Doxepin inhibits GPVI-dependent platelet Ca²⁺ signaling and collagen-dependent thrombus formation

Abstract

Platelet adhesion, activation, and aggregation are essential for primary hemostasis, but are also critically involved in the development of acute arterial thrombotic occlusion. Stimulation of the collagen receptor glycoprotein VI (GPVI) leads to phospholipase Cγ2-dependent inositol triphosphate (IP) production with subsequent platelet activation, due to increased intracellular Ca concentration ([Ca]). Although tricyclic antidepressants have been shown to potentially impair platelet activation, nothing is hitherto known about potential effects of the tricyclic antidepressant doxepin on platelet Ca signaling and thrombus formation. As shown in the present study, doxepin significantly diminished the stimulatory effect of GPVI agonist collagen-related peptide (CRP) on intracellular Ca release as well as subsequent extracellular Ca influx. Doxepin was partially effective by impairment of CRP-dependent IP production. Moreover, doxepin abrogated CRP-induced platelet degranulation and integrin αβ activation and aggregation. Finally, doxepin markedly blunted in vitro platelet adhesion to collagen and thrombus formation under high arterial shear rates (1,700). In conclusion, doxepin is a powerful inhibitor of GPVI-dependent platelet Ca signaling, platelet activation, and thrombus formation.

Platelet integrin αIIbβ3: signal transduction, regulation, and its therapeutic targeting

“…PLCγ tyrosine phosphorylation is mediated by the immunoreceptor tyrosine-based activation motif (ITAM)-bearing receptors FcRγ and FcRγIIa. PLCγ is also activated by GPVI-collagen interactions through FcRγ signaling involving tyrosine kinases, such as Src and spleen tyrosine kinase (Syk) [117]. In addition to PLCγ, phosphatidylinositol-3-kinase (PI3K) is another key molecule downstream of GPVI and GPIb-IX-V [118].…”

The mechanism of oleic acid inhibiting platelet activation stimulated by collagen

“…Intracellular Ca 2+ signaling is a major feature of platelet activation and thrombosis. Platelet Ca 2+ signaling and activation could be both induced by thrombin and collagen which acts via G-protein coupled receptors [ 39 ]. In this study, we used calcium chelating agents EGTA and BAPTA-AM, demonstrated that OA could inhibit not only intracellular Ca 2+ mobilization, but also extracellular influx during platelet activation, which is mutually confirmed with AMPK activation by increasing Ca 2+ concentrations [ 40 ].…”

Ligustrazine suppresses platelet aggregation through inhibiting the activities of calcium sensors

“…Elevation of the intra-platelet Ca 2+ concentration aggravates platelet aggregation (Geue et al, 2017). Thus, changes in the intra-platelet Ca 2+ concentration could accurately reflect the state of platelet aggregation.…”