Phosphoinositide-3-Kinase/Akt–Endothelial Nitric Oxide Synthase Signaling Pathway Mediates the Neuroprotective Effect of Sevoflurane Postconditioning in a Rat Model of Hemorrhagic Shock and Resuscitation

Although extensive reports have demonstrated the neuroprotection of sevoflurane postconditioning in cases of focal and global cerebral ischemia/reperfusion, the underlying mechanisms are not completely elucidated. This study investigated whether this effect is related to endothelial nitric oxide synthase (eNOS) and mediated by the phosphoinositide-3-kinase pathway in a rat model of hemorrhagic shock and resuscitation. Adult male Sprague Dawley rats were subjected to hemorrhagic shock for 60 minutes and then resuscitation for 30 minutes in experimental groups. Sevoflurane postconditioning was performed at the beginning of resuscitation to completion. At 24 hours after resuscitation, the brain infarct volume was evaluated by 2,3,5-triphenyltetrazolium chloride staining. The neuronal morphological changes and apoptosis were determined by hematoxylin and eosin staining and immunohistochemistry analysis, respectively. The activity of phosphorylated Akt and eNOS was evaluated by Western blot analysis. Brain injuries such as the cerebral infarct volume and pathological neuronal changes as well as cell apoptosis were observed in the hippocampus after hemorrhagic shock and resuscitation. Postconditioning with 2.4% sevoflurane significantly attenuated brain injuries. Wortmannin prevented the improvements of neuronal characteristics elicited by sevoflurane postconditioning as well as the hyperactivity of eNOS and phosphorylated Akt. Sevoflurane postconditioning could attenuate brain injury induced by hemorrhagic shock and resuscitation, and this neuroprotective effect may be partly by upregulation of eNOS through the phosphoinositide-3-kinase/Akt signaling pathway.