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

Yingqiu Liu; Tianyi Liu; Kevin Ding; Zengyuan Liu; Yuanyuan Li; Taotao He; Weimin Zhang; Yunpeng Fan; Wuren Ma; Li Cui; Xiaoping Song

doi:10.3389/fphar.2018.01293

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

Front Pharmacol. 2018 Nov 6:9:1293. doi: 10.3389/fphar.2018.01293. eCollection 2018.

Authors

Yingqiu Liu¹, Tianyi Liu², Kevin Ding³, Zengyuan Liu¹, Yuanyuan Li¹, Taotao He¹, Weimin Zhang¹, Yunpeng Fan¹, Wuren Ma¹, Li Cui⁴, Xiaoping Song¹

Affiliations

¹ Laboratory of Traditional Chinese Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Yangling, China.
² Department of Neurosurgery, The First Hospital of Jilin University, Changchun, China.
³ University of Illinois at Urbana-Champaign, Urbana, IL, United States.
⁴ Department of Neurosciences, University of California, San Diego School of Medicine, La Jolla, CA, United States.

Abstract

Scope: 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 Panax notoginseng over these drugs. The dual-directional regulatory effect should be ascribed to the resourceful Panax notoginseng 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. Methods: In the in vitro 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 B₂ (TXB₂) and 1,4,5-inositol trisphosphate (IP₃) concentrations were measured by corresponding ELISA kits. Calcium concentrations ([Ca²⁺]) were estimated through the fluorescence intensity emitted from Fluo-4. In the in vivo study, thrombus model was induced by FeCl₃. The effect of Fc on thrombosis was evaluated by measurement of protein content and observation of injured blood vessel. Results: thrombin, collagen and ADP induced platelet aggregation were all suppressed by incubating platelets with Fc. Platelet PLCγ2 and subsequent DAG-PKC-TXA₂ and IP₃ were down-regulated by Fc as well. However, the basal [Ca²⁺] in platelet was not altered by Fc. Nevertheless, thrombin triggered activation of PLCγ2 and subsequent DAG-PKC-TXA₂ and IP₃-[Ca²⁺] were all abolished by Fc. Fc also attenuated platelet aggregation and PLCγ2 signaling activation induced by PLC activator, m-3M3FBS. In the in vivo study, FeCl₃ induced thrombosis in rat femoral artery was significantly alleviated by administration of Fc. Conclusion: The results above suggested the antiplatelet and antithrombotic effects of Fc are carried out through oppression of PLCγ2 and subsequent DAG-PKC-TXA₂ and IP₃-[Ca²⁺]. The present study provided theoretical support for new anti-thrombotic drug exploitation by Panax notoginseng.

Keywords: Notoginsenoside Fc; Panax notoginseng; antiplatelet effect; phospholipase Cγ2; platelet aggregation; thrombosis.