Pyrroloquinoline Quinone Preconditioning Alleviates Ischemic Cerebral Injury Through Antioxidant and Anti-Inflammatory Mechanisms.

The underlying pathological mechanism of ischemic stroke is complex, with oxidative stress and inflammation being two key factors that are intertwined and mutually influential. They also serve as important potential targets for the intervention of cerebral ischemia. Pyrroloquinoline quinone (PQQ) is known for its neuroprotective properties and the ability to modulate immune system function. Previous studies have demonstrated that PQQ mitigates brain infarction in rodent models of cerebral ischemia; however, the neuroprotective mechanisms underlying PQQ's effects against ischemic brain injury are not yet fully understood. This study used an MCAO rat model, an OGD model with SH-SY5Y cells, and an LPS-activated BV2 microglia model to investigate the neuroprotective functions of PQQ on brain ischemia. Using various experimental methods, including cell viability assays, oxidative stress damage assessments, inflammatory factor expression analysis, behavioral tests in animal models, and histological evaluations, we discovered that PQQ activates the nuclear translocation of Nrf2 in neurons, thereby enhancing downstream antioxidant responses. Additionally, PQQ inhibits NF-kB activation in microglia and suppresses their M1-type polarization, leading to decreased pro-inflammatory mediators' expression levels and reduced neural inflammatory damage. These results provide further insights into the neuroprotective mechanisms involved in PQQ's effects against cerebral ischemia and may offer evidence for its translational application in treating brain ischemia.