title: Estradiol-induced protection against ischemia-induced heart mitochondrial damage and caspase activation is mediated by protein kinase G.
abstract: We have previously reported that estradiol can protect heart mitochondria from the ischemia-induced mitochondrial permeability transition pore-related release of cytochrome c and subsequent apoptosis. In this study we investigated whether the effect of 17-beta-estradiol on ischemia-induced mitochondrial dysfunctions and apoptosis is mediated by activation of signaling protein kinases in a Langendorff-perfused rat heart model of stop-flow ischemia. We found that pre-perfusion of non-ischemic hearts with 100nM estradiol increased the resistance of subsequently isolated mitochondria to the calcium-induced opening of mitochondrial permeability transition pore and this was mediated by protein kinase G. Loading of the hearts with estradiol prevented ischemia-induced loss of cytochrome c from mitochondria and respiratory inhibition and these effects were reversed in the presence of the inhibitor of Akt kinase, NO synthase inhibitor L-NAME, guanylyl cyclase inhibitor ODQ and protein kinase G inhibitor KT5823. Estradiol prevented ischemia-induced activation of caspases and this was also reversed by KT5823. These findings suggest that estradiol may protect the heart against ischemia-induced injury activating the signaling cascade which involves Akt kinase, NO synthase, guanylyl cyclase and protein kinase G, and results in blockage of mitochondrial permeability transition pore-induced release of cytochrome c from mitochondria, respiratory inhibition and activation of caspases.
authors.affiliation: Institute for Biomedical Research, Department of Biochemistry, Kaunas University of Medicine, Eiveniu 4, LT-50009 Kaunas, Lithuania.
authors.forename: Ramune
authors.initials: R
authors.lastname: Morkuniene
authors.forename: Odeta
authors.initials: O
authors.lastname: Arandarcikaite
authors.forename: Laima
authors.initials: L
authors.lastname: Ivanoviene
authors.forename: Vilmante
authors.initials: V
authors.lastname: Borutaite
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D002227:Carbazoles / Q000494:pharmacology; D020169:Caspases / Q000378:metabolism*; D017869:Cyclic GMP-Dependent Protein Kinases / Q000378:metabolism*; D045304:Cytochromes c / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D066298:In Vitro Techniques; D008929:Mitochondria, Heart / Q000187:drug effects* / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins / Q000378:metabolism; D000083162:Mitochondrial Permeability Transition Pore; D008955:Models, Cardiovascular; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D002227:Carbazoles; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; C073601:KT 5823; D004958:Estradiol; D045304:Cytochromes c; D017869:Cyclic GMP-Dependent Protein Kinases; D020169:Caspases; D002118:Calcium; D019331:NG-Nitroarginine Methyl Ester