ABSTRACT
Objective To investigate the long-term effects of propofol postconditioning on cerebral ischemia-reperfusion (I/R) injury in rats.Methods One hundred and forty-four healthy male SD rats,aged 7-8 weeks,weighing 250-280 g,were equally and randomly divided into 4 groups:sham operation group (group S),I/R group,propofol postconditioning group (group P) and intralipid group (group I).The animals were anesthetized with intraperitoneal 10％ chloral hydrate 300 mg/kg.Focal cerebral ischemia was induced by occlusion of middle cerebral artery for 60 min using a nylon thread with a rounded tip which was inserted into internal carotid artery in groups I/R,P and I.Two hour infusion of propofol was started at 20 mg· kg- 1· h- 1 immediately after the onset of reperfusion in group P,while the equal volume of normal saline was given instead in S and I/R groups,and 10％ intralipid was given instead in group I.Five rats in each group were chosen on day 1,14 and 28 after operation for assessment of neurological behavior and detection of cerebral infarct volume.Six rats in each group were chosen to perform Morris water maze test at day 9 and 23 after operation for 6 consecutive days.Five rats in each group were sacrificed on day 1,14 and 28 after operation and the hippocampal tissues were isolated for determination of the expression of GluR1-containing AMPA (GluR1-AMPA) receptor and GluR1-AMPA receptor in cell membrane.The ratio of GluR1-AMPA receptor in cell membrane/GluR1-AMPA receptor was calculated.Results Compared with group S,neurological behavior scores and the number of animals' swimming across the platform were significantly decreased,cerebral infarct volume was significantly enlarged,escape latency was significantly prolonged,and ratio of GluR1-AMPA receptor in cell membrane/GluR1-AMPA receptor was significantly increased ( P ＜ 0.05),while no significant change in the expression of GluR1-AMPA receptor was found in I/R group ( P ＞0.05).Propofol postconditioning inhibited cerebral I/R-induced changes mentioned above ( P ＜ 0.05).Conclusion The brain protection against focal I/R injury by propofol postconditioning can last for 28 days after operation and the inhibition of trafficking of GluR1-AMPA receptor from cytoplasm to cell membrane may contribute to this long-term brain protection.