N-stearoyltyrosine attenuates ischemia-reperfusion injury by inhibiting caspase-dependent apoptosis and...

Cerebral ischemia‑reperfusion (I/R) injury induces neuronal death via caspase-dependent apoptosis and parthanatos, a poly (ADP-ribose) polymerase 1 (PARP-1)/apoptosis-inducing factor (AIF)-mediated caspase-independent pathway. Simultaneous inhibition of these pathways may provide enhanced neuroprotection. N-Stearoyltyrosine (NsTyr), a synthetic analogue of the endocannabinoid anandamide (AEA), exhibits neuroprotective effects in various models, however, its efficacy and mechanism in middle cerebral artery occlusion (MCAO) remain unclear. Neuronal oxygen-glucose deprivation/ reoxygenation (OGD/R) and rat MCAO models were employed to evaluate the neuroprotection of NsTyr. Neuronal viability and apoptosis were assessed using MTT assay, flow cytometry, TUNEL staining, and Hoechst 33342 staining. The cognitive impairment was evaluated using the Morris water maze. Mitochondrial function and ultrastructure were eassessed by JC-1 assay and transmission electron microscopy (TEM). Expression levels of key apoptotic-related proteins were determined by immunoblotting. Intracellular NAD⁺ and ATP levels were measured to assess PARP-1 activity. NsTyr significantly improved neuronal survival, reduced apoptosis, and ameliorated cognitive deficits in both in vitro and in vivo models. Mechanistically, NsTyr preserved mitochondrial integrity, maintained the Bcl-2/Bax balance, suppressed cytochrome c release and caspase-3 activation, and inhibited nuclear translocation of AIF. Concurrently, NsTyr attenuated PARP-1 overactivation, preserved NAD⁺ and ATP levels, and thereby suppressed parthanatos. These findings demonstrate that NsTyr confers potent neuroprotection against I/R injury by dual inhibition of caspase-dependent apoptosis and PARP-1/AIF-mediated parthanatos through the maintenance of mitochondrial integrity, supporting its potential as a therapeutic candidate for ischemic stroke.