Lü Lu, Zhang Dan, Sun Bo, Hu Yanwu, Yan Mengtong, Liu Kai, Li Xiangjun, Ren Liqun
Pharmazie. 2017 Jan 10;72(1):41-48. doi: 10.1691/ph.2017.6703.
Apocynum leaf extract is an extract of the dried leaves of Apocynum venetum (a member of the Apocynaceae family) that has many effects on the cardiovascular system. The aim of the present study was to evaluate the protective effects of apocynum leaf extract on the atherosclerosis in rats induced by high-fat diet combined with vitamin D3 intraperitoneal injection. The atherosclerosis in rats were induced with a high-fat diet and an intraperitoneal injection of VD3 once daily for three contiguous days at a total injection dose of 70 U/kg. At the end of the 18th week, serum total cholesterol (TC) and triglyceride (TG) contents were measured. Hydroxyproline content in the aorta were measured by the alkali hydrolysis method. The hematoxylin-eosin (HE) and immunohistochemical staining were applied to evaluate the morphological changes and the collagen I and α-smooth muscle actin expression. The protein expression and the mRNA level of AMPK and mTOR were detected by western blot analysis and reverse transcript PCR. After treatment with apocynum leaf extract, the serum total cholesterol and triglyceride concentration of the atherosclerotic rats were significantly decreased, both the Collagen I expression and the hydroxyproline content in the aorta were significantly reduced, and the α-SMA, a smooth muscle-specific marker, expression were also lower than the untreated atherosclerotic rats. Western blot analyses showed that the apocynum can marked increase the p-AMPK but decrease the mTOR protein expression. The apocynum leaf extract also exhibited higher AMPK and lower mTOR mRNA expression of the aorta in the atherosclerotic rats. We believe that the apocynum leaf extract can effectively reduce blood lipid levels in rats with atherosclerosis, delay atherosclerotic progression by inhibiting excessive collagen synthesis and inhibiting smooth muscle cell over-proliferation. The underlying mechanism may be related to the AMPK/mTOR signaling pathway activity. Our results contribute towards validation of the traditional use of apocynum leaf extract in the treatment of atherosclerosis.
罗布麻叶提取物是夹竹桃科植物罗布麻干燥叶的提取物，对心血管系统有多种作用。本研究旨在评估罗布麻叶提取物对高脂饮食联合腹腔注射维生素D3诱导的大鼠动脉粥样硬化的保护作用。大鼠动脉粥样硬化模型通过高脂饮食和每天腹腔注射一次VD3，连续注射三天，总注射剂量为70 U/kg诱导。在第18周结束时，测量血清总胆固醇（TC）和甘油三酯（TG）含量。采用碱水解法测定主动脉中羟脯氨酸含量。应用苏木精-伊红（HE）染色和免疫组化染色评估形态学变化以及I型胶原蛋白和α-平滑肌肌动蛋白的表达。通过蛋白质免疫印迹分析和逆转录PCR检测AMPK和mTOR的蛋白质表达及mRNA水平。用罗布麻叶提取物处理后，动脉粥样硬化大鼠的血清总胆固醇和甘油三酯浓度显著降低，主动脉中I型胶原蛋白表达和羟脯氨酸含量均显著降低，并且平滑肌特异性标志物α-SMA的表达也低于未处理的动脉粥样硬化大鼠。蛋白质免疫印迹分析表明，罗布麻可显著增加p-AMPK但降低mTOR蛋白表达。罗布麻叶提取物还使动脉粥样硬化大鼠主动脉中AMPK mRNA表达升高而mTOR mRNA表达降低。我们认为，罗布麻叶提取物可有效降低动脉粥样硬化大鼠的血脂水平，通过抑制过度的胶原蛋白合成和抑制平滑肌细胞过度增殖来延缓动脉粥样硬化进展。其潜在机制可能与AMPK/mTOR信号通路活性有关。我们的结果有助于验证罗布麻叶提取物在治疗动脉粥样硬化方面的传统用途。
