OBJECTIVE  To explore the effects and mechanisms of cycloartenol on myocardial ischemia-reperfusion injury in mice.

  METHODS  In vitro experiments, primary cardiomyocytes were extracted from 1-3 days SD mice. The hypoxia/reoxygenation model was established by incubating cells in a hypoxic culture box for 3 hours followed by reoxygenation in a normal culture box for 3 hours. The primary cardiomyocytes were divided into Control group, H/R group, low-dose (3 μmol·L^-1) and high-dose (10 μmol·L^-1) cycloartenol groups, and SB203580 group. CCK-8 was used to detect cell viability, the apoptosis rate was detected by flow cytometry, and Western blot was used to detect the expression levels of p38 MAPK and p-p38 MAPK in each group. In an in vivo experiment, 7-week-old male C57BL/6J mice were randomly divided into a Control group, an I/R group, and three doses of cycloartenol (0.2, 0.5, 1.0 mg·kg^-1) groups. The mice were continuously administered for seven days before the surgery. The model was prepared by ligation of the left anterior descending coronary artery (LAD) for 30 minutes, followed by reperfusion for 24 hours to induce myocardial ischemia-reperfusion injury. Left ventricular ejection fraction (LVEF), cardiac output (CO), left ventricular fractional shortening (LVFS) of each group of mice were detected by small animal ultrasound. TTC staining was used to detect the changes of ischemic infarct size in each group. The changes of myocardial tissue in each group were observed by HE staining. The expression levels of p38 MAPK, p-p38 MAPK, IL-6 and TNF-α in myocardial tissue of mice were detected by Western blot. Serum levels of creatine kinase isoenzyme (CK-MB), lactate dehydrogenase (LDH), cardiac troponin I (cTnI), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were measured using ELISA kits.

  RESULTS  In vitro experiments demonstrated that compared with the H/R group, both the cycloartenol and SB203580 pretreatment groups showed a significant increase in myocardial cell viability and the apoptosis rate decrease, which can downregulate the protein expression level of p-p38 MAPK and decrease the ratio of p-p38 MAPK/p38 MAPK(P < 0.05). In vivo experiments confirmed that compared with the I/R group, cycloartenol pretreatment significantly improved LVEF, LVFS, and CO values (P < 0.05), reduce myocardial ischemic infarct size, thereby enhancing myocardial function. The protein expression level of p-p38 MAPK in myocardial tissue was down-regulated, the ratio of p-p38 MAPK/p38 MAPK was decreased, and the expression levels of IL-6 and TNF-α were decreased. Additionally, cycloartenol pretreatment reduced the levels of CK-MB, LDH, cTnI, IL-6, and TNF-α in mouse serum (P < 0.05).

  CONCLUSION  Pre-treatment with cycloartenol can protect mouse cardiac function and alleviate myocardial ischemia-reperfusion injury. Its mechanism of action may be related to the inhibition of p38 MAPK phosphorylation, reducing inflammatory reactions.