title: Obesity is associated with increased seminal insulin and leptin alongside reduced fertility parameters in a controlled male cohort.
abstract: BACKGROUND
  Obesity appears to be associated with male reproductive dysfunction and infertility, although this has been inconsistent and inconclusive. Insulin and leptin are known mediators and modulators of the hypothalamus-pituitary-testes axis, contributing to the regulation of male reproductive potential and overall wellbeing. These hormones are also present in semen influencing sperm functions. Although abdominal obesity is closely associated with insulin resistance (hyperinsulinaemia), hyperleptinaemia and glucose dysfunction, changes in seminal plasma concentrations of insulin, leptin and glucose in obese males has not previously been investigated.
  
  
  METHODS
  This small case controlled study assessed serum and seminal concentrations of insulin, leptin and glucose in obese (BMI > =30; n = 23) and non-obese (BMI < 30; n = 19) males. Following a detailed medical history and examination, participants meeting the inclusion criteria were entered for data analysis. Body parameters such as BMI, waist and hip circumference and the waist hip ratio were measured. Serum and semen samples were collected and assayed for insulin, leptin and glucose. Semen samples also underwent a standard semen analysis, with sperm mitochondrial membrane potential (MMP) and DNA fragmentation (DF).
  
  
  RESULTS
  Obesity was associated with increased serum and seminal insulin and leptin, with no significant difference in seminal glucose. Serum and seminal concentrations of insulin and leptin were positively correlated. Furthermore, obesity was associated with decreased sperm concentration, sperm vitality and increased MMP and DF, with a non-significant impact on motility and morphology.
  
  
  CONCLUSIONS
  Hyperinsulinaemia and hyperleptinaemia are associated with increased seminal insulin and leptin concentrations, which may negatively impact male reproductive function in obesity. Insulin was also found to be highly concentrated in the seminal plasma of both groups. This data will contribute to the contradictive information available in the literature on the impact of obesity and male reproduction.
authors.forename: Kristian
authors.initials: K
authors.lastname: Leisegang
authors.forename: Patrick J D
authors.initials: PJ
authors.lastname: Bouic
authors.forename: Roelof
authors.initials: R
authors.lastname: Menkveld
authors.affiliation: Department of Medical Biosciences, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa. rhenkel@uwc.ac.za.
authors.forename: Ralf R
authors.initials: RR
authors.lastname: Henkel
mesh_terms: D000328:Adult; D015992:Body Mass Index; D016022:Case-Control Studies; D015331:Cohort Studies; D053938:DNA Fragmentation; D006801:Humans; D006946:Hyperinsulinism / Q000209:etiology; D007248:Infertility, Male / Q000209:etiology*; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D020738:Leptin / Q000097:blood / Q000378:metabolism*; D008297:Male; D053078:Membrane Potential, Mitochondrial; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000378:metabolism / Q000503:physiopathology*; D010865:Pilot Projects; D012661:Semen / Q000378:metabolism*; D055101:Semen Analysis; D013019:South Africa; D015854:Up-Regulation; D055815:Young Adult
chemical_list: D007328:Insulin; D020738:Leptin