DL-3-n-Butylphthalide Protects Against PrP^{106 -126}-Induced Neurotoxicity Through NRF2 Signaling and...

Prion diseases are fatal neurodegenerative diseases caused by misfolded prion protein. DL-3-n-butylphthalide (NBP), a synthetic agent derived from celery seeds, exhibits neuroprotective effects in multiple neurological disorders. However, its effects against prion peptide-induced neurotoxicity remain unclear.

A PrP^106-126-induced neurotoxicity model was established in N2a cells to evaluate the effects of NBP. Apoptosis, oxidative stress, mitochondrial function, mitochondrial dynamics, and respiratory chain integrity were assessed following NBP pretreatment. Mechanistic causality was examined using OPA1 knockdown, DRP1 overexpression, NRF2 inhibition, and NRF2 overexpression. Key findings were further validated in human iPSC-derived neurons.

NBP attenuated PrP^106-126-induced neuronal apoptosis, decreasing cytochrome c release and caspase 3 cleavage. NBP also alleviated oxidative stress by lowering ROS and MDA levels, restoring T-AOC and SOD activity, and increasing NRF2/HO-1 signaling. In parallel, NBP preserved mitochondrial integrity and bioenergetics by maintaining MMP, ATP production, OCR, and mtDNA content, while sustaining respiratory chain complex expression and activity. NBP further normalized mitochondrial dynamics, restoring OPA1 levels and reducing DRP1 enrichment in mitochondrial fractions. Functionally, OPA1 knockdown, DRP1 overexpression, or NRF2 inhibition abolished NBP-mediated protection, whereas NRF2 overexpression recapitulated key protective effects and normalized OPA1/DRP1-related markers. Consistent protective trends were observed in human iPSC-derived neurons.

NBP mitigates PrP^106-126-induced neurotoxicity by engaging NRF2-dependent antioxidant signaling and preserving mitochondrial homeostasis, with associated normalization of OPA1/DRP1-related mitochondrial dynamics. These findings support further evaluation of NBP in prion disease-relevant models.