Learning in Monkeys Fed Elevated Amino Acid Diets

Abstract

Diets containing altered levels of specific amino acids or their metabolites were fed to rhesus macaques during infancy and during fetal life. Learning tests, after the animals were placed on a normal diet, indicated permanent mental retardation in monkeys that received phenylalanine either prenatally or for 3, 6, or 12 months postnatally, and also in monkeys fed parachlorophenylalanine, which inhibits the metabolism of phenylalanine. Retardation was not detected in monkeys fed diets high in other amino acids or in pair-fed control animals.

Dietary and metabolic effects on rhesus social behavior: Phenylalanine‐related dietary alterations

“…But their mothers had been fed a diet supplemented with about lglkg body weightlday of L-phenylalanine throughout most of their pregancy. (Details can be found in Kerr et al, 1968; see also Chamove, Kerr, & Harlow, 1973. ) Procedure Beginning at 3 months of age social experience and testing were started.…”

Dietary effects on rhesus social behavior: Altered amino acid diets

“…To this purpose, a number of different amino acids were evaluated, some of which are directly or indirectly associated with human inborn errors of metabolism, and some not so associated. We have fed high levels of the above amino acids to developing animals, but, with the exception of phenylalanine, we have discovered no learning deficits (Chamove, Kerr, & Harlow, 1973).…”

“…A total of 41 rhesus monkeys (Macaca mulutta), mostly male, were separated from their mothers at birth and reared in single cages, as described by Chamove et al (1973). The infants were offered Similac (Ross Laboratories, Columbus, Ohio), a modified milk diet for human infants, every 4 hr.…”

Rhesus plasma cortisol response at four dominance positions

“…At the beginning of the experiment, the 16 monkeys of each replication had been living for the previous 9-33 months in four "original groups" (OG) of four animals each, confined in wire mesh cages, measuring 0.66 X 0.76 X 1.47 m for the older, larger animals and 0.49 X 0.61 X 1.28 m for the younger, smaller ones. Animals were accustomed to handling and blood sampling, as they had been used as controls for experiments on dietary abnormalities (8).…”