RESUMO
Background: Prevention of diabetic heart myocardial ischemia-reperfusion (IR) injury (MIRI) is challenging. Propofol attenuates MIRI through its reactive oxygen species scavenging property at high doses, while its use at high doses causes hemodynamic instability. Salvianolic acid A (SAA) is a potent antioxidant that confers protection against MIRI. Both propofol and SAA affect metabolic profiles through regulating Adenosine 5'-monophosphate-activated protein kinase (AMPK). The aim of this study was to investigate the protective effects and underlying mechanisms of low doses of propofol combined with SAA against diabetic MIRI. Methods: Diabetes was induced in mice by a high-fat diet followed by streptozotocin injection, and MIRI was induced by coronary artery occlusion and reperfusion. Mice were treated with propofol at 46 mg/kg/h without or with SAA at 10 mg/kg/h during IR. Cardiac origin H9c2 cells were exposed to high glucose (HG) and palmitic acid (PAL) for 24 h in the absence or presence of cluster of differentiation 36 (CD36) overexpression or AMPK gene knockdown, followed by hypoxia/reoxygenation (HR) for 6 and 12 h. Results: Diabetes-exacerbated MIRI is evidenced as significant increases in post-ischemic infarction with reductions in phosphorylated (p)-AMPK and increases in CD36 and ferroptosis. Propofol moderately yet significantly attenuated all the abovementioned changes, while propofol plus SAA conferred superior protection against MIRI to that of propofol. In vitro, exposure of H9c2 cells under HG and PAL decreased cell viability and increased oxidative stress that was concomitant with increased levels of ferroptosis and a significant increase in CD36, while p-AMPK was significantly reduced. Co-administration of low concentrations of propofol and SAA at 12.5 µM in H9c2 cells significantly reduced oxidative stress, ferroptosis and CD36 expression, while increasing p-AMPK compared to the effects of propofol at 25 µM. Moreover, either CD36 overexpression or AMPK silence significantly exacerbated HR-induced cellular injuries and ferroptosis, and canceled propofol- and SAA-mediated protection. Notably, p-AMPK expression was downregulated after CD36 overexpression, while AMPK knockdown did not affect CD36 expression. Conclusions: Combinational usage of propofol and SAA confers superior cellular protective effects to the use of high-dose propofol alone, and it does so through inhibiting HR-induced CD36 overexpression to upregulate p-AMPK.
RESUMO
The hearts of subjects with diabetes are vulnerable to ischemia-reperfusion injury (IRI). In contrast, experimentally rodent hearts have been shown to be more resistant to IRI at the very early stages of diabetes induction than the heart of the non-diabetic control mice, and the mechanism is largely unclear. Ferroptosis has recently been shown to play an important role in myocardial IRI including that in diabetes, while the specific mechanisms are still unclear. Non-diabetic control (NC) and streptozotocin-induced diabetic (DM) mice were treated with the antioxidant N-acetylcysteine (NAC) in drinking water for 4 week starting at 1 week after diabetes induction. Mice were subjected to myocardial IRI induced by occluding the coronary artery for 30 min followed by 2 h of reperfusion, subsequently at 1, 2, and 5 week of diabetes induction. The post-ischemic myocardial infarct size in the DM mice was smaller than that in NC mice at 1 week of diabetes but greater than that in the NC mice at 2 and 5 week of diabetes, which were associated with a significant increase of ferroptosis at 2 and 5 week but a significant reduction of ferroptosis at 1 week of diabetes. NAC significantly attenuated post-ischemic ferroptosis as well as oxidative stress and reduced infarct size at 2 and 5 week of diabetes. Application of erastin, a ferroptosis inducer, reversed the cardioprotective effects of NAC. It is concluded that increased oxidative stress and ferroptosis are the major factors attributable to the increased vulnerability to myocardial IRI in diabetes and that attenuation of ferroptosis represents a major mechanism whereby NAC confers cardioprotection against myocardial IRI in diabetes.