七氟醚后处理对失血性休克复苏大鼠海马CHOP表达的影响

Effect of sevoflurane postconditioning on expression of CHOP in a rat model of hemorrhagic shock and resuscitation

目的评价七氟醚后处理对失血性休克复苏大鼠海马C／EBP同源蛋白（CHOP）表达的影响。方法清洁级健康成年雄性SD大鼠36只，体重300～350g，采用随机数字表法分为3组（n=12）：假手术组（s组）、失血性休克复苏组（HSR组）和七氟醚后处理组（sP组）。采用右侧颈总动脉放血30min，失血量为大鼠总血容量40％，1h后经左侧颈静脉30min内回输全部自体血的方法制备大鼠失血性休克复苏模型。SP组于血液回输即刻吸入2．4％七氟醚30rain。各组每隔10rain监测MAP，于放血前（T0）、放血结束后即刻（T1）、放血结束后1h（T2）和自体血回输结束后即刻（T3）采集颈总动脉血样行血气分析。血液回输后4d时各组随机取6只大鼠，采用水迷宫实验检测学习记忆能力，随后断头取海马，采用TUNEL法检测海马CA1区神经元细胞的凋亡情况。血液回输后72h时处死各组余6只大鼠取海马，采用Westernblot法检测CHOP的表达。结果与S组比较，HSR组和SP组T1，2时MAP降低，乳酸浓度升高，HSR组逃避潜伏期延长，目标象限停留时间百分比降低，海马CA1区神经元凋亡数目升高，CHOP表达上调（P〈0．05）；与HSR组比较，sP组逃避潜伏期缩短，目标象限停留时间百分比升高，海马CA1区神经元凋亡数目减少，CHOP表达下调（P〈0．05）。结论七氟醚后处理改善失血性休克复苏大鼠认知功能的机制与其下调CHOP表达，抑制海马神经元凋亡有关。

Objective To evaluate the effect of sevoflurane postconditioning on the expression of CCAAT/enhancer-binding protein homologous protein （CHOP） in a rat model of hemorrhagic shock and resuscitation. Methods Thirty-six healthy adult male Sprague-Dawley rats, weighing 300-350 g, were divided into 3 groups （n = 12 each） using a random number table： sham operation group （group S） , hemor- rhagic shock and resuscitation group （group HSR） and sevoflurane postconditioning group （group SP）. Hemorrhagic shock was induced by withdrawing 40% of the total blood volume from the right carotid artery over an interval of 30 min, and 1 h later the removed blood was reinfused via the left jugular vein for resus- citation. Group SP inhaled 2.4% sevoflurane for 30 min starting from the onset of reinfusion. Mean arterial pressure was monitored and recorded at a 10 min interval. Before withdrawing blood （T0） , immediately after the end of withdrawing blood （T1 ） , at 1 h after the end of withdrawing blood （T2） and immediately after the end of reinfusion （T3 ） , blood samples were collected from the common carotid artery for blood gas analysis. At 4 days after reinfusion, 6 rats of each group were selected to detect spatial learning and memory ability by using Morris water maze test. The animals were then sacrificed, brains were removed for determination of neuronal apoptosis in hippocampal CA1 area using TUNEL. The rest 6 rats in each group were sacrificed at 72 h after reinfusion, and the hippocampus was isolated to detect the expression of CHOP by Western blot. Results Compared with group S, mean arterial pressure was significantly decreased, and lactic acid concentrations were increased at Tt.2 in HSR and SP groups, and the escape latency was signifi- cantly prolonged, the percentage of time staying at the target quadrant was decreased, the number of apop- totic neurons in hippocampal CA1 area was increased, and the expression of CHOP was up-regulated in group HSR （P〈0.05）. Compared with group HSR, the escape latency was significantly shortened, the percentage of time staying at the target quadrant was increased, the number of apoptotic neurons in hippocampal CA1 area was decreased, and the expression of CHOP was down-regulated in group SP （P〈0.05）. Conclusion The mechanism by which sevoflurane postconditioning improves cognitive function is related to down-regulation of CHOP expression and inhibition of apoptosis in hippocampal neurons in a rat model of hemorrhagic shock and resuscitation.