Effects of monosodium glutamate.

Abstract

Monosodium glutamate (MSG) is a possible precursor of L-glutamic acid ( 9 ) . Literature suggests glutamic acid to be a central nervous system excitant (6 , 7, 9 ) . Other behavioral and psychological effects of glutamic acid on animals include: (a ) hyperemotionality and increase in biting behaviors, ( b ) seizures (1, 2, 4 ) . and (c) hypothalamic brain lesions (3, 5, 8 ) . Several experiments have been conducted for exploratory reasons and for support of findings reported previously. Samples used in each of the experiments included: ( a ) Exp. 1 : 5 male rats, (b) Exp. 2 : 10 male rats ( 5 treaunent, 5 control), (c) Exp. 3: 4 male rats, ( d ) Exp. 4: 5 male rats, (e) Exp. 5 : 5 male rats. All treatment groups were administered MSG adulterated food or water. Exp. 1, performed to determine the amount of MSG rats would consume voluntarily per day, resulted in an average daily intake of 500. mg. MSG. Exp. 2, conducted to determine effects of MSG on emotionality and biting behaviors, indicated no significant variance, though there was some suggestion that biting was affected. Exps. 3, 4, and 5 were conducted to assess effects of MSG on activity level and to observe seizurc activity during MSG treatmenr In Exp. 3 some increase in activity was found, however, analysis of variance indicated that this wss not significant. A significant increase in activity level was found after ingestion of MSG in Exps. 4 and 5; activiry level increased further during follow-up in Fxp. 4. Other behaviors observed during treatment were: decrease of grooming, increase in water and food consumption, tremors and convulsions, increase in bitin and reduction of sleep time. The samples were small, and the e f t a s variant. Therefore, results should be considered cautiously. Significant increases in activity might support previous data; further follow-up increases in activity possibly indicate lasting effects of MSG. Results did not support hyperemotionalig, however, increase in biting is suggestive. The presence of seizures and tremors confirms those found in previous reports. Finally apparent decrease in sleep and grooming during treatment mighr support MSG as a psychic energizer. The work is exploratory. Funher research on the effects of MSG is needed.