Salidroside pretreatment alleviates ferroptosis induced by myocardial ischemia/reperfusion through mitochondrial superoxide-dependent AMPKα2 activation

Abstract

Background: Ferroptosis, a form of regulated cell death (RCD) that relies on excessive reactive oxygen species (ROS) generation, Fe²⁺accumulation, abnormal lipid metabolism and is involved in various organ ischemia/reperfusion (I/R) injury, expecially in myocardium. Mitochondria are the powerhouses of eukaryotic cells and essential in regulating multiple RCD. However, the links between mitochondria and ferroptosis are still poorly understood. Salidroside (Sal), a natural phenylpropanoid glycoside isolated from Rhodiola rosea, has mult-bioactivities. However, the effects and mechanism in alleviating ferroptosis caused by myocardial I/R injury remains unclear.

Purpose: This study aimed to investigate whether pretreated with Sal could protect the myocardium against I/R damage and the underlying mechanisms. In particular, the relationship between Sal pretreatment, AMPKα2 activity, mitochondria and ROS generation was explored.

Study design and methods: Firstly, A/R or I/R injury models were employed in H9c2 cells and Sprague-Dawley rats. And then the anti-ferroptotic effects and mechanism of Sal pretreatment was detected using multi-relevant indexes in H9c2 cells. Further, how does Sal pretreatment in AMPKα2 phosphorylation was explored. Finally, these results were validated by I/R injury in rats.

Results: Similar to Ferrostatin-1 (a ferroptosis inhibitor) and MitoTEMPO, a mitochondrial free radical scavenger, Sal pretreatment effectively alleviated Fe²⁺ accumulation, redox disequilibrium and maintained mitochondrial energy production and function in I/R-induced myocardial injury, as demonstrated using multifunctional, enzymatic, and morphological indices. However, these effects were abolished by downregulation of AMPKα2 using an adenovirus, both in vivo and in vitro. Moreover, the results also provided a non-canonical mechanism that, under mild mitochondrial ROS generation, Sal pretreatment upregulated and phosphorylated AMPKα2, which enhanced mitochondrial complex I activity to activate innate adaptive responses and increase cellular tolerance to A/R injury.

Conclusion: Overall, our work highlighted mitochondria are of great impotance in myocardial I/R-induced ferroptosis and demonstrated that Sal pretreatment activated AMPKα2 against I/R injury, indicating that Sal could become a candidate phytochemical for the treatment of myocardial I/R injury.

Keywords: AMP-Activated protein kinaseα2; Ferroptosis; Mitochondria; Myocardial ischemia-reperfusion injury; Salidroside.