Differential tolerance to dietary amino acid-induced changes in aggressive behavior and locomotor activity in mice

• Published in: Psychopharmacology 1979-01, Vol.66 (3), p.301-308
• Main Authors: Thurmond, J B, Lasley, S M, Kramarcy, N R, Brown, J W
• Format: Article
• Language: English
• Subjects: Aggression - drug effects; Amino Acids - metabolism; Amino Acids - pharmacology; Animals; Brain Chemistry - drug effects; Catecholamines - metabolism; Diet; Drug Tolerance; Humans; Male; Mice; Motor Activity - drug effects; Time Factors
• ISSN: 0033-3158; 1432-2072
• DOI: 10.1007/BF00428324

Male albino mice were maintained on a semisynthetic 12% casein protein diet for 2 weeks, then switched to diets modified by the addition of a 4% L-amino acid supplement (L-tyrosine, L-phenylalanine, and L-tryptophan) or 4% casein (control). Territorial=induced aggressive behavior increased following 1 week on the amino acid supplements, especially after tyrosine, but an apparent tolerance developed to these effects after 5 weeks on the amino acid supplements. Locomotor activity also increased following 1 week on the supplements, most notably after phenylalanine alone or in combination with tyrosine, and these effects tended to persist after 5 weeks on the supplements. Endogenous whole brain levels of dopamine, norepinephrine, serotonin, 5-hydroxyindoleacetic acid, tyrosine, phenylalanine, and tryptophan showed no tolerance to increased concentrations of brain catecholamines and indoleamines over the 5-week period, and no clear relation between the concentrations of these monoamines and the behavioral changes.