Pattern of 11 beta-hydroxysteroid dehydrogenase type 1 messenger ribonucleic acid expression in the ovine uterus during the estrous cycle and pregnancy

The present study was designed to examine the pattern and cellular localization of 11 beta-hydroxysteroid dehydrogenase type 1 (11 beta-HSD1) gene expression in the ovine uterus during pregnancy and at 3 mo postpartum. High levels of 11 beta-HSD1 mRNA were detected in the endometrium from Days 60 to 143 (term = 145 days), and the levels did not change significantly during that time. The level of 11 beta-HSD1 mRNA in the endometrium was always much higher than that in the myometrium, in which the mRNA was not readily detectable throughout pregnancy; at 3 mo postpartum, 11 beta-HSD1 mRNA became undetectable in both endometrium and myometrium. Within the endometrium, intense immunoreactive 11 beta-HSD1 was localized exclusively to the luminal epithelium, and the intensity of 11 beta-HSD1 immunostaining closely followed the level of 11 beta-HSD1 mRNA. To determine whether the level of endometrial 11 beta-HSD1 mRNA was related to the status of ovarian function, tissues from non-pregnant animals at different stages of their reproductive cycle were also examined. It was found that 11 beta-HSD1 mRNA was undetectable in the endometrium of cycling animals up to Day 9 of the estrous cycle but was detectable thereafter. Taken together, these results demonstrate that within the ovine uterus the endometrium is always the dominant site of 11 beta-HSD1 gene expression in relation to the myometrium. Furthermore, the expression of 11 beta-HSD1 mRNA in the endometrium is closely related to the status of the reproductive cycle. The mRNA for 11 beta-HSD1 is highly expressed only during pregnancy and in non-pregnant animals during the late luteal phase. Since circulating levels of progesterone are elevated during both of these periods, the present findings suggest a progesterone effect on uterine 11 beta-HSD1 gene expression.     

Estrogen and progesterone receptors, cell proliferation, and c-fos expression in the ovine uterus during early pregnancy

To evaluate uterine growth during pregnancy and the potential roles of estrogen and progesterone in regulating uterine cell proliferation and c-fos expression, ewes were assigned randomly to slaughter on day 12 after estrus (nonpregnant, NP), and on days 12, 18, 24, or 30 after mating (pregnant, P) in Exp 1 (n = 7 ewes/day) and on days 12 or 14 after estrus and on days 12, 14, 16, 18, 21, or 24 after mating in Exp 2 (n = 3-6 ewes/day). In Exp 1, endometrial expression of c-fos mRNA was evaluated, and labeling index was determined both in vitro (incorporation of 3H-thymidine) and in vivo (iv injection of bromodeoyxuridine [BrdU], a thymidine analog). Endometrial expression of the c-fos proto-oncogene was increased by approximately 10-fold on days 18, 24, and 30 P compared with day 12 NP or P. Labeling index (proportion of cells incorporating 3H-thymidine or BrdU, which provides an index of the rate of cell proliferation) of endometrial caruncular and intercaruncular tissues was low for day 12 NP or P, increased on day 18 P, and remained elevated on days 24 P and 30 P. On day 18 P, labeling index also was greater for gravid than nongravid horns for both caruncular and intercaruncular tissues. In Exp 2, estrogen receptors (ER), progesterone receptors (PR), and proliferating (BrdU-positive) cells were immunolocalized. The percentage of cells exhibiting specific staining for ER, PR, and BrdU was quantified morphometrically for epithelial, stromal, and glandular tissues within luminal and deep regions, as well as for myometrial tissues. For luminal epithelium and glands, the rate of cell proliferation increased dramatically by day 18 P, even though ER and PR levels were low in these compartments. Conversely, the rate of cell proliferation remained low throughout early pregnancy in deep glands, deep stroma, and myometrium, in association with sustained or transient increases in ER and PR levels. For luminal stroma, the rate of cell proliferation increased by day 21 P even though ER levels were low and PR levels remained high. Thus, during early pregnancy, c-fos expression increased concomitantly with increased endometrial cell proliferation. In addition, during early pregnancy, ER and PR levels were inversely related to the rate of cell proliferation in most of the uterine tissue compartments except luminal stroma, which exhibited increased cell proliferation even though ER levels were low and PR levels remained high.     

