Role of mitophagy regulated by Parkin/DJ-1 in remote ischemic postconditioning-induced mitigation of focal cerebral ischemia-reperfusion.

OBJECTIVE: We evaluated the role of mitophagy controlled by Parkin/DJ-1 in remote ischemic post conditioning-induced mitigation of focal cerebral ischemia-reperfusion (I/R) injury in rats.

MATERIALS AND METHODS: Ninety adult male rats were randomly assigned into 5 groups including a sham operation group (S) and ischemia-reperfusion group (I/R). Focal cerebral I/R was induced by right middle cerebral artery occlusion (MCAO). I/R+remote ischemic postconditioning (I/R+RIPoC), I/R+RIPoC+ mitophagy inhibitor Mdivi-1 (I/R+RIPoC+M), and I/R+RIPoC+ normal saline (I/R+RIPoC+NS) groups all received 3 cycles of 10 minutes reperfusion followed by 10 minutes ischemia in bilateral femoral arteries at the beginning of cerebral reperfusion. I/R+RIPoC+M received mitochondrial division inhibitor (Mdivi-1) before ischemia and after 24h of reperfusion, neurological deficit scores (NDSs) were measured and rats were then sacrificed. Brain was removed and size of the infarct was determined. Apoptosis index and LC3-II/I ratio, Parkin/DJ-1 proteins expression, SOD activity, MDA and 15-F2t-Isoprostane content in cerebral ischemic penumbra were studied. Linear correlation between Parkin/DJ-1 proteins expression and LC3-II/I ratio and cerebral infarct size were analyzed.

RESULTS: In experimental groups the NDSs, percentage of cerebral infarct size, apoptosis index, LC3-II/I ratio, MDA and 15-F2t-Isoprostane content significantly increased and Parkin/DJ-1 proteins were up-regulated (p<0.05). In I/R+RIPoC and I/R+RIPoC+NS groups, NDSs, percentage of cerebral infarct size, apoptosis index, MDA and 15-F2t-Isoprostane content decreased significantly while LC3-II/I ratio and SOD activity increased compared to I/R group. Parkin/DJ-1 proteins were up-regulated in I/R+RIPoC, I/R+RIPoC+NS and I/R+RIPoC+M groups (p<0.05). LC3-II/I ratio and SOD activity significantly decreased (p<0.05). Parkin/DJ-1 proteins expression didn't changed in I/R+RIPoC+M group (p>0.05). The Parkin/DJ-1 proteins expression were positively correlated with LC3-II/I ratio, and negatively correlated with cerebral infarct size (p<0.05).

CONCLUSIONS: Remote Ischemic Post Conditioning (RIPoC) promoted the mitophagy via up-regulation of Parkin/DJ-1 proteins expression and inhibiting the oxidative stress responses, thus mitigating focal cerebral I/R injury in rats.