Chronic Effects of Monosodium Glutamate on Anxiety and Motor Function in Swiss Albino Mice: Evaluation Using Hole Board and Rear Cylinder Tests

Abstract

Background: Monosodium glutamate (MSG) is a widely used flavour enhancer. While generally considered safe, concerns persist regarding the neurological consequences of long-term exposure, as excessive glutamate activity may lead to excitotoxicity and behavioural disturbances. This study investigated the chronic effects of MSG on anxiety-like behaviour and motor function in Swiss albino mice.

Methods: Forty adult male mice were randomly assigned to four groups (n=10) and administered either distilled water (control) or MSG (40, 60, or 80 mg/kg) via intraperitoneal injection daily for three months. Behavioural changes were assessed using the Hole Board Test to measure anxiety (head-dipping frequency) and the Rear Cylinder Test to evaluate locomotor activity (rearing movements). Statistical significance was determined at p < 0.05.

Results: Results demonstrated a significant, dose-dependent reduction in head-dipping frequency in MSG-treated groups compared to controls, indicating anxiogenic effects, with the most pronounced outcomes at 60 mg/kg and 80 mg/kg doses. Conversely, there were no statistically significant differences in rearing movements across any groups, indicating preserved motor coordination.

Conclusion: In conclusion, chronic MSG administration induces dose-dependent anxiety-like behavioural patterns, likely mediated by altered glutamatergic neurotransmission, without significant motor impairment. These findings highlight the potential for long-term MSG exposure to impact emotional regulation pathways and warrant further histopathological and neurochemical investigation to elucidate the underlying mechanisms.