Influence of glycogen synthase kinase-3β inhibition on autophagy in rats with cerebral ischemia/reperfusion injury and possible mechanism

Abstract:

Objective：To investigate the influence of glycogen synthase kinase-3β（GSK-3β） inhibition on autophagy in rats with cere－bral ischemia/reperfusion injury and the mechanism of affecting autophagy via Unc-51 like autophagy activating kinase 1（ULK1）. Methods：Sprague-Dawley rats were divided into sham-operation group（Sham group，ligation of the internal carotid artery alone），middle cerebral artery occlusion（MCAO） group（MCAO was performed to establish a model of focal cerebral ischemia/reperfusion），GSK-3β interference fragment group（siGSK-3β group；the GSK-3β interference fragment was injected at 24 hours before model establishment），GSK-3β non-significant sequence group（ConsiGSK-3β group；non-significant sequence was injected at 24 hours before model establishment），and GSK-3β inhibitor group（SB216763 group；the inhibitor SB216763 was injected at 6 hours before model establishment），with 5 rats in each group. Western blotting was used to measure the expression of tyrosine-216-phosphorylated GSK-3β [GSK-3β（P-tyr216）]，autophagy microtubule-associated protein light chain 3 antibody Ⅰ/Ⅱ（LC3B Ⅰ/Ⅱ），sequestosome 1（P62），phosphorylated ULK1（P-ULK1），and acetylated ULK1 （AcK） in the cerebral cortex. An electron microscope was used to measure the number of autophagosomes. Results：Compared with the Sham group，the MCAO group had a significant increase in the expression of GSK-3β（P-tyr216）（P=0.000）. Compared with the MCAO group，the siGSK-3β group and the SB216763 group had significant increases in the expression of LC3B I/II and P-ULK1（P=0.000） and significant reductions in the expression of P62（P=0.000） and AcK（SB216763 group：P<0.05；siGSK-3β group：P<0.01），and autophagosomes were observed under the electron microscope. Conclusion：GSK-3β inhibition can enhance au－tophagy via phosphorylated ULK1 in cerebral ischemia/reperfu－sion injury.