Polygalasaponin F ameliorates middle cerebral artery occlusion-induced focal ischemia in rats through inhibiting TXNIP/NLRP3 signaling pathway

Abstract Polygalasaponin F (PGSF), an oleanane triterpenoid saponin extracted from Polygala japonica , has been demonstrated with neuroprotective effect. However, the therapeutic effects and mechanism of PGSF on focal ischemia remain unknown. In this study, we first established a rat model of focal ischemia using middle cerebral artery occlusion (MCAO) to evaluate the therapeutic effect of PGSF intervention and to investigate the impact of PGSF on the thioredoxin-interacting protein/NOD-, LRR-, and pyrin domain-containing protein 3 (TXNIP/NLRP3) inflammatory pathway. Secondly, brain neuron cells were isolated, and the cells received oxygen-glucose deprivation/reoxygenation (OGD/R) culture to establish the cell injury model in vitro . The mechanism of PGSF on the TXNIP/NLRP3 pathway was further validated. Our results showed that PGSF treatment reduced neurological scores, brain tissue water content and infarct volume and ameliorated the pathological changes in cerebral cortex in MCAO-induced focal ischemia rats. The TNF-α, IL-1β and IL-6 levels decreased in MCAO-induced focal ischemia rats after PGSF treatment. Moreover, PGSF down-regulated the protein expressions of TXNIP, NLRP3, ASC, cleaved caspase-1, IL-1β, and IL-18 in MCAO-induced focal ischemia rats. Meanwhile, PGSF treatment reduced the levels of apoptosis, ROS, inflammatory cytokine and TXNIP/NLRP3 pathway-related proteins (TXNIP, NLRP3, ASC, cleaved caspase-1, IL-1β, and IL-18) in OGD/R-induced neuronal injury cells. Finally, PGSF treatment also inhibited the interaction between NLRP3 and TXNIP in vitro . In conclusion, our study demonstrated the therapeutic effects of PGSF on MCAO-induced focal ischemia rats. Moreover, the neuroprotective mechanism of PGSF on focal ischemia was associated with the inhibition of TXNIP/NLRP3 signaling pathway.