The preconditioning effect of sevoflurane on the oxygen glucose-deprived hippocampal slice: the role of tyrosine kinases and duration of ischemia.

摘要

BACKGROUND: The neuroprotective efficacy of anesthetics observed in experimental models remains unproven in the clinical setting. The nonreceptor tyrosine kinase focal adhesion kinase (FAK) has been suggested to be involved in the neuroprotective effect of anesthetics observed experimentally. In the present work, we investigated whether FAK and the duration of ischemia play a role in the preconditioning effect of sevoflurane on brain tissue. METHODS: Rat acute hippocampal slices were subjected to oxygen and glucose deprivation (OGD) challenge during increasing periods of time (10, 20, 30, 45, 50, and 60 min) followed by 1 h reperfusion. A preconditioning sevoflurane concentration (10(-4) M, 1 h) was applied 3 h before initiation of OGD. Protein expression of FAK and cleaved caspase 3 (a marker of activation of the apoptotic cascade) was measured by immunoblotting. Cell death was assessed by propidium iodide (PI) fluorescence. RESULTS: Both PI fluorescence and expression of cleaved caspase 3 significantly increased with duration of ischemia until reaching a ceiling effect for durations of ischemia longer than 30 min. Sevoflurane (10(-4) M) increased FAK expression and markedly reduced the increase in PI fluorescence and cleaved caspase 3 expression for periods of ischemia of 10, 20, and 30 min. In contrast, the protective effect was no longer observed for periods of ischemia longer than 30 min. 4-amino-5-(4-chlorophenyl)-7-(t-butyl) pyrazolo[3,4-d] pyrimidine (PP2, 10(-5) M, an inhibitor of src tyrosine kinases) application 60 min before and throughout that of sevoflurane significantly reduced the neuroprotective effect of sevoflurane on both caspase 3 expression and PI fluorescence. CONCLUSION: In the OGD rat acute hippocampal slice, the preconditioning effect of a clinically relevant concentration of sevoflurane was very likely to involve FAK and was observed only for periods of ischemia