title: Impact of Diet-Induced Obesity and Testosterone Deficiency on the Cardiovascular System: A Novel Rodent Model Representative of Males with Testosterone-Deficient Metabolic Syndrome (TDMetS).
abstract: BACKGROUND
  Current models of obesity utilise normogonadic animals and neglect the strong relationships between obesity-associated metabolic syndrome (MetS) and male testosterone deficiency (TD). The joint presentation of these conditions has complex implications for the cardiovascular system that are not well understood. We have characterised and investigated three models in male rats: one of diet-induced obesity with the MetS; a second using orchiectomised rats mimicking TD; and a third combining MetS with TD which we propose is representative of males with testosterone deficiency and the metabolic syndrome (TDMetS).
  
  
  METHODS
  Male Wistar rats (n = 24) were randomly assigned to two groups and provided ad libitum access to normal rat chow (CTRL) or a high fat/high sugar/low protein "obesogenic" diet (OGD) for 28 weeks (n = 12/group). These groups were further sub-divided into sham-operated or orchiectomised (ORX) animals to mimic hypogonadism, with and without diet-induced obesity (n = 6/group). Serum lipids, glucose, insulin and sex hormone concentrations were determined. Body composition, cardiovascular structure and function; and myocardial tolerance to ischemia-reperfusion were assessed.
  
  
  RESULTS
  OGD-fed animals had 72% greater fat mass; 2.4-fold greater serum cholesterol; 2.3-fold greater serum triglycerides and 3-fold greater fasting glucose (indicative of diabetes mellitus) compared to CTRLs (all p<0.05). The ORX animals had reduced serum testosterone and left ventricle mass (p<0.05). In addition to the combined differences observed in each of the isolated models, the OGD, ORX and OGD+ORX models each had greater CK-MB levels following in vivo cardiac ischemia-reperfusion insult compared to CTRLs (p<0.05).
  
  
  CONCLUSIONS
  Our findings provide evidence to support that the MetS and TD independently impair myocardial tolerance to ischemia-reperfusion. The combined OGD+ORX phenotype described in this study is a novel animal model with associated cardiovascular risk factors and complex myocardial pathology which may be representative of male patients presenting with TDMetS.
authors.affiliation: Heart Foundation Research Centre, Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia.
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Donner
authors.affiliation: Heart Foundation Research Centre, Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia.
authors.forename: Grace E
authors.initials: GE
authors.lastname: Elliott
authors.affiliation: School of Allied Health Sciences, Griffith University, Gold Coast, Queensland, Australia.
authors.forename: Belinda R
authors.initials: BR
authors.lastname: Beck
authors.affiliation: Heart Foundation Research Centre, Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Bulmer
authors.affiliation: Heart Foundation Research Centre, Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia.
authors.forename: Eugene F
authors.initials: EF
authors.lastname: Du Toit
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D004032:Diet / Q000009:adverse effects*; D004195:Disease Models, Animal; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood* / Q000139:chemically induced; D015428:Myocardial Reperfusion Injury / Q000097:blood*; D009765:Obesity / Q000097:blood* / Q000139:chemically induced; D051381:Rats; D017208:Rats, Wistar; D013739:Testosterone / Q000172:deficiency*; D014280:Triglycerides / Q000097:blood
chemical_list: D001786:Blood Glucose; D014280:Triglycerides; D013739:Testosterone