title: Emotional modulation of muscle pain is associated with polymorphisms in the serotonin transporter gene.
abstract: The perception of pain is determined by a combination of genetic, neurobiological, cultural, and emotional factors. Recent studies have demonstrated an association between specific genotypes and pain perception. Particular focus has been given to the triallelic polymorphism in the promoter region of the serotonin transporter gene in relation to pain perception. The aim of this study was to investigate whether the modulatory effect of emotions mediated by visual stimuli on muscular pain perception is genotype dependent. A total of 150 healthy subjects were selected on the basis of their polymorphism in the serotonin transporter gene. First, visual conditioning was performed with positive, negative, and neutral pictures from the International Affective Picture System, and the unpleasantness/pleasantness of the pictures was rated. Second, visual conditioning stimuli were presented while experimental jaw muscle pain was evoked by injection of hypertonic saline into the masseter muscle, and participants continuously rated pain intensity on an electronic visual analogue scale. The pictures induced similar changes in emotions across the 3 genotype groups, and hypertonic saline evoked moderate pain levels in all participants. However, in participants with a high expression of the serotonin transporter protein, conditioning with negative pictures increased pain intensity and positive pictures decreased pain intensity when compared with neutral pictures. In contrast, there were no significant effects of the pictures on pain perception in participants with either intermediate or low expression of the protein. These results suggest that polymorphisms in the serotonin transporter gene play an important role in emotions modulation of muscle pain.
authors.affiliation: Danish Pain Research Center, Aarhus University Hospital, Aarhus, Denmark. emilia.horjales@ki.au.dk
authors.forename: Emilia
authors.initials: E
authors.lastname: Horjales-Araujo
authors.forename: Ditte
authors.initials: D
authors.lastname: Demontis
authors.forename: Ellen Kielland
authors.initials: EK
authors.lastname: Lund
authors.forename: Lene
authors.initials: L
authors.lastname: Vase
authors.forename: Nanna Brix
authors.initials: NB
authors.lastname: Finnerup
authors.forename: Anders D
authors.initials: AD
authors.lastname: Børglum
authors.forename: Troels Staehelin
authors.initials: TS
authors.lastname: Jensen
authors.forename: Peter
authors.initials: P
authors.lastname: Svensson
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D004644:Emotions / Q000502:physiology; D005260:Female; D005820:Genetic Testing; D005838:Genotype; D006801:Humans; D008297:Male; D063806:Myalgia / Q000235:genetics* / Q000503:physiopathology* / Q000523:psychology; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology; D010775:Photic Stimulation; D011110:Polymorphism, Genetic / Q000235:genetics*; D011569:Psychiatric Status Rating Scales; D050486:Serotonin Plasma Membrane Transport Proteins / Q000235:genetics*; D014796:Visual Perception / Q000235:genetics; D055815:Young Adult
chemical_list: D050486:Serotonin Plasma Membrane Transport Proteins