title: Effects of age on DNA double-strand breaks and apoptosis in human sperm.
abstract: OBJECTIVE
  This study was designed to explore the relationship between men's age and DNA damage and apoptosis in human spermatozoa.
  
  
  METHODS
  Semen samples were collected from men between the ages of 20 and 57 years. Sperm DNA double-strand breaks were assessed using the neutral microgel electrophoresis (comet) assay, and apoptosis was estimated using the DNA diffusion assay.
  
  
  METHODS
  Academic medical center.
  
  
  METHODS
  Sixty-six men aged 20 to 57 years were recruited from infertility laboratory and general populations and consented to donate a semen sample. Recruitment was determined by time and day of analysis; the only exclusions were for azoospermia, prostatitis, or prior cancer therapy.
  
  
  METHODS
  None.
  
  
  METHODS
  DNA damage and apoptosis in human sperm.
  
  
  RESULTS
  Age correlated with an increasing percentage of sperm with highly damaged DNA (range: 0-83%) and tended to inversely correlate with percentage of apoptotic sperm (range: 0.3%-23%). For example, percentage of sperm with highly damaged DNA, comet extent, DNA break number, and other comet measures was statistically significantly higher in men aged 36-57 years than in those aged 20-35 years, but percentage apoptosis was statistically significantly lower in the older group. Semen analysis showed percentage motility to be significantly higher in younger age groups.
  
  
  CONCLUSIONS
  This study clearly demonstrates an increase in sperm double-stranded DNA breaks with age. Our findings also suggest for the first time an age-related decrease in human sperm apoptosis. These novel findings may indicate deterioration of healthy sperm cell selection process with age.
authors.affiliation: Department of Bioengineering, University of Washington, Seattle, Washington 98195-7962, USA. narendra@u.washington.edu
authors.forename: Narendra P
authors.initials: NP
authors.lastname: Singh
authors.forename: Charles H
authors.initials: CH
authors.lastname: Muller
authors.forename: Richard E
authors.initials: RE
authors.lastname: Berger
mesh_terms: D000328:Adult; D000367:Age Factors; D000375:Aging / Q000235:genetics*; D017209:Apoptosis / Q000502:physiology*; D004249:DNA Damage; D006801:Humans; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D012661:Semen / Q000166:cytology; D013094:Spermatozoa / Q000166:cytology / Q000502:physiology*