Luteoloside attenuates anoxia/reoxygenation-induced cardiomyocytes injury via mitochondrial pathway mediated by 14-3-3η protein.

Ischemia/reperfusion (I/R) injury is the major cause of acute cardiovascular disease worldwide. 14-3-3η protein has been demonstrated to protect myocardium against I/R injury. Luteoloside (Lut), a flavonoid found in many Chinese herbs, exerts myocardial protection effects. However, the mechanism remains unclear. We hypothesize that the cardioprotective role of Lut is exerted by regulating the 14-3-3η signal pathway. To investigate our hypothesis, an in vitro I/R model was generated in H9C2 cardiomyocytes by anoxia/reoxygenation (A/R) treatment. The effects of Lut on cardiomyocytes with A/R injury were assessed by determining the cell viability, lactate dehydrogenase levels, intracellular reactive oxygen species levels, mitochondrial permeability transition pores (mPTP) openness, caspase-3 activity, and apoptosis rate. The effects on protein expression were tested using western blot analysis. Lut attenuated A/R-induced injury to cardiomyocytes by increasing the expression of 14-3-3η protein and cell viability; decreasing levels of lactate dehydrogenase, reactive oxygen species, mPTP openness, caspase-3 activity, and low apoptosis rate were observed. However, the cardioprotective effects of Lut were blocked by AD14-3-3ηRNAi, an adenovirus knocking down the intracellular 14-3-3η expression. In conclusion, to our knowledge, this is the first study to demonstrate that Lut protected cardiomyocytes from A/R-induced injury via the regulation of 14-3-3η signaling pathway.

Capsaicin prevents mitochondrial damage, protects cardiomyocytes subjected to anoxia/reoxygenation injury mediated by 14-3-3η/Bcl-2.

Capsaicin(Cap) is an active component of chili peppers that is extracted from capsicum plants. Recent studies have reported that Cap can ameliorate myocardial ischemia/reperfusion(I/R) injury. Mitochondria play an important role in pathways of apoptosis induced by myocardial I/R injury. However, the underlying mechanisms of Cap that improve mitochondrial function during I/R injury is not yet understood. The aim of this study was to evaluate whether Cap regained normal mitochondrial function in myocardial I/R injury, and to further explore the underlying mechanisms of action involved. In this study, an acute myocardial anoxia/reoxygenation(A/R) injury model was established using H9c2 cells. The cell viability was detected by MTS assay. LDH activity, mitochondrial permeability transition pores(mPTP) opening, and caspase-3 activity were analyzed using an ultra violet spectrophotometer. Levels of intracellular reactive oxygen species and apoptosis were evaluated by flow cytometry. Western blot analysis was used to determine the expression of 14-3-3η, Bcl-2, and Bax. The data showed that pretreatment with Cap decreased LDH release and increased cell viability in H9c2 cells that underwent A/R. Cap pretreatment significantly attenuated generation of reactive oxygen species, inhibited mPTP opening and caspase-3 activation, downregulated Bax, upregulated 14-3-3η and Bcl-2, and ultimately reduced apoptosis in H9c2 cells that underwent A/R. Moreover, 14-3-3ηRNAi adenovirus markedly eliminated the protective effects of Cap in H9c2 cells that underwent A/R. In addition, ABT-737(inhibitor of Bcl-2) significantly eliminated Cap protection. Taken together, the present study suggested that the cardioprotective effect of Cap against A/R injury involves the 14-3-3η pathway and prevention of mitochondrial damage.

Protective Effects of Isorhamnetin on Cardiomyocytes Against Anoxia/Reoxygenation-induced Injury Is Mediated by SIRT1.

It has been reported that apoptosis plays a very important role on anoxia/reoxygenation (A/R)-induced injury, and human silent information regulator type 1 (SIRT1) can inhibit the apoptosis of cardiomyocytes. It has been proved that isorhamnetin (IsoRN), 3'-O-methyl-quecetin, can protect the cardiomyocytes, but the mechanism is still not clear. The aim of the study was to explore whether the protective effects of IsoRN on the cardiomyocytes against the A/R-induced injury are mediated by SIRT1. The effects of IsoRN on cardioprotection against A/R injury in neonatal rat cardiomyocytes were monitored by cell viability, the levels of mitochondrial membrane potential (Δψm), apoptosis, and intracellular reactive oxygen species (ROS), the levels of lactate dehydrogenase (LDH), creatine phosphokinase (CPK) and mitochondrial permeability transition pores (mPTP). The effects on protein expression were measured by western blot assay. The results showed that IsoRN can reduce A/R-induced injury by decreasing the level of lactate dehydrogenase and creatine phosphokinase release from the cardiomyocytes, increasing cell viability and expression of SIRT1, reducing the generation of reactive oxygen species, inhibiting opening of mitochondrial permeability transition pores and loss of Δψm and activation of caspase-3, and decreasing the release of cytochrome c, and reducing apoptosis. In addition, sirtinol, a SIRT1 inhibitor, drastically reduced the protective effects of IsoRN on cardioprotective effects in cardiomocytes. In conclusion, we firstly demonstrated that SIRT1 may be involved in the protective effects of IsoRN on cardiomocytes against the A/R-induced injury.