The aim of this study was to test the hypothesis that temporomandibular joint (TMJ) pain is influenced by circulating levels of neuropeptide Y, serotonin, and interleukin-1 beta in rheumatoid arthritis.
Forty-three seropositive (RF+) or seronegative (RF-) rheumatoid arthritis patients and 24 healthy individuals were included in the study.
High serum concentrations of serotonin were associated with low TMJ pressure pain thresholds and pain during mandibular movement in the RF+ patients. The results of this study do not support a relationship between circulating neuropeptide Y or interleukin-1 beta and TMJ pain. The RF+ patients had higher C-reactive protein levels and erythrocyte sedimentation rates than the RF- patients. There were also higher plasma levels of interleukin-1 beta in the RF+ patients than in the healthy individuals. Plasma levels of neuropeptide Y in the RF- patients were higher than in the healthy individuals.
This study indicates that the serum concentration of serotonin is associated with TMJ allodynia in seropositive rheumatoid arthritis.