远端肢体缺血预处理对氯胺酮致发育期大鼠海马CA1区神经细胞Bcl-2和Bax表达失衡的影响

Effects of remote limb ischemic preconditioning on the imbalance of Bcl-2 and Bax in hippocampal CA1 neurons of neonatal rats during ketamine anesthesia

目的研究远端肢体缺血预处理对氯胺酮麻醉导致的发育期大鼠海马CA1区神经细胞抗凋亡因子B淋巴细胞瘤-2(Bcl-2)和凋亡因子Bcl-2相关X蛋白(Bax)表达失衡的影响。方法SD新生大鼠48只,5日龄,体重8~12 g,随机分为四组:对照组(C组)于出生第7天腹腔注射生理盐水8 ml/kg,间隔2 h注射一次,共注射6次;远端肢体缺血预处理组(RIPC组)于出生第5天行右后肢缺血5 min,再灌注5 min预处理,4个循环,48 h后腹腔注射生理盐水8 ml/kg,方法同C组;氯胺酮组(K组)于出生第7天腹腔注射氯胺酮20mg/kg,方法同C组;肢体缺血预处理+氯胺酮组(RK组)于出生第5天行远端肢体缺血预处理,48 h后腹腔注射氯胺酮20 mg/kg,方法同C组。四组于腹腔注射完成后12 h经心脏灌注取脑,分别采用免疫组化法和Western blot法观察大鼠海马CA1区凋亡因子Bax和抗凋亡因子Bcl-2阳性细胞数量和蛋白含量。结果与RIPC组比较,K组和RK组海马CA1区神经细胞Bax阳性细胞数量明显增多,蛋白含量明显升高(P<0.05),Bcl-2阳性细胞数量明显减少,蛋白含量明显降低(P<0.05)。C组和RIPC组海马CA1区神经细胞Bcl-2和Bax阳性细胞数量和蛋白含量差异无统计学意义。与K组比较,RK组海马CA1区神经细胞Bax阳性细胞数量明显减少,蛋白含量明显降低(P<0.05),Bcl-2阳性细胞数量明显增多,蛋白含量明显升高(P<0.05)。结论远端肢体缺血预处理可减轻氯胺酮大剂量、多次注射导致的发育期大鼠海马CA1区神经细胞Bcl-2、Bax表达失衡。

Objective To study the effects of remote limb ischemic preconditioning(RIPC)on the expression imbalance of B cell lymphoma-2(Bcl-2)and B cell lymphoma-2 assaciated X protein(Bax)in hippocampal CA1 neurons of the neonatal rats under ketamine anesthesia.Methods Forty-eight Sprague-Dawley rats on postnatal day 5,weighing 8-12 g,were randomly divided into four groups:control group(group C),remote limb ischemic preconditioning group(group RIPC),ketamine group(group K),remote limb ischemic preconditioning+ketamine group(group RK).In group C,normal saline 8 ml/kg was intraperitoneally injected on postnatal day 7,6 times at an interval of 2 hours.Rats in group RIPC were subjected to limb ischemia for 5 minutes and reperfusion for 5 minutes for 4 cycles on postnatal day 5,and then injected with the same volume of saline after 48 hours.Rats in group K were intraperitoneally injected with ketamine 20 mg/kg instead of normal saline,once every 2 hours after administration for 6 times.Rats in group RK were subjected to remote ischemic preconditioning on postnatal day 5 and underwent the same treatment as group K after 48 hours.Rats in the four groups were sacrificed to cardiac perfusion on postnatal day 9.The changes of Bcl-2 and Bax expression in the hippocampal CA1 were observed by immunohistochemistry and western blot.Results Compared with group RIPC,expression of Bax in groups K and RK was significantly increased while Bcl-2 expression was significantly decreased(P<0.05).There was no significant change in the expression of Bcl-2 and Bax between group RIPC and group C.Compared with group K,Bax in group RK was significantly decreased while Bcl-2 expression was significantly increased(P<0.05).Conclusion Remote limb ischemic preconditioning reduces the imbalance of Bcl-2,Bax in the hippocampal CA1 region induced by multiple exposure of ketamine in developmental rats.