Mahmoud Hashemzaei - Department of Pharmacology and Toxicology, Faculty of Pharmacy, Zabol University of Medical Sciences, Zabol, Iran
Saeed Keykha - Department of Pharmacology and Toxicology, Faculty of Pharmacy, Zabol University of Medical Sciences, Zabol, Iran
Fatemeh Shahraki - Student of veterinary medicine, faculty of veterinary, university of zabol, Iran
Amirhooshang Mohammadpour - Department of Clinical Pharmacy, Faculty of Pharmacy, Mashhad University of Medical Sciences,Mashhad, Iran

Context: Relapse to opioid dependence, even long time after withdrawal, is one of the most important problems of opiate withdrawal programs for addicted people. Magnesium has been shown that inhibit glutamate release and induce N-Methyl-D-aspartate (NMDA) antagonistic effects; moreover, glutamate NMDA antagonists contribute to the reinforcement of morphine. Objectives: In the current study, the effects of magnesium sulfate on the acquisition and reinstatement of morphine-induced conditioned place preference (CPP) were investigated in an animal model Materials& Methods: A three-compartment apparatus was used in two stages of the experiment. During the first stage, CPP acquisition was established, using morphine for 4 days (40 mg/kg daily via injection). In the second stage, the mice underwent the same procedure, followed by extinction training on day 16 of CPP reinstatement, using the remaining 10mg/kg morphine.Results: Three doses of magnesium sulfate (150, 300, and 600 mg/kg) were used in this study. Our results showed that the intraperitoneal injection of magnesium sulfate 300 and 600 mg/kg (not 150mg/kg) reduced morphine dependence. Additionally, in the second stage, after day 16 (after reminding 10mg/kg morphine), tendency of animals to the white compartment of CPP chamber significantly decreased.Discussion: Magnesium sulfate inhibit morphine tendency and reinstatement probably via NMDA antagonistic effects.Conclusion: The results showed that magnesium sulfate decreased the acquisition and reinstatement of morphine-induced CPP in an animal model.

Magnesium Sulfate, Morphine, Conditioned Place Preference