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Title: [Beneficial effects and related mechanism of hawthorn leaves flavonoids on cardiac function in rats with acute myocardial infarction].
Author: Zhang XH, Liu JD, Yu FW, Wang DW.
Journal: Zhonghua Xin Xue Guan Bing Za Zhi; 2021 Jul 24; 49(7):701-707. PubMed ID: 34256438.
Abstract:
Objective: To explore the effect and related regulatory mechanism of hawthorn leaf flavonoids (FHL) on cardiac function in rats with acute myocardial infarction (AMI). Methods: Sixty SPF male Sprague-Dawley rats (9-week-old, weighing 300-350 g) were used in this study. Ten rats were assigned to sham operation group, and the remaining 50 rats were used to establish the AMI model with coronary artery ligation method, AMI was successfully established in 36 rats. AMI rats were randomly divided into AMI group and FHL low-, medium-, and high-dose groups (n=9 for each group). Rats received intraperitoneal injection (10 ml·kg^-1·day^-1) with physiological saline and FHL solution with concentrations of 0.3, 0.6, and 1.2 mg/ml, respectively for 4 consecutive weeks. Echocardiography was performed at the end of experiments. Left ventricular end diastolic diameter (LVEDD), left ventricular end diastolic anterior wall thickness (LAWD), left ventricular ejection fraction (LVEF) and left ventricular end diastolic pressure (LVEDP) were measured. Then the rats were sacrificed under deep anesthesia, and the left ventricular anterior wall tissue was used for pathological examinations by hematoxylin-eosin (HE) staining. Other myocardial tissue was used for in situ terminal transferase labeling (TUNEL) staining, and the apoptosis rate of cardiomyocytes was calculated. The myocardial cell apoptosis rate, the mRNA, and protein expressions of phosphatidylinositol 3β-kinase (PI3K), protein kinase B (Akt), glycogen synthetase kinase-3 (GSK3β), cyclin D1 and the protein expressions of p-Akt and p-GSK3β were detected by real-time fluorescent quantitative PCR (RT-qPCR) and Western blot respectively. Results: Compared with sham operation group, the LVEDD and LVEDP of the rats in AMI group and FHL low-, medium-and high-dose groups were increased, and the LAWD and LVEF were reduced (all P<0.05). Compared with AMI group, LVEDD and LVEDP were reduced, and LAWD and LVEF were increased in FHL low-, medium-and high-dose groups (all P<0.05). LVEDD and LVEDP decreased, and LAWD and LVEF increased in proportion to the increase of FHL dose (all P<0.05). LVEDD and LAWD values were similar between FHL low-dose and medium-dose groups (both P>0.05). HE staining results evidenced necrotic myocardial tissue, together with disordered arrangement of myocardial fibers, and a large number of inflammatory cells infiltrated in the myocardial tissue in AMI group. The myocardial damage of rats in FHL low-, medium-, and high-dose groups was less than that of AMI group. The myocardial fibers were arranged neatly, but there were still partial breaks and a small amount of inflammatory