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Effect of acute tryptophan depletion on the response to controllable and uncontrollable noise stress
Rebecca A Richell1, J F William Deakin, Ian M Anderson
1Psychiatry Group, Medical Research Council Clinical Sciences Centre, Imperial College, London. rebecca.richell@imperial.ac.uk
Background:
Previous research provides evidence linking serotonin (5-hydroxytryptamine, 5-HT) with stress and depression. The controllable/uncontrollable (C/UC) stress paradigm aims to generate a state/condition, namely a feeling of lack of control in the context of a stressor, which might be an important factor in precipitating a negative mood state. Acute tryptophan depletion (ATD) is a technique that produces a decrease in central 5-HT levels in vivo. This study investigated the role of 5-HT in the behavioral response to a C/UC stress paradigm with ATD.
Methods:
Healthy adult volunteers were randomly assigned to receive either a TRP-supplemented (n = 15) or TRP-deficient (n = 13) amino acid drink. At 5 hours postdrink, volunteers were subjected to sessions of controllable and uncontrollable noise stress (100-dB white noise). Subjective ratings of mood were obtained before and after the interventions.
Results:
Participants who received the tryptophan-depleting drink had greater self-report ratings of negative mood on visual analogue scales and the Profile of Mood States after the uncontrollable stress than did participants who received the balanced drink.
Conclusions:
The results suggest that 5-HT might play a role in providing resilience to uncontrollable stress. Additional studies with specific 5-HT pharmacologic probes will further clarify the results.
