Temporal and Spatial Regulation of miR-320 in the Uterus during Embryo Implantation in the Rat

Abstract: The implantation process is complex, requiring reciprocal interactions between implantation-competent blastocysts and the receptive uterus. There were reports to show that some microRNAs (miRNAs) may play a key role during embryo implantation in mouse. However, the miR-320 expression profiles in the rat uterus during peri-implantation are unknown. In the present study, we found that the expression level of miR-320 was lower on day 5 of gestation (g.d. 5) in rats than g.d.3 and g.d.4 and restored gradually from g.d.6. MiR-320 was specifically localized in glandular and luminal epithelia and decidua. The expression of miR-320 was not significantly different in the pseudopregnant uterus and decreased in the uteri of rats subjected to activation of delayed implantation. Artificial decidualization and treatment with progesterone increased the miR-320 expression. Thus, miR-320 was differentially expressed in the rat uterus during implantation. The expression level was affected by active blastocysts and decidualization during the window of implantation. Steroid hormones, progesterone stimulated miR-320 expression.