Abstract
In this study, we investigated steroid regulation of the hyaluronan (HA) system in ovine endometrium including HA synthases (HAS), hyaluronidases, and HA receptor-CD44 using 30 adult Welsh Mountain ewes. Eight ewes were kept intact and synchronized to estrous (day 0). Intact ewes were killed on day 9 (luteal phase; LUT; n=5) and day 16 (follicular phase; FOL; n=3). The remaining ewes (n=22) were ovariectomized and then treated (i.m.) with vehicle (n=6) or progesterone (n=8) for 10 days, or estrogen and progesterone for 3 days followed by 7 days of progesterone alone (n=8). Estradiol and progesterone concentrations in plasma correlated with the stage of estrous or steroid treatment. Our results showed trends (P<0.1) and statistically significant effects (P<0.05, by t-test) indicating that LUT had lower HAS1 and HAS2 and higher HAS3 and CD44 mRNA expression compared with FOL. This was reflected in immunostaining of the corresponding HAS proteins. Similarly, in ovariectomized ewes, progesterone decreased HAS1 and HAS2 and increased HAS3 and CD44, whereas estradiol tended to increase HAS2 and decrease CD44. Sometimes, HAS mRNA expression did not follow the same trend observed in the intact animals or the protein expression. HA and its associated genes and receptors were regulated by the steroids. In conclusion, these results show that the level of HA production and the molecular weight of HA in the endometrium are regulated by ovarian steroids through differential expression of different HAS both at the gene and at the protein levels.
Highlights
During the female reproductive cycle, the ovarian steroid hormones estradiol and progesterone play a central role in regulating reproductive events that lead to the establishment of pregnancy
Effect of estrous cycle and ovarian steroids on mRNA expression of genes related to the HA system in the endometrium
The data on endometrial mRNA expression of HA synthases (HAS) (HAS1, HAS2, and HAS3), as well as HYAL1, HYAL2, and CD44, during different stages of the estrous cycle in the intact ewes and in the ovariectomized animals treated with or without progesterone in the presence or absence of estrogen are presented in Tables 1 and 2 respectively
Summary
During the female reproductive cycle, the ovarian steroid hormones estradiol and progesterone play a central role in regulating reproductive events that lead to the establishment of pregnancy. The progesterone-dominant luteal (LUT) phase of the estrous cycle is a window of receptivity of the endometrium to the conceptus and is characterized by uterine gland secretions, producing arrays of hormones, cytokines, and growth factors, collectively referred to as histotroph, which support the blastocyst before implantation (Roberts & Bazer 1988) These changes in the endometrial environment require specific changes in the degree of tissue hydration and glycosaminoglycan content (Tellbach et al 2002) and are associated with ovarian steroid-mediated changes q 2013 Society for Reproduction and Fertility ISSN 1470–1626 (paper) 1741–7899 (online) in the composition and organization of glycosaminoglycans in the extracellular matrix (Cidadao et al 1990). To investigate the specific role of ovarian steroids in the regulation of HA, we used ovariectomized ewes treated with progesterone (OVXP) or a combination of progesterone and estrogen (OVXEP) or vehicle (OVX) and analyzed mRNA and protein expression of HAS (HAS1–3), HYALs (HYAL1 and HYAL2), and receptor CD44 and determined localization, content, and molecular weight distribution of the HA in the endometrium
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