Fear expression is suppressed by tyrosine administration

SORANZO, Alessandro and AQUILI, Luca (2019). Fear expression is suppressed by tyrosine administration. Scientific Reports, 9.

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Official URL: https://www.nature.com/articles/s41598-019-52610-x
Open Access URL: https://www.nature.com/articles/s41598-019-52610-x... (Published version)

Abstract

Animal studies have demonstrated that catecholamines regulate several aspects of fear conditioning. In humans, however, pharmacological manipulations of the catecholaminergic system have been scarce, and their primary focus has been to interfering with catecholaminergic activity after fear acquisition or expression had taken place, using L-Dopa, primarily, as catecholaminergic precursor. Here, we sought to determine if putative increases in presynaptic dopamine and norepinephrine by tyrosine administered before conditioning could affect fear expression. Electrodermal activity (EDA) of 46 healthy participants (24 placebo, 22 tyrosine) was measured in a fear instructed task. Results showed that tyrosine abolished fear expression compared to placebo. Importantly, tyrosine did not affect EDA responses to the aversive stimulus (UCS) or alter participants' mood. Therefore, the effect of tyrosine on fear expression cannot be attributed to these factors. Taken together, these findings provide evidence that the catecholaminergic system influences fear expression in humans.

Item Type: Article
SWORD Depositor: Symplectic Elements
Depositing User: Symplectic Elements
Date Deposited: 22 Oct 2019 09:37
Last Modified: 19 Nov 2019 09:45
URI: http://shura.shu.ac.uk/id/eprint/25314

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