Control of secretory leukocyte protease inhibitor gene expression in the porcine periimplantation endometrium: a case of maternal-embryo communication

The contributions of the conceptus (embryo and associated membranes) and of the maternal endocrine milieu to control of endometrial secretory leukocyte protease inhibitor (SLPI, also designated antileukoproteinase) expression during the periimplantation stages of embryo development were examined in the present study. Uterine endometrium from distinct sites was collected from pigs at Days 16-25 of pregnancy and analyzed for steady-state SLPI mRNA levels. Endometrium situated directly beneath conceptuses (mesometrial) had greater (p < 0.05) SLPI mRNA levels than that obtained from antimesometrial and interimplantation sites and myometrium. This site-specific difference was most pronounced during late (Days 19-21) and post (Days 23-25)-implantation stages and was also observed, albeit to a lesser degree, for the mRNA encoding uteroferrin (Uf). Conditioned medium (CM; 50% v:v) from Day 21, but not Day 12, conceptuses increased (p < 0.05) SLPI mRNA levels, while neither CM affected mRNA levels for Uf and several other genes expressed in endometrial explants. One inducing factor in Day 21 CM was characterized as a low-molecular-mass (< 12 kDa), relatively heat-stable protein. Transforming growth factor (TGF alpha) increased (p < 0.05), epidermal growth factor (EGF) tended to increase (p = 0.10), and insulin-like growth factor (IGF)-I and IGF-II had no effect (p > 0.10) on, SLPI mRNA levels in Day 12 endometrial explants. Medium conditioned by the pig trophoblast cell line, Jag-1, but not by other mammalian cell lines, had SLPI inducer activity. The maternal endocrine contribution to SLPI gene expression was examined using freshly isolated and short-term-cultured Day 12 and Day 21 pregnant pig endometrium. Steady-state SLPI mRNA levels were increased (p < 0.05) in Day 12, but not Day 21, tissues upon short-term culture in serum-free medium. This increase was time dependent, was similarly demonstrated for Uf mRNA, was not observed in corresponding lung and liver, and was inhibited by inclusion of serum from pigs of diverse endocrine status. In summary, two potential modulators of endometrial SLPI gene expression were identified: 1) a conceptus-derived low-molecular-mass protein, possibly TGF alpha, that mediates in part the up-regulation of SLPI gene expression in endometrium closely associated with implantation sites, and 2) an inhibitory component(s) present in maternal serum. Results suggest opposing actions of maternal and embryonic factors at the maternal-embryo interface and highlight involvement of the periimplantation embryo in directing the spatiotemporal expression of endometrial genes implicated in its development.     

Impairment of the nitric oxide-mediated vasodilator response to mental stress in hypertensive but not in hypercholesterolemic patients

A role for connective tissue growth factor (CTGF) in reproductive function has been suggested from recent studies in the pig. To extend these findings, we have analyzed the immunohistochemical localization of CTGF during the estrous cycle and early pregnancy in mice. During the diestrous and early proestrous stages, CTGF was localized at high levels to both luminal and glandular uterine epithelial cells and at much lower levels in the stroma or myometrium. Epithelial expression of CTGF was considerably reduced at estrus. On Days 1.5-3.5 of pregnancy, CTGF was localized mainly to the uterine epithelial cells, which showed a substantially reduced level of CTGF on Day 4.5. On Days 5.5 and 6.5, CTGF was present at high levels in uterine decidual cells. CTGF was detected in the trophectoderm and inner cell mass of the preimplantation embryo on Day 4.5 and became preferentially localized to embryonic endoderm and mesoderm on Days 5.5-6.5. Multiple mass forms of CTGF (Mr 14 000-38 000) were present in endometrial extracts and uterine luminal flushings. Collectively, these data support a role for CTGF in uterine cell growth, migration, adhesion, and extracellular matrix production during the estrous cycle and early pregnancy, as well as in early development of the embryo.     

