Effect of tryptophan treatment on self-biting andcentral nervous system serotonin metabolism in rhesus monkeys (Macaca mulatta) (1998)

Weld, K. P., Mench, J. A., Woodward, R. A. et al.

Abstract

Two studies were conducted to examine the effects of oral L-tryptophan (TRP) supplementation as a treatment for self-injurious behavior (SIB) and to investigate behavior and central serotonin turnover of male rhesus monkeys. In Study One, TRP was administered to seven individually housed rhesus monkeys with a recent history of spontaneous SIB. While the monkeys were on TRP treatment (100 mg/kg twice a day), cisternal cerebrospinal fluid (CSF) concentrations of 5-hydroxyindoleacetic acid increased markedly (p = .0013) above baseline (baseline mean = 207.6 pmol/ml +/- 39; TRP mean = 320.3 pmol/ml +/- 83.4), and the duration of self-biting behavior decreased below baseline (p = .03). .. Conclusions: Supplemental tryptophan in well-tolerated doses reduced self-biting and increases serotonin turnover rate in male monkeys with a recent history of SIB. The same doses of TRP do not affect behavior or serotonin metabolism in male monkeys without a history of SIB.