Localization of oestradiol, progesterone and oxytocin receptors in the uterus during the oestrous cycle and early pregnancy of the ewe

1993 ◽  
Vol 138 (3) ◽  
pp. 479-NP ◽  
Author(s):  
D. C. Wathes ◽  
M. Hamon
Keyword(s):  
Progesterone Receptor ◽  
Early Pregnancy ◽  
Luteal Phase ◽  
Specific Binding ◽  
Progesterone Receptors ◽  
Oestrous Cycle ◽  
Luminal Epithelium ◽  
Paracrine Factors ◽  
Plasma Progesterone ◽  
Oxytocin Receptors

ABSTRACT Uterine tissue samples were collected from 47 ewes at various stages of the oestrous cycle and early pregnancy (until day 21) and during seasonal anoestrus. Cryostat sections were immunostained to determine the localization of oestradiol and progesterone receptors using specific monoclonal antibodies. Oxytocin receptors were localized by autoradiography in sections from the same ewes using the 125I-labelled oxytocin antagonist d(CH2)5[Tyr(Me)2,Thr4,Tyr-NH29]- vasotocin. Plasma progesterone measurements were made during the preceding cycle up to the time of slaughter. Oestradiol receptor concentrations were maximal in all regions of the tract at oestrus. Immunostaining of the luminal epithelium, superficial glandular epithelium, stroma and myometrium decreased in the early luteal phase but was maintained for longer in the deep glands. Progesterone receptor immunostaining in the luminal epithelium and superficial glands developed in the early luteal phase (days 1–2) with a somewhat later appearance in the deep glands (days 5–7). Progesterone receptor concentrations in the stroma and myometrium also reached a maximum in the early luteal phase. Myometrial staining was clearly maintained throughout the luteal phase whereas stromal staining was variable between ewes. For both oestradiol and progesterone receptors no differences were apparent between pregnant and non-pregnant ewes between days 2 and 12, but pregnant ewes did not show the general increases in oestradiol receptor staining associated with luteolysis on days 14–15. Oxytocin receptors first developed in the luminal epithelium of non-pregnant ewes on day 14 of the cycle and spread to the superficial glands, caruncular stroma, deep glands and myometrium at oestrus before decreasing in reverse order on days 1–2. Specific binding was not detectable on days 5–12 of the cycle or on days 14 or 21 of pregnancy. The appearance of oxytocin receptors in the luminal epithelium on day 14 preceded that of both the oestradiol and progesterone receptors in the epithelial cells and the fall in plasma progesterone. It was followed by the development of oestradiol and oxytocin receptors in the superficial glands, deep glands, caruncular stroma and myometrium, with the two receptor populations showing a significant positive association in these tissues. The loss of oxytocin receptors in all regions occurred as plasma progesterone levels were increasing, but the association between these two variables was only significant in the superficial glands. The development of progesterone receptors in different tissues could not be explained on the basis of either oestradiol receptor content or plasma progesterone. We conclude that all three receptor populations change in a dynamic manner during the oestrous cycle with variations both between days and between different uterine compartments. The complex pattern of receptor formation and loss suggests that, in addition to the circulating steroid hormone concentrations, local paracrine factors are likely to be involved in their regulation. Journal of Endocrinology (1993) 138, 479–491

scholarly journals Expression of oxytocin, oestrogen and progesterone receptors in uterine biopsy samples throughout the oestrous cycle and early pregnancy in cows

Reproduction ◽  
2001 ◽  
pp. 965-979 ◽  
Author(s):  
RS Robinson ◽  
GE Mann ◽  
GE Lamming ◽  
DC Wathes
Keyword(s):  
Progesterone Receptor ◽  
Early Pregnancy ◽  
Oestrogen Receptor ◽  
Expression Patterns ◽  
Oestrous Cycle ◽  
Receptor Expression ◽  
Luminal Epithelium ◽  
Receptor Alpha ◽  
Oestrogen Receptor Alpha ◽  
Oxytocin Receptors

