Atherosclerosis is attenuated by acacetin via Sirt1-mediated activation of AMPK/Sirt3 signals in diabetic ApoE-/- mice

BackgroundThe strategy of decreasing atherosclerotic cardiovascular disorder is imperative to reduce premature death and improve quality of life in patients with diabetes mellitus. The present study was designed to investigate whether the natural flavone acacetin could improve diabetes- accelerated atherosclerotic lesions.MethodsDiabetic model was established in 7-week-old ApoE^−/− mice by intraperitoneal injection of STZ (daily 50 mg/kg) for 5 days. Animals of control, control with acacetin treatment, STZ-diabetes, STZ-diabetes with acacetin treatment received acacetin prodrug subcutaneously (20 mg/kg, b.i.d.) or equivolume saline for 12 weeks, and the elasticity of carotid artery and the ability of vascular wall movement were determined with ultrasound and magnetic resonance imaging. Human umbilical vein endothelial cells (HUVECs) were cultured with medium containing 5.5 mM or 33 mM glucose and treated with acacetin or vehicle. Changes of related aortic lesions and signaling molecules were determined by biochemical and molecular approaches in animals and cultured HUVECs.ResultsIt was found that acacetin significantly suppressed atherosclerotic lesions and neointima hyperplasia, improved the elasticity of carotid artery and the ability of vascular wall movement without reducing blood glucose level and reversed the impaired signaling molecules (i.e. SOD, Bcl2, PGC-1α, pAMPK, Sirt3 and Sirt1) in artery tissues in diabetic mice. In cultured HUVECs, high glucose-induced cell viability reduction, ROS over-production, decrease of anti-oxidation, increase of apoptosis, and impairment of mitochondrial function were countered by acacetin (0.3-3 µM) in a concentration-dependent manner. Moreover, acacetin relies on Sirt1 activation by increasing NAMPT and NAD⁺ followed by Sirt3, pAMPK and PGC-1α activation. Silencing Sirt1 abolished acacetin-induced activation of Sirt3, pAMPK, and PGC-1α.ConclusionsThese results indicate that Sirt1-mediated activation of pAMPK/Sirt3 signals is involved in protective effects of acacetin against atherosclerosis in diabetes by preserving mitochondrial function via reducing mitochondrial apoptosis and ROS production and enhancing its biogenesis, which suggests that acacetin may be a drug candidate for reducing atherosclerotic cardiovascular disorder in patients with diabetes.