The aim of this study was to investigate the effects of magnesium as a N-Methyl–D-Aspartate (NMDA) receptor Antagnist and bromocriptine as a dopamine receptor agonist on morphine dependence and withdrawal symptoms. In the present study different groups of mice were received morphine (50 mg/kg, i.p.) for four days and on fourth day 1.5 hour after the last morphine administration they received different doses of magnesium (40, 60, 80 mg/kg, i.p.) or bromocriptine (5, 10, 20 mg/kg, i.p.) and 0.5 hour later naloxan (4 mg/kg, i.p.) was administrated and withdrawal symptoms was assessed during 30 min. This study shows that administration of magnesium or bromocriptine has decreased the morphine-dependence and withdrawal symptoms significantly.
Magnesium can prevent the development of morphine tolerance and dependence. The mechanism of this effect is related to the property of magnesium to block the NMDA receptors. On the other hand, bromocriptine decreased the withdrawal symptoms and this mechanism may be related to dopamine agonist and ?2 agonist behavior of bromocriptine.