This study examined the expression patterns of oxytocin and steroid receptors in the bovine endometrium during the oestrous cycle and early pregnancy to elucidate their respective roles in the regulation of luteolysis and the maternal recognition of pregnancy. In Expt 1, uterine biopsies were collected from four cows throughout three oestrous cycles each, to provide daily samples. In Expt 2, uterine tissue was collected on days 12, 14, 16 and 18 of the oestrous cycle (n = 20) or early pregnancy (n = 16). Oxytocin receptor, oestrogen receptor alpha and progesterone receptor mRNAs were localized by in situ hybridization, and localization of oestrogen receptor and progesterone receptor was confirmed by immunocytochemistry. All three receptors showed time- and cell-specific expression patterns. Oestrogen receptor alpha increased in all regions at oestrus but high concentrations were also found in the luminal epithelium during the mid-luteal phase and in the deep glands throughout the oestrous cycle. Progesterone receptor expression was higher in the stroma than it was in the types of epithelial cell, and increased expression was observed at oestrus and during the early luteal phase. The cyclical upregulation of oxytocin receptors in the luminal epithelium on about day 16 was not related to preceding changes in the endometrial expression of either oestradiol alpha or progesterone receptors. During early pregnancy, oxytocin receptor expression was suppressed. Oestrogen receptor a concentrations increased in the non-pregnant cows and decreased in the pregnant cows between days 16 and 18, but these changes followed rather than preceded the upregulation of oxytocin receptors in the non-pregnant cows. It is concluded that the initial upregulation of oxytocin receptors in the luminal epithelium, which triggers luteolysis, is not associated directly with changes in expression of oestrogen receptor alpha.

scholarly journals Early Pregnancy in the Ewe: Effects of Oestradiol and Progesterone on Uterine Metabolism and on Embryo Survival

1977 ◽  
Vol 30 (4) ◽  
pp. 279 ◽  
Author(s):  
BG Miller ◽  
NW Moore ◽  
Leigh Murphy ◽  
GM Stone
Keyword(s):  
Embryo Transfer ◽  
Embryo Development ◽  
Early Pregnancy ◽  
Protein Metabolism ◽  
Hormonal Regulation ◽  
Luteal Phase ◽  
Progesterone Receptors ◽  
Oestrous Cycle ◽  
Embryo Survival ◽  
Day Of Embryo Transfer

The hormonal regulation of embryo development during early pregnancy in the ewe has been examined. Ovariectomized ewes received injections of oestradiol (E2) and progesterone (P) according to schedules designed to simulate endogenous ovarian secretion during the luteal phase of the previous oestrous cycle (priming P), around the time of oestrus (oestrous E2 ) and during early pregnancy (maintenance P, maintenance E2)' Embryos were transferred to the ewes on the 4th day after induced oestrus, and ewes were killed at 6 or 13 days after transfer to assess embryo development. Cytosol concentrations of oestradiol 'and progesterone receptors and RNA and protein metabolism in the endometrium and amounts of protein in uterine flushings were examined on the day of embryo transfer and 6 days after transfer.

ALTERATIONS IN PROGESTERONE RECEPTORS IN THE RAT UTERUS BEARING AN INTRA-UTERINE DEVICE DURING THE OESTROUS CYCLE AND EARLY PREGNANCY

1980 ◽  
Vol 87 (3) ◽  
pp. 365-373 ◽  
Author(s):  
LESLIE MYATT ◽  
M. G. ELDER ◽  
LOUIS LIM
Keyword(s):  
Progesterone Receptor ◽  
Nuclear Receptor ◽  
Early Pregnancy ◽  
Dissociation Constants ◽  
Progesterone Receptors ◽  
Oestrous Cycle ◽  
Rat Uterus ◽  
Binding Characteristics ◽  
Receptor Complexes ◽  
And Control

The binding characteristics, content and intracellular distribution of cytosolic and nuclear progesterone receptors have been investigated, using [3H]progesterone as ligand, in the rat uterus bearing a unilateral intra-uterine device (IUD) during the oestrous cycle and from days 3 to 6 of pregnancy. The dissociation constants of nuclear and cytosolic progesterone–receptor complexes for IUD-containing and control uterine horns were similar. Cytosolic receptor concentrations in the IUD-containing uterus were always lower but changed in a manner similar to the control during the periods studied. Nuclear receptor concentrations in the control horn reflected changes in hormone levels during the oestrous cycle although concentrations measured were greater than previously reported. However, in IUD-containing uteri the pattern was completely reversed with minimal levels at pro-oestrus. Nuclear receptor concentrations were little different in both horns during early pregnancy. Total progesterone receptor synthesis determined between metoestrus and pro-oestrus in IUD-containing horns was significantly less than that of control horns. This correlated with the attenuated rise of nuclear oestrogen receptor levels previously observed between these times in IUD-containing uterine horns.

scholarly journals 226.Regulated expression of adhesion and anti-adhesion molecules in mouse endometrium during early pregnancy

