Role of PI3K∕Akt∕GSK-3βsignaling pathway in hydrogen-induced inhibition of neuronal apoptosis induced by focal cerebral ischemia-reperfusion in rats / 中华麻醉学杂志

ABSTRACT

Objective To investigate the role of phosphatidylinositol 3?kinase∕protein kinase B∕glycogen synthase kinase?3β ( PI3K∕Akt∕GSK?3β) signaling pathway in hydrogen?induced inhibition of neuronal ap?optosis induced by focal cerebral ischemia?reperfusion ( I∕R) in rats. Methods One hundred and twenty healthy adult male Sprague?Dawley rats, weighing 200-220 g, were divided into 5 groups ( n=24 each) u?sing a random number table sham operation group ( group S); cerebral I∕R group ( group I∕R); hydrogen group (group H2); LY294002 (specific PI3K inhibitor) group (group LY); LY294002+hydrogen group ( group LY+H2 ) . Focal cerebral I∕R was induced by occlusion of the middle cerebral artery for 1 h followed by 24 h reperfusion. In H2 and H2+LY groups, the animals inhaled 67% H2+33% O2 for 2 h starting from onset of reperfusion, and then inhaled H2 for 2 h every 6 h. In LY and LY+ H2 groups, LY294002 ( 10 mmol∕L) 10 μl was injected into the lateral cerebral ventricle at 10 min before reperfusion. Neurologic defi?cit was evaluated and scored ( NDS) at 24 h of reperfusion. The rats were then sacrificed, and the brains were removed for measurement of the cerebral infarct size ( by TTC staining) and apoptosis in cortical neu?rons ( by TUNEL) and for determination of the expression of Akt in the ischemic cerebral cortex, phospho?rylated Akt ( p?Akt) , GSK?3β and phosphorylated GSK?3β ( p?GSK?3β) and Bcl?2 and Bax positive cell count in the ischemic cerebral cortex ( by immuno?histochemistry) . The apoptosis index ( AI) , p?Akt∕Akt ratio and p?GSK?3β∕GSK3?β ratio were calculated. Results Compared with group S, the NDS, cerebral infarct size, AI, p?Akt∕Akt ratio, p?GSK?3β∕GSK?3β ratio and Bax positive cell count were significantly increased, and the Bcl?2 positive cell count was significantly decreased in group I∕R ( P0?05) . Compared with group H2 , the NDS, cerebral infarct size, AI and Bax positive cell count were significantly increased, and the p?Akt∕Akt ratio, p?GSK?3β∕GSK?3βratio and Bcl?2 positive cell count were significantly decreased in group LY+H2 ( P<0?05) . Conclusion The mechanism by which hydrogen inhibits focal cerebral I∕R?induced neuronal apoptosis is associated with the activation of PI3K∕Akt∕GSK?3β signaling pathway in rats.