spatial memory. The underling mechanism(s) to these phenomenon remains to be elucidated.