Immunocytochemical localization and changes in endometrial progestin receptor protein during the porcine oestrous cycle and early pregnancy

Abstract

Changes of progesterone receptor (PR) protein and cellular localization in the endometrium were evaluated during the oestrous cycle and early pregnancy of the gilt. During the oestrous cycle, the concentration of total PR protein within the endometrium was highest on Days 0-5 and decreased on Day 10. The endometrial concentration of PR reached a nadir on Day 12 and this level was maintained throughout the remainder of the oestrous cycle (Day 18). In pregnant gilts, the concentration of endometrial PR protein from Day 10 to Day 18 was similar to that in cyclic gilts. Western blot analysis with antiserum specific for the A and B isoforms of PR indicated that porcine endometrium expresses both isoforms of PR. Immunostaining was detectable for both the A and B isoforms of PR from Day 0 to Day 12 of the oestrous cycle. However, no staining was observed on Day 15 and Day 18 of the oestrous cycle or pregnancy Immunocytochemical localization of PR in the endometrium of cyclic gilts and pregnant gilts indicated that there was intense staining for PR in surface epithelium and glandular epithelium during oestrus (Day 0) and on Day 5. However, the staining was less intense on Day 7 and Day 10 of the oestrous cycle and no epithelial staining was observed after Day 12. PRs were present in the stroma and myometrium throughout the oestrous cycle and early pregnancy. The presence of conceptuses during pregnancy did not affect the loss of PR from the uterine epithelium after Day 10 of gestation. Down-regulation of epithelial PR might be one factor involved in the timing of luteolysis during the oestrous cycle as well as conceptus growth and placentation during early pregnancy.

Identification of a 71 kDa protein as a putative non-genomic membrane progesterone receptor in boar spermatozoa

“…2). Furthermore, when Western blot analysis was performed using the other boar tissues including uterus, which is known to contain genomic progesterone receptor isoforms A and B (Geisert et al 1994, Slomezynska et al 2000, the 71 kDa protein was detected only from the membrane fraction of spermatozoa in contrast to the 86 and 120 kDa proteins detected from the cytosolic fraction of uterus by mAb C-262, verifying that 71 kDa protein is a novel protein with a high probability of being a novel mPR. Even though mAb C-262 detected a single protein band of 71 kDa in the Western blot analysis, since the immunoreactivity cannot guarantee the presence of a functional progesterone receptor, we performed the ligand blot assay.…”

Temporal and spatial associations of oestrogen receptor alpha and progesterone receptor in the endometrium of cyclic and early pregnant mares

“…Previous studies in ewes (Ott et al 1993, Spencer & Bazer 1995, sows (Geisert et al 1993(Geisert et al , 1994 and mares (Tomanelli et al 1991, McDowell et al 1999) demonstrated relatively high levels of oestrogen and progesterone receptor levels around oestrus, when peripheral levels of oestrogen are high, and low levels during mid-to late-dioestrus, when circulating progesterone levels are high. Therefore, we hypothesized that regulation of endometrial steroid receptors during the oestrous cycle of mares is similar to that described for sheep and involves both changes in circulating levels of oestrogen and progesterone as well as temporal and spatial changes in the expression of their respective receptors (Spencer & Bazer 2002).…”

“…Studies in sheep (Ott et al 1993, Spencer & Bazer 1995, pigs (Geisert et al 1993(Geisert et al , 1994 and mares (Tomanelli et al 1991, Watson et al 1992, McDowell et al 1999) have all demonstrated relatively high endometrial levels of ER and PR mRNA and protein during oestrus, when peripheral levels of oestrogen are high, and relatively low levels during mid to late dioestrus, when circulating progesterone levels are high. In sheep, the species for which endometrial steroid receptor expression has been most comprehensively described, oestrogen generally up-regulates and progesterone generally down-regulates steroid receptor expression in endometrial epithelia (Spencer & Bazer 2002).…”

Uterine MHC Class I Molecules and β2-Microglobulin Are Regulated by Progesterone and Conceptus Interferons during Pig Pregnancy

“…This expression was blocked by ZK137,316, a progesterone receptor antagonist, indicating that induction by progesterone is mediated via progesterone receptors. Because progesterone receptors in pigs are down-regulated in endometrial LE and GE by day 10 of the estrous cycle and pregnancy, but maintained in stromal cells and myometrium (49), the endocrine effects of ovarian progesterone on endometrial LE expression of SLA class I and ␤ 2 m genes may be mediated indirectly by either progesterone-induced paracrine-acting factors (progestamedins) produced by the progesterone receptor-positive stromal cells, or by induction of factors in LE that down-regulate progesterone receptors to either allow or stimulate expression of endometrial genes (50,51).…”