Remote ischemic preconditioning enhances antioxidant capacity in cerebral ischemia-reperfusion injured rats via the ARE pathway.

Background: Remote ischemic preconditioning (RIPC) is a protective strategy in which transient ischemia and reperfusion in one organ confers protection to another. This can be mediated by humoral responses, transcriptional processes, or both. These protective effects are hypothesized to result from enhanced cellular tolerance to ischemia. Herein, we investigated the protective effects of RIPC in middle cerebral artery occlusion (MCAO) rats.

Methods: RIPC was performed by applying an elastic rubber tourniquet to the right hindlimb to induce transient ischemia. This involved tightening and releasing the tourniquet for 15 min per cycle (2 cycles for 30 min or 4 for 60 min). MCAO was then induced 12 or 24 h post-limb ischemia and maintained for 90 min. Seven days after MCAO, neurobehavioral outcomes and brain infarction volumes were evaluated. Oxidative stress markers, including malondialdehyde, myeloperoxidase, and dihydroethidium, alongside antioxidant parameters such as glutathione (GSH), the GSH/GSSG ratio, and γ-glutamyl cysteine ligase (GCS), were assessed. The expression levels of Nrf-1 and Nrf-2 were analyzed by western blotting and immunofluorescence.

Results: RIPC for 60 min (4 cycles), but not for 30 min, significantly reduced infarct volumes and improved behavioral outcomes. In addition, reductions in neutrophil infiltration, lipid peroxidation, and neuronal degeneration were observed. Nrf1 and Nrf2 levels and GSH, HO-1, and GCS activities were significantly elevated after RIPC for 60 min compared to the control.

Conclusion: RIPC in the hind limbs for 60 min leads to neuroprotection in a rat MCAO model. RIPC may be a potential adjunctive strategy for clinical stroke management.