Autophagy inhibitors 3‐MA and BAF may attenuate hippocampal neuronal necroptosis after global cerebral ischemia–reperfusion injury in male rats by inhibiting the interaction of the RIP3/AIF/CypA complex

Abstract

AbstractOur previous study found that receptor interacting protein 3 (RIP3) and apoptosis‐inducing factor (AIF) were involved in neuronal programmed necrosis during global cerebral ischemia–reperfusion (I/R) injury. Here, we further studied its downstream mechanisms and the role of the autophagy inhibitors 3‐methyladenine (3‐MA) and bafilomycin A1 (BAF). A 20‐min global cerebral I/R injury model was constructed using the 4‐vessel occlusion (4‐VO) method in male rats. 3‐MA and BAF were injected into the lateral ventricle 1 h before ischemia. Spatial and activation changes of proteins were detected by immunofluorescence (IF), and protein interaction was determined by immunoprecipitation (IP). The phosphorylation of H2AX (γ‐H2AX) and activation of mixed lineage kinase domain‐like protein (p‐MLKL) occurred as early as 6 h after reperfusion. RIP3, AIF, and cyclophilin A (CypA) in the neurons after I/R injury were spatially overlapped around and within the nucleus and combined with each other after reperfusion. The survival rate of CA1 neurons in the 3‐MA and BAF groups was significantly higher than that in the I/R group. Autophagy was activated significantly after I/R injury, which was partially inhibited by 3‐MA and BAF. Pretreatment with both 3‐MA and BAF almost completely inhibited nuclear translocation, spatial overlap, and combination of RIP3, AIF, and CypA proteins. These findings suggest that after global cerebral I/R injury, RIP3, AIF, and CypA translocated into the nuclei and formed the DNA degradation complex RIP3/AIF/CypA in hippocampal CA1 neurons. Pretreatment with autophagy inhibitors could reduce neuronal necroptosis by preventing the formation of the RIP3/AIF/CypA complex and its nuclear translocation.