Effect of emulsified isoflurane preconditioning on neuronal apoptosis in hippocampal CA1 region induced by focal cerebral ischemia-reperfusion injury in rats / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effect of preconditioning with emulsified isoflurane (eISO) on neuronal apoptosis in hippocampal CA1 region induced by focal cerebral ischemia-reperfusion (I/R) injury in rats. Methods Forty-eight healthy adult male SD rats weighing 250-300 g were randomly divided into 6 groups (n = 8 each) sham operation group (group S); I/R group; eISO + I/R group (group EI); LY294002 (a specific PI3K inhibitor) + eISO + I/R group (group L+ EI); LY294002 + I/R group (group L) and DMSO (solvent for LY294002) + I/R group (group DMSO). Focal cerebral I/R was induced by 2 h middle cerebral artery occlusion ( MCAO). A nylon thread (0.26 mm in diameter) with rounded tip was inserted into internal carotid artery and advanced cranially until resistance was met (depth of insertion about 18-20 mm) . eISO 10.5 ml/kg (120 mg/ml) was injected intraperitoneally (IP) in groups EI and L+ EI. LY294002 (25 mmol/L) 5 pi was injected into cerebral ventricle on the ischemic side in group L + EI ( at 30 min before eISO) and group L. DMSO 5 μl was injected into the cerebral ventricle on ischemic side before MCAO in group DMSO. Neurologic deficit was assessed and scored (0 = normal, 4 = unconscious) at 24 h of reperfusion. The animals were then killed and their brains were removed for detection of neuronal apoptosis (by TUNEL) and p-Akt expression (by immuno-histochemistry) in hippocampal CA1 region. Results Cerebral I/R significantly increased the neurologic deficit scores, the number of apoptotic cells and p-Akt expression in group I/R as compared with group S. Preconditioning with elSO attenuated the I/R-induced increase in neurologic deficit scores and number of apoptotic cells but further increased p-Akt expression. The neuroprotective effect of eISO preconditioning against I/R-induced changes was counteracted by LY294002. Conclusion eISO preconditioning can attenuate focal cerebral I/R-induced neuronal apoptosis in rats by activating PI3K/Akt pathway.