Temporal Pattern and Crosstalk of Necroptosis Markers with Autophagy and Apoptosis Associated Proteins in Ischemic Hippocampus

Necroptosis, a novel type of programmed cell death, has been recently implicated as a possible mechanism for cerebral ischemia-reperfusion (I/R) injury. We herein studied time-dependent changes of necroptosis markers along with apoptosis- and autophagy-associated proteins in rat hippocampus at 1, 3, 6, 12, 24, and 48 h after global cerebral I/R injury. Furthermore, to determine the cross talk between autophagy and necroptosis, we examined the effects of pretreatment with bafilomycin-A1 (Baf-A1), as a late-stage autophagy inhibitor, on necroptosis. Highest levels of receptor-interacting protein 1 and 3 (RIP1 and RIP3), as key mediators of necroptosis, were observed at 24 h after reperfusion. Alongside, activity of glutamate dehydrogenase (GLUD1), downstream enzyme of RIP3, was increased. Peak time of necroptosis was subsequent to caspase-3-dependent cell death that peaked at 12 h of reperfusion but concurrent with autophagy. Administration of Baf-A1 could attenuate necroptosis, verified by decrease in RIP1 and RIP3 protein levels, as well as GLUD1 activity. However, there was no significant change in caspase-3-dependent cell death. Taken together, our results highlight that global cerebral I/R activates necroptosis that could be triggered by autophagy and interacts reversely with caspase-3-dependent apoptosis.