Neuroprotection by post-stroke administration of the slow-releasing hydrogen sulfide (H2S) donor AP39: Long-Term functional, MRI, and molecular evidence in a rodent stroke model.

Hydrogen sulfide (H2S) is an endogenous gaseous signalling molecule with potential cytoprotective properties in neurological disorders. AP39, a mitochondria-targeted H2S donor, has previously demonstrated neuroprotection in stroke models. Here, we investigated the therapeutic efficacy of AP39 administered after stroke in a rat model of transient middle cerebral artery occlusion (MCAO). AP39 (100 nmol/kg) was delivered intravenously 10 min after reperfusion. Animals underwent longitudinal assessments at 24 h and 7 days post-stroke, including neurological deficit assessment, grid-walking test, MRI (T2-weighted, diffusion tensor imaging [DTI], perfusion-weighted imaging [PWI]), and molecular analyses (qRT-PCR, Western blot, Luminex). AP39 treatment significantly reduced infarct volume at both 24 h and 7 d. A reduction in infarct core was observed at 24 h, while penumbra volume was decreased at 7 d. Treated animals showed improved neurological and motor function, preserved blood-brain barrier integrity, and attenuated microstructural damage based on fractional anisotropy (FA) and mean diffusivity (MD) metrics. Post-stroke administration of AP39 improved neurological and MRI outcomes and was accompanied by reduced neuroinflammation, including a significant decrease in the number of activated microglia. AP39 also downregulated apoptotic markers while upregulating neurotrophic factors at 24 h. Collectively, our findings provide substantial evidence supporting the therapeutic potential of AP39 when administered post-ischemia, thereby highlighting its therapeutic potential in mitigating the detrimental consequences of ischemic stroke.