Serotonin content of platelets in inflammatory rheumatic diseases

Abstract

Significantly decreased platelet serotonin contents were measured in rheumatoid arthritis, systemic lupus erythematosus (SLE), progressive systemic sclerosis, and mixed connective tissue disease. An inverse relationship between platelet serotonin levels and clinical disease activity was observed in both rheumatoid arthritis and systemic lupus erythematosus. SLE patients with multiple organ involvement showed the lowest platelet serotonin values. No correlation was observed between platelet serotonin contents and nonsteroidal antiinflammatory drug treatment, presence of circulating platelet reactive IgG, or the amount of circulating immune complexes. The results are interpreted as indicating platelet release occurring in vivo during inflammatory episodes of the rheumatic disorders investigated.In addition to their role in blood coagulation, platelets have been shown to play an important part as intravascular inflammatory cells (1). Substances such as thrombin, collagen, ADP, prostaglandin endoperox- Supported by the Deutsche Forschungsgemeinschaft, Sonderforschungsbereich 5 4 4 3 .

Blood serotonin and joint pain in seropositive versus seronegative rheumatoid arthritis

“…The thrombocytes may become activated during inflammation by platelet-activating factors such as the rheumatoid factor to release 5-HT, which increases plasma and thereby also tissue 5-HT levels. 12,15 Presence of the rheumatoid factor in the blood of patients with RA has been found to be associated with poor prognosis and higher disease activity with respect to the TMJ, 20 and patients with seropositive RA generally present more pronounced TMJ symptoms, 24,25 which was also the fact in the present study. The lack of significant correlation between the plasma level of 5-HT and the thrombocyte particle count in our study indicates that other sources of 5-HT (e.g.…”

“…Accordingly, the thrombocyte content of 5-HT is decreased during acute episodes of RA. 15 Plateletactivating factors such as immune complexes, including the rheumatoid factor, activate thrombocytes to release 5-HT. 16,19 Presence of the rheumatoid factor in the blood from patients with RA has been associated with high inflammatory activity and poor prognosis with respect to temporomandibular joint (TMJ) involvement 20 , which might partly be explained by thrombocyte activation.…”

The MRL/lpr Mouse Strain as a Model for Neuropsychiatric Systemic Lupus Erythematosus

“…There are also decreased levels of serotonin in brain regions such as the hypothalamus, which regulate stress and response to appetitive stimuli (among other things) [133], and increased levels in the hippocampus [58]. This observation is consistent with altered serotonin levels in lupus patients similar to those that occur in depressed patients [134–136], including those in which depression has been induced by cytokine therapy [137–139]. Decreased levels of noradrenaline evident in the prefrontal cortex of MRL/lpr mice would also be consistent with depressive-like behavior [58, 140–142].…”

Influence of serotonin on the analgesic effect of granisetron on temporomandibular joint arthritis

“…3 Peripheral 5-HT is mainly stored in thrombocytes, and several signal substances involved in the mediation of inflammation can induce 5-HT release from these cells. 4,5 In patients with RA, thrombocytes have been found to be increased in number and to release 5-HT. 4 Richardson and Engel showed that 5-HT participates in the mediation of resting pain from inflamed peripheral tissues by sensitizing or exciting fine afferent units via the 5-HT 3 receptor.…”