Oxytocin receptor concentrations, inositol phosphate turnover and prostaglandin release by endometrium from ewes induced to ovulate during the early post-partum period

1993 ◽  
Vol 136 (1) ◽  
pp. 17-NP ◽  
Author(s):  
J. M. Wallace ◽  
M. G. Thompson ◽  
R. P. Aitken ◽  
M. A. Cheyne
Keyword(s):  
Receptor Binding ◽  
Inositol Phosphate ◽  
Post Partum ◽  
Oxytocin Receptor ◽  
Receptor Expression ◽  
Luteal Function ◽  
Induction Of Ovulation ◽  
Release Device ◽  
Prostaglandin F

ABSTRACT Induction of ovulation early post partum in sheep is associated with a high incidence (30–40%) of premature luteolysis. The present study was designed to characterize oxytocin receptor levels, oxytocin-stimulated inositol phosphate (IP) turnover (second messenger) and oxytocin-stimulated prostaglandin F2α (PGF2α) release in the endometrium of post-partum ewes induced to ovulate 21 days after parturition and expected to exhibit a range of corpus luteal functions subsequently. Ovulation was induced on day 21 post partum using a controlled internal drug release device and pregnant mare serum gonadotrophin, and uterine tissues were collected on days 5, 10 or 15 of the cycle (n = 4/day). A further 12 ewes whose interval from previous parturition exceeded 150 days were similarly treated and acted as controls. Measurement of daily peripheral progesterone concentrations revealed that while all control ewes exhibited normal luteal function, abnormal luteal function was evident in two, two and one post-partum ewes studied on days 5, 10 and 15 of the cycle respectively. Oxytocin receptor binding was detected (by receptor-binding assay and in-vitro autoradiography) in the endometrium and myometrium of post-partum ewes at all three stages of the oestrous cycle but only at day 15 in control ewes. To determine IP turnover, 100 mg caruncular endometrium was incubated in duplicate for 2·5 h with 10 μCi [3H]inositol and treated with 0 or 2 μmol oxytocin/l for 30 min, then [3H]inositol mono-, bis- and trisphosphates were quantified. Oxytocin stimulated total IPs in all day-5 and day-15 post-partum ewes, in three of four day-10 ewes and in all day-15 control ewes. Basal endometrial PGF2α release measured in triplicate (100 mg/well) during a 2 h incubation was higher in post-partum versus control ewes on days 5 and 10 but not on day 15 of the cycle. Similarly, oxytocin stimulated PGF2α release to varying levels at all stages of the cycle in post-partum ewes but only on day 15 in control ewes. Irrespective of the treatment group endometrial oxytocin receptor number was significantly (P < 0·001) correlated with oxytocin-stimulated IP turnover and PGF2α release. Thus the induction of ovulation and the subsequent luteal phase in post-partum ewes is against a back ground of high oxytocin receptor expression and enhanced PGF2α release which in some ewes may contribute to abnormal luteal function. Journal of Endocrinology (1993) 136, 17–25

Corpus luteum and endometrial function in ewes post partum: a study in vivo and in vitro

1992 ◽  
Vol 4 (1) ◽  
pp. 77 ◽  
Author(s):  
JM Wallace ◽  
CJ Ashworth ◽  
RP Aitken ◽  
MA Cheyne
Keyword(s):  
Corpus Luteum ◽  
Post Partum ◽  
Polyacrylamide Gel Electrophoresis ◽  
Uterine Horn ◽  
Corpora Lutea ◽  
Luteal Function ◽  
Progesterone Production ◽  
Release Device

Induction of ovulation post partum is associated with a high incidence of prematurely regressing corpora lutea. However, inadequate luteal function is not the sole reason for pregnancy failure, because ewes with normal corpus luteum function and successful fertilization also fail to establish pregnancies. The effects of suckling status and the interval from post partum to rebreeding on corpus luteum and endometrial function were examined in vivo and in vitro. Ewes were weaned early or allowed to lactate, induced to ovulate using a progesterone-impregnated controlled internal drug release device and an intramuscular injection of pregnant mare serum gonadotrophin, and inseminated (intrauterine) at either 21 or 35 days post partum (n = 10 per group). A further 10 standard ewes whose interval from parturition was in excess of 150 days were included for comparative purposes. On Day 10 after insemination the pregnancy rate was determined in four ewes from each of the post-partum groups and five standard ewes. These ewes were then ovariectomized and hysterectomized for studies in vitro. The incidence of premature luteal regression, as assessed by progesterone concentrations in peripheral blood was independent of the suckling stimulus but dependent on stage post partum (21 days post partum, 6 of 19 ewes; 35 days post partum, 0 of 19 ewes; P less than 0.05). Luteal function was normal in all standard ewes. Ovulation rate, corpus luteum weight, corpus luteum progesterone content and basal progesterone production in vitro were significantly less in 21-day than in 35-day post-partum ewes. Pregnancy rates as determined on Day 10 or at term were low in all post-partum groups (7 out of the 38 ewes inseminated) compared with standard ewes (8 of 10). Uterine function was assessed by culturing endometrial tissue from the tip and body of each uterine horn in the presence of [3H]leucine for 30 h at 37 degrees C. Incorporation of radiolabel into non-dialysable proteins synthesized and secreted by the endometrium in vitro was independent of uterine horn location and suckling status but was significantly lower (P less than 0.001) in media from 21-day than from 35-day post-partum ewes. Irrespective of treatment group, incorporation of radiolabel was positively correlated with mean plasma progesterone concentrations on Days 2-10 after insemination and with basal progesterone production in vitro. Secreted proteins were detected by two-dimensional-polyacrylamide-gel electrophoresis and fluorography.(ABSTRACT TRUNCATED AT 400 WORDS)

