title: Activation of Akt/GSK-3beta signaling pathway is involved in intermedin(1-53) protection against myocardial apoptosis induced by ischemia/reperfusion.
abstract: Intermedin (IMD) is a novel member of the calcitonin/calcitonin gene-related peptide family. We investigated the cardioprotective mechanism of IMD(1-53) in the in vivo rat model of myocardial ischemia/reperfusion (I/R) injury and in vitro primary neonatal cardiomyocyte model of hypoxia/reoxygenation (H/R). Myocardial infarct size was measured by 2,3,5-triphenyl tetrazolium chloride staining. Cardiomyocyte viability was determined by trypan blue staining, cell injury by lactate dehydrogenase (LDH) leakage, and cardiomyocyte apoptosis by terminal deoxyribonucleotidyl transferase-mediated dUTP nick-end labeling assay, Hoechst staining, gel electrophoresis and caspase 3 activity. The translocation of mitochondrial cytochrome c of myocardia and expression of apoptosis-related factors Bcl-2 and Bax, phosphorylated Akt and phosphorylated GSK-3beta were determined by western blot analysis. IMD(1-53) (20 nmol/kg) limited the myocardial infarct size in rats with I/R; the infarct size was decreased by 54%, the apoptotic index by 30%, and caspase 3 activity by 32%; and the translocation of cytochrome c from mitochondria to cytosol was attenuated. IMD(1-53) increased the mRNA and protein expression of Bcl-2 and ratio of Bcl-2 to Bax by 81 and 261%, respectively. IMD(1-53) (1 x 10(-7) mol/L) inhibited the H/R effect in cardiomyocytes by reducing cell death by 43% and LDH leakage by 16%; diminishing cellular apoptosis; decreasing caspase 3 activity by 50%; and increasing the phosphorylated Akt and GSK-3beta by 41 and 90%, respectively. The cytoprotection of IMD(1-53) was abolished with LY294002, a PI3K inhibitor. In conclusion, IMD(1-53) exerts cardioprotective effect against myocardial I/R injury through the activation of the Akt/GSK-3beta signaling pathway to inhibit mitochondria-mediated myocardial apoptosis.
authors.affiliation: Department of Physiology and Pathophysiology, Peking University Health Science Center, 100191, Beijing, China.
authors.forename: Jun-Qiu
authors.initials: JQ
authors.lastname: Song
authors.forename: Xu
authors.initials: X
authors.lastname: Teng
authors.forename: Yan
authors.initials: Y
authors.lastname: Cai
authors.forename: Chao-Shu
authors.initials: CS
authors.lastname: Tang
authors.forename: Yong-Fen
authors.initials: YF
authors.lastname: Qi
mesh_terms: D053607:Adrenomedullin / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002316:Cardiotonic Agents / Q000008:administration & dosage / Q000494:pharmacology; D002867:Chromones / Q000494:pharmacology; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D000860:Hypoxia / Q000150:complications; D008297:Male; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D015428:Myocardial Reperfusion Injury / Q000150:complications / Q000201:enzymology* / Q000517:prevention & control; D009206:Myocardium / Q000201:enzymology / Q000473:pathology*; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D009336:Necrosis; D009479:Neuropeptides / Q000008:administration & dosage / Q000494:pharmacology*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: C499411:Adm2 protein, rat; D002316:Cardiotonic Agents; D002867:Chromones; D009025:Morpholines; D009479:Neuropeptides; D000081082:Phosphoinositide-3 Kinase Inhibitors; D053607:Adrenomedullin; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D000071679:Glycogen Synthase Kinase 3 beta; C000605508:Gsk3b protein, rat; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3