从IGF-1/PI3Kα/Akt/mTORs/自噬角度探讨坎离颗粒干预压力超负荷心肌肥厚的分子机制

It has been known that the pathway of IGF-1/PI3Kα/Akt could reduce myocardial hypertrophy, while autophagy inducing by mTORs aggravates it. More and more researches concerned about this cellular pathway. In previous studies, we found that KANLI granule could improve the heart function of pressure overloaded myocardial hypertrophy rat , as while as, the heart showed slightly hypertrophy with less fibrosis and lower fetal gene expressing level. Basing on these findings, we conclude that KANLI granule can maintain adaptive myocardial hypertrophy and delay the process of heart failure..Further investigation will focus on molecular regulatory pathways of adaptive cardiac hypertrophy to uncover the mechanism of KANLI granule theraputic effects. We will make a maladaptive hypertrophy model by constricting abdominal aorta and an adaptive hypertrophy model by exercising of rat to explore the mechanism of KANLI granule therapeutic effects from two aspects: 1) inspect the characteristic of adaptive cardiac hypertrophy basing on heart function, pathological morphology phenotype and fetal gene expression to determine the nature of the cardiac hypertrophy after the intervention of KANLI granule. 2) test the level of the pathway of IGF-1/PI3K alpha /Akt/mTOR and autophagy activation to uncover the mechanism of adaptive cardiac hypertrophy and the intervention effects of Kanli granule on this pathway to explore the mechanism of its anti heart failure effects. The project may provide a scientific basis for the protection mechanism of initial interpretation of adaptive cardiac hypertrophy and provide laboratory evidence for chinese medicine treatment of heart failure.

研究已经证实IGF-1/PI3Kα/Akt/mTOR/自噬在心肌肥厚进程中起延缓作用，是近年研究热点。课题组前期研究发现，坎离颗粒预防给药能改善压力超负荷心肌肥厚大鼠心功能、抗心肌纤维化、降低胚胎基因表达水平，并可抑制过度激活的细胞自噬；据此我们提出坎离颗粒能通过维持心肌适应性肥厚进而延缓心衰进程。.本课题以已知适应性心肌肥厚分子调控通路为切入点，以腹主动脉缩窄压力超负荷心肌肥厚模型及运动致生理性心肌肥厚模型为研究对象，拟从:①功能学、病理形态学、胚胎基因再表达等方面明确适应性心肌肥厚的特征，并据此确定坎离颗粒干预后心肌肥厚的性质。② IGF-1/PI3Kα/Akt/mTOR信号转导通路的激活水平以及自噬水平明确适应性心肌肥厚形成的机理，以及坎离颗粒干预对其影响来探讨该药抗心衰作用的效应机制；为初步阐释适应性心肌肥厚的保护机制提供科学依据，尝试从激活心肌代偿机制角度为心衰治疗提供新靶点。

目的：心衰发生是一个连续过程，从心肌适应性肥厚（AMH）逐步发展到适应不良性肥厚（MMH）进而发生心衰，目前尚缺乏针对保护心脏代偿机制、维持适应性肥厚的治疗措施。前期发现坎离颗粒可维持心肌肥厚前提下保护心功能，本研究拟证实其疗效并探讨机制。.方法：以腹主动脉缩窄致心肌肥厚以及运动致心肌肥厚大鼠为研究对象，①观察两者在心功能、结构及胚胎基因表达的差别，明确AMH的特征，据此确定坎离颗粒干预后心肌肥厚的性质。②观察两者IGF-1/PI3K/Akt/mTOR通路及自噬水平的差异，明确AMH形成机理，观察坎离颗粒对上述通路的影响。.结果：①功能上，运动组LVEDP显著降低（vs model,P＜0.01）、EF显著升高（P＜0.01），说明AMH心脏舒缩功能均较MMH增强。坎离干预可显著降低LVSP、LVEDP水平（P＜0.05），提高EF（P＜0.05）。②结构上，模型组和运动组CW/BW、LVW/BW（vs sham,P＜0.01）、LVPWd（P＜0.05）均显著增高，运动组LVDd（P＜0.05）和LVSd（P＜0.01）比模型组缩小，说明两种模型心肌肥厚造模成功，AMH不伴心腔扩大；间质重构上，模型组I、III型胶原显著增加（P＜0.01），I/III型比值下降（P＜0.05）。坎离颗粒干预后LVPWD较厚，但LVSD较小（P＜0.05），符合AMH表现；坎离还可降低III型胶原（P＜0.05）。③在心肌细胞基因表型上，运动组αMHC和αMHC/βMHC比值较模型组升高（P＜0.01）；坎离组αMHC/βMHC升高，更接近运动组。④在细胞通路方面，运动组IGF-1（P＜0.01）、PI3Kα（P＜0.05）较模型组增高；坎离颗粒干预后 IGF-1（P＜0.05）、PI3Kα（P＜0.05）、p-AKT（P＜0.01）表达均增加，说明其可激活此通路。运动组LC3b（P＜0.05）、P62（P＜0.01）、Beclin（P＜0.05）表达高于模型组，说明AMH自噬流增加；以雷帕霉素抑制mTOR，各组未见显著变化，说明IGF-1/PI3K/Akt与mTOR/自噬并非通过mTORs依赖的通路调控。与对照组比较，中药有抑制自噬作用。.结论：坎离颗粒干预后心脏保持了适应性心肌肥厚的状态，它可能通过激活IGF-1/PI3K/Akt通路，延长了心肌代偿机制从而达到抗心衰作用。