No relationship between the ins del polymorphism of the serotonin transporter promoter and pain perception in fibromyalgia patients and healthy controls.
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.
Potvin
Stéphane
S
Service of Neurosurgery, Faculty of Medicine, University of Sherbrooke, Sherbrooke, Canada.
Larouche
Annie
A
Normand
Edith
E
de Souza
Juliana Barcellos
JB
Gaumond
Isabelle
I
Marchand
Serge
S
Grignon
Sylvain
S
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
D050486:Serotonin Plasma Membrane Transport Proteins