The effects of chronic intraperitoneal monosodium glutamate in social interaction and on rotating rod in adult Swiss albino mice

Background: Short-term use of monosodium glutamate (MSG) induces anxiety in animals. Due to the lack of stringent regulations for food supplements and increase in the use of MSG in the past decade, the long-term effects of MSG need to be evaluated. There is a scarcity of the literature on the chronic effects of MSG on anxiety, hence the present study. Since anxiety models require an intact motor function, motor function was also evaluated. Aims and Objectives: The aim of the study was to evaluate the long-term effects of intraperitoneal (i.p.) MSG on mice models of anxiety (social interaction) and motor function (accelerating rota rod). Materials and Methods: The present prospective interventional study was conducted on 40 adult male Swiss albino mice. Mice were randomly divided into four equal groups to receive, distilled water, and MSG at doses of 40, 60, and 80 mg/kg/day for 3 months. Parameters were assessed at baseline, 1 month, 2 months, and 3 months of daily MSG administration. Statistical tests of significance were the Wilcoxon signed-rank test and Friedman test (within group) and Kruskal–Wallis Test (between groups), P < 0.05 was considered statistically significant. Results: Social interaction time was reduced in all the MSG-treated groups (P < 0.05) without any change in motor function (P > 0.05). Anxiety was evident from 40 mg/kg/day MSG from the 1st month till 3 months compared to baseline and controls. Duration-dependent change in social interaction was observed with MSG at doses of 40 mg/kg/day and 60 mg/kg/day. Dose-dependent change in social interaction was not observed among treatment groups. Conclusion: Long-term administration of MSG produced anxiogenic effects at doses of 40 mg/kg, 60 mg/kg, and 80 mg/kg without impairing the motor functions in the mice.