Effect of Magnesium Oxide Nanoparticles on Atropine-Induced Memory Impairment in Adult Male Mice

Previous studies have shown that magnesium oxide nanoparticles (MgO-n) improve passive avoidance memory in adult male mice. Alternatively, muscarinic receptors of the cholinergic system have a primary role in memory formation but their relationship with the improvement effects of magnesium on memory is not clear. The aim of this study was to investigate the effect of nano magnesium oxide on memory deficits induced by atropine as a muscarinic receptor antagonist in passive avoidance memory tests. In this experimental study, NMRI male mice were placed in groups receiving atropine (0.1 and 1 mg/kg), recipient of MgO-n (1, 2.5, and 5 mg/kg) and groups receiving atropine in effective dose and different doses of MgO-n were used. Saline was used as a vehicle for drugs in the control groups. Memory was evaluated with a step-down apparatus to determine the coming down latency from a safe platform on days 1, 3, and 7 after training. Locomotor activity was also evaluated through an open field test in all groups after memory measurements. The results showed that atropine (1 mg/kg) decreased the latency time of coming down from the podium and induced memory deficits (P < 0.01). MgO-n in doses of 2.5 and 5 mg/kg caused a significant increase in latency time of coming down from the podium over one week (P < 0.001). MgO-n was able to reverse memory impairments resulting from atropine (1 mg/kg) (P < 0.001). Locomotor activity did not change in any of the groups. It seems that the potentiating effect of MgO-n on memory is due to interference with the cholinergic pathway.