Nitric oxide as a regulator in preimplantation embryo development and apoptosis.
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.
Chen
H W
HW
Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Taipei Medical College, Taipei, Taiwan.
Jiang
W S
WS
Tzeng
C R
CR
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
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