Downstream signaling of reactive oxygen species, protein kinase C epsilon translocation and delayed neuroprotection in sevoflurane preconditioned rats following cerebral ischemia/reperfusion

Zhi Ye; Qulian Guo; E Wang; Yundan Pan; Qing Li; Honghao Zhou

doi:10.3969/j. issn. 1673-5374.2009.03.007

摘要：BACKGROUND: Brief exposure to the anesthetic sevoflurane results in delayed neuroprotection.However, few studies have addressed delayed neuroprotection after preconditioning with a single administration of sevoflurane.OBJECTIVE: To explore the relationship between a single preconditioning administration of sevoflurane and reactive oxygen species production and protein kinase C-epsilon (PKC- ε ) translocation.DESIGN, TIME, AND SETTING: The randomized, controlled, animal experiment was conducted at the Central Laboratory, Xiangya Hospital, Central South University, China from November 2007 to April 2008.MATERIALS: A total of 120 healthy, male, Sprague Dawley rats were equally and randomly assigned into five groups: sham operation, ischemia/reperfusion, sevoflurane, 2-mercaptopropionylglycine (2-MPG, a selective reactive oxygen species scavenger) + sevoflurane (MPG + sevoflurane), and MPG. Sevoflurane (Baxter, USA) and MPG (Sigma, USA) were used in this study.METHODS: Intervention consisted of three procedures. (1) MPG injection: a selective reactive oxygen species scavenger, MPG (20 mg/kg), was infused into the rat caudal vein in the MPG and MPG + sevoflurane groups. (2) Sevoflurane preconditioning: 30 minutes following MPG injection,rats in the sevoflurane and MPG + sevoflurane groups breathed a mixed gas of 2.4% sevoflurane and 97.6% oxygen for 60 minutes. Rats in the sham operation, ischemia/reperfusion, and MPG groups breathed 100% pure oxygen for 60 minutes. (3) Ischemia/reperfusion: 24 hours after sevoflurane or pure oxygen preconditioning, middle cerebral artery occlusion models were established in the ischemia/reperfusion, sevoflurane, MPG + sevoflurane, and MPG groups.Following 2 hours ischemia/6 hours and 24 hours reperfusion, the carotid artery was separated, but the middle cerebral artery was not occluded, in the sham operation group.MAIN OUTCOME MEASURES: In the ischemic hemisphere, PKC-ε translocation in the rat parietal cortex was measured by Western blot analysis. Infarct volume was calculated using the TTC assay. Neurological deficits were evaluated in rats using a scoring system of 8 points.RESULTS: After 6 hours reperfusion, the ratio of PKC- ε in membrane/(cytosol + membrane) was significantly less in the sham operation group than in the ischemia/reperfusion, sevoflurane, MPG +sevoflur.ane), and MPG groups (P < 0.05). The ratio of PKC- ε in membrane/(cytosol + membrane)was significantly greater in the sevoflurane group than in the sham operation, ischemia/reperfusion,MPG + sevoflurane, and MPG groups (P< 0.05). No significant differences were observed in the ischemia/reperfusion, MPG + sevoflurane, and MPG groups (P> 0.05). Following 24 hours reperfusion,the ratio of PKC-ε in membrane/(cytosol + membrane) was significantly less in the sham operation group than in the ischemiaJreperfusion, sevoflurane, MPG + sevoflurane, and MPG groups (P < 0.05).No significant differences were detected in the ischemia/reperfusion, sevoflurane, MPG + sevoflurane,and MPG groups (P> 0.05). Compared with the ischemia/reperfusion, MPG + sevoflurane, and MPG groups, infarct volume was significantly smaller, and neurological deficits were significantly improved,in the sevoflurane group (P < 0.05). No significant differences in infarct volume and neurological deficits were observed among the ischemia/reperfusion, MPG + sevoflurane, and MPG groups (P>0.05). Infarcts or neurological deficits were not detected in the sham operation group.CONCLUSION: A single preconditioning administration of sevoflurane reduced infarct volumes and improved neurological deficits in ischemic rats. Delayed neuroprotection may be mediated by reactive oxygen species and correlated to PKC-ε activation.