title: Norepinephrine induces apoptosis in neonatal rat endothelial cells via a ROS-dependent JNK activation pathway.
abstract: Our previous study demonstrated that norepinephrine (NE) induces endothelial apoptosis mainly through down-regulation of Bcl-2 protein and activation of the beta-adrenergic and caspase-2 pathways. However, whether reactive oxygen species (ROS) and mitogen-activated protein kinases (MAPKs) are involved in this signal transduction remains unknown. Endothelial cells cultured from neonatal rat heart were treated with 100 microM NE. Proteins of MAPKs and Bcl-2 family were assayed by Western blotting. Apoptosis was determined by terminal deoxynucleotidyl transferase-mediated nick end-labeling assay. ROS was analyzed with flow cytometry. Caspase activity was measured using specific fluorogenic substrates. Treatment with NE increased intracellular ROS level and extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 phosphorylation. Whereas the phosphorylated form of Akt was decreased. The NE-induced apoptosis was abrogated by SP600125 (a specific inhibitor of JNK). Antioxidants such as vitamin C and N-acetyl cysteine inhibited NE-induced ROS production, JNK phosphorylation, caspase activation and apoptosis. Exogenously added superoxide dismutase or catalase markedly diminished NE-induced ROS production and cell death. In conclusions, our study is the first report documenting that NE induces apoptosis in neonatal rat endothelial cells via a ROS-dependent JNK activation pathway. Antioxidants may be useful in the prevention and management of NE-mediated endothelial apoptosis during heart failure.
authors.affiliation: Department of Pediatrics, Taichung Veterans General Hospital, Taichung, Taiwan.
authors.forename: Yun-Ching
authors.initials: YC
authors.lastname: Fu
authors.forename: Sui-Chu
authors.initials: SC
authors.lastname: Yin
authors.forename: Ching-Shiang
authors.initials: CS
authors.lastname: Chi
authors.forename: Betau
authors.initials: B
authors.lastname: Hwang
authors.forename: Shih-Lan
authors.initials: SL
authors.lastname: Hsu
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D001205:Ascorbic Acid / Q000494:pharmacology; D015536:Down-Regulation; D042783:Endothelial Cells / Q000166:cytology* / Q000378:metabolism; D004789:Enzyme Activation; D006861:Hydrogen Peroxide / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D009206:Myocardium / Q000166:cytology; D019255:NADPH Oxidases / Q000378:metabolism; D009638:Norepinephrine / Q000494:pharmacology / Q000502:physiology*; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*; D011941:Receptors, Adrenergic / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D000975:Antioxidants; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D011941:Receptors, Adrenergic; D006861:Hydrogen Peroxide; D019255:NADPH Oxidases; D051057:Proto-Oncogene Proteins c-akt; D048031:JNK Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; D001205:Ascorbic Acid; D000111:Acetylcysteine; D009638:Norepinephrine