2004 ◽  
Vol 16 (9) ◽  
pp. 226 ◽  
Author(s):  
M. J. Jasper ◽  
A. Stocker ◽  
S. A. Robertson
Keyword(s):  
Real Time ◽  
Adhesion Molecules ◽  
Early Pregnancy ◽  
Embryo Implantation ◽  
Early Embryo ◽  
Luminal Epithelium ◽  
Paracrine Factors ◽  
Mean Values ◽  
Actin Mrna ◽  
Further Development

To implant and establish the connections that are vital for further development, the early embryo must attach to and then breech the barrier posed by the epithelium of the maternal tract. Expression of adhesion and anti-adhesion molecules in the luminal epithelium of the endometrium are thought to fluctuate in a temporal pattern to 'frame' the implantation site, with their expression regulated by endocrine and paracrine factors. Anti-adhesion molecules, such as members of the mucin family, provide a barrier to implantation in sites or at times unsuitable for embryo development. Expression of adhesion molecules, or specific integrins, are thought to aid in the adhesion of the embryo, allowing it to induce changes in the underlying tissue promoting embryo invasion and pregnancy. The aim of this study was to quantitate the expression of mRNA encoding the integrins αυ, α4 and β3 and MUC1 and MUC4 from Day 0 (oestrous) to Day 4 of pregnancy (implantation) using quantitative real time RT-PCR. Uterine tissues were collected at oestrous and at Days 1, 2, 3 and 4 of pregnancy (Day 1 corresponding to the presence of a vaginal plug), total RNA was extracted, DNAse treated, reverse transcribed into cDNA, and quantified by real-time PCR using SYBR Green chemistry. All specific primers were designed using GenBank sequences and data were normalised to β-actin mRNA expression. Expression of MUC1 and MUC4 mRNAs was dramatically reduced, with mean values 20-fold and 100-fold less than at oestrous respectively, by Day 4 of pregnancy. In contrast, expression of mRNAs encoding integrins αυ, α4 and β3 was detected throughout early pregnancy. These data demonstrate that adhesion and anti-adhesion molecules are differentially expressed in the murine uterus during early pregnancy and may be key mediators in embryo implantation, promoting attachment of the embryo to the luminal epithelium in an environment conducive to embryo growth and development. Supported by a Clive & Vera Ramaciotti Project Grant to MJ Jasper.

scholarly journals Delayed effect of low progesterone concentrations on bovine uterine PGF(2alpha) secretion in the subsequent oestrous cycle

Reproduction ◽  
2001 ◽  
pp. 643-648 ◽  
Author(s):  
A Shaham-Albalancy ◽  
Y Folman ◽  
M Kaim ◽  
M Rosenberg ◽  
D Wolfenson
Keyword(s):  
Corpus Luteum ◽  
Luteal Phase ◽  
Oestrous Cycle ◽  
Delayed Effect ◽  
Plasma Progesterone ◽  
Progesterone Secretion ◽  
Progesterone Treatment ◽  
Late Luteal Phase ◽  
Subsequent Cycle ◽  
Concentration Curves

Low progesterone concentrations during the bovine oestrous cycle induce enhanced responsiveness to oxytocin challenge late in the luteal phase of the same cycle. The delayed effect of low progesterone concentrations during one oestrous cycle on uterine PGF(2alpha) secretion after oxytocin challenge on day 15 or 16 of the subsequent cycle was studied by measuring the concentrations of the major PGF(2alpha) metabolite (13,14-dihydro-15-keto PGF(2alpha); PGFM) in plasma. Two experiments were conducted, differing in the type of progesterone treatment and in the shape of the low progesterone concentration curves. In Expt 1, progesterone supplementation with intravaginal progesterone inserts, with or without an active corpus luteum, was used to obtain high, or low and constant plasma progesterone concentrations, respectively. In Expt 2, untreated cows, representing high progesterone treatment, were compared with cows that had low but increasing plasma progesterone concentrations that were achieved by manipulating endogenous progesterone secretion of the corpus luteum. Neither experiment revealed any differences in plasma progesterone concentrations between the high and low progesterone groups in the subsequent oestrous cycle. In both experiments, both groups had similar basal concentrations of PGFM on day 15 (Expt 1) or 16 (Expt 2) of the subsequent oestrous cycle, 18 days after progesterone treatments had ended. In both experiments, the increases in PGFM concentrations in the low progesterone groups after an oxytocin challenge were markedly higher than in the high progesterone groups. These results indicate that low progesterone concentrations during an oestrous cycle have a delayed stimulatory effect on uterine responsiveness to oxytocin during the late luteal phase of the subsequent cycle. This resulting increase in PGF(2alpha) secretion may interfere with luteal maintenance during the early stages of pregnancy.

