Reproduction Abstracts

Previous studies indicate a pattern of expression for hyaluronan (HA) synthases in the reproduction system regulated by steroid hormones which produce different HA sizes with diverse physiological functions. The objective of the present study was to determine the effect of low molecular weight (LMW) and high molecular weight (HMW) HA on molecular markers of embryo implantation using in vitro model of endometrial cell culture system. Sheep endometrial cells at confluence were treated with 1 mg/ml LMWHA or 1 mg/ml HMWHA or 4-methylumbelliferone (4-MU, 1 mM) or the basic culture media as the negative control for 24 h. mRNA expressions of adhesive molecule cluster domain 44 (CD44) and anti-adhesive gylocprotein mucin 1 (MUC1), the level of phosphorylation of MAPK1/3 proteins and the amount of prostaglandins (PGF_2α and PGE₂) produced into the media were determined. LMW and HMW HA supplementation significantly increased CD44 expression (P<0.05) in the endometrial cells compared to the control, whereas 4-MU treatment had no effect. In contrast to HMWHA which increased MUC1 mRNA expression (P<0.01), LMWHA reduced (P<0.05) it as compared to the control. LMWHA increased total and phosphorylated levels of MAPK1 and MAPK3 levels. 4-MU treatment reduced PGE₂ production (P<0.05) by the endometrial cells, whereas HA supplementation did not influence PGs production. Similar molecular changes were reported at the feto-maternal interface in vivo. Modulation of molecular markers of embryo implantation in a pattern that enhances implantation as demonstrated in this study may be one of the possible mechanisms through which HA facilitates blastocyst implantation.