Characterization and autoradiographical localization of oxytocin receptors within the ovine endometrium in relation to post-partum corpus luteum function

1991 ◽  
Vol 128 (2) ◽  
pp. 253-NP ◽  
Author(s):  
J. M. Wallace ◽  
P. J. Morgan ◽  
R. Helliwell ◽  
R. P. Aitken ◽  
M. Cheyne ◽  
...  
Keyword(s):  
Post Partum ◽  
Oxytocin Receptor ◽  
Corpora Lutea ◽  
Uterine Endometrium ◽  
Oxytocin Receptors ◽  
High Incidence ◽  
Prostaglandin F ◽  
Group A ◽  
And Control

ABSTRACT The induction of ovulation in early post-partum ewes is associated with a high incidence of premature luteal regression which is independent of the suckling stimulus but dependent on the stage post partum. The aim of the present study was to determine whether oxytocin receptors are present on uterine endometrium early in the luteal phase and hence ascertain whether oxytocin-induced uterine prostaglandin F2α release is a possible mechanism involved in the premature regression of these post-partum corpora lutea. Ovarian and uterine tissues were collected on day 4 of the cycle in ewes induced to ovulate at either 21 or 35 days post partum (n = 4 per group). A further four cyclic ewes were similarly synchronized to ovulate and acted as controls. Corpora lutea from the 21-day post-partum group were significantly (P < 0·01) smaller, had a lower progesterone content and a reduced capacity to secrete progesterone in vitro than corpora lutea from 35-day post-partum or control ewes. A highly specific oxytocin receptor ligand 125I-labelled d(CH2)5[Tyr(Me)2,Thr4,Tyr-NH29]-vasotocin was used to localize and characterize high affinity oxytocin receptors in uterine endometrium (dissociation constant 145 pmol/l). Oxytocin receptor concentrations in endometrium from ewes induced to ovulate at 21 days post partum were on average five-fold higher (P < 0·05) than in 35-day post-partum and control groups. Journal of Endocrinology (1991) 128, 253–260

Intrauterine injection of ovine interferon-τ alters oestrogen receptor and oxytocin receptor expression in the endometrium of cyclic ewes

1995 ◽  
Vol 15 (2) ◽  
pp. 203-220 ◽  
Author(s):  
T E Spencer ◽  
N H Ing ◽  
T L Ott ◽  
J S Mayes ◽  
W C Becker ◽  
...  
Keyword(s):  
Progesterone Receptor ◽  
Oestrogen Receptor ◽  
Plasma Concentrations ◽  
Oxytocin Receptor ◽  
Receptor Expression ◽  
Glandular Epithelium ◽  
Receptor Density ◽  
Receptor Mrna ◽  
Prostaglandin F

ABSTRACT This study determined the effects of intrauterine injections of recombinant ovine interferon-τ (roIFN-τ; 2 × 107 antiviral units/day) or control proteins (6 mg/day) from day 11 to day 14 post-oestrus (oestrus=day 0) on endometrial expression of receptors for oestrogen, progesterone and oxytocin in cyclic ewes. Plasma concentrations of progesterone were greater on day 15 in ewes receiving roIFN-τ compared with control proteins (P<0·02, treatment × day). Ewes injected with roIFN-τ had lower endometrial levels of oestrogen receptor mRNA (P<0·10) and protein (P<0·01) on day 15 compared with ewes receiving control proteins. In situ hybridization analysis indicated that oestrogen receptor mRNA was more abundant in the luminal and glandular epithelium of control ewes compared with roIFN-τ-treated ewes. Immunoreactive oestrogen receptor was also present in the luminal and glandular epithelium of control, but not roIFN-τ-treated ewes. Endometrial levels of progesterone receptor mRNA and protein were not different (P>0·10) between control and roIFN-τ-treated ewes. In situ hybridization analyses indicated that progesterone receptor mRNA abundance was low in endometrial epithelium and stroma of both control and roIFN-τ-injected ewes. Immunoreactive progesterone receptors were present in the endometrial stroma and epithelium of control ewes, but confined to the stroma of roIFN-τ-treated ewes. Oxytocin receptor density was lower (P<0·10) in the endometrium of ewes injected with roIFN-τ than control proteins; however, oxytocin receptor affinity was not affected (P>0·10) by treatment. Concentrations of 13,14-dihydro-15-keto-prostaglandin F2α (PGFM) were not increased by exogenous oxytocin administration in control and roIFN-τ-treated ewes on days 10 or 12 post-oestrus. However, on day 14, control ewes responded to oxytocin with increased plasma concentrations of PGFM, whereas ewes receiving roIFN-τ remained unresponsive to oxytocin. These results indicate that the antiluteolytic effects of IFN-τ are to prevent increases in endometrial oestrogen receptor mRNA and protein and oxytocin receptor density which abrogates uterine release of prostaglandin F2α during maternal recognition of pregnancy. IFN-τ may inhibit the synthesis of oestrogen receptor mRNA by a transcriptional or post-transcriptional regulatory mechanism to suppress oxytocin receptor formation during early pregnancy in ewes.

