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The neuropeptide substance P and its receptor NK1 have been implicated in emotion, anxiety and stress in preclinical studies. However, the role of NK1 receptors in human brain function is less clear and there have been inconsistent reports of the value of NK1 receptor antagonists in the treatment of clinical depression. The present study therefore aimed to investigate effects of NK1 antagonism on the neural processing of emotional information in healthy volunteers. Twenty-four participants were randomized to receive a single dose of aprepitant (125 mg) or placebo. Approximately 4 h later, neural responses during facial expression processing and an emotional counting Stroop word task were assessed using fMRI. Mood and subjective experience were also measured using self-report scales. As expected a single dose of aprepitant did not affect mood and subjective state in the healthy volunteers. However, NK1 antagonism increased responses specifically during the presentation of happy facial expressions in both the rostral anterior cingulate and the right amygdala. In the emotional counting Stroop task the aprepitant group had increased activation in both the medial orbitofrontal cortex and the precuneus cortex to positive vs. neutral words. These results suggest consistent effects of NK1 antagonism on neural responses to positive affective information in two different paradigms. Such findings confirm animal studies which support a role for NK1 receptors in emotion. Such an approach may be useful in understanding the effects of novel drug treatments prior to full-scale clinical trials.

Original publication

DOI

10.1017/S1461145709990150

Type

Journal article

Journal

The international journal of neuropsychopharmacology / official scientific journal of the Collegium Internationale Neuropsychopharmacologicum

Publication Date

2009

Volume

12

Pages

1261 - 1274

Keywords

Adolescent Adult Affect Amygdala/drug effects/metabolism Brain Mapping/methods Double-Blind Method *Emotions *Facial Expression Female Humans Magnetic Resonance Imaging Male Mental Processes/*drug effects Morpholines/*pharmacology Neural Pathways/*drug effects Pattern Recognition, Visual/drug effects Photic Stimulation Prefrontal Cortex/*drug effects/metabolism Receptors, Neurokinin-1/*antagonists & inhibitors/metabolism Young Adult