The Effect of Magnesium on on Morphine Withdrawal Signs in Rats

Background and Glutamatergic system has a role on morphine withdrawal sign, and magnesium has inhibitory effect on the NMDA receptors of glutamatergic system. The present study aimed to determine the effects of magnesium injection on morphine withdrawal signs in male and female rats. In this experimental study, 48 Male and female rats (200-250 gr) were used. The animals divided into 6 equal groups: two male and female control groups received normal saline; two male and female groups receiving magnesium sulfate 150 mg/kg; and the last two groups receiving magnesium sulfate 300 mg/kg. All groups received 3% sucrose in tap water with morphine 0.4mg/ml (for 21 days) to become addicted. In the end of 21st day, NS or magnesium administrated 30 min before naloxone (2mg/kg) and then withdrawal signs evaluated for next 30 min. The obtained data were analyzed in SPSS using ANOVA and complementary tests with p<0.05 as significant. The results of this study showed that the injection of magnesium in dose of 150 mg/kg could significantly reduce many withdrawal symptoms in male addicted rats [Jumping 62.96% (2.5± 1.14), standing 45.4% (6.62 ±1.45)] and in female addicted rats [Jumping 77.75% (1.25 ±0.54), climbing 24.51% (8.87 ± 1.65), standing 52.57% (5.57 ± 1.26)]. The injection of magnesium with dose of 300 mg/kg also reduced dramatically withdrawal symptoms in male rats [Jumping 87.03% (6.75 ± 1.66), climbing 34.34% (12.87 ± 1.27), standing 56.12% (12.125 ± 1.27)] and female rats [Jumping 84.43% (0.875 ± 0.25), climbing 36.17% (7.5 ± 1.08), standing 69.07 % (3.75 ± 0.64)]. The administration of magnesium in both doses caused a significant reduction of most withdrawal symptoms, and its effect on both sexes was almost similar. It seems that the injection of magnesium during morphine withdrawal can considerably reduce the symptoms of withdrawal syndrome in rats.