Dietary modification of amphetamine stereotyped behaviour: the action of tryptophan, methionine, and lysine.

Rats fed diets high in tryptophan, methionine, and tryptophan plus methionine or lysine were subsequently injected with 10 mg/kg d-amphetamine. The amount of amphetamine-induced stereotyped behaviour observed varied as a function of the dietary addition, with methionine showing the greatest difference to controls, and lysine the least. Whole brain catecholamine levels and 5-hydroxytryptamine levels also showed amino acid-specific changes.