Network-pharmacology-guided elucidation of Cornus officinalis-mediated protection against paraquat-induced neurotoxicity via restoration of dopaminergic and GABAergic signaling pathways.

Paraquat (PQ; 1,1'-dimethyl-4,4'-bipyridinium dichloride) is a widely used herbicide and environmental contaminant that disrupts neuronal homeostasis through oxidative stress and apoptosis, leading to dopaminergic and GABAergic dysfunction resulting in neurotransmitter imbalance and Parkinson's disease-like phenotype. Here, we combined phytochemical profiling, network pharmacology, molecular docking, and zebrafish-based assays to elucidate the neuroprotective mechanisms of Cornus officinalis ethanolic extract (COE). UHPLC-MS and HPLC-DAD analyses identified morroniside (133.50 mg/g dry extract) and loganin (62.90 mg/g dry extract) as the predominant constituents of COE. Integrative bioinformatics and transcriptomic analysis identified eight hub genes (th, slc6a3, hspa8, syn2, gap43, gad1, sncb, and drd2) as core targets of COE, with significant enrichment in dopaminergic and GABAergic synaptic pathways. Molecular docking further predicted a high binding affinity (-10.4 kcal mol-1) between p-hydroxycinnamic acid and tyrosine hydroxylase. In vivo experiments demonstrated that PQ exposure (100 μM) induced reactive oxygen species (ROS) accumulation, apoptosis, and the transcriptional downregulation of neuro-markers in zebrafish larvae, resulting in measurable locomotor deficits. Conversely, COE co-treatment (5-20 μg/mL) attenuated ROS production and apoptotic cell death. These effects were accompanied by the upregulation of nrf2 and bcl-2, and the restoration of th and slc6a3 expression. Imaging of Tg(HuC:GFP) and Tg(Hb9:GFP) transgenic lines confirmed that COE preserves neuronal integrity, while behavioral assays validated the recovery of locomotor activity and light/dark responsiveness. Collectively, these findings demonstrate that COE exerts neuroprotection by modulating oxidative stress, inhibiting apoptosis, and stabilizing dopaminergic/GABAergic neurotransmission. This study positions C. officinalis as a potent therapeutic candidate for mitigating pesticide-induced neurodegeneration and provides a comprehensive mechanistic framework for its network-level actions.