Phospholipase Cγ2 Signaling Cascade Contribute to the Antiplatelet Effect of Notoginsenoside Fc.

Bleeding, the main drawback of clinically used chemical anti-thrombotic drug is resulted from the unidirectional suppression of platelet activity. Therefore, dual-directional regulatory effect on platelet is the main preponderance of over these drugs. The dual-directional regulatory effect should be ascribed to the resourceful saponins (PNS). Clarifying the mechanism of main PNS in both inhibiting and promoting platelet aggregation will give a full outlook for the dual-directional regulatory effect. The present study is aimed at explaining the mechanism of Notoginsenoside Fc (Fc), a main PNS, in inhibiting platelet aggregation. In the study, after incubating platelets with Fc and m-3M3FBS, platelet aggregation was triggered by thrombin, collagen or ADP. Platelet aggregation was measured by aggregometer. Phospholipase Cγ2 (PLCγ2) and protein kinase C (PKC) activities were studied by western blotting. Diacylglycerol (DAG), thromboxane B (TXB) and 1,4,5-inositol trisphosphate (IP) concentrations were measured by corresponding ELISA kits. Calcium concentrations ([Ca]) were estimated through the fluorescence intensity emitted from Fluo-4. In the study, thrombus model was induced by FeCl. The effect of Fc on thrombosis was evaluated by measurement of protein content and observation of injured blood vessel. thrombin, collagen and ADP induced platelet aggregation were all suppressed by incubating platelets with Fc. Platelet PLCγ2 and subsequent DAG-PKC-TXA and IP were down-regulated by Fc as well. However, the basal [Ca] in platelet was not altered by Fc. Nevertheless, thrombin triggered activation of PLCγ2 and subsequent DAG-PKC-TXA and IP-[Ca] were all abolished by Fc. Fc also attenuated platelet aggregation and PLCγ2 signaling activation induced by PLC activator, m-3M3FBS. In the study, FeCl induced thrombosis in rat femoral artery was significantly alleviated by administration of Fc. The results above suggested the antiplatelet and antithrombotic effects of Fc are carried out through oppression of PLCγ2 and subsequent DAG-PKC-TXA and IP-[Ca]. The present study provided theoretical support for new anti-thrombotic drug exploitation by .