title: Testosterone protects cardiac myocytes from superoxide injury via NF-κB signalling pathways.
abstract: OBJECTIVE
  Cellular and molecular mechanisms underlying the effects of androgenic hormone testosterone on the heart remain unclear. This study examined the impact of testosterone on viability of cardiac myocytes and the role of NF-κB signalling pathways.
  
  
  METHODS
  Rat H9c2 myocytes were cultured in steroid-free media and incubated with hydrogen peroxide (H2O2, 200 μM, 6h). NF-κB expression was knocked down by RelA (p65) siRNA interference. Testosterone (5-100 nM, 24-48 h) was provided into the media and androgen receptor (AR) blocked by flutamide (100 nM). Cell apoptotic/necrotic death was determined by morphological examination and flow-cytometric analysis. Gene expression was examined by Western blotting analysis.
  
  
  RESULTS
  Testosterone supplements reduced the superoxide-induced apoptotic/necrotic death, stimulated NF-κB (RelA) expression, activated Akt activity, and inhibited Caspase-3 expression in the cardiac myocytes. The hormonal effects were abolished by either AR blocker flutamide or NF-κB-knockdown. Testosterone also induced ERK1/2 activation, which was not affected by flutamide or NF-κB knockdown, and blocking the ERK activity did not affect the protective effect of the hormone on the cells.
  
  
  CONCLUSIONS
  This study demonstrates that exogenous testosterone supplementation protects cardiac myocytes from superoxide injury via AR mediation and dependent on normally functional canonical NF-κB (RelA/p50) signalling pathways. The NF-κB signalling may be an important key molecular basis for myocardial benefits of hormone (testosterone) therapy.
authors.affiliation: Department of Biotechnology, Guilin Medical University, Guilin, Guangxi 541001, PR China. Electronic address: fyxiao@hotmail.com.
authors.forename: Fu-Ying
authors.initials: FY
authors.lastname: Xiao
authors.affiliation: Department of Medicine, Monash University Central Clinical School, Prahran, Melbourne, Victoria 3181, Australia.
authors.forename: Lina
authors.initials: L
authors.lastname: Nheu
authors.affiliation: Department of Medicine, Monash University Central Clinical School, Prahran, Melbourne, Victoria 3181, Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Komesaroff
authors.affiliation: Department of Medicine, Monash University Central Clinical School, Prahran, Melbourne, Victoria 3181, Australia.
authors.forename: Shanhong
authors.initials: S
authors.lastname: Ling
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000235:genetics / Q000276:immunology; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects*; D005786:Gene Expression Regulation / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000276:immunology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects* / Q000276:immunology* / Q000473:pathology; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats; D011944:Receptors, Androgen / Q000276:immunology; D015398:Signal Transduction / Q000187:drug effects; D013481:Superoxides / Q000276:immunology*; D013739:Testosterone / Q000276:immunology / Q000494:pharmacology*
chemical_list: D016328:NF-kappa B; D034741:RNA, Small Interfering; D011944:Receptors, Androgen; D013481:Superoxides; D013739:Testosterone; D006861:Hydrogen Peroxide; D053148:Caspase 3
keywords: Androgen receptor (AR); Cardiac myocytes; Flutamide (PubChem CID 3397); Hydrogen peroxide (PubChem CID 784); Nuclear factor-κB (NF-κB); Superoxide injury; Testosterone; Testosterone (PubChem CID 6013)