Intrauterine cortisol, aldosterone, and corticosteroid binding globulin-like activity during early porcine pregnancy and the estrous cycle

Studies were conducted to determine whether the corticosteroids cortisol and aldosterone, and corticosteroid-binding globulin (CBG) were present in the porcine early-embryonic environment. Cortisol was measured in uterine flushings from white crossbred gilts at Days 7, 10, 13, and 16 of the estrous cycle and pregnancy. Total content of cortisol increased (p < 0.01) between Days 13 and 16, and immunoreactive CBG (ir-CBG) increased (p < 0.01) between Days 10 and 13, in both cyclic and pregnant gilts. In a separate study with Chinese Meishan gilts, total cortisol and aldosterone content of uterine flushings increased (p < 0.02) between Days 10 and 15 of the estrous cycle and pregnancy. In another study with white crossbred gilts, CBG-like binding activity in uterine flushings was low at Day 10, then increased over 100-fold at Day 15 (p < 0.01). However, levels of CBG-like binding activity on Day 15 were 100-fold lower than those of ir-CBG measured in the previous study and could bind less than 4% of the uterine luminal cortisol. Differences between ir-CBG and CBG binding might be due to the ability of the CBG antibody to recognize either biologically inactive CBG or structurally similar molecules. CBG-like binding activity, which appeared unrelated to glucocorticoid receptors, was also present in the endometrial cytosol of white crossbred gilts. Concentrations (fmol/mg protein) of endometrial CBG-like activity decreased (p = 0.03) between Days 10 and 15 of the estrous cycle and pregnancy, did not differ with reproductive status, and on Day 15 were comparable to concentrations in uterine flushings but threefold lower (p < 0.01) than those in the serum. Equilibrium dissociation constants for CBG-like binding activities were comparable among the three locations. These studies indicate that corticosteroids are present-primarily in the free form-within the porcine uterine lumen and could influence early porcine conceptus development. Endometrial CBG-like binding activity could mediate actions of cortisol or progesterone on uterine function.     

Determination of porcine endometrial phospholipase A2 activity and detection of immunoreactive cyclooxygenase during the oestrous cycle and early pregnancy

Experiments examined the characteristics and activity of phospholipase A2 (PLA2) and examined the presence of immunoreactive cyclooxygenase in endometrium of pigs during the oestrous cycle and early pregnancy. Endometrial PLA2 was calcium-independent and activity of the enzyme was greatest at a pH of 8.0. Activity of PLA2 on Days 10, 12, 14 and 16 of the oestrous cycle did not differ (P > 0.1) from activity on those days during pregnancy. During oestrus and early metoestrus (Days 0-3), cyclooxygenase was present in both glandular and surface epithelium. After Day 10 of the oestrous cycle or pregnancy, staining for cyclooxygenase was less intense in the lower and middle uterine glands. However, the upper glandular epithelium near the surface epithelium stained intensely. By Day 15 of the oestrous cycle or pregnancy, intense staining for cyclooxygenase appeared restricted to the upper uterine glands. These results indicate changes in localization of immunoreactive cyclooxygenase throughout the oestrous cycle and suggest that these are not related to altered secretion of prostaglandins (PGs) during early pregnancy. The stimulatory effects of porcine conceptus products on secretion of PGs during early pregnancy are apparently not associated with increased activity of endometrial PLA2.     

