N-acetylserotonin derivative ameliorates hypoxic-ischemic brain damage by promoting PINK1/Parkin-dependent mitophagy to inhibit NLRP3 inflammasome-induced pyroptosis.

Neonatal hypoxic-ischemic brain damage is the main cause of hypoxic-ischemic encephalopathy and cerebral palsy, whose clinical treatment is still limited to therapeutic hypothermia with limited efficacy. N-[2-(5-hydroxy-1H-indol-3-yl) ethyl]-2-oxopiperidine-3-carboxamide (HIOC), a derivative of N-acetylserotonin, has shown neuroprotective properties. This study was conducted to evaluate the neuroprotective and molecular mechanisms of HIOC. We established an in vitro model using Oxygen-glucose deprivation/reoxygenation (OGD/R) in HT22 cells, alongside an in vivo model via the modified Rice-Vannucci method. The results showed that HIOC reduced OGD/R-induced HT22 cell pyroptosis and inhibited NOD-like receptor pyrin domain- containing protein 3 (NLRP3) inflammasome activation. With the addition of the mitophagy inhibitor 3-MA, we demonstrated that HIOC promoted PTEN-induced putative kinase 1 (PINK1)/Parkin-mediated mitophagy to reduce HT22 cell pyroptosis. Mechanistically, HIOC stimulated mitophagy to remove damaged mitochondria. The clearance of injured mitochondria reduced reactive oxygen species generation, which consequently inhibited NLRP3 inflammasome expression. In vivo, HIOC remarkably lessened cerebral blood flow, infarct volume, neuronal injury by activating mitophagy. HIOC activated mitophagy to produce antipyroptosis effects. Together, our finding demonstrated that HIOC improves brain injury by promoting PINK1/Parkin-dependent mitophagy to inhibit NLRP3 inflammasome activation and pyroptosis, suggesting its potential for hypoxic-ischemic brain damage treatment.