title: Leptin protects H9c2 rat cardiomyocytes from H2O2-induced apoptosis.
abstract: Obesity is a known risk factor for induction of myocardial infarction, but, paradoxically, may also confer a protective effect against subsequent remodeling leading to heart failure. In this study, we investigated the effect of leptin, the product of the obese (ob) gene, on cardiomyocyte apoptosis, a well-characterized component of cardiac remodeling after myocardial infarction. Exposing H9c2 cells to H(2)O(2) decreased cell viability, and this was attenuated by pretreating cells with leptin for 1 h, but not 24 h. Leptin also attenuated the ability of H(2)O(2) to increase phosphatidylserine exposure and annexin V binding. Further investigation of underlying mechanisms of leptin's protective effect demonstrated that the H(2)O(2)-induced decrease in mitochondrial membrane potential (Psi) leading to cytochrome c release was attenuated by leptin pretreatment, and this was associated with reduced translocation of the pro-apoptotic Bax protein to the mitochondrial membrane. Finally, leptin prevented H(2)O(2)-induced increases in caspase-3 cleavage and activity, although again 24 h leptin pretreatment did not confer significant protection. In summary, we have demonstrated that acute leptin pretreatment mediates anti-apoptotic effects in H9c2 rat cardiomyocytes, which may be of significance in clarifying the direct impact of leptin on the heart.
authors.affiliation: Department of Biology, York University, Toronto, Ontario, Canada.
authors.forename: Megumi
authors.initials: M
authors.lastname: Eguchi
authors.forename: Yuantao
authors.initials: Y
authors.lastname: Liu
authors.forename: Eyun-Jung
authors.initials: EJ
authors.lastname: Shin
authors.forename: Gary
authors.initials: G
authors.lastname: Sweeney
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D045304:Cytochromes c / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000037:antagonists & inhibitors*; D020738:Leptin / Q000494:pharmacology*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010718:Phosphatidylserines / Q000032:analysis; D051381:Rats; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D020738:Leptin; D010718:Phosphatidylserines; D051028:bcl-2-Associated X Protein; D045304:Cytochromes c; D006861:Hydrogen Peroxide; D053148:Caspase 3