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Decreased density of serotonin 5-HT2A receptors in rheumatoid arthritis
  1. A Kling1,
  2. S Rantapää-Dahlqvist2,
  3. H Stenlund3,
  4. T Mjörndal1
  1. 1Department of Pharmacology and Clinical Neurosciences, Division of Clinical Pharmacology, Umeå University Hospital, Umeå, Sweden
  2. 2Department of Rheumatology, Umeå University Hospital
  3. 3Department of Public Health and Clinical Medicine, Epidemiology and Public Health Sciences, Umeå University
  1. Correspondence to:
    Dr Anders Kling
    Division of Clinical Pharmacology, Umeå University Hospital, S-901 85 Umeå, Sweden; anders.kling{at}


Background: Animal studies have indicated that 5-HT2A receptors could play a role in arthritic diseases.

Objective: To analyse the binding properties of 5-HT2A receptors in patients with rheumatoid arthritis.

Methods: Using a radioactive binding assay, 43 patients with rheumatoid arthritis were compared with 49 sex and age matched controls for density and affinity (measured as Bmax and Kd) of 5-HT2A serotonin receptors. Genotyping, using polymerase chain reaction, was undertaken to exclude the possibility that differences in the genetic polymorphism T102C for the 5-HT2A receptor determine differences in receptor density.

Results: Mean of Bmax of 5-HT2A receptors in rheumatoid patients was significantly lower than in controls, at 45.3 v 57.4 fmol/mg protein (p = 0.004), but there was no significant difference in Kd. The T102C receptor polymorphism genotypes showed a skewed distribution between the two groups. Even when adjusted for this, there was a significant difference in Bmax between the groups.

Conclusions: The density of 5-HT2A serotonin receptors in patients with rheumatoid arthritis is markedly reduced. This could either reflect a difference involved in the susceptibility to the disease or be a secondary effect of the disease.

  • AA, adjuvant induced arthritis
  • [3H]LSD, [3H]-lysergic acid diethylamide
  • 5-HT, 5-hydroxytryptamine (serotonin)
  • rheumatoid arthritis
  • serotonin
  • serotonin receptor 5-HT2A

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