Repeated Monosodium Glutamate (Chinese Salt) Administration Impaired Memory Functions in Rats: Relationship with Decreased Plasma and Brain Tryptophan

In the current study adverse effects of monosodium glutamate (MSG) on memory functions were evaluated. Our objective was to examine the association between MSG use and memory functions in male rats. Alteration of behavioral performance and changes in plasma and brain tryptophan (TRP) levels after MSG administration was also investigated. Fourteen adult locally bred male albino Wistar rats were divided into control and test groups (n=7). The test group was intraperitoneally injected with MSG (4 mg/kg/ml) for three weeks while control animals were injected with saline (1ml/kg). Water maze test and novel object recognition task was used for the assessment of memory function following MSG administration. Brain and plasma TRP levels were determined by HPLC-UV method. The result showed that MSG administration for 3 weeks significantly (p<0.05) impaired recognition memory in MSG treated rats. Short term memory (p<0.01) and long term memory (p<0.01) of MSG treated rats were significantly impaired in water maze test. Repeated MSG administration for three weeks significantly decreased brain TRP (p<0.05) and plasma TRP (p<0.01) levels. Present study clearly indicates that repeated MSG administration significantly altered the neurobehavioral performance in rats. Impairment in memory function following MSG administration may be due to decreased TRP levels in plasma and brain. The present study suggests that decreased plasma and brain TRP levels may be responsible for the impaired memory functions observed in MSG treated rats.