Paracrine inducers of uterine endometrial spermidine/spermine N1-acetyltransferase gene expression during early pregnancy in the pig

The endogenous factors that underlie the transient induction of the gene encoding spermidine/spermine N1-acetyltransferase (SSAT), the rate-limiting enzyme in cellular polyamine catabolism, in pig uterine endometrium during periimplantation are not known. The present study examined a number of peptide growth factors and regulatory molecules that are present within the uterine environment at early pregnancy, coincident with maximal SSAT gene expression, for their ability to manifest endogenous SSAT gene-inducing activity. Basal SSAT expression in luminal epithelial cells was higher (p < 0. 01) than that for glandular epithelial (GE) or stromal (ST) cells. Recombinant human insulin-like growth factor-I (IGF-I; 50 ng/ml) had no effect on steady-state SSAT mRNA levels, but it increased mitogenesis in all three cell types. In contrast, IGF-I caused a marked induction (p < 0.01) of SSAT mRNA levels in the human endometrial carcinoma cell line Hec-1-A. Uterine explants incubated with interleukin-6, transforming growth factor alpha, epidermal growth factor (each at 1, 10, and 100 ng/ml), retinoic acid and retinol (each at 0.01, 0.1, and 1 microM), and estradiol-17beta (10 nM) had SSAT mRNA levels similar to controls. By contrast, leukemia inhibitory factor (LIF; at 10 and 100 ng/ml) caused a modest, but significant (p < 0.05), increase in SSAT mRNA levels over those of untreated explants. This effect of LIF, however, did not approach the level of induction observed in GE or ST cells after addition of medium conditioned by Day 12 or 17 porcine conceptuses and in endometrial explants supplemented with medium conditioned by Day 21 porcine conceptuses or a continuous cell line (Jag-1) derived from Day 14 porcine trophoblast. We suggest that transient induction of endometrial SSAT gene expression at implantation is mediated by the functional interactions of specific conceptus-derived regulatory factors, distinct from estrogen, with endometrial-derived factor(s) such as LIF. These complex interactions are probably requisite for the transient, yet dramatic, induction of SSAT gene expression and may be critical for successful implantation.     

Immunocytochemical localization of progesterone receptor in the reproductive tract of adult female rats

The distribution of the progesterone receptor (PR) was investigated immunocytochemically in female reproductive tracts of rats during the estrous cycle and early pregnancy through use of an anti-PR monoclonal antibody. PR was localized predominantly in the nuclei of epithelial, stromal, and muscle cells in the uterus and vagina during the estrous cycle. In the uterus, the nuclei of epithelial cells were stained intensively at diestrus, while the PR staining of the stromal cells was more intense at proestrus than at any other stage of the cycle. PR expression during the cycle in muscle cells of the myometrium was similar to that in the endometrial stromal cells. In the vagina, however, PR expression during the cycle was approximately the same among epithelial, stromal, and muscle cells, the nuclei of which were stained deeply at proestrus. Ovariectomy at various stages of the cycle altered the PR expression appearing in the uterus and vagina during the cycle. In ovariectomized rats, estrogen increased the PR immunoreaction of various types of cells examined in the uterus and vagina except for the uterine epithelial cells. The reaction of these uterine epithelial cells was decreased by estrogen but was increased by progesterone given after estrogen; however, progesterone given alone reduced the reaction. In the epithelial and stromal cells of the uterus, intensity of the staining was increased after mating, reaching maximum on Day 3 of pregnancy, and then decreased on Day 4 (day of implantation), while in epithelial and stromal cells of the vagina the staining remained weak during early pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)     

Immunohistochemically-determined changes in the distribution of insulin-like growth factor-I (IGF-I) and epidermal growth factor (EGF) in the bovine endometrium during the estrous cycle

