柴胡皂苷A调节cAMP/PKA/CREB信号通路对失眠大鼠的改善作用及机制研究

Study on the Improvement Effect and Mechanism of Saikosaponin A on Insomnia Rats by Regulating cAMP/PKA/CREB Signaling Pathway

目的基于cAMP/PKA/CREB通路探讨柴胡皂苷A对失眠大鼠的改善作用及机制。方法将75只SD大鼠随机分为空白组、模型组、柴胡皂苷A低剂量组(0.625 mg·kg^(-1))、柴胡皂苷A高剂量组(2.500 mg·kg^(-1))、艾司唑仑组(0.1 mg·kg^(-1)),每组15只。采用腹腔注射苯丙氨酸(PCPA,0.1 mg·kg^(-1))复制失眠大鼠模型。观察大鼠一般情况及昼夜节律;采用戊巴比妥钠翻正实验测定大鼠睡眠潜伏期及睡眠持续时间;观测大鼠睡眠时相,记录慢波睡眠第1期(SWS1)、慢波睡眠第2期(SWS2)、快速眼球运动睡眠期(REMS)时长以及总睡眠时长(TST);qRT-PCR法测定下丘脑节律基因Clock、Bmal1 mRNA及钟控基因Rev-erbα、RorαmRNA的表达水平;免疫荧光法测定海马组织NeuN表达水平;ELISA法测定脑组织中的cAMP水平;Western Blot法测定脑组织中Clock、Bmal1、Rev-erbα、Rorα及cAMP/PKA/CREB通路相关蛋白表达水平。结果与空白组比较,模型组大鼠昼伏夜出的节律紊乱,极度兴奋,易激惹,睡眠减少;睡眠潜伏期明显延长(P<0.05),睡眠持续时间及SWS1、SWS2、REMS、TST均明显缩短(P<0.05);神经元排列紊乱,NeuN阳性神经元IOD值明显降低(P<0.05);脑组织Clock、Bmal1、Rev-erbα、RorαmRNA及蛋白表达水平明显降低(P<0.05);脑组织cAMP、p-PKA/PKA、p-CREB/CREB蛋白表达水平明显降低(P<0.05)。与模型组比较,给药组大鼠的攻击性明显减弱,昼伏夜出有节律性,活动减少,睡眠增多;睡眠潜伏期明显缩短(P<0.05),睡眠持续时间及SWS1、SWS2、REMS、TST均明显延长(P<0.05);神经元排列紊乱情况有所恢复,NeuN阳性神经元IOD值明显升高(P<0.05);脑组织Clock、Bmal1、Rev-erbα、RorαmRNA及蛋白表达水平明显升高(P<0.05);脑组织cAMP、p-PKA/PKA、p-CREB/CREB蛋白表达水平明显升高(P<0.05)。结论柴胡皂苷A可能通过激活cAMP/PKA/CREB通路改善失眠大鼠的昼夜节律。

Objective To explore the improving effect and mechanism of saikosaponin A on insomnia rats based on cAMP/PKA/CREB pathway.Methods Seventy-five SD rats were randomly divided into blank group,model group,low-dose saikosaponin A group(0.625 mg·kg^(-1)),high-dose saikosaponin A group(2.500 mg·kg^(-1))and Estazolam group(0.1 mg·kg^(-1)),with 15 rats in each group.Insomnia rat model was established by intraperitoneal injection of Phenylalanine(PCPA,0.1 mg·kg^(-1)).The general condition and circadian rhythm of rats were observed;the sleep latency and sleep duration of rats were measured by pentobarbital sodium righting experiment.The sleep phase of rats was observed,and the duration of slow wave sleep phase 1(SWS1),slow wave sleep phase 2(SWS2),rapid eye movement sleep phase(REMS)and total sleep time(TST)were recorded.The mRNA expression levels of hypothalamic circadian genes Clock,Bmal1 and clock-controlled genes Rev-erbαand Rorαwere determined by qRT-PCR.The expression level of NeuN in hippocampus was determined by immunofluorescence.The level of cAMP in brain tissue was determined by ELISA.The expression levels of Clock,Bmal1,Rev-erbα,Rorαand cAMP/PKA/CREB pathway-related proteins in brain tissue were determined by Western Blot.Results Compared with the blank group,the rats in the model group had disordered circadian rhythms,extreme excitement,irritability,and reduced sleep;the sleep latency was significantly prolonged(P<0.05),and the sleep duration and SWS1,SWS2,REMS and TST were significantly shortened(P<0.05).The arrangement of neurons was disordered,and the IOD value of NeuN positive neurons was significantly decreased(P<0.05).The mRNA and protein expression levels of Clock,Bmal1,Reverbαand Rorαin brain tissue were significantly decreased(P<0.05).The expression levels of cAMP,p-PKA/PKA and p-CREB/CREB in brain tissue were significantly decreased(P<0.05).Compared with the model group,the aggressiveness of the rats in the administration group was significantly weakened,the circadian rhythm was rhythmic,the activity was reduced,and the sleep was increased.The sleep latency was significantly shortened(P<0.05),and the sleep duration and SWS1,SWS2,REMS and TST were significantly prolonged(P<0.05).The disorder of neuronal arrangement was restored,and the IOD value of NeuN positive neurons was significantly increased(P<0.05).The mRNA and protein expression levels of Clock,Bmal1,Rev-erbαand Rorαin brain tissue were significantly increased(P<0.05).The protein expression levels of cAMP,p-PKA/PKA and p-CREB/CREB in brain tissue were significantly increased(P<0.05).Conclusion Saikosaponin A may improve the circadian rhythm of insomnia rats by activating cAMP/PKA/CREB pathway.