cell infiltration in the myocardial tissue and there were scattered islands of normal myocardial tissue in the infarct area of these groups. Among them, myocardial damage was the least in FHL high-dose group. The results of TUNEL staining showed that compared with AMI group, the apoptosis rate of myocardial cells was significantly reduced in FHL low-, medium-, and high-dose groups (all P<0.001), but was still higher than that in sham operation group (all P<0.001). Myocardial cell apoptosis rate decreased in proportion with increasing FHL dose (P<0.05). The RT-qPCR results showed that compared with AMI group, the expression levels of PI3K and cyclin D1 mRNA were significantly upregulated in the myocardial tissue of rats in FHL low-, medium-, and high-dose groups, but still lower than those in sham operation group (all P<0.05), and PI3K and cyclin D1 mRNA expression levels increased with the increase dose of FHL (P<0.05). Western blot results showed that compared with AMI group, the expression levels of PI3K, p-Akt, p-GSK3β, and cyclin D1 were significantly upregulated in the myocardial tissue of rats in FHL low-, medium-, and high-dose groups, but still lower than those in sham operation group (all P<0.05), and the protein expression levels of PI3K, p-Akt, p-GSK3β, and cyclin D1 increased in proportion with the increase dose of FHL (all P<0.05). Conclusion: FHL can effectively improve cardiac function in rats with AMI, and the beneficial effects may be partly mediated through activating PI3K/GSK3β/cyclin D1 signaling pathway. 目的： 探讨山楂叶总黄酮（FHL）对急性心肌梗死（AMI）大鼠心功能的影响及其作用机制。 方法： SPF级雄性Sprague-Dawley大鼠60只，9周龄，体重300~350 g，采用随机数字表法选取 10只作为假手术组，余50只用于建立AMI模型。采用冠状动脉结扎法建立大鼠AMI模型，其中36只建模成功，随机数字表法将其分为AMI组及FHL低、中、高剂量组（每组n=9），按10 ml/kg体重分别腹腔注射生理盐水及浓度为0.3、0.6、1.2 mg/ml的FHL溶液。假手术组仅穿线不结扎，按10 ml/kg体重给予等量生理盐水。给药干预均为1次/d，连续4周。超声心动图检测各组大鼠左心室舒张末期内径（LVEDD）、左心室舒张末期前壁厚度（LAWD）、左心室射血分数（LVEF）及左心室舒张末压（LVEDP）。然后处死大鼠，取左心室前壁组织制作切片，常规苏木精-伊红（HE）染色观察大鼠心肌组织病理学改变。另取切片进行原位末端转移酶标记法（TUNEL）染色，计算心肌细胞凋亡率。分别采用实时荧光定量PCR（RT-qPCR）和Western blot法检测大鼠心肌组织中磷脂酰肌醇3-激酶（PI3K）、蛋白激酶B（Akt）、糖原合成酶激酶3（GSK3β）、细胞周期蛋白D1（cyclin D1）mRNA和蛋白的相对表达水平及磷酸化Akt（p-Akt）、磷酸化GSK3β（p-GSK3β）蛋白的相对表达水平。 结果： 与假手术组比较，AMI组及FHL低、中、高剂量组大鼠LVEDD、LVEDP均较大，LAWD、LVEF均较小（P均<0.05）。与AMI组比较，FHL低、中、高剂量组大鼠LVEDD、LVEDP均较小，LAWD、LVEF均较大（P均<0.05），且随FHL剂量增加LVEDD和LVEDP减小，LAWD和LVEF增大（P均<0.05）。FHL低、中剂量组大鼠的LVEDD和LAWD差异无统计学意义（P均>0.05）。HE染色结果显示，假手术组大鼠心肌组织结构正常，AMI组大鼠梗死区可见坏死心肌组织，心肌纤维排列紊乱，心肌间质大量炎性细胞浸润，FHL低、中、高剂量组大鼠心肌损伤较AMI组轻，心肌纤维排列整齐，但仍有部分断裂及少量炎性细胞浸润，梗死区有散在的岛状正常心肌组织，其中FHL高剂量组大鼠心肌损伤最轻。TUNEL染色结果显示，与AMI组比较，FHL低、中、高剂量组大鼠心肌细胞凋亡率均较低（P均<0.001），但仍均高于假手术组（P均<0.001），且随FHL剂量增加心肌细胞凋亡率降低（P均<0.05）。RT-qPCR检测结果显示，与AMI组比较，FHL低、中、高剂量组大鼠心肌组织中PI3K、cyclin D1 mRNA表达水平较高，但仍低于假手术组（P均<0.05），且随FHL剂量增加PI3K、cyclin D1 mRNA表达水平升高（P均<0.05）。Western blot法检测结果显示，与AMI组比较，FHL低、中、高剂量组大鼠心肌组织中PI3K、p-Akt、p-GSK3β、cyclin D1蛋白表达水平较高，但仍低于假手术组（P均<0.05），且随FHL剂量增加PI3K、p-Akt、p-GSK3β、cyclin D1蛋白表达水平升高（P均<0.05）。 结论： FHL可有效改善AMI大鼠心功能，其可能通过激活PI3K/GSK3β/cyclin D1信号通路发挥调控作用。.

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