No relationship between the ins del polymorphism of the serotonin transporter promoter and pain perception in fibromyalgia patients and healthy controls

• Published in: European journal of pain Vol. 14; no. 7; pp. 742 - 746
• Main Authors: Potvin, Stéphane, Larouche, Annie, Normand, Edith, Souza, Juliana Barcellos de, Gaumond, Isabelle, Marchand, Serge, Grignon, Sylvain
• Format: Journal Article
• Language: English
• Published: Oxford, UK Elsevier Ltd 01-08-2010; Blackwell Publishing Ltd
• Subjects: Adult; Alleles; Anesthesia & Perioperative Care; Diffuse noxious inhibitory controls; Endophenotyping; Female; Fibromyalgia - genetics; Fibromyalgia - physiopathology; Fibromyalgia - psychology; Gene Frequency; Genotype; Hot Temperature; Humans; Hyperalgesia; Hyperalgesia - genetics; Hyperalgesia - physiopathology; Hyperalgesia - psychology; Male; Middle Aged; Pain Measurement - psychology; Pain Medicine; Pain Threshold - physiology; Pain Threshold - psychology; Polymorphism, Single Nucleotide; Promoter Regions, Genetic; Regression Analysis; Serotonin Plasma Membrane Transport Proteins - genetics; Serotonin transporter; Surveys and Questionnaires; Thermal pain thresholds; Serotonin transporter; Diffuse noxious inhibitory controls; Thermal pain thresholds; Endophenotyping; Hyperalgesia
• ISSN: 1090-3801; 1532-2149
• DOI: 10.1016/j.ejpain.2009.12.004

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. Discussion 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.