Therapeutic Effects of Cordycepin on Monocrotaline-induced Pulmonary Arterial Hypertension in Rats via cGMP/PKG/PPAR-γ Signaling Pathway

Cordycepin can relax the blood vessels and inhibit vascular remodeling. In this study, we investigate the effects of Cordycepin on monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH) in rats and its underlying mechanism. After 28 days of intragastric Cordycepin administration (50 mg/kg), the right ventricular systolic pressure (RVSP) and right ventricular hypertrophy index (RVHI) of rats with PAH are seen to decrease significantly. HE staining is used to evaluate pulmonary vascular remodeling, and Cordycepin is found to reduce it in rats with PAH. ELISA shows that cGMP is significantly increased in plasma from the Cordycepin group. Compared with the MCT group, Cordycepin can increase the protein expression levels of PKG and PPAR-γ. In cell experiments, the optimum concentration of Cordycepin on pulmonary artery smooth muscle cells (PASMCs) is found to be 50 μM by CCK-8 assay. In scratch experiments, Cordycepin is shown to inhibit the migration of PASMCs to a large extent. EDU and TUNEL experiments show that Cordycepin can inhibit the proliferation and promote the apoptosis of PASMCs. Western blot results show that PCNA expression decreases, BAX/Bcl-2 expression increases, Caspase3 expression increases and PKG and PPAR-γ protein expression increases in Cordycepin-treated PASMCs. However, the PKG inhibitor (HA-100) and PPAR-γ inhibitor (T0070907) can reverse this process, promote the proliferation of PASMCs, inhibit apoptosis and reduce the expression of PKG and PPAR-γ. Cordycepin can increase the expression of cGMP compared with the MCT group. In conclusion, Cordycepin may improve rat PAH and other specific mechanisms by enhancing the cGMP/PKG/PPAR-γ signaling pathway. As such, it may be a candidate drug for PAH treatment.

虫草素（Cordycepin）可舒张血管并抑制血管重构。本研究探讨了虫草素对野百合碱（MCT）诱导的大鼠肺动脉高压（PAH）的干预作用及其潜在分子机制。连续28天以50 mg/kg剂量灌胃给予虫草素后，肺动脉高压模型大鼠的右心室收缩压（RVSP）与右心室肥厚指数（RVHI）均显著降低。采用苏木精-伊红（HE）染色评估肺血管重构程度，结果显示虫草素可减轻肺动脉高压模型大鼠的肺血管重构。酶联免疫吸附测定（ELISA）结果表明，虫草素组大鼠血浆中环磷酸鸟苷（cGMP）水平显著升高；与野百合碱模型组相比，虫草素可上调蛋白激酶G（PKG）与过氧化物酶体增殖物激活受体γ（PPAR-γ）的蛋白表达水平。
细胞实验部分，通过CCK-8细胞增殖检测法筛选出虫草素作用于肺动脉平滑肌细胞（PASMCs）的最适浓度为50 μM。划痕实验结果显示，虫草素可显著抑制肺动脉平滑肌细胞的迁移能力。5-乙炔基-2'-脱氧尿苷（EDU）与末端脱氧核苷酸转移酶介导的dUTP缺口末端标记（TUNEL）实验结果表明，虫草素可抑制肺动脉平滑肌细胞增殖并促进其凋亡。蛋白质免疫印迹（Western blot）结果显示，经虫草素处理的肺动脉平滑肌细胞中，增殖细胞核抗原（PCNA）的表达水平下调，BAX/Bcl-2比值升高，半胱氨酸天冬氨酸蛋白酶3（Caspase3）的表达水平上调，同时PKG与PPAR-γ的蛋白表达水平升高。
然而，PKG抑制剂（HA-100）与PPAR-γ抑制剂（T0070907）可逆转上述效应：促进肺动脉平滑肌细胞增殖、抑制其凋亡，并降低PKG与PPAR-γ的蛋白表达水平。与野百合碱模型组相比，虫草素可升高血浆cGMP水平。
综上，虫草素可通过增强cGMP/PKG/PPAR-γ信号通路改善大鼠肺动脉高压，其潜在作用机制如上所述，因此有望成为肺动脉高压治疗的候选药物。