title: No relationship between the ins del polymorphism of the serotonin transporter promoter and pain perception in fibromyalgia patients and healthy controls.
abstract: BACKGROUND
  In animals, decades of research have shown that serotonin (5-HT) is involved in endogenous pain inhibition systems, which are deficient in chronic pain disorders such as fibromyalgia (FM). In humans, there is preliminary evidence showing that 5-HT is involved in the FM pathophysiology. In the current endophenotyping study, we sought to investigate, for the first time in humans, the relationships between the serotonin transporter promoter region (5-HTTLPR) polymorphism and experimentally-induced pain perception/inhibition in healthy controls (HC) and FM patients.
  
  
  METHODS
  Participants were 58 FM patients and 60 HC, who did not differ in age, sex or menstrual cycle. Thermal stimuli were used to measure pain thresholds. Pain inhibition was elicited using a tonic thermal test (Peltier thermode) administered before and after activation of the diffuse noxious inhibitory controls (DNIC) by means of a cold-pressor test (CPT).
  
  
  RESULTS
  Thermal pain thresholds were higher in HC compared to FM patients. Pain ratings during the CPT were lower in HC, relative to FM patients. Also, DNIC efficacy was stronger in HC compared to FM patients. However, there was no relationship between 5-HTTLPR and experimentally-induced pain perception/inhibition.
  
  
  CONCLUSIONS
  Our results further confirm that FM is associated with thermal hyperalgesia and deficient DNIC. However, we found no evidence showing that the 5-HTTLPR polymorphism influences pain perception and DNIC. Potential reasons for this negative result will be discussed. Further endophenotyping studies of 5-HT-related gene polymorphisms are required to ascertain the potential relationships between 5-HT and human pain perception/inhibition.
authors.affiliation: Service of Neurosurgery, Faculty of Medicine, University of Sherbrooke, Sherbrooke, Canada.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Potvin
authors.forename: Annie
authors.initials: A
authors.lastname: Larouche
authors.forename: Edith
authors.initials: E
authors.lastname: Normand
authors.forename: Juliana Barcellos
authors.initials: JB
authors.lastname: de Souza
authors.forename: Isabelle
authors.initials: I
authors.lastname: Gaumond
authors.forename: Serge
authors.initials: S
authors.lastname: Marchand
authors.forename: Sylvain
authors.initials: S
authors.lastname: Grignon
mesh_terms: D000328:Adult; D000483:Alleles; D005260:Female; D005356:Fibromyalgia / Q000235:genetics* / Q000503:physiopathology / Q000523:psychology; D005787:Gene Frequency; D005838:Genotype; D006358:Hot Temperature; D006801:Humans; D006930:Hyperalgesia / Q000235:genetics* / Q000503:physiopathology / Q000523:psychology; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement / Q000523:psychology*; D017288:Pain Threshold / Q000502:physiology / Q000523:psychology*; D020641:Polymorphism, Single Nucleotide; D011401:Promoter Regions, Genetic; D012044:Regression Analysis; D050486:Serotonin Plasma Membrane Transport Proteins / Q000235:genetics*; D011795:Surveys and Questionnaires
chemical_list: D050486:Serotonin Plasma Membrane Transport Proteins