Panax notoginseng Saponins Attenuate Cerebral Ischemia-Reperfusion Injury via Mitophagy-Induced Inhibition of NLRP3 Inflammasome in Rats

Background: The mitophagy/NLRP3 inflammasome pathway is a promising therapeutic target for cerebral ischemia-reperfusion (I/R). Panax notoginseng (Burkill) F.H. Chen, one of the most valuable components of traditional Chinese medicine, and Panax notoginseng saponins (PNS), the main active ingredients of P. notoginseng, are patent medicines commonly used to treat cardio- and cerebrovascular diseases. However, their effects on the mitophagy and the NLRP3 inflammasome activation in I/R remain unclear. Therefore, in this study, we investigated how PNS might affect the mitophagy/NLRP3 inflammasome pathway in I/R. Methods: Cerebral I/R injury was induced by middle cerebral-artery occlusion, and expression levels of NLRP3 inflammasome signaling pathway-associated proteins were detected by western blot. We tested I/R injury using a neurological-deficit score, infarct volume, and hematoxylin and eosin staining, after which we detected both mitophagy- and NLRP3 inflammasome-related proteins in PNS-treated rats to determine whether PNS could attenuate I/R injury and the possible mechanisms involved. Results: Our results showed that cerebral I/R could induce activation of the NLRP3 inflammasome, aggravating brain injury, whereas PNS effectively alleviated cerebral I/R injury in rats by inhibiting the NLRP3 inflammasome and promoting mitophagy via the PINK1/Parkin pathway. Moreover, mitophagy inhibited the NLRP3 inflammasome and mediated the anti-injury effects of PNS. Conclusions: In conclusion, PNS could promote mitophagy via the PINK1/Parkin pathway by inhibiting activation of the NLRP3 inflammasome, alleviating cerebral I/R injury in rats.