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Disruption of the endothelial nitric oxide synthase gene affects ovulation, fertilization and early embryo survival
Pilar Pallares1, Rosa A Garcia-Fernandez, Luis M Criado
1Fundacion Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Melchor Fernandez Almagro 3, 28029 Madrid, Spain.
Abstract:
Two consecutive experiments determined whether disruption of the endothelial nitric oxide synthases (NOS) gene (Nos3) affects ovulation, fertilization, implantation, and embryo development. In the first trial, Nos3-knockout mice (groups Nos3(-/-)) and wild-type mice (groups Nos3(+/+)) showed significant differences in mean number of corpora lutea (9.7+/-1.2 in Nos3(-/-) versus 14.2+/-1.2 in Nos3(+/+); P<0.01), rate of anovulation (48.3+/-7.3% in Nos3(-/-) versus 29.7+/-6.3 in Nos3(+/+); P<0.05), total mean number of recovered oocytes/zygotes (4.0+/-1.1 in Nos3(-/-) versus 10.4+/-1.6 in Nos3(+/+); P<0.01), and non-fertilization rate (50.7 in Nos3(-/-) versus 3.3% in Nos3(+/+); P<0.001). In the second trial, implantation and early pregnancy losses in Nos3-knockout and wild-type dams were detected by real-time ultrasound imaging. The number of embryos reaching implantation was higher in Nos3(+/+) than in Nos3(-/-) mice (7.5+/-0.4 vs 4.0+/-0.4; P<0.005); thereafter, embryo losses were detected between days 8.5 and 13.5, in 62.5% of the Nos3-knockout dams and, at days 10.5 and 11.5, in 16.7% of the control females (P<0.005). Thus, NO and NOS3 deficiencies affect reproductive and developmental features in the Nos3-knockout mouse model.
Insights
Disrupting the endothelial nitric oxide synthase (NOS3) gene significantly impairs ovulation, fertilization, and embryo development in mice. These findings highlight the critical role of NOS3 in successful reproduction and pregnancy outcomes.
Area of Science:
- Reproductive Biology
- Developmental Biology
- Molecular Genetics
Background:
- Endothelial nitric oxide synthase (NOS3) plays a crucial role in vascular function.
- The impact of NOS3 deficiency on female reproductive processes remains incompletely understood.
- Nitric oxide (NO) is implicated in various physiological functions, including reproduction.
Purpose of the Study:
- To investigate the effects of disrupting the NOS3 gene on ovulation, fertilization, implantation, and embryo development in a mouse model.
- To determine the specific reproductive and developmental deficits associated with NOS3 deficiency.
Main Methods:
- Two consecutive experiments were conducted using Nos3-knockout (Nos3(-/-)) and wild-type (Nos3(+/+)) mice.
- Reproductive parameters including corpora lutea count, anovulation rate, oocyte/zygote recovery, and fertilization rates were assessed.
- Implantation and early pregnancy losses were monitored using real-time ultrasound imaging.
Main Results:
- Nos3(-/-) mice exhibited significantly lower corpora lutea counts and higher anovulation rates compared to Nos3(+/+) mice.
- Fertilization rates were markedly reduced in Nos3(-/-) mice, with a higher non-fertilization rate.
- Implantation rates were lower in Nos3-knockout dams, and they experienced significantly higher rates of early embryo loss during pregnancy.
Conclusions:
- Deficiency in NOS3 significantly impairs key stages of female reproduction, from ovulation to embryo development.
- The study demonstrates that impaired nitric oxide signaling due to NOS3 disruption negatively affects reproductive success.
- These findings underscore the importance of the NOS3/NO pathway in mammalian reproductive health and early development.
