Tryptophan depletion and aggressive responding in healthy males.
In order to study the effect of decreasing plasma tryptophan levels on aggressive responding in a controlled laboratory setting, we administered two doses (25 g and 100 g) of a tryptophan-free amino acid mixture to ten healthy male subjects after 24 h of a low tryptophan diet. Subjects were screened for current or past psychiatric, or non-psychiatric medical illness. Aggressive responding on a free-operant laboratory measure of aggression (the Point Subtraction Aggression Paradigm) and plasma tryptophan levels were measured before and after drinking the amino acid mixture. There was a significant increase in aggressive responding 5 h after the 100 g mixture and a significant increase in aggressive responding 6 h after the 25 g mixture compared to a baseline day when no drink was administered. There was also a significant decrease in plasma tryptophan at 5 hours after ingestion compared to baseline for both doses of amino acid mixture. This study supports the hypothesis that tryptophan depletion increases aggressive responding in healthy males in a laboratory setting, probably by decreasing brain serotonin.
Moeller
F G
FG
Department of Psychiatry and Behavioral Sciences, University of Texas Houston Health Science Center 77030, USA.
Dougherty
D M
DM
Swann
A C
AC
Collins
D
D
Davis
C M
CM
Cherek
D R
DR
D000328:Adult; D000374:Aggression / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008297:Male; D014364:Tryptophan / Q000097:blood* / Q000494:pharmacology
D014364:Tryptophan