title: Preconditioning by 17beta-estradiol in isolated rat heart depends on PI3-K/PKB pathway, PKC, and ROS.
abstract: To study the cell signaling events leading to 17beta-estradiol (E(2))-induced acute cardioprotection, we subjected isolated rat hearts to three 5-min cycles of 10 microM E(2) before 30 min of regional ischemia, followed by 2 h of reperfusion. Protection was judged by changes in infarct size in percentage of risk zone volume. To test the importance of phosphoinositide 3-kinase (PI3-K), protein kinase C (PKC), or reactive oxygen species (ROS) in E(2)-induced protection, we combined wortmannin (1 microM), chelerythrine (2 microM), and 2-mercaptopropionylglycine (300 microM), respectively, with E(2) exposure. Changes in phosphorylation of protein kinase B (PKB) and selected PKC isoforms were tested by immunoblotting of total lysates and subcellular fractions, along with assessment of PKC translocation from soluble to membrane fraction of heart tissue homogenates. Intracellular ROS levels induced by E(2) preconditioning were investigated. E(2) preconditioning led to significant reduction in infarct size from 31.8 +/- 5.3 to 20.2 +/- 2.6% in male hearts and from 42.7 +/- 4.7 to 17.1 +/- 3.4% in female hearts (P < 0.05). Protection was abolished by wortmannin (30.0 +/- 3.2%), chelerythrine (45.1 +/- 4.4%), and 2-mercaptopropionylglycine (36.8 +/- 4.7%). E(2) preconditioning induced phosphorylation of PKB, PKCalpha, and PKCepsilon and membrane translocation of PKCepsilon and PKCdelta. Intracellular ROS levels were found elevated after transient treatment with hormone. Therefore, our data demonstrate the ability of E(2) to induce preconditioning-like cardioprotection via cell signaling events shared by classic ischemic preconditioning.
authors.affiliation: Dept. of Biochemistry, Institute of Medical Biology, Faculty of Medicine, Univ. of Tromsø, N-9037 Tromsø, Norway. mikhails@fagmed.uit.no
authors.forename: Mikhail A
authors.initials: MA
authors.lastname: Sovershaev
authors.forename: Elena M
authors.initials: EM
authors.lastname: Egorina
authors.forename: Thomas V
authors.initials: TV
authors.lastname: Andreasen
authors.forename: Anne K
authors.initials: AK
authors.lastname: Jonassen
authors.forename: Kirsti
authors.initials: K
authors.lastname: Ytrehus
mesh_terms: D000470:Alkaloids; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D053119:Benzophenanthridines; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004958:Estradiol / Q000502:physiology*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D006321:Heart / Q000187:drug effects* / Q000502:physiology; D019157:Ischemic Preconditioning, Myocardial; D008297:Male; D009203:Myocardial Infarction / Q000473:pathology / Q000517:prevention & control; D010617:Phenanthridines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015427:Reperfusion Injury / Q000378:metabolism; D015398:Signal Transduction; D008625:Tiopronin / Q000494:pharmacology; D000077191:Wortmannin
chemical_list: D000470:Alkaloids; D000730:Androstadienes; D053119:Benzophenanthridines; D004791:Enzyme Inhibitors; D010617:Phenanthridines; D047428:Protein Kinase Inhibitors; D017382:Reactive Oxygen Species; D004958:Estradiol; D008625:Tiopronin; C016299:chelerythrine; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D011493:Protein Kinase C; D000077191:Wortmannin