Electroacupuncture Potentiates Astragaloside IV Cerebral Delivery via P‐Glycoprotein‐Mediated Transcellular Transport: A Novel Blood–Brain Barrier Penetration Strategy for Ischemic Stroke Therapy

BACKGROUND: Astragaloside IV (AS-IV) exhibits therapeutic potential in central nervous system (CNS) disorders. However, its brain bioavailability is restricted by P-glycoprotein (P-gp)-mediated efflux at the blood-brain barrier (BBB). This study aims to investigate whether electroacupuncture (EA) can enhance the cerebral delivery of AS-IV by inhibiting nuclear factor-kappa B (NF-κB) nuclear translocation to downregulate P-gp expression. METHODS: The permeability of the BBB was assessed using Evans blue (EB) staining and transmission electron microscopy. The intracerebral concentration of AS-IV was quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The therapeutic efficacy of AS-IV in combination with EA was evaluated using triphenyltetrazolium chloride (TTC) staining and neurological function assessments. mRNA and protein expression levels of relevant factors were analyzed through real-time quantitative polymerase chain reaction (RT-qPCR), western blot, and immunofluorescence. RESULTS: In normal mice, EA effectively increases the levels of EB and AS-IV in brain tissue. The combination of EA and AS-IV significantly activates the Wnt/β-catenin signaling pathway and promotes the expression of zonula occludens protein (ZO)-1 and Claudin-5. Furthermore, EA inhibits NF-κB nuclear translocation and mitigates AS-IV-induced upregulation of P-gp expression. Notably, EA significantly elevates the AS-IV content in ischemic brain tissue. The combination therapy demonstrates enhanced therapeutic effects in ischemic rats, including reductions in neurological function scores, infarct size, and pro-inflammatory factor levels, along with increased expression of anti-inflammatory factors. Additionally, this combination significantly inhibits NF-κB nuclear translocation and reduces P-gp expression in the brain tissue of ischemic stroke rats. CONCLUSION: These findings indicate that EA enhances the brain uptake and neuroprotective effects of AS-IV, irrespective of BBB integrity. The underlying mechanism involves P-gp-mediated transcellular transport rather than the paracellular pathway.