Abstract
Background: Efforts to model putative serotonergic deficits associated with affective
disorders have frequently involved acute tryptophan depletion (ATD) as a manipulation
strategy aimed at lowering brain serotonin synthesis. In an attempt to widen the scope
of the measurement probes used in these investigations, the central actions of ATD
and a subsequent dose of fenfluramine were examined via utilization of quantitative
electroencephalography (EEG) and mood ratings.
Methods: Electroencephalograms (EEG) and subjective mood ratings were assessed in
28 healthy men before and after double-blind ingestion of a tryptophan-depleting (T−)
amino acid mixture, or a nutritionally balanced (B) amino acid mixture containing
tryptophan, and again after a single-blind oral dose of d,l-fenfluramine hydrochloride (60 mg).
Results: Compared to the B mixture, the T− mixture reduced total plasma tryptophan
by more than 75% 5 hours after ingestion. Tryptophan depletion was associated with
a modest lowering of mood and a slowing of EEG as indicated by increases in delta
amplitude. Fenfluramine caused no change in mood but increased fast wave (beta) activity
in anterior recordings when administered after the T−, but not after the B mixture.
Conclusions: Quantitative EEG measurements may be a promising method for studying
the central mechanisms underlying serotonin-mediated changes in mood and behavior.
Keywords
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Article info
Publication history
Accepted:
September 29,
1998
Received in revised form:
April 16,
1998
Received in revised form:
September 11,
1998
Received:
November 19,
1997
Identification
Copyright
© 1999 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.