The aims of this study were to investigate whether there are cell-specific distributions of insulin-like growth factor I (IGF-I) and epidermal growth factor (EGF) in the endometrium, and to determine whether or not the expression of these factors varies with the stage of the estrous cycle. Fifty-four endometrial biopsy specimens were collected from normal cycle Holstein-Friesian heifers. The endometrial specimens were divided into nine groups (at least five different animals per group) corresponding to the following days of the cycle: days 20-0, 1-3, 4-5, 6-7, 8-10, 11-13, 14-15, 16-17, and 18-19 (day 0 = estrus). IGF-I and EGF were localized by immunohistochemistry in the intact heifer endometrium throughout the estrous cycle. Throughout the estrous cycle, IGF-I was localized in the luminal epithelium and stroma with a little staining in the glandular epithelium (P < 0.01). In the luminal epithelium, the number of IGF-I-positive cells increased on days 1-3, 6-7, 11-13, and 16-17. In the stroma, the number of IGF-I-positive cells increased on days 8-10 and 20-3. The number of positively stained cells in the glandular epithelium increased around the estrous period. EGF stained intensely in the stroma but very little in the luminal and glandular epithelia (P < 0.01). In the stroma, three peaks in the number of EGF-positive cells were observed: on days 1-3, 6-7, and 11-13. These results demonstrate cyclical changes in the endometrial cell types localization of IGF-I and EGF.     

Relationships between estrogen receptor and estradiol-stimulated progesterone synthesis in the rabbit corpus luteum

The effects of estradiol on luteal estrogen receptor and steroidogenesis were examined on Days 9 through 11 of pseudopregnancy. In normal pseudopregnant rabbits, unoccupied cytoplasmic and total nuclear estrogen receptor were 2.6 +/- 0.4 fmol/microgram DNA and 0.4 +/- 0.1 fmol/microgram DNA, respectively, on Day 10 of pseudopregnancy. An i.v. injection of 4 micrograms of estradiol caused the translocation of cytoplasmic receptor and a 6.6-fold increment in total nuclear receptor within 15 min, which was followed by rapid processing of the nuclear receptor. Both cytoplasmic and nuclear estrogen receptor returned to normal values within 24 h, and during this period, serum progesterone did not change significantly. Withdrawal of an estradiol implant from animals on Day 9 of pseudopregnancy initiated a marked decline in serum progesterone within 24 h. Following an injection of saline or of 4 micrograms estradiol on Day 10, unoccupied cytoplasmic estrogen receptor in saline- and estradiol-injected rabbits was 1.0 +/- 0.1 fmol/microgram DNA and 1.9 +/- 0.1 fmol/microgram DNA, respectively, on Day 11 of pseudopregnancy. Associated with the increase in cytoplasmic receptor there was an increase in serum progesterone (8.2 +/- 1.5 ng/ml), in contrast to saline-injected animals in which serum progesterone continued to decline (1.6 +/- 0.4 ng/ml). Despite the significant differences in cytoplasmic receptor and in progesterone synthesis, total nuclear estrogen receptor was not different in these animals. These data suggest that in corpora lutea already secreting progesterone at high rates during midpseudopregnancy, the rapid translocation of available estrogen receptor does not cause further stimulation of progesterone synthesis. However, if steroidogenesis is first reduced experimentally, then an injection of 4 micrograms of estradiol can readily stimulate progesterone synthesis, and this stimulation is associated with an increase in cytoplasmic receptor.     

Immunolocalization of 11beta-hydroxysteroid dehydrogenase types 1 and 2 in rat uterus: variation across the estrous cycle and regulation by estrogen and progesterone

