Role of music in morphine rewarding effects in mice using conditioned place preference method.

OBJECTIVES This research aims at studying the neuroendocrine effects of music on creating morphine dependence in mice using conditioned place preference (CPP). METHODS The mice treated with 10 mg/kg morphine subcutaneously, fast music and slow music. Morphine was used to create dependence. In order to recognize the morphine rewarding effects, CPP technique was used. In the conditioning stage that lasted for 8 days, different groups of mice, after receiving the treatment were randomly placed in compartment for 30 minutes. The post-conditioning stage included the fourth day, the ninth day, the 12th day and the 16th day. RESULTS Comparing place preference between morphine group and the control group, a significant increase (p<0.05) was observed in the place preference of morphine group, while a significant decrease (p<0.05) was demonstrated in the place preferences of morphine + taxi girl music group compared with morphine group alone. In addition morphine + alone in the rain music group demonstrated a significantly increased conditioned place preference (p<0.05) compared with the morphine group. CONCLUSIONS Alone in the rain music acts as a positive pleasant emotion increasing the dopaminergic activity in the Nucleus Accumbens (NAc) and Ventral Tegmental Area (VTA) and through associated learning mechanisms of reward-related behavior increases morphine addiction. However, taxi girl music may act as unpleasant experiences producing negative emotions and reducing morphine addiction.