c-jun、SERCA-2a及cTnI基因与应激性高血压大鼠心脏功能的关系

Relationship between c-jun, SERCA-2a and cTnI genes and cardiac function in stress-induced hypertension rats

目的探讨c-Jun氨基末端激酶(c-Jun N-terminal kinase,c-Jun)、肌浆网的钙ATP酶(sarco/endoplasmicreticulum Ca2+-ATPase 2a,SERCA-2a)及心肌肌钙蛋白复合体I亚基(cardiac troponin I,cTnI)基因与应激性高血压大鼠心脏功能的关系。方法选取6~8周鼠龄的SPF级雄性Wistar大鼠28只,适应性喂养1周后,按照完全随机法分为应激性高血压(stress induce hypertension,SIH)模型组和正常组,每组14只。利用声光间断足底电、声光等复合应激因素,每天刺激2 h,持续12周构建SIH大鼠模型。采用RT-qPCR和免疫组织化学方法分别检测SIH模型组和正常组大鼠心脏组织c-jun、c-fos、SERCA-2a、 cTnI基因mRNA表达和SERCA-2a、cTnI蛋白表达,c-jun (ser63位点)、 AP-1、cTnI蛋白磷酸化水平的变化。结果与正常组相比,SIH模型组大鼠收缩压与舒张压均明显升高(P<0.05);在SIH模型组中c-jun、c-fos、SERCA-2a、 cTnI基因mRNA表达水平没有发生变化(P>0.05);SERCA-2a蛋白表达水平明显下调(P<0.05),cTnI蛋白表达和c-jun(ser63位点)、AP-1蛋白磷酸化水平明显上调(P<0.05), cTnI蛋白磷酸化水平无明显差异(P>0.05)。结论在SIH大鼠模型中,心肌舒张因子SERCA-2a蛋白表达量的下调可能是应激性高血压大鼠心脏舒张功能障碍、血压升高的原因之一。收缩因子cTnI蛋白表达量的上调,可能增强应激性高血压大鼠心脏的收缩功能。

Objective To investigate the relationship between c-Jun N-terminal kinase(c-jun), sarcoplasmic reticulum Ca2+-ATPase 2 a(SERCA-2 a) and cardiac troponin I(cTnI) genes and cardiac function in stress-induced hypertension rats. Methods Twenty-eight male SPF Wistar rats aged 6-8 weeks were selected, after 1 week of adaptive feeding, they were divided into stress-induced hypertension(SIH) model group and normal group according to the completely randomized method, with 14 rats for each group. The SIH rat model was constructed by using a compound stress factor combination of sound, light and interrupted foot electric shock. Stimulate 2 hours a day for 12 weeks. RT-qPCR and immunohistochemistry were used selectively to detect the expression level and changes of c-jun, c-fos, SERCA-2 a, cTnI mRNA and SERCA-2 a, cTnI protein and c-jun(Ser63), AP-1, cTnI protein phosphorylation. Results Compared with the normal group, the systolic blood pressure and diastolic blood pressure of the SIH model group were significantly increased(P<0.05);there was no change in mRNA expression of c-jun, c-fos, SERCA-2 a and cTnI genes in the SIH model group(P>0.05);The expression level of SERCA-2 a protein was significantly down-regulated(P<0.05), cTnI protein expression and c-jun(ser63 locus) and AP-1 protein phosphorylation levels were significantly up-regulated(P<0.05). cTnI protein expression and c-jun(ser63), AP-1 protein phosphorylation levels were significantly up-regulated(P<0.05). There was no significant difference in phosphorylation level of cTnI protein(P>0.05). Conclusion In the SIH rat model, down-regulation of myocardial relaxing factor SERCA-2 a protein expression may be one of the causes of diastolic dysfunction and elevated blood pressure in stress-induced hypertensive rats. Up-regulation of the expression of the contractile factor cTnI protein may lead to an increase in myocardial contractile function.