Evaluation of platelet aggregation in patients with Raynaud's phenomenon: Particularly on concerning the effect of serotonergic receptor (5-HT 2 A) antagonist

Abstract

Abnormalities in interactions in platelets and endothelial cells triggered by temporary microscopic thrombosis induced by serotonin in peripheral blood are noted for a potential cause for Raynaud's phenomenon. First, we evaluated the spontaneous and serotonin-induced platelet aggregation of patients with Raynaud's phenomenon using by laser-light scattering platelet aggregometer. Next, the changes in platelet aggregation of the patients were observed before and after treatment with a serotonergic receptor (5-HT 2 A) antagonist, sarpogrelate hydrochloride (SPG). Ten patients with Raynaud's phenomenon and ten healthy controls were enrolled in this study. Spontaneous aggregation was not detected in controls and patients before and after the SPG treatment. Serotonin-induced aggregation was significantly less in patients before the treatment than in healthy controls. After eight-week treatment with SPG, serotonin-induced aggregation unexpectedly showed a tendency to increase compared with that in patients before treatment. The observed platelet hyperag-gregation against exogenous serotonin after the SPG treatment may be due to the up-regulation of serotonergic receptors on platelet surface in response to the long-term reduction of plasma serotonin.