The Effect of Short- term Physical Activity (treadmill running) on Spatial Learning and Memory in the Intact and Morphine Dependent Male rats

It has been shown that the activity of some neurotransmitters may be changed by exercise. It can also affect on pleasure center through Opioid Systems and releasing neurotransmitters. Based on the effect of exercise, in this research, we studied the effect of exercise and physical activity with treadmill running on spatial learning and memory in the intact and morphine dependent male rats.Healthy male Wistar rats, weighting about 250gr 4 month age, were divided into four groups as follows: control (without treadmill running and morphine), exercise (treadmill running and without morphine), morphine (morphine treatment without treadmill running) and exercise+morphine treatment (n=10). Compulsive running on rat treadmill were performed in a ten- days period (1hr per day, at a speed of 17m/min and an incline of 15 degrees). Intraperitoneal injection of dissolved morphine with increasing doses of 10 mg/kg, 20 mg/kg and 40mg/kg for the first, second and third every 3 days, respectively, were applied to make rats morphine dependence. Corresponding control rats went through spatial learning process on a Morris water maze for 8 days. The time to reach the platform (latency), the length of swim path, and the swim speed were used for the evaluation of spatial learning.On the basis of this results, in comparison of total mean of the eight days spatial learning and memory experiment, for three parameters (path length, latency and swim speed), between control groups and exercise + morphine treatment groups are significant different (P< 0. 05). The differences of these parameters between exercise + morphine groups with another groups is significant (P0.05).We found that treadmill running can improve spatial learning and memory in morphine dependent rats significantly. These results confirm with our previously reports. According to effect of exercise on the release of endorphin and activation of neurotransmitters systems such as dopaminergic, serotonergic and glutamatergic, It could be short- term of exercise with opioid system together increase spatial learning and memory in rats morphine dependence, suggesting the pleasure center in the brain is the same for addiction and memory.