Panax notoginseng saponins protect the blood–brain barrier against oxidative stress by activating the Akap12–PI3K/AKT–AQP1 signaling axis

Oxidative stress is a key pathological factor that contributes to blood–brain barrier (BBB) disruption during ischemic injury. Panax notoginseng saponins (PNS), the primary bioactive components of Panax notoginseng, possess potent antioxidative and vasoprotective activities. This study aimed to elucidate the molecular mechanisms by which PNS regulate endothelial integrity and BBB permeability under oxidative stress conditions. Mouse brain microvascular endothelial cells (bEnd.3) were treated with hydrogen peroxide to induce oxidative damage, followed by intervention with PNS. Transcriptomic and proteomic analyses revealed that Akap12 (A-kinase anchoring protein 12) and Aquaporin 1 (AQP1) were key molecules involved in PNS-mediated endothelial protection. H₂O₂ exposure markedly suppressed Akap12 expression and inhibited the PI3K/AKT signaling pathway, leading to elevated AQP1 expression and increased BBB permeability. PNS treatment reversed these effects by restoring Akap12 expression, reactivating PI3K/AKT signaling, and reducing AQP1 levels. Functional validation further showed that AQP1 dysregulation altered the expression balance of tight junction proteins, including Claudin-5 and ZO-1, thereby impairing barrier function. Collectively, these findings demonstrate that PNS protect endothelial cells from oxidative injury by activating Akap12-dependent PI3K/AKT signaling and modulating AQP1-associated tight junction remodeling. This study provides new mechanistic insights into the molecular basis of PNS-mediated BBB protection and suggests potential therapeutic targets for oxidative or ischemic cerebrovascular diseases.