Glucocorticoid hormone action in several target tissues is dependent not only on the expression of the glucocorticoid receptor, but also on that of the 11beta-hydroxysteroid dehydrogenase (11betaHSD) enzymes, 11betaHSD-1 and -2. In the uterus, glucocorticoids can exert inhibitory effects on a range of important functions, particularly in relation to the effects of estrogen. Therefore, the present study examined immunolocalization of the two 11betaHSD enzymes in the rat uterus at each stage of the estrous cycle and after ovariectomy with or without estrogen/progesterone replacement. In cycling rats 11betaHSD-1 was localized to luminal and glandular epithelial cells and to eosinophils in both the endometrial stroma and myometrium. In contrast, 11betaHSD-2 immunostaining was localized to endometrial stromal cells and myometrial cells, with no staining evident in epithelial cells or eosinophils. Immunostaining for both enzymes was cycle dependent, being maximal at proestrus and minimal at diestrus. Western blot analysis of whole uterus at proestrus showed the presence of 34- and 40-kDa immunoreactive species for 11betaHSD-1 and -2, respectively. These immunoreactive signals were almost abolished by ovariectomy, but this effect was reversed for both enzymes by estrogen replacement with or without progesterone. These effects of ovariectomy and steroid replacement were confirmed by immunocytochemical analysis, with the exception that progesterone appeared to enhance the stimulatory effects of estrogen on 11betaHSD-2 specifically within the endometrial stroma. In conclusion, these results establish the presence of both 11betaHSD-1 and -2 in the nonpregnant rat uterus and show distinct distributions for the two enzymes and cyclic variation related to positive regulation by ovarian steroids. The physiological implications of these patterns of 11betaHSD expression will ultimately depend on the reaction direction for each enzyme, but 11betaHSD-2 is likely to limit disruptive effects of glucocorticoids on the endometrial stroma, and 11betaHSD-1 may then serve to selectively reactivate glucocorticoids in epithelial cells.     

Prostaglandin E2 receptor subtype EP2 gene expression in the mouse uterus coincides with differentiation of the luminal epithelium for implantation

Among the PGs, PGE2 is considered especially important for implantation and decidualization. Four major PGE2 receptor subtypes, EP1, EP2, EP3, and EP4, mediate various PGE2 effects via their coupling to distinct signaling pathways. Previously, we have shown that the EP1, EP3, and EP4 genes are expressed in the periimplantation mouse uterus in a spatio-temporal manner, suggesting compartmentalized actions of PGE2 during this period. In this study, we examined the expression of the EP2 gene in the mouse uterus during the periimplantation period (days 1-8) and during experimentally induced progesterone (P4)-maintained delayed implantation and its resumption by 17beta-estradiol (E2). We also examined its regulation in the uterus by ovarian steroid hormones. Our results establish that EP2 messenger RNA (mRNA) is expressed exclusively in the luminal epithelium primarily on day 4 (the day of implantation) and day 5 (early implantation) of pregnancy. In (P4)-maintained delayed implanting mice, EP2 mRNA was present in the luminal epithelium, and the expression was further enhanced regardless of the location of the blastocysts after reinitiation of implantation. This observation suggests little or no embryonic influence in regulating EP2 expression and, instead, shows its regulation by P4 and E2. Indeed, treatment with E2 and/or P4 exhibited unique regulation of this gene. The treatment of adult ovariectomized mice with E2 down-regulated the basal levels of EP2 mRNA, whereas that with P4 up-regulated its levels in the luminal epithelium. The up-regulation of EP2 mRNA levels by P4 was further augmented by superimposition of the E2 treatment, suggesting a synergistic interaction between E2 and P4 in regulating this gene in the uterus. Collectively, the results suggest that EP2 could be a potential mediator of PGE2 actions in regulating luminal epithelial differentiation and serve as a marker for uterine receptivity for implantation.     

Regulation of oxytocin, oestradiol and progesterone receptor concentrations in different uterine regions by oestradiol, progesterone and oxytocin in ovariectomized ewes

