Evaluation of Anxiety and Motor Function Following Chronic Monosodium Glutamate Exposure in Swiss Albino Mice Using Open Field and Scurry Speed Tests

Abstract

Background: Monosodium glutamate (MSG) is a widely used flavour enhancer responsible for the characteristic umami taste in many foods. Although regulatory authorities classify MSG as generally safe, several experimental studies suggest that excessive or prolonged exposure may affect neurological and behavioural functions. Glutamate is the principal excitatory neurotransmitter in the central nervous system, and excessive activation of glutamate receptors may lead to neuronal excitotoxicity, oxidative stress, and behavioural disturbances. Therefore, evaluating the neurobehavioral consequences of chronic MSG exposure is important. The present study aimed to evaluate the effects of chronic MSG administration on anxiety-like behaviour and motor function in Swiss albino mice.

Methods: A prospective interventional experimental animal study was conducted using forty adult male Swiss albino mice weighing 20–30 g. The animals were randomly divided into four groups (n = 10 per group). The control group received distilled water, while the experimental groups received MSG at doses of 40 mg/kg, 60 mg/kg, and 80 mg/kg intraperitoneally for three months. Behavioural assessments were conducted at baseline and at three days, one month, two months, and three months.

Anxiety-like behaviour was evaluated using the Open Field Test, where the number of line crossings and time spent in the central area were recorded as indicators of exploratory activity and anxiety level. Motor function was assessed using the Scurry Speed Test by measuring the time taken by mice to traverse a straight-line track leading to a dark compartment. Reduced exploratory behaviour in the open field indicates increased anxiety-like behaviour, whereas increased traversal time in the scurry speed apparatus reflects impaired locomotor activity.

Results: The results demonstrated a progressive reduction in exploratory behaviour in MSG-treated groups during the study period. The most pronounced behavioural change was observed in the MSG 60 mg/kg group, where median central square exploration decreased significantly at three months compared with baseline. Motor function analysis using the Scurry Speed Test showed a mild increase in traversal time in MSG-treated groups; however, these changes were not statistically significant.

Conclusion: In conclusion, chronic MSG administration produced dose-dependent anxiety-like behavioural changes without marked impairment of motor function in mice.