TPPU, a soluble epoxide hydrolase inhibitor, mitigates Aβ-induced neurotoxicity via dual modulation of mitochondrial stabilization and JNK suppression

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive cognitive decline, primarily driven by β-amyloid (Aβ) aggregation and neuronal apoptosis. This study aims to investigate the neuroprotective effects of soluble epoxide hydrolase (sEH) inhibition against Aβ-induced cytotoxicity in PC-12 cells, focusing on cell viability, apoptosis, and the c-Jun N-terminal kinase (JNK) signaling pathway. Western blotting and fluorometric assays revealed elevated sEH expression and activity in Aβ1-42-treated PC-12 cells compared to untreated controls. Treatment with N-[1-(1-Oxopropyl)-4-piperidinyl]-N'-[4-(trifluoromethoxy)phenyl]urea (TPPU), a potent sEH inhibitor, significantly attenuated Aβ-induced apoptosis in PC-12 cells and enhanced cell viability. These findings were corroborated by CCK-8 assays and flow cytometry analyses. Furthermore, TPPU reversed Aβ-induced cleaved Caspase-3 dysregulation and restored mitochondrial membrane potential. Notably, exogenous administration of epoxyeicosatrienoic acids partially mimicked the protective effects of TPPU, primarily by preserving mitochondrial function. Western blot analysis confirmed that TPPU pretreatment suppressed the phosphorylation of JNK, thereby contributing to its anti-apoptotic effects. Collectively, these findings demonstrate that TPPU attenuates Aβ-induced neurotoxicity via dual mechanisms—restoring mitochondrial function and suppressing JNK activation—highlighting its potential as a therapeutic agent for AD.