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KMID : 0350519960490020583
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Journal of Catholic Medical College
1996 Volume.49 No. 2 p.583 ~ p.594
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Effects of Exposure to Nitrous Oxide After Fertilization on Embryo in Vitro and in Vivo Development in Mice
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Abstract
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It is well known that nitrous oxide exposure for long periods during gestation causes the in creased fetal wastage, growth retardation, morphological abnormalities of body structures in rodents. Most studies have explained deleterious effects of
nitrous
oxide on postimplantation embryo development, but the effects of exposure prior to implantation is little known. Therefore, the aim of this study was to evaluate the effects of nitrous oxide on embryo after the fertilization in superovulated
BALB/c
mice.
In this experiment, pregnant rats were exposed to 70% nitrous oxide in oxygen for 6, 12 and 24 hours beginning on the day of gestation (gestation 0), and 2-cell stage embryos were removed from the oviduct and cultured to blastocyst. The embryo
development was scored at 24 hours (4-cell), 72 hours (morula) and 96 hours (blastocyst) of culture. To evaluate the protective effect of folinic acid or methionine against inhibition of 2-cell embryo development caused by 24 hours of nitrous
oxide,
30mg/kg folinic acid or 70mg/kg methionine was injected intraperitoneally at 30 minutes before the nitrous oxide exposure.
Another experiment was performed to probe embryonic development in vivo based on embryonic developmental failure in vitro by nitrous oxide exposure.
Another experiment was performed to probe embryonic development in vivo based on embryonic developmental failure in vitro by nitrous oxide. Beginning on the day of gestation, pregnant rats were exposed to 70% nitrous oxide for 24 hours and then
reproductive data were determined at cesarean section of 16th day of gestation and the protective effects of folinic acid or those of methonine were also evaluated.
@ES The results were as follows:
@EN 1. No significant differences in development of 4-cell embryos were observed among the exposure groups. Morula and blastocyst development expressed as cleavage rate were significantly lower in 12 hours and 24 hours nitrous oxide group than in
control group and 6 hours nitrous oxide group. In 24 hours nitrous oxide group pretreatment of folinic acid or methionine did not associated with the development of 2-cell embryos.
2. Pregnancy rate and mean number of implantations were significantly lower in 24 hours nitrous oxide group than in control group.
3. No significant differences in percentage of living fetus and dead fetus and resorption per implantation and mean fetal weight and crown-rump length were observed between nitrous oxide group and control group.
4. There was no significant difference in pregnancy rate, mean number of implantations between the nitrous oxide group and the nitrous oxide exposed group receiving methionine and folinic acid.
These results suggest that the exposure to high concentration of nitrous oxide for a long time after the fertilization in mice may be possibility of the early abortion of embryos, whereas there is not influence on fetus after the implantation.
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