RESUMEN
Betulinic acid (BA) exerts protective effects on organs in septic animals. However, whether BA can improve cardiac function in sepsis and the underlying mechanism remain unclear. Here, male Sprague-Dawley rats were pretreated with BA (25 mg/ kg/ d, i. g.) for 5 days and then intraperitoneally injected with lipopolysaccharide (LPS, 10 mg/ kg). The rats were anesthetized to determine transthoracic echocardiography using a high-resolution imaging system for small animals after they were treated with LPS for 6 h. Histopathologic alterations were examined by HE staining. Myocardial injury markers (cTnI and CK-MB) and inflammatory factors (TNF-α, IL-1β and IL-6) in the serum were measured by the enzyme-linked immunosorbent assay. Autophagy-related proteins (p62 and LC3 Ⅱ) and AKT-modulated autophagy pathways in the myocardium were determined by Western blotting. Pretreatment with BA markedly improved left ventricular ejection fraction (EF) and fraction shortening (FS) (P<0. 05), improved myocardial histomorphology, and significantly inhibited cTnI, CK-MB, TNF-α, IL-1β and IL-6 (P<0. 05) in the septic rat serum. BA markedly decreased p62 (P<0. 01), increased LC3 Ⅱ (P< 0. 001), and significantly down-regulated p-AKT (Thr308), p-AMPKα (Ser485/ 491), p-mTOR (Ser2448) and p-S6K (Thr389) (P<0. 05), while markedly up-regulated p-AMPKα (Thr172) and pULK1 (Ser317) (P<0. 01) in septic rat hearts. The findings indicate that BA can attenuate sepsis-induced myocardial dysfunctions associated with down-regulating autophagy inhibiting pathways mediated by AKT/ mTOR and AKT/ AMPK pathways.