Nrf2/STAT3-mediated activation of SLC6A3 underlies the neuroprotective effect of quercetin in ischemic stroke

Ischemic stroke (IS) is a leading cause of mortality and long-term disability, yet effective neuroprotective strategies remain limited. Oxidative stress and dopaminergic dysfunction are key contributors to neuronal injury following cerebral ischemia. Quercetin, a natural flavonoid with antioxidant properties, has shown promise in preclinical models; however, its precise mechanisms of action remain incompletely understood.

We employed a combination of network pharmacology, in vivo middle cerebral artery occlusion (MCAO) models, and in vitro oxygen-glucose deprivation/reperfusion (OGD/R) assays. Bioinformatics analyses identified potential therapeutic targets of quercetin, which were validated through Western blotting, immunofluorescence, qRT-PCR, CRISPR-Cas9, and co-immunoprecipitation. Functional outcomes were evaluated via behavioral tests, TUNEL staining, and oxidative stress marker assays.

Quercetin significantly reduced cerebral edema, improved neurological function, and inhibited neuronal apoptosis following MCAO. Mechanistically, quercetin activated the Nrf2/STAT3 signaling pathway, promoting nuclear translocation of Nrf2 and transcriptional upregulation of the dopamine transporter gene SLC6A3. This regulatory axis was critical for mitigating oxidative DNA damage and preserving neuronal integrity. Network pharmacology and molecular docking identified Nrf2, STAT3, and SLC6A3 as core targets of quercetin. Inhibition of Nrf2 or STAT3 abrogated the protective effects of quercetin in both in vitro and in vivo models.

Our findings identify the Nrf2/STAT3/SLC6A3 axis as a key mediator of quercetin's neuroprotective effects in ischemic stroke. To our knowledge, this is the first study to identify the Nrf2/STAT3/SLC6A3 axis as a key regulatory pathway underlying the neuroprotective action of quercetin.