Objective: To observe the effect of moxibustion on cardiac function and the expression of autophagy-related proteins microtubule-associated protein 1 light chain 3 (LC3) and selective autophagy receptor signaling adaptor sequestosome 1 (SQSTM1/p62) in rats with chronic heart failure (CHF), so as to explore its underlying mechanisms in preventing and treating CHF.
Methods: Sixty male SD rats were randomly divided into normal, model, moxibustion, autophagy inhibitor 3-methyladenine (3-MA) and autophagy agonist rapamycin (RAPA) groups (n＝12 rats/group). The CHF model was established by intrape-ritoneal injection of adriamycin (ADR, 2 mg/kg, once every week for 12 weeks). Mild moxibustion was applied to bilateral "Feishu" (BL13) and "Xinshu" (BL15) for 20 min every time. Rats of the 3-MA group were treated by intraperitoneal injection of 3-MA suspension (15 mg/kg), and those of the RAPA group treated by gavage of RAPA suspension (2 mg/kg). All the treatments were given once a day for 3 weeks. The heart rate (HR), cardiac output (CO), left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP) and maximum rising and lowering rates of left ventricular pressure (±dp/dtmax) were measured for assessing the cardiac performance. Histopathological changes of the left ventricular myocardium were observed by HE staining. The expression levels of LC3-Ⅰ， LC3-Ⅱ and p62 proteins of the left ventricle myocardium tissue were detected by Western blot.
Results: After modeling, the pathological changes of myocardium (as myocardial cell swelling with vacuoles, myocardial fibre breakage, etc.) were obvious, and the HR, LVEDP, LC3-Ⅱ and LC3-Ⅱ/Ⅰ protein expression levels were significantly increased in the model group compared with the normal group (P<0.01), while the CO, LVSP, ±dp/dtmax, and the expression of p62 protein were significantly down-regulated (P<0.01). Following the interventions, the myocardial injury was reduced, the HR, LVEDP, LC3-Ⅱ and LC3-Ⅱ/Ⅰ levels in both moxibustion and 3-MA groups were significantly decreased (P<0.05, P<0.01), while the CO, LVSP, ±dp/dtmax and p62 expression level were significantly increased relevant to the model group (P<0.05, P<0.01). In addition, the ratio of LC3-Ⅱ/Ⅰ was significantly increased, and the expression level of p62 significantly down-regulated in the RAPA group compared with the model group (P<0.01).
Conclusion: Moxibustion can improve cardiac function in CHF rats, which may be related to its effects in down-regulating the ratio of LC3-Ⅱ/Ⅰ and up-regulating the expression of p62 protein to inhibit cardiomyocyte autophagy.
Keywords: Chronic heart failure; Microtubule-associated protein 1 light chain 3; Moxibustion; Myocardial cell autophagy; Sequestosome 1(SQSTM1/p62).