Effect of amino acid supplementation to a low-protein diet on brain neurotransmitters and memory-learning ability of rats.
The supplementation of methionine and threonine to a 10% soy protein isolate diet caused sharp decreases in the concentrations of brain tryptophan, serotonin and 5HIAA (5-hydroxyindole acetic acid) (e.g., in the hypothalamus, hippocampus, amygdala, locus coeruleus and brain stem). The serum tryptophan ratio (i.e., the ratio of the serum concentration of tryptophan to the sum of the concentrations of other large neutral amino acids, such as tyrosine, phenylalanine, leucine, isoleucine, valine and methionine) significantly decreased. The changes in catecholamines were small on the supplementation of amino acids to the soy protein diet. In the brightness-discrimination learning test, the number of total responses (R+, correct; R-, incorrect) of rats fed the amino acid-supplemented diet increased as compared with that of rats fed the nonsupplemented diet. The correct response ratio in the primary learning test did not change, but in the reverse learning test, the response ratio of rats fed the amino acid-supplemented diet increased. Therefore, it may be considered that the learning ability is correlated with the nutritional state.
Laboratory of Nutritional Biochemistry, School of Food and Nutritional Sciences, University of Shizuoka, Japan.
H
H
Yokogoshi
M
M
Nomura
D000596:Amino Acids / Q000008:administration & dosage / Q000494:pharmacology*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects* / Q000502:physiology; D004032:Diet; D004044:Dietary Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D004193:Discrimination Learning / Q000187:drug effects / Q000502:physiology; D007858:Learning / Q000187:drug effects* / Q000502:physiology; D008027:Light; D008297:Male; D008568:Memory / Q000187:drug effects* / Q000502:physiology; D018377:Neurotransmitter Agents / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012055:Reinforcement Schedule
D000596:Amino Acids; D004044:Dietary Proteins; D018377:Neurotransmitter Agents