基于HDAC5/MEF2C通路探讨柴金解郁安神方调节失眠并发抑郁大鼠海马神经元突触可塑性的机制

Mechanism of Chaijin JieYu Anshen formula regulating synaptic plasticity of hippocampal neurons in insomnia-concomitant depression rats based on HDAC5/MEF2C pathway

目的基于组蛋白去乙酰酶5(histone deacetylase 5,HDAC5)/肌细胞增强因子2C(myocyte enhancer factor 2C,MEF2C)通路,探讨柴金解郁安神方调节失眠并发抑郁模型大鼠抑郁样行为及海马神经元突触可塑性的机制。方法通过对氯苯丙氨酸(PCPA)注射联合慢性温和不可预知应激(chronic unpredictable mild stress,CUMS)建立失眠并发抑郁大鼠模型,实验分为空白组、模型组、柴金解郁安神方高、中、低剂量组、阳性药组。通过糖水偏好实验、旷场实验和水迷宫实验评估大鼠的抑郁情况;酶联免疫吸附检测(enzyme linked immunosorbent assay,ELISA)血清中5-羟色胺(5-hydroxytryptamine,5-HT)、多巴胺(dopamine,DA)的水平;HE染色和Nissl染色观察海马神经元病理损伤;高尔基染色(golgi staining)观察海马神经元树突棘损伤情况;免疫印迹法(Western blot)、免疫组化和免疫荧光法检测大鼠海马HDAC5、MEF2C、突触后致密物(postsynaptic density-95,PSD-95)和突触素(synaptophysin 1,SYN1)的表达情况。结果与模型组相比,柴金解郁安神方可以提高模型大鼠的糖水偏好率,减少旷场实验中的不动时间,增加总活动路程,缩短定位航行实验的逃避潜伏期,延长空间探索实验中平台所在象限的停留时间;此外,柴金解郁安神方还能改善海马神经元及树突棘的损伤,增加海马神经元的树突分支长度和树突棘密度;恢复失眠并发抑郁模型大鼠血清中5-HT、DA的水平;下调HDAC5蛋白,上调MEF2C、PSD-95、SYN1蛋白的表达。结论柴金解郁安神方可能通过降低HDAC5蛋白的表达,从而解除对转录因子MEF2C的抑制,促进PSD-95、SNY1蛋白的表达,发挥对海马神经元及突触的保护作用,从而缓解模型大鼠抑郁样行为。

Aim To investigate the mechanisms of Chaijin JieYu Anshen formula modulating the depressive behaviors and the synaptic plasticity of hippocampal neurons in insomnia-concomitant depression rats based on the histone deacetylase 5(HDAC5)/myocyte enhancer factor 2C(MEF2C)pathway.Methods A rat model of insomnia-concomitant depression was established by PCPA injection combined with chronic unpredictable mild stress(CUMS),and the experiment was divided into the control group,the model group,the high,medium and low dose group of Chaijin JieYu Anshen formula,and the positive drug group.The depression of rats was evaluated by sugar-water preference test,open field test and morris water maze.The levels of 5-hydroxytryptamine(5-HT)and dopamine(DA)in serum were measured by enzyme linked immunosorbent assay(ELISA).The pathological damage of hippocampal neurons was observed by HE staining and Nissl staining.The damage of dendritic spines of hippocampal neurons was observed by Golgi staining,and the levels of HDAC5,MEF2C,postsynaptic density-95(PSD-95)and synaptophysin 1(SYN1)in hippocampus were measured by Western blot,immunohistochemistry and immunofluorescence.Results Compared with the model group,the Chaijin JieYu Anshen formula could increase the sugar-water preference rate of the model rats,reduce the immobility time in the open field experiment,increase the total activity distance,shorten the evasion latency in the localization navigation experiment,and prolong the residence time in the quadrant where the platform was located in the space exploration experiment(P<0.05,P<0.01).Moreover,the Chaijin JieYu Anshen formula improved the hippocampal neuron and dendritic spine damage and increase the dendritic branch length and dendritic spine density of hippocampal neurons(P<0.01,P<0.01),restore the serum levels of 5-HT and DA in insomnia-concomitant depression rats(P<0.05,P<0.01),down-regulate the HDAC5 protein,and up-regulate the expression of MEF2C,PSD-95,and SYN1 protein(P<0.05,P<0.01 or P<0.001).Conclusions Chaijin JieYu Anshen formula may alleviate the depression-like behavior of model rats by reducing the expression of HDAC5 protein,thus deregulating the inhibition of transcription factor MEF2C,promoting the expression of PSD-95 and SNY1 protein,and exerting a protective effect on hippocampal neurons and synapses.