title: Molecular mechanisms underlying oxytocin-induced cardiomyocyte protection from simulated ischemia-reperfusion.
abstract: Oxytocin (OT) stimulates cardioprotection. Here we investigated heart-derived H9c2 cells in simulated ischemia-reperfusion (I-R) experiments in order to examine the mechanism of OT protection. I-R was induced in an anoxic chamber for 2 hours and followed by 2 h of reperfusion. In comparison to normoxia, I-R resulted in decrease of formazan production by H9c2 cells to 63.5 ± 1.7% (MTT assay) and in enhanced apoptosis from 1.7 ± 0.3% to 2.8 ± 0.4% (Tunel test). Using these assays it was observed that treatment with OT (1-500 nM) exerted significant protection during I-R, especially when OT was added at the time of ischemia or reperfusion. Using the CM-H2DCFDA probe we found that OT triggers a short-lived burst in reactive oxygen species (ROS) production in cells but reduces ROS production evoked by I-R. In cells treated with OT, Western-blot revealed the phosphorylation of Akt (Thr 308, p-Akt), eNOS and ERK 1/2. Microscopy showed translocation of p-Akt and eNOS into the nuclear and perinuclear area and NO production in cells treated with OT. The OT-induced protection against I-R was abrogated by an OT antagonist, the Pi3K inhibitor Wortmannin, the cGMP-dependent protein kinase (PKG) inhibitor, KT5823, as well as soluble guanylate cyclase (GC) inhibitor, ODQ, and particulate GC antagonist, A71915. In conditions of I-R, the cells with siRNA-mediated reduction in OT receptor (OTR) expression responded to OT treatment by enhanced apoptosis. In conclusion, the OTR protected H9c2 cells against I-R, especially if activated at the onset of ischemia or reperfusion. The OTR-transduced signals include pro-survival kinases, such as Akt and PKG.
authors.affiliation: Cardiovascular Biochemistry Laboratory, CRCHUM, Montréal, Québec, Canada; Department of Experimental Medicine, McGill University.
authors.forename: Araceli
authors.initials: A
authors.lastname: Gonzalez-Reyes
authors.affiliation: Cardiovascular Biochemistry Laboratory, CRCHUM, Montréal, Québec, Canada.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Menaouar
authors.affiliation: Cardiovascular Biochemistry Laboratory, CRCHUM, Montréal, Québec, Canada; Department of Experimental Medicine, McGill University.
authors.forename: Denis
authors.initials: D
authors.lastname: Yip
authors.affiliation: Cardiovascular Biochemistry Laboratory, CRCHUM, Montréal, Québec, Canada.
authors.forename: Bogdan
authors.initials: B
authors.lastname: Danalache
authors.affiliation: Cardiovascular Biochemistry Laboratory, CRCHUM, Montréal, Québec, Canada.
authors.forename: Eric
authors.initials: E
authors.lastname: Plante
authors.affiliation: Department of Surgery, Faculty of Medicine, University of Montreal.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Noiseux
authors.affiliation: Cardiovascular Biochemistry Laboratory, CRCHUM, Montréal, Québec, Canada; Department of Experimental Medicine, McGill University; Department of Medicine, University of Montreal.
authors.forename: Jolanta
authors.initials: J
authors.lastname: Gutkowska
authors.affiliation: Cardiovascular Biochemistry Laboratory, CRCHUM, Montréal, Québec, Canada; Department of Medicine, University of Montreal. Electronic address: marek.jankowski@umontreal.ca.
authors.forename: Marek
authors.initials: M
authors.lastname: Jankowski
mesh_terms: D002316:Cardiotonic Agents / Q000494:pharmacology*; D015687:Cell Hypoxia; D002460:Cell Line; D002478:Cells, Cultured; D017869:Cyclic GMP-Dependent Protein Kinases / Q000378:metabolism; D004353:Drug Evaluation, Preclinical; D032446:Myoblasts / Q000378:metabolism; D015428:Myocardial Reperfusion Injury / Q000188:drug therapy; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D010121:Oxytocin / Q000494:pharmacology*; D011499:Protein Processing, Post-Translational; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D018045:Receptors, Oxytocin / Q000378:metabolism
chemical_list: D002316:Cardiotonic Agents; D017382:Reactive Oxygen Species; D018045:Receptors, Oxytocin; D009569:Nitric Oxide; D010121:Oxytocin; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D051057:Proto-Oncogene Proteins c-akt; D017869:Cyclic GMP-Dependent Protein Kinases
keywords: Apoptosis; Cardiomyocyte; Ischemia–reperfusion; Mitochondria; Oxytocin; Signal transduction