MS275对发育期惊厥大鼠p38 MAPK信号通路的调控机制研究

Regulatory mechanism of MS275 on the p38 MAPK signaling pathway in rats with convulsion in the developmental stage

目的探讨组蛋白去乙酰化酶抑制剂MS275在发育期大鼠惊厥发病中对p38 MAPK信号通路的调控机制。方法将32只雄性大鼠随机分为对照组、戊四唑(PTZ)组、低剂量MS275组(3 mg/kg)及高剂量MS275组(6 mg/kg)(n=8)。通过腹腔注射PTZ制作发育期大鼠惊厥模型,对照组仅注射生理盐水;MS275在PTZ诱导惊厥前2 h腹腔注射给药。造模成功后24 h,每组取6只大鼠,Western blot法检测海马组织p38、MK2、CREB和IL-6蛋白表达;qRT-PCR法检测p38、MK2、CREB和IL-6 mRNA表达;苏木精-伊红(HE)染色观察脑组织病理变化;Western blot法检测小胶质细胞活化标志物CD11b的表达。结果 PTZ组大鼠海马组织中p38、MK2、CREB和IL-6 mRNA及其蛋白的表达均较对照组显著增高(P<0.05);而MS275能抑制上述指标m RNA及其蛋白在发育期惊厥大鼠中的表达水平(P<0.05);6 mg/kg MS275对CREB mRNA及其蛋白、IL-6 mRNA的抑制作用比3 mg/kg MS275更显著(P<0.05)。HE染色结果可见PTZ组海马组织有明显的神经元凋亡及细胞水肿,伴有较多的炎性细胞浸润;而MS275干预组能减轻发育期惊厥大鼠神经元凋亡及细胞水肿,同时减少炎性细胞浸润。PTZ组小胶质细胞活化明显增多,而MS275能抑制发育期惊厥大鼠小胶质细胞活化(P<0.05);且6 mg/kg MS275的抑制作用比3 mg/kg MS275更显著(P<0.05)。结论组蛋白去乙酰化酶抑制剂MS275能抑制发育期惊厥大鼠p38 MAPK信号通路、海马神经元的凋亡和小胶质细胞活化,从而减少炎症反应及惊厥性脑损伤;且MS275的作用可能存在剂量依赖性。

Objective To study the regulatory mechanism of MS275, a histone deacetylase inhibitor, on the p38 MAPK signaling pathway in rats with convulsion in the developmental stage. Methods Thirty-two male rats were randomly divided into four groups: control, pentylenetetrazol(PTZ), PTZ+3 mg/kg MS275, and PTZ+6 mg/kg MS275(n=8 each). A rat model of convulsion in the developmental stage was prepared by an intraperitoneal injection of PTZ. The rats in the control group were given an injection of normal saline alone. MS275 was given by an intraperitoneal injection at 2 hours before PTZ injection. At 24 hours after successful modeling, 6 rats were taken from each group. Western blot and qRT-PCR were used to measure the protein and mRNA expression of p38, MK2, cAMP response element-binding protein(CREB), and interleukin-6(IL-6) in the hippocampus. Hematoxylin-eosin(HE) staining was used to observe brain pathological changes. Western blot was used to measure the expression of CD11b as a marker for the activation of microglial cells. Results Compared with the control group, the PTZ group had significant increases in the mRNA and protein expression of p38, MK2, CREB, and IL-6(P<0.05). MS275 significantly inhibited the mRNA and protein expression of the above markers in the rats with convulsion in the developmental stage(P<0.05), and 6 mg/kg MS275 had a significantly better inhibitory effect on the mRNA and protein expression of IL-6 and CREB than 3 mg/kg MS275(P<0.05). HE staining showed that the PTZ group had marked neuron apoptosis, cellular edema, and inflammatory cell infiltration, while MS275 intervention alleviated neuron apoptosis and cellular edema and reduced inflammatory cell infiltration in the rats with convulsion. The PTZ group had a significant increase in the activation of microglial cells, while MS275 significantly inhibited the activation of microglial cells in the rats with convulsion(P<0.05);6 mg/kg MS275 had a significantly better inhibitory effect than 3 mg/kg MS275(P<0.05). Conclusions In rats with convulsion in the developmental stage, the histone deacetylase inhibitor MS275 can inhibit the p38 MAPK signaling pathway, the apoptosis of hippocampal neurons, and the activation of microglial cells and thus reduce inflammatory response and convulsion-induced brain injury in a dose-dependent manner.