Monosodium glutamate studies in four species of neonatal and infant animals

Abstract

As an extension of our previous work, the effect of both intragastric and sc administration of monosodium glutamate (MSG) was studied in four species of neonatal animals (mice, rats, beagle dogs and cynomolgus monkeys). Control groups were dosed with sodium chloride, sodium gluconate, potassium glutamate and distilled water. A uniform dose level of 1 g/kg body weight (10 ml of a 10% aqueous solution/kg) was used. Animals were killed at 3, 6 or 24 hr (and in the case of dogs also at 52 wk) after dosage. Several monkeys were also dosed orally with MSG or sodium chloride at 4 g/kg. No adverse effect was observed on growth, appearance or behaviour in any of the species. Examination of multiple sections of the brain, eyes and pituitaries by light microscopy revealed no pathological alteration. Failure to observe in the arcuate nuclei of the hypothalamus the lesion described by Olney ( Science, N.Y. 1969, 164, 719) is discussed, in relation particularly to the 1 g/kg dosage level, which is many times the estimated maximum human dietary level.