Effect of Treadmill Running on Morphine Dependence Before and After Medial Prefrontal Cortex Lesion in Rats.

BACKGROUND: Previous studies on the medial prefrontal cortex (mPFC) has shown that this area plays an important role in addiction behavior. Other studies also indicated that exercise decreases use of morphine.

OBJECTIVES: The aim of this study was to evaluate the effects of short-term exercise on trends for use of morphine with an intact mPFC and lesion of that area.

METHODS: 50 rats randomly were selected and divided into 5 groups. 1-exercise. 2- Morphine + Lesion. 3- Morphine + Exercise + Lesion. 4- Morphine. 5- Morphine and Exercise. All groups received morphine for 9 days except exercise group. On the 10th day, the symptoms of addiction were evaluated. To determine the effects of exercise, a treadmill apparatus was used for exercising.

RESULTS: Our results indicated that exercise with intact mPFC area significantly decreased the tendency of using morphine which is verified by changes in symptoms (P < 0.05), but after a lesion of this area exercise did not significantly affect these withdrawal symptoms.

CONCLUSIONS: It seems that a lesion of mPFC area significantly reduced the effect of short-term exercise on the usage pattern of morphine.