Abstract:
This study was performed to clarify the critical role of optimal levels ofnitric oxide on fecun-dity in mice during the implantation period. Maturefemale pregnant mice were treated with either nitric oxide donor molsidomine(3, 15, 60 mg kg<emph type="7">-1) or nitric oxide synthase inhibitorNG-nitro-L-arginine methyl ester (L-name; 0.3, 1.5, 6 mgkg<emph type="7">-1) every 12 h, seven times from the night of Day 2 toDay 5 of gestation. They were killed on Day 14 of gestation. Pregnancy ratesin each group (n = 22) and the number of live orabsorbed fetuses in each mouse was calculated. The pregnancy rates in theexperimental group were reduced in a dose-dependent manner. The rate in thecontrol group was 100%, whereas those in the 60-mg mol-sidomine and6-mg L-name groups were 40.9 and 31.8%, respectively. Histologicalanalysis of uteri on Day 5 of gestation after treatment with 60 mg molsidomineor 6 mg L-name suggested retarded decidualization of stromal cells ordefective function of predecidualized cells. In conclusion, optimal levels ofnitric oxide are crucial for endometrial function and embryo implantation.