title: Nitric oxide as a regulator in preimplantation embryo development and apoptosis.
abstract: OBJECTIVE
  To investigate the mechanisms of nitric oxide (NO) in the development and apoptosis of preimplantation mouse embryos.
  
  
  METHODS
  Prospective, controlled study.
  
  
  METHODS
  Medical college laboratory.
  
  
  METHODS
  Two-cell embryos from outbred ICR mice.
  
  
  METHODS
  Hyperstimulation protocol, two-cell embryos were collected, then treated with or without an NO synthase inhibitor (L-NAME) or an NO donor (SNP) and combined with a cGMP analogue (8-Br-cGMP) or a selective inhibitor of NO-sensitive soluble guanylyl cyclase (ODQ).
  
  
  METHODS
  The development of ICR mouse embryo from two cells to blastocyst stages in vitro.
  
  
  RESULTS
  The development of blastocyst was inhibited by L-NAME in a concentration-dependent manner (0.1-10 microM) and 0.1 microM SNP reversed this effect (80.5% of control). Annexin-V/propidium iodide and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling techniques demonstrated that excessive NO (> or =10 microM) might induce apoptosis in the mouse embryos. 8-Br-cGMP reversed the inhibitory effect of L-NAME and rescued the embryo growth. ODQ inhibited the embryo development in a dose-responsive fashion (0.1--100 microM) but had no effect in the NO-induced embryo apoptosis. P53 and Bax were found to be up-regulated during the embryo fragmentation.
  
  
  CONCLUSIONS
  These results indicate that the cGMP pathway might be involved in the NO-regulated embryonic development, but not in NO-induced apoptosis, for which P53/Bax pathway might be involved.
authors.affiliation: Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Taipei Medical College, Taipei, Taiwan.
authors.forename: H W
authors.initials: HW
authors.lastname: Chen
authors.forename: W S
authors.initials: WS
authors.lastname: Jiang
authors.forename: C R
authors.initials: CR
authors.lastname: Tzeng
mesh_terms: D000818:Animals; D021461:Animals, Outbred Strains; D017209:Apoptosis / Q000502:physiology*; D001755:Blastocyst / Q000502:physiology; D006152:Cyclic GMP / Q000502:physiology; D004622:Embryo, Mammalian / Q000502:physiology*; D047108:Embryonic Development; D005314:Embryonic and Fetal Development / Q000502:physiology; D005260:Female; D051379:Mice; D009569:Nitric Oxide / Q000502:physiology*; D011247:Pregnancy; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D015854:Up-Regulation; D051028:bcl-2-Associated X Protein
chemical_list: C494827:Bax protein, mouse; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; D009569:Nitric Oxide; D006152:Cyclic GMP