Disruption of the endothelial nitric oxide synthase gene affects ovulation, fertilization and early embryo survival in a knockout mouse model

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.