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

1996 ◽  
Vol 151 (3) ◽  
pp. 375-393 ◽  
Author(s):  
D C Wathes ◽  
G E Mann ◽  
J H Payne ◽  
P R Riley ◽  
K R Stevenson ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Low Dose ◽  
Progesterone Receptors ◽  
Cell Types ◽  
Oxytocin Receptor ◽  
Luminal Epithelium ◽  
Time Points ◽  
Progesterone Treatment ◽  
Oxytocin Receptors ◽  
Receptor Concentration

Abstract 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-NH29]-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. The presence of oxytocin receptors in the luminal epithelium of ovariectomized ewes suggests that oestradiol is not essential for oxytocin receptor synthesis at this site. Oestradiol was able to sustain its own receptor at all sites, but high circulating progesterone was always inhibitory to oestradiol receptors. In general, oestradiol stimulated progesterone receptors in epithelial cells whereas progesterone abolished its own receptor from epithelial cells over a period of time, but had a lesser effect on stromal cells. The concentration of all three receptors is therefore differentially regulated between different uterine cell types, suggesting the importance of paracrine effects which remain to be elucidated. Journal of Endocrinology (1996) 151, 375–393

Localization of oxytocin receptor mRNA in the ovine uterus during the oestrous cycle and early pregnancy

1994 ◽  
Vol 12 (1) ◽  
pp. 93-105 ◽  
Author(s):  
K R Stevenson ◽  
P R Riley ◽  
H J Stewart ◽  
A P F Flint ◽  
D C Wathes
Keyword(s):  
Mrna Expression ◽  
Optical Density ◽  
Receptor Gene ◽  
Oxytocin Receptor ◽  
Oestrous Cycle ◽  
Luminal Epithelium ◽  
Binding Studies ◽  
Receptor Mrna ◽  
Oxytocin Receptors ◽  
Ovine Uterus

ABSTRACT A synthetic 45-mer oligonucleotide corresponding to part of the ovine endometrial oxytocin receptor cDNA was hybridized to sections of ovine uterus collected from 40 ewes at different stages during the oestrous cycle, the first 3 weeks of pregnancy and seasonal anoestrus. The quantity of oxytocin receptor mRNA was measured as the optical density (OD) value on autoradiographs using image analysis. Message first appeared in the luminal epithelium on days 14–15 of the cycle, increasing to a peak OD of 0·48 at oestrus and decreasing again between days 2 and 5. Oxytocin receptor mRNA in the superficial glands, deep glands and caruncular stroma increased between day 15 and oestrus to peak OD values of 0·17, 0·11 and 0·11 respectively, declining again by day 2 and reaching basal values (OD<0·015) by day 5. Hybridization to the myometrium tended to rise from a mean OD value of 0·01 on days 2–15 to a peak of 0·03±0·01 (mean±s.e.m.) on days 0–1, but the change was not significant. In pregnant ewes there was no detectable oxytocin receptor mRNA on days 14–15 in any region, but hybridization to the luminal epithelium was present in two of three ewes on day 21. In anoestrous ewes oxytocin receptor mRNA concentrations in all areas of the endometrium were approximately half those measured at oestrus. Optical density readings for oxytocin receptor mRNA in the various uterine compartments were compared with measurements of oxytocin receptors in the same regions as assessed by binding studies using the 125I-labelled oxytocin antagonist d(CH2)5[Tyr(Me)2,Thr4,Tyr-NH29]-vasotocin (125I-labelled OTA). In the endometrium, receptor mRNA and 125I-labelled OTA binding patterns changed in parallel, and both sets of measurements were significantly correlated (P<0·01). In the myometrium, a significant increase in 125I-labelled OTA binding occurred at oestrus; this was not accompanied by a similar increase in oxytocin receptor mRNA hybridization. This study helps to confirm that the previously identified cDNA clone is derived from the ovine oxytocin receptor, as patterns of oxytocin receptor mRNA expression in the endometrium closely resembled those of oxytocin binding. Maximum expression and binding both occurred at oestrus, suggesting that regulation of the oxytocin receptor gene in the uterus occurs principally at the transcriptional, rather than at the translational, level. Failure to detect a significant increase in myometrial mRNA expression at oestrus may indicate that the endometrial and myometrial oxytocin receptors are of different isoforms.

