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Published on: September 23, 2015
Effects of oral 5-hydroxytryptophan on a standardized planning task: insight into possible dopamine/serotonin
Mathew H Gendle1, Erica L Young, Alexandra C Romano
1Department of Psychology, Elon University, Elon, NC 27244, USA. mgendle@elon.edu
Objective:
Several studies have suggested that exogenous administration of the serotonin precursor 5-hydroxytryptophan (5-HTP) can result in the ectopic production of serotonin in dopaminergic neurons and a concomitant reduction in dopamine release. This study tested this hypothesis using the Tower of London (TOL), a test of planning and executive control that is sensitive to changes in forebrain dopamine activity, but insensitive to alterations in serotonin.
Methods:
A sample of 68 undergraduates participated, and each received either three 50-mg 5-HTP capsules or placebos, and completed the TOL following a set absorption period.
Results:
5-HTP significantly lengthened the average time needed to complete each of the 10 trials of the TOL. 5-HTP did not affect accuracy on this task.
Conclusions:
Oral exogenous 5-HTP disrupts dopaminergic function in the human forebrain.
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