The regulation of oxytocin, oestradiol and progesterone receptors in different uterine cell types was studied in ovariectomized ewes. Animals were pretreated with a progestogen sponge for 10 days followed by 2 days of high-dose oestradiol to simulate oestrus. They then received either low-dose oestradiol (Group E), low-dose oestradiol plus progesterone (Group P) or low-dose oestradiol, progesterone and oxytocin (via osmotic minipump; Group OT). Animals (three to six per time-point) were killed following ovariectomy (Group OVX), at oestrus (Group O) or following 8, 10, 12 or 14 days of E, P or OT treatment. In a final group, oxytocin was withdrawn on day 12 and ewes were killed on day 14 (Group OTW). Oxytocin receptor concentrations and localization in the endometrium and myometrium were measured by radioreceptor assay, in situ hybridization and autoradiography with the iodinated oxytocin receptor antagonist d(CH2)5[Tyr(Me)2,Thr4,Tyr-NH2(9)]-vasotocin. Oestradiol and progesterone receptors were localized by immunocytochemistry. Oxytocin receptors were present in the luminal epithelium and superficial glands of ovariectomized ewes. In Group O, endometrial oxytocin receptor concentrations were high (1346 +/- 379 fmol [3H]oxytocin bound mg protein-1) and receptors were also located in the deep glands and caruncular stroma in a pattern resembling that found at natural oestrus. Continuing low-dose oestradiol was unable to sustain high endometrial oxytocin receptor concentrations with values decreasing significantly to 140 +/- 20 fmol mg protein-1 (P < 0.01), localized to the luminal epithelium and caruncular stroma but not the glands. Progesterone treatment initially abolished all oxytocin receptors with none present on days 8 or 10. They reappeared in the luminal epithelium only between days 12 and 14 to give an overall concentration of 306 +/- 50 fmol mg protein-1. Oxytocin treatment caused a small increase in oxytocin receptor concentration in the luminal epithelium on days 8 and 10 (20 +/- 4 in Group P and 107 +/- 35 fmol mg protein-1 in Group OT, P < 0.01) but the rise on day 14 was not affected (267 +/- 82 in Group OT and 411 +/- 120 fmol mg protein-1 in Group OTW). In contrast, oestradiol treatment was able to sustain myometrial oxytocin receptors (635 +/- 277 fmol mg protein-1 in Group O and 255 +/- 36 in Group E) and there was no increase over time in Groups P, OT and OTW with values of 61 +/- 18, 88 +/- 53 and 114 +/- 76 fmol mg protein-1 respectively (combined values for days 8-14). Oestradiol receptor concentrations were high in all uterine regions in Group O. This pattern and concentration was maintained in Group E. In all progesterone-treated ewes, oestradiol receptor concentrations were lower in all regions at all time-points. The only time-related change occurred in the luminal epithelium in which oestradiol receptors were undetectable on day 8 but developed by day 10 of progesterone treatment. Progesterone receptors were present at moderate concentrations in the deep glands, caruncular stroma, deep stroma and myometrium in Group O. Oestradiol increased progesterone receptors in the luminal epithelium, superficial glands, deep stroma and myometrium. Progesterone caused the loss of its own receptor from the luminal epithelium and superficial glands and decreased its receptor concentration in the deep stroma and myometrium at all time-points. There was a time-related loss of progesterone receptors from the deep glands of progesterone-treated ewes between days 8 and 14. These results show differences in the regulation of receptors between uterine regions. In particular loss of the negative inhibition by progesterone on the oxytocin receptor by day 14 occurred only in the luminal epithelium, but is unlikely to be a direct effect of progesterone as no progesterone receptors were present on luminal epithelial cells between days 8 and 14.     

Ovary-independent estrogen receptor expression in neonatal porcine endometrium

Effects of age and ovariectomy (OVX) at birth on uterine growth, endometrial development, and estrogen receptor (ER) expression were determined for intact and OVX gilts (n = 5 per day) hysterectomized on postnatal days (PND) 0, 15, 30, 60, 90, or 120. Uteri were evaluated histologically, and ER protein and mRNA expression were characterized immunohistochemically and by in situ hybridization. OVX did not affect uterine weight or endometrial thickness until after PND 60, when both increased more rapidly in intact gilts. Neither did it affect genesis of uterine glands, which were present and which proliferated after PND 0, or endometrial ER expression patterns in glandular epithelium (GE), luminal epithelium (LE), or stroma (S) between PND 0 and 120. Endometrium was ER negative at birth. On PND 15, the ER signal was strong in GE, weak in S, and effectively absent in LE. Thereafter, although the ER signal remained strong in GE and increased through PND 60 in S, it was not evident consistently until after PND 30 in LE. The data indicate that 1) porcine uterine growth and endometrial morphogenesis are ovary-independent processes before PND 60; 2) uterine gland genesis is associated temporally with development of ER-positive endometrial GE and S; and 3) regulation of endometrial ER expression is ovary independent between PND 0 and 120. The results establish the ER as a marker of GE differentiation and implicate this receptor in mechanisms regulating endometrial morphogenesis in the neonatal pig.     

