title: Human sperm endothelial nitric oxide synthase expression: correlation with sperm motility.
abstract: OBJECTIVE
  To characterize the pattern of endothelial nitric oxide synthase (eNOS) expression on human spermatozoa and to determine whether sperm eNOS expression correlates with sperm function.
  
  
  METHODS
  Prospective, observational study.
  
  
  METHODS
  University infertility clinic.
  
  
  METHODS
  Twelve nonazoospermic infertile men.
  
  
  METHODS
  Semen samples (n=12) obtained from nonazoospermic infertile men were fractionated on discontinuous Percoll gradients. Endothelial nitric oxide synthase staining on spermatozoa was correlated with sperm motility in Percoll gradient-fractionated spermatozoa. Endothelial nitric oxide synthase protein was detected with the use of a previously characterized monoclonal antibody. Control slides were incubated with preabsorbed antibody or mouse immunoglobulin G.
  
  
  METHODS
  Localization of eNOS on human spermatozoa and correlation between the pattern of sperm eNOS expression and sperm motility.
  
  
  RESULTS
  Morphologically normal spermatozoa exhibited postacrosomal and equatorial eNOS immunostaining. However, abnormally shaped spermatozoa often exhibited aberrant staining (in the midpiece and/or head region). A significant negative correlation was observed between the percentage of sperm with aberrant eNOS immunostaining and the percentage of motile sperm (r=-.46).
  
  
  CONCLUSIONS
  The specific localization of eNOS to human spermatozoa suggests that nitric oxide may be involved in normal sperm physiology. However, aberrant patterns of sperm eNOS expression are associated with decreased sperm motility, possibly through the generation of excessive cytotoxic oxidants.
authors.affiliation: The Population Council, Center for Biomedical Research, New York, New York, USA.
authors.forename: M K
authors.initials: MK
authors.lastname: O'Bryan
authors.forename: A
authors.initials: A
authors.lastname: Zini
authors.forename: C Y
authors.initials: CY
authors.lastname: Cheng
authors.forename: P N
authors.initials: PN
authors.lastname: Schlegel
mesh_terms: D006801:Humans; D007150:Immunohistochemistry; D007248:Infertility, Male / Q000201:enzymology*; D016014:Linear Models; D008297:Male; D019001:Nitric Oxide Synthase / Q000096:biosynthesis*; D052250:Nitric Oxide Synthase Type III; D011446:Prospective Studies; D013081:Sperm Motility / Q000502:physiology*; D013094:Spermatozoa / Q000201:enzymology*
chemical_list: C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III