七氟醚对老龄血管性认知功能障碍大鼠认知功能的影响及其机制研究

Effect and mechanism of sevoflurane on the cognitive function in elderly rats with vascular cognitive impairment

目的探讨七氟醚对老龄血管性认知功能障碍大鼠认知功能的影响及作用机制。方法将60只6月龄雌性Wistar大鼠分为3组,每组各20只。A组大鼠为假手术组,B组大鼠实施右侧颈动脉结扎术;C组大鼠实施右侧颈动脉结扎术后吸入2%七氟醚。采用穿梭箱和水迷宫试验评价大鼠的认知功能,原位末端脱氧核苷酸转移酶标记法检测海马神经元凋亡指数,流式细胞仪检测神经元细胞的凋亡指数和钙离子荧光指数,ELISA检测海马组织和外周血炎性因子[血管内皮生长因子(VEGF)、IL-1β、TNF-α]水平以及海马神经元细胞匀浆中线粒体呼吸链复合体Ⅰ~Ⅳ的活性。结果穿梭箱试验中B、C组大鼠的电击次数多于A组、主动逃避次数少于A组、学习和记忆潜伏期较A组延长(P均<0.01),而C组大鼠电击次数较B组减少、主动逃避次数较B组增多、学习和记忆潜伏期短于C组(P均<0.01)。B、C组大鼠海马组织及外周血血清VEGF水平低于A组、IL-1β和TNF-α水平高于A组(P均<0.05);与B组比较,C组VEGF水平较高、IL-1β和TNF-α水平较低(P均<0.05)。大鼠血清VEGF水平与电击次数、学习潜伏期、记忆潜伏期均呈负相关(P均<0.05),与主动逃避次数呈正相关。IL-1β水平和TNF-α水平与电击次数、学习潜伏期、记忆潜伏期均呈正相关(P均<0.05),与主动逃避次数均呈负相关(P均<0.05)。A、C组大鼠的海马神经元细胞凋亡指数和钙离子荧光指数均低于B组(P均<0.01)、海马中线粒体呼吸链复合物Ⅰ、Ⅱ活性高于B组(P均<0.05),A、C上述指标组间比较差异均无统计学意义(P>0.05)。结论七氟醚干预可减轻老龄大鼠血管性认知功能障碍,其机制可能与增加VEGF表达、减轻炎症损伤有关。

Objective To investigate the effect and mechanisnl of sevoflurane on the cognitive function in elderly rats with vascular cognitive impairment. Methods Sixty male Wistar rats aged 6 months were divided into three groups （n = 20 for each group）. In group A, sham operation was performed. In group B, rats were treated with unilateral carotid artery ligation. In group C, unilateral carotid artery ligation was performed, followed by the inhalation of 2% sevoflurane. The cognitive function of rats was evaluated by shuttle box and water maze tests. The apoptotic index of hippocampal neurons was detected by TUNEL. The apoptotic rate and calcium ion fluorescent index of neurons were measured by flow cytometry. The expression levels of infammatory cytokines （VEGF, IL-1α and TNF-1β in the hippocampal tissues and peripheral blood and the activity of mitochondrial respiratory chain complex I-IV in the hippocampal neurons were quantitatively detected by ELISA. Results During the shuttle box test, the number of electrical shocks was significantly more, the number of active escape was considerably less and the learning and memory latency was significantly longer in groups B and C compared with those in group A （all P 〈 0. 01）. In group C, the number of electrical shocks was significantly decreased, the number of active escape was considerably increased and the latency of learning and memory was significantly longer than those in group B （ all P 〈 0. 01 ）. In groups B and C, the expression levels of VEGF in hippocampal tissues and peripheral blood were significantly lower, whereas the expression levels of IL-1β and TNF-α were significantly higher than those in group A （ both P 〈 0. 05 ）. Compared with group B, the expression level of VEGF was evidently higher, whereas the expression levels of IL-1β and TNF- α were significantly lower in group C （ all P 〈 0. 05 ）. The expression level of serum VEGF was negatively correlated with the number of electrical shocks, learning and menlory latency （ both P 〈 0. 05 ） , whereas positively associated with the number of active escape. The expression levels of IL-1β and TNF-α were positively correlated with the number of electrical shocks, learning and menlory latency （ all P 〈 0. 05 ） , whereas negatively correlated with the number of active escape （P 〈 0. 05）. In groups A and C, the apoptotic index of hippocampal neurons and calcium ion fluorescent index were significantly lower （ both P 〈 0. 01 ） , whereas the activity- of nfi- tochondrial respiratorychain complex Ⅰ and Ⅱ was considerably higher （ both P 〈 0. 05 ） than those in group B. No statistical significance was noted in these parameters between groups A and C （ all P 〉 0. 05 ）. Conclusion Sevoflurane intervention can alleviate vascular cognitive impairment in aged rats, which is probably correlated with up-regulating the expression of VEGF and nfitigating inflammatory injury.