NPY应激诱导PGC-1α表达对心肌细胞线粒体功能的影响及信号传导机制研究

Stress cardiomyopathy (SCM) is a rare atypical cardiomyopathy induced by psychological or physical stress. Sometimes SCM can cause sudden death, but the exact pathogenic mechanism is unclear currently. Previous study of our group have founded increased neuropeptide Y (NPY) and elevated the expression level of peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) both in SCM rat’s heart tissue and cultured neonatal rat cardiac myocytes ; based on the literatures, we hypothesize that NPY may be one of the upstream activators of PGC-1α expression. In this study, primary cultured neonatal rat cardiac myocytes were used with different concentrations of NPY, the expression level of PGC-1α, the roles of CaN/CaMK and p38 MAPK signaling pathways in NPY-stress induced PGC-1α expression, mitochondrial structure as well as membrane potential and ATP content will be observed; and the impact of different levels of PGC-1α expression on the mitochondrial function,intracellular calcium transients, calcium distribution, sarcoplasmic reticulum calcium regulatory system will also be determined. Finally, we want to dissect the signaling pathway between NPY stimulation and PGC-1α expression levels in order to make clear the role of NPY and PGC-1α in the cause of SCM, to provide a theoretical support for forensic identification and clinical treatment of SCM.

应激性心肌病(SCM)是一种由心理和（或）躯体应激所诱发的非典型心肌病，严重者可致猝死，目前其发病机理不明。本课题组在前期实验动物模型和分子生物学观察的基础上, 推测NPY为PGC-1α表达调控的上游激活因子之一，其通过诱导PGC-1α表达, 激活线粒体的生物合成,引起心肌细胞线粒体结构和功能障碍,可能是引起心肌收缩功能异常而导致SCM发生的分子机理之一;本研究利用原代培养的大鼠心肌细胞，以不同浓度NPY进行应激刺激，通过观察NPY对心肌细胞PGC-1α的表达及线粒体超微结构、膜电位和ATP含量的影响; CaN/CaMK和p38 MAPK信号途径在NPY诱导的心肌细胞PGC-1α表达中作用；不同水平PGC-1α表达对心肌细胞钙瞬变、钙分布、肌浆网钙调控系统的影响，说明NPY诱导PGC-1α表达及导致心肌细胞线粒体功能障碍发生的分子机理，为SCM的法医学鉴定及临床治疗提供理论依据。

心肌肥大是心肌细胞在各种病理因素刺激下产生的一种慢性代偿性的反应，是多种心血管事件发生时共有的病理表现，可导致心源性猝死的发病危险大大增加。神经肽Y（NPY）是一种由36个氨基酸组成的神经递质，广泛分布于中枢和外周神经系统。研究表明NPY参与了多种心血管疾病包括心肌肥大的发生发展过程。申请人前期研究结果表明，在应激情况下大鼠心肌肥大伴有心脏组织内NPY表达水平显著上升，在结合实验动物模型和分子生物学观察的基础上推测NPY为PGC-1α表达调控的上游激活因子之一。这些结果初步表明NPY参与大鼠的应激性心肌肥大。本项目将在前期工作基础上，以体外培养的新生大鼠的原代心肌细胞作为实验材料，检测NPY对心肌细胞肥大和线粒体功能的影响，并对其潜在的分子机制进行探讨，以期为心血管疾病的预防和治疗提供理论依据。实验证明，NPY诱导新生SD大鼠原代心肌细胞肥大和线粒体功能损伤，心肌细胞内ROS生成的增加参与了NPY诱导的Ca2+/CaN、Ca2+/CaMK II及p38 MAPK信号转导通路的激活，激活的Ca2+/CaN、Ca2+/CaMK II及p38 MAPK信号转导通路参与了NPY诱导的心肌细胞线粒体功能改变和细胞肥大。