Effects of excess amounts of synthetic amino acid preparations on hypothalamus of mice and kittens.

The relationship between the neurotoxicity caused by excess amounts of synthetic amino acid preparations and serum levels of a certain amino acid was examined using suckling mice and kittens. Three preparations, two of which contained aspartic acid and glutamic acid, were injected intraperitoneally into neonatal mice. Almost all the animals which were treated with the preparations containing aspartic acid and glutamic acid at a dosage of more than 40 microliters/g body weight (b.w.) showed hypothalamic lesions. The severity of these increased according to each dose increment. On the other hand, none of the animals treated with the preparation containing neither aspartic acid nor glutamic acid sustained hypothalamic lesions. All kittens injected intravenously with the preparation containing aspartic acid and glutamic acid at dosages of more than 20 microliters/g b.w. also showed hypothalamic lesions, but none of the kittens treated with dosages of less than 10 microliters/g b.w. did. Serum levels of each amino acid reached their highest values as early as 5 min after injection and then returned abruptly to the control value within 3 h.