Diosmetin alleviates cerebral ischemia-reperfusion injury through Keap1-mediated Nrf2/ARE signaling pathway activation and NLRP3 inflammasome inhibition

Diosmetin was found to exert protective effect on renal and myocardial ischemia-reperfusion (IR) injury. This study aimed to investigate the role of diosmetin in cerebral IR (CIR) injury. PC12 neurons were exposed to oxygen-glucose deprivation/reoxygenation (OGD/R) to establish CIR injury model in vitro and then incubated with diosmetin, and we found that diosmetin alleviated OGD/R-induced viability inhibition, LDH release, apoptosis, and oxidative stress in PC12 cells. Then our results showed that diosmetin downregulated kelch like ECH-associated protein 1 (Keap1) expression, and upregulated nuclear factor E2-related factor 2 (Nrf2) expression, antioxidant response element (ARE) activity and the mRNA and protein expression of heme oxygenase 1 (HO-1) and NAD(P)H: quinone oxidoreductase 1 (NQO1). Keap1 overexpression or Nrf2 silencing both attenuated the neuroprotective effect of diosmetin on PC12 cells. Moreover, diosmetin inhibited the levels of nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) pyrin domain containing 3 (NLRP3) inflammasome pathway related proteins and inflammatory cytokines interleukin (IL)-1β and IL-18. Additionally, a middle cerebral artery occlusion (MCAO) rat model was established and diosmetin was injected for treatment. Diosmetin alleviated CIR-induced neurological deficits, cerebral infarction, brain edema and histopathological damage, and neuronal apoptosis and oxidative stress in MCAO rats. In conclusion, diosmetin attenuated OGD/R-induced PC12 cell viability inhibition, apoptosis, oxidative stress and inflammation through Keap1-mediated Nrf2/ARE signaling activation and NLRP3 inflammasome inhibition, and alleviated CIR-induced neurological injury in MCAO rat model. Our study may provide a novel therapeutic strategy for CIR injury.