title: Does endogenous testosterone mediate the lower preconditioning threshold in males?
abstract: BACKGROUND
  Preconditioning is injury-induced protection from subsequent insult. Recent data indicates that males have lower preconditioning thresholds compared to females. Therefore, we hypothesized that testosterone may mediate the lower preconditioning threshold observed in males.
  
  
  METHODS
  Adult normal and castrated male Sprague-Dawley rats (n = 4-5) were given intraperitoneal (i.p.) injections of 125 or 500 microg/kg Salmonella typhimurium lipopolysaccharide (ETX) or 0.4 ml normal saline (NS). Another i.p. injection of 500 microg/kg ETX (injury dose) was given 24 h later. After 6 h, myocardial function was evaluated via the Langendorff perfusion model. Shams received only NS, while non-preconditioned rats (PC-) received NS followed by the 500 microg/kg ETX injury dose. Preconditioned rats received injections of 125 mug/kg ETX (PC +125) or 500 microg/kg ETX (PC +500), followed by the 500 microg/kg ETX injury dose.
  
  
  RESULTS
  Normal PC +125 and PC +500 males were preconditioned and maintained cardiac function similar to shams (P > 0.05). Castrated PC +125 and PC +500 males were also preconditioned and maintained cardiac function similar to castrated shams (P > 0.05). Conversely, both normal and castrated PC-males showed significantly decreased cardiac function compared to shams (P < 0.05).
  
  
  CONCLUSIONS
  Endogenous testosterone does not mediate the lower preconditioning threshold in males.
authors.affiliation: Department of Surgery, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
authors.forename: Nicholas T
authors.initials: NT
authors.lastname: Nelson
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Mahomed
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Pitcher
authors.forename: Ben M
authors.initials: BM
authors.lastname: Tsai
authors.forename: Meijing
authors.initials: M
authors.lastname: Wang
authors.forename: Yousuf
authors.initials: Y
authors.lastname: Mahomed
authors.forename: John W
authors.initials: JW
authors.lastname: Brown
authors.forename: Paul
authors.initials: P
authors.lastname: Crisostomo
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Meldrum
mesh_terms: D000818:Animals; D002369:Castration; D007249:Inflammation; D019194:Ischemic Preconditioning; D008070:Lipopolysaccharides / Q000633:toxicity; D008297:Male; D009206:Myocardium / Q000473:pathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012486:Salmonella typhimurium / Q000472:pathogenicity; D012737:Sex Factors; D013739:Testosterone / Q000502:physiology*
chemical_list: D008070:Lipopolysaccharides; D013739:Testosterone