Regulation of prostaglandin D synthase and prostacyclin synthase in the endometrium of cyclic, pregnant, and pseudopregnant rats and their regulation by sex steroids

Abstract

Prostaglandins (PGs) are critical regulators of a number of reproductive processes. To date, the presence and regulation of PGS in the rat endometrium have not yet been described. The objective of the present study was to investigate the expression of PGD synthase (PGDS) and prostacyclin synthase (PGIS) in the endometrium. Endometrial proteins and tissues were collected from cyclic non-pregnant, pregnant, and steroid-induced pseudopregnant rats. PGIS and PGDS were detected in the endometrium of cyclic, pregnant, and pseudopregnant rats but were not influenced by the estrous cycle. During early pregnancy, PGIS was significantly higher at day 5 and was gradually decreased from day 5 . 5 to 6 . 5. Later during pregnancy, PGIS was maximal on day 12 and gradually decreased to the end of pregnancy. PGDS expression was high during early and was maximal at the end of pregnancy. During pseudopregnancy, PGDS and PGIS were increased in a time-dependent manner and were maximal at day 5. Immunohistochemical analysis revealed that PGDS and PGIS were found in luminal as well as glandular epithelial cells and in stroma during late pregnancy. We also found a significant increase of PGD 2 serum metabolite at days 21 and 22 of pregnancy. During steroidinduced pseudopregnancy, PGI 2 serum metabolite was increased in a time-dependent manner and was maximal at day 7. These results suggest that PGDS and PGIS are present and could be regulated by steroids in the rat uterus during pregnancy, and that the endometrium could be a significant source of PGD 2 and PGI 2 at specific times during pregnancy.

Spatial differences in gene expression in the bovine oviduct

“…Prostaglandin D2 synthase 21 kDa (PTGDS or PGDS) synthetizes PGD2 and induces sleep, allergic responses, inhibition of platelet aggregation, and relaxation of vascular and non-vascular smooth muscle (Kengni et al 2007). There are two types of PGD2 synthase: lipocalin type PGDS (L-PGDS) and hematopoietic PGDS (H-PGDS).…”

“…H-PGDS is highly expressed in the rat oviduct and also in human uterine epithelial cells, endometrial gland cells and trophoblast (Kanaoka et al 1997, Michimata et al 2002. Ptgds is upregulated during pregnancy in rats and it has been suggested that its expression is dependent on the presence of an embryo (Kengni et al 2007). In addition, in humans PGD2 may contribute to the maintenance of pregnancy by suppressing antigen presentation (Michimata et al 2002).…”

Bridging endometrial receptivity and implantation: network of hormones, cytokines, and growth factors

“…Previously, we have shown that prostaglandin-D synthase and prostacyclin synthase are present in the rat uterus during pregnancy and high levels could be seen at the early stage of pregnancy. The steroids controlled the expression of various PG synthases, which further produce PGD 2 and PGI 2 at specific times during pregnancy in endometrium (Kengni et al 2007). Blockade of PG synthesis before or during the time of implantation causes complete inhibition, a delay in implantation or a reduction in the number of implantation sites with diminished decidual tissue.…”

Diverse Roles of Prostaglandins in Blastocyst Implantation

“…In early pregnancy in rats, COX-2 expression is increased between days 2 to 5 [89] suggesting that PGs are required in the process of stromal cells decidualization. While PGE 2 and PGF 2 α are the main PGs involved, prostacyclin (PGI 2 ) has also been implicated in decidualization in view that in mice, the expression of PGIS significantly increases at day 5 and gradually decreases thereafter [90]. In addition to the elevated expression of PG biosynthetic enzymes, the reported increase in the expression of EP2 and PPAR- δ in mouse decidual cells further provides evidence on the involvement of PGs in this process [91].…”