Salidroside improves endothelial function and alleviates atherosclerosis by activating a mitochondria-related AMPK/PI3K/Akt/eNOS pathway

Aim Salidroside （SAL） is a phenylpropanoid glycoside isolated from the medicinal plant Rhodiola rosea. A recent study has reported that SAL can efficiently decrease atherosclerotic plaque formation in low-density lipoprotein receptor - deficient mice. This study was to investigate the molecular mechanism of antiatherogenic effects of SAL. Method Six-week old apoE-/- male mice were fed a high-fat diet for 8 weeks and then were ad- ministered with SAL for another 8 weeks. Atherosclerotic lesion and vascular function were analyzed. Primary cul- tured human umbilical vein endothelial cells （HUVECs） were prepared. Superoxide anion （O2^-）, NO produc- tion, mitochondrial membrane potential （△ψm） and intracellular ATP and AMP levels were measured. Expression of eNOS and AMPK were analyzed by Western blot. Result SAL significantly improved endothelial function asso- ciated with increasing eNOS activation thus reduced the atherosclerotic lesion area. SAL increased eNOS-Serl177 phosphorylation and decreased eNOS-Thr495 phosphorylation. SAL significantly activated AMP-activated protein ki- nase （AMPK）. Both AMPK inhibitor and AMPK small interfering RNA （siRNA） abolished SAL-induced Akt- Ser473 and eNOS-Serl177 phosphorylation. In contrast, LY294002, the PI3k/Akt pathway inhibitor, abolished SAL-induced phosphorylation and expression of eNOS. SAL decreased cellular ATP content and increased the cel- lular AMP/ATP ratio, which was associated with the activation of AMPK. SAL was found to decrease A^m, which is likely consequence of reduced ATP production. Conclusion The action of SAL to reduce atherosclerotic lesion formation may at least be attributed to its effect on improving endothelial function by promoting nitric oxide （NO） production, which was associated with mitochondria depolarization and subsequent activation of the AMPK/PI3 IC/ Akt/eNOS pathway. Taken together, our data described the effects of SAL on mitochondria, which played critical roles in improving endothelial function in atherosclerosis.