Effect of the conceptus and lack of effect of uterine space on endometrial protein secretion during mid-gestation in swine

The effect of the conceptus and of reduced uterine space on endometrial protein secretion was examined on Days 40, 60, and 80 of gestation in white crossbred gilts. Twenty-nine gilts were checked daily for estrus, and 15 were given 5 mg estradiol valerate daily from Days 11 to 15 (Day 0 = day of estrus) of the estrous cycle to induce pseudopregnancy. The remaining 14 pigs were mated during estrus. All pigs were laparotomized on Day 4, and one uterine horn was ligated to produce one crowded and one roomy uterine environment. Pigs were killed on Days 40, 60, and 80 of pregnancy or pseudopregnancy. The reproductive tracts were collected, and placental tissues from pregnant pigs and endometrial tissues from all pigs were cultured in the presence of 3H-leucine to evaluate protein secretion. Conditioned medium was dialyzed, measured for incorporation of radioactivity into nondialyzable macromolecules, and then subjected to two-dimensional (2D)-PAGE to determine the effect of uterine space and day of pregnancy or pseudopregnancy on overall protein secretion rate and secretion of specific proteins. Fetal survival, fetal weight, and placental weight were decreased (p < 0.01) in the crowded uterine environment compared to the roomy uterine environment. Incorporation of 3H-leucine into nondialyzable macromolecules by endometrial tissue in culture was not affected by uterine space. Secretion of nondialyzable macromolecules by endometrium from pregnant pigs was not different from that by endometrium from pseudopregnant pigs on Day 40 but was greater (p < 0.01) on Days 60 and 80.(ABSTRACT TRUNCATED AT 250 WORDS)     

Follicle-stimulating hormone, human chorionic gonadotropin, and prolactin receptors in hamster corpora lutea or dispersed luteal cells during pregnancy

In vitro progesterone (P4) production by hamster luteal cells is stimulated throughout pregnancy by FSH and LH. Prolactin (PRL) by itself, however, increases P4 synthesis only on Day 12; on Day 4, FSH+LH+PRL induces optimal P4 secretion [Biol Reprod 1994; 51:43-49]. In light of these findings, in this study we investigated FSH, hCG, and PRL receptors in hamster CL or dispersed luteal cells on Days 4, 8, and 12 of pregnancy. Scatchard analysis of hamster CL on Days 4 and 8 showed considerably more unoccupied hCG receptors than FSH receptors: on Day 4, there was 9.5 fmol/mg protein for FSH binding sites vs. 1741 fmol/mg protein for hCG binding. Moreover, the binding affinity of hCG was greater than for FSH: the Day 4 Kd was 0.136 nM for hCG vs. 0.308 for FSH. Similar differences were observed on Day 8. Dispersed luteal cells (large+small cells) were incubated for 24 h with or without 10 ng of ovine FSH, LH, and PRL or human recombinant FSH (r-hFSH), alone or in different combinations. The cells were then washed and incubated for 4 h with iodinated hCG, FSH, or PRL with or without 100-fold excess of unlabeled hormones. The number of binding sites per 200,000 luteal cells did not change appreciably for FSH and hCG on Days 4 and 12 of pregnancy, whereas PRL binding sites significantly increased on Day 12.(ABSTRACT TRUNCATED AT 250 WORDS)