51 Effects of modulating early luteal phase progestin concentration on endometrial function in early pregnant mares

2019 ◽  
Vol 31 (1) ◽  
pp. 151
Author(s):  
C. Aurich ◽  
T. Beyer ◽  
D. Scarlet
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Progesterone Receptor ◽  
Luteal Phase ◽  
Free Amino ◽  
Progesterone Receptors ◽  
Wilcoxon Test ◽  
Down Regulation ◽  
Once Daily ◽  
Endometrial Epithelium

Progesterone prepares the endometrium for pregnancy. This requires down-regulation of progesterone receptors in the endometrial epithelium as a prerequisite for the expression of pregnancy-associated proteins. We investigated effects of modulated peripheral progestin concentration in early luteal phase mares on endometrial function on Day 14 of pregnancy. Genitally healthy oestrous mares (n=8; age 4 to 14 years) were inseminated until ovulation and treated with either altrenogest (0.044mg kg−1 once daily orally) on Days 5 to 10 after ovulation (ALT), cloprostenol (125mg once daily intramuscularly) on Days 0 to 3 after ovulation (CLO) or left untreated (CON). The ALT and CLO treatments were chosen to increase and decrease total peripheral progestin concentration, respectively. Each treatment was given to every mare in consecutive cycles at random order. On Day 14 after ovulation, endometrial fluid was collected with a cotton roll (Salivette, Sarstedt, Germany) inserted into the uterus and an endometrial biopsy for immunohistological examination was collected. In endometrial fluid, free amino acid concentrations were analysed by ion exchange liquid chromatography with an amino acid analyser (Institut Kuhlmann, Analytik-Zentrum Ludwigshafen, Germany). Cell nuclei staining positive for the progesterone receptor were determined in the luminar and glandular epithelium as well as in the stroma. Statistical analysis was performed by non-parametric Friedman test with subsequent Wilcoxon test. Values are given as mean±standard error of mean. Pregnancy rate was 0.6±0.1 (13 cycles/8 pregnancies), 1.0±0 (8 cycles/8 pregnancies), and 0.7±0.1 (11 cycles/8 pregnancies) in CON, ALT, and CLO cycles, respectively (P=0.062). Conceptus size between Days 10 and 14 did not differ among treatments. The percentage of luminal epithelial cells staining positive for progesterone receptor differed among treatments (CON 72.8±4.1, ALT 70.7±4.7, and CLO 84.1±1.9%; P&lt;0.05) and was higher in CLO than in ALT and CON cycles (P&lt;0.05). Free amino acids glutamic acid and glycine were most abundant in endometrial fluid, but their concentrations did not differ among treatments. The concentrations of the amino acids isoleucine (CON 0.17±0.03, CLO 0.14±0.02, and ALT 0.23±0.04 µmol) and lysine (CON 0.27±0.08, CLO 0.18±0.05, and ALT 0.44±0.13 µmol) were influenced by treatment (P&lt;0.05) and lower in CLO than in ALT and CON cycles. In conclusion, impaired luteal function due to CLO treatment during the early luteal phase of pregnant mares delayed down-regulation of progesterone receptors in the endometrial epithelium on Day 14. This influenced endometrial function as reflected in lower concentrations of the amino acids lysine and isoleucine in endometrial secretions.

Effect of nutrition on endometrial progesterone receptor expression in ewes

2003 ◽  
Vol 2003 ◽  
pp. 81-81
Author(s):  
J.A. Abecia ◽  
C. Sosa ◽  
J.M. Lozano ◽  
C. Viñoles ◽  
F. Forcada ◽  
...  
Keyword(s):  
Food Intake ◽  
Progesterone Receptor ◽  
Progesterone Receptors ◽  
Cell Types ◽  
Receptor Expression ◽  
Progesterone Receptor Expression ◽  
Endometrial Cell ◽  
Embryo Survival ◽  
Plasma Progesterone ◽  
Uterine Environment

It has been postulated that undernourishment could affect embryo survival through changes in the uterine environment (Abecia et al., 1995). Moreover, we have shown that undernourished ewes had higher plasma progesterone (P4) concentrations and a lower endometrial content of P4 (Lozano et al., 1998), suggesting that this lower endometrial content could be due to a decrease in the content of endometrial progesterone receptors (PR). The aim of this study was to investigate the effect of low and high levels of food intake on PR in different endometrial cell types.

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