ABSTRACT
OBJECTIVE: To investigate the antioxidative effect and mechanism of luteolin on rat cardiomyocytes and isolated hearts followed by simulated ischemia/reperfusion (SI/R) injury. METHODS: The left ventricular cardiomyocytes and the isolated hearts from adult rats were subjected to SI/R injury. The experiment groups included control, SI/R, luteolin + SI/R (Lut + SI/R), vitamin E (Vit E) + SI/R, and LY294002 + luteolin + SI/R (LY + Lut + SI/R) groups. Cell viability, shortening amplitude, lactate dehydrogenase (LDH) release, superoxide dismutase (SOD) activity, the production of reactive oxygen species (ROS) and malondialdehyde (MDA), expression levels of Akt, phosphorylated Akt, NOX2 (gp91phox), NOX2 mRNA, mitogen-activated protein kinase (p38 MAPK) and phosphorylated p38MAPK were all measured after 3-h simulated ischemia and 2-h simulated reperfusion procedure in cardiomyocytes. Vit E was used as a standard control. The contractile function of isolated hearts was further observed after they were subjected to 30-min global ischemia and 120-min reperfusion. RESULTS: Pretreatment with 8-µmol/L luteolin substantially increased cell viability and shortening amplitude, while reducing evidence of oxidative stress-induced damage in the cells. In addition, the expression of NOX2, NOX2 mRNA and phosphorylation of p38MAPK were all downregulated. Furthermore, pretreatment with 40-µmol/L luteolin improved the recovery of myocardial contractile function following SI/R-induced injury, and luteolin markedly increased phosphorylation of Akt. However, all of the above effects were partially inhibited by the phosphatidylinositol 3-kinase (PI3K) inhibitor, LY294002. CONCLUSIONS: Luteolin prevents SI/R-induced myocardial damage by reducing oxidative stress-induced injury in isolated rat hearts and cardiomyocytes, and the cardioprotection induced by luteolin was partially mediated by the PI3K/Akt pathway.
Subject(s)
Antioxidants/therapeutic use , Luteolin/therapeutic use , Myocardial Reperfusion Injury/drug therapy , Myocardium/pathology , Myocytes, Cardiac/pathology , Perfusion , Animals , Antioxidants/pharmacology , Cell Survival/drug effects , Culture Media , Heart Ventricles/drug effects , Heart Ventricles/pathology , Heart Ventricles/physiopathology , L-Lactate Dehydrogenase/metabolism , Luteolin/pharmacology , Male , Malondialdehyde/metabolism , Models, Biological , Myocardial Contraction/drug effects , Myocardial Reperfusion Injury/pathology , Myocardial Reperfusion Injury/physiopathology , Myocytes, Cardiac/drug effects , Myocytes, Cardiac/metabolism , NADPH Oxidases/genetics , NADPH Oxidases/metabolism , Oxidative Stress/drug effects , Phosphorylation/drug effects , RNA, Messenger/genetics , RNA, Messenger/metabolism , Rats, Sprague-Dawley , Reactive Oxygen Species/metabolism , Superoxide Dismutase/metabolism , p38 Mitogen-Activated Protein Kinases/metabolismABSTRACT
The diverse biological effects of nanomaterials form the basis for their applications in biomedicine but also cause safety issues. Induction of autophagy is a cellular response after nanoparticles exposure. It may be beneficial in some circumstances, yet autophagy-mediated toxicity raises an alarming concern. Previously, it has been reported that upconversion nanoparticles (UCNs) elicit liver damage, with autophagy contributing most of this toxicity. However, the detailed mechanism is unclear. This study reveals persistent presence of enlarged autolysosomes in hepatocytes after exposure to UCNs and SiO2 nanoparticles both in vitro and in vivo. This phenomenon is due to anomaly in the autophagy termination process named autophagic lysosome reformation (ALR). Phosphatidylinositol 4-phosphate (PI(4)P) relocates onto autolysosome membrane, which is a key event of ALR. PI(4)P is then converted into phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2 ) by phosphatidylinositol-4-phosphate 5-kinase. Clathrin is subsequently recruited by PI(4,5)P2 and leads to tubule budding of ALR. Yet it is observed that PI(4)P cannot be converted in nanoparticle-treated hepatocytes cells. Exogenous supplement of PI(4,5)P2 suppresses the enlarged autolysosomes in vitro. Abolishment of these enlarged autolysosomes by autophagy inhibitor relieves the hepatotoxicity of UCNs in vivo. The results provide evidence for disrupted ALR in nanoparticle-treated hepatocytes, suggesting that the termination of nanoparticle-induced autophagy is of equal importance as the initiation.
Subject(s)
Autophagy , Hepatocytes/cytology , Hepatocytes/metabolism , Lysosomes/metabolism , Nanoparticles/chemistry , Animals , Autophagy/drug effects , Cells, Cultured , Hepatocytes/drug effects , Liver/metabolism , Lysosomes/drug effects , Male , Mice, Inbred C57BL , Models, Biological , Nanoparticles/toxicity , Phosphatidylinositol Phosphates/metabolismABSTRACT
OBJECTIVE: To reveal the correlation between HQT gene and the biosynthesis of chlorogenic acid in Lonicera japonica. METHODS: RT-PCR was used to measure the relative expression of HQT gene and reference gene Actin, and agarose gel electrophoresis was used to analyse the PCR results. RESULTS: The brightness of Actin gene strips of different organs was properly similar to each other,but the brightness of HQT gene strips was significantly different. HQT gene strips of alabastrum were the brightest,the brightness of HQT gene strip of leaves took the second place, and the brightness of HQT gene strips of stems was very faint. This result was in accordance with the content of chlorogenic acid in different organs of Lonicera japonica. CONCLUSION: The expression of HQT gene with the biosynthesis of chlorogenic acid has necessary relation with Lonicera japonica.