THE SERUM LEVELS OF PROGESTERONE AND 20α-DIHYDROPROGESTERONE, AND THE OVARIAN LH, FSH AND PRL BINDING DURING LUTEOLYSIS OF THE SUPERLUTEINIZED RAT OVARY

1977 ◽  
Vol 86 (1) ◽  
pp. 162-172 ◽  
Author(s):  
Peter A. Torjesen ◽  
Asbjørn Aakvaag
Keyword(s):  
Binding Sites ◽  
Ovarian Tissue ◽  
Serum Levels ◽  
Plasma Progesterone ◽  
Luteal Function ◽  
Prostaglandin Analogues ◽  
Prostaglandin F ◽  
Serum Gonadotropin ◽  
Rat Ovary

ABSTRACT The process of luteolysis has been studied in immature rats in which superluteinization had been induced with pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotrophin (HCG). Following prostaglandin F2α and the prostaglandin analogues, and at the end of the pseudopregnancy, the plasma levels of progesterone and 20α-dihydroprogesterone were measured and used as parameters of luteal function in relation to the capacity of the ovarian tissue to bind LH, FSH and prolactin (PRL) in vitro. On day 19 after HCG a marked decrease in the progesterone level from the day 8 level was observed concomitant with a marked increase in 20α-dihydroprogesterone. The capacity of the ovarian tissue to bind LH in vitro was markedly reduced on day 19 compared to day 8. Identical changes were observed 21 h after 1 mg prostaglandin F2α or prostaglandin analogues. Progesterone decreased from about 600 ng/ml to about 50 ng/ml, whereas the increase in 20α-dihydroprogesterone was from about 200 ng/ml to 500–1000 ng/ml and the reduction in LH binding sites was from 1.7 × 10−12 to 0.5 × 10−12 mol/mg protein. Nanogram amounts of the analogues were as effective as 1 mg of prostaglandin F2α. The number of FSH or PRL binding sites was not affected by spontaneous luteolysis or the treatment given. By the use of graded doses of the prostaglandin analogues a negative correlation (r=−0.81) was found between plasma progesterone and 20α-dihydroprogesterone levels, and a positive correlation (r = 0.84) between LH binding sites and plasma progesterone levels. The luteolysis induced by prostaglandin F2α or prostaglandin analogues was indistinguishable from the spontaneous luteolysis using these parameters.

FSH receptor binding inhibitor influences estrogen production, receptor expression and signal pathway during in vitro maturation of sheep COCs

2017 ◽  
Vol 101 ◽  
pp. 144-150 ◽  
Author(s):  
Gong Zhuandi ◽  
Liang Haoqin ◽  
Deng Yingying ◽  
Lai Luju ◽  
Wei Suocheng ◽  
...  
Keyword(s):  
Receptor Binding ◽  
In Vitro Maturation ◽  
Signal Pathway ◽  
Receptor Expression ◽  
Fsh Receptor ◽  
Estrogen Production

scholarly journals Functional significance of muscarinic receptor expression within the proximal and distal rat vagina

2009 ◽  
Vol 297 (5) ◽  
pp. R1486-R1493 ◽  
Author(s):  
Maureen Basha ◽  
Edward F. LaBelle ◽  
Gina M. Northington ◽  
Tanchun Wang ◽  
Alan J. Wein ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Muscarinic Receptor ◽  
Functional Significance ◽  
Inositol Phosphate ◽  
Receptor Expression ◽  
Pcr Analysis ◽  
Muscarinic Agonists ◽  
Inositol Phosphate Production ◽  
Vaginal Smooth Muscle

Information regarding the role of cholinergic nerves in mediating vaginal smooth muscle contraction is sparse, and in vitro studies of the effects of muscarinic agonists on vaginal smooth muscle are discrepant. The goal of this study was to determine the expression of muscarinic receptors in the vaginal wall of the rat. In addition, we sought to determine the effect of the muscarinic receptor agonist carbachol on contractility and inositol phosphate production of the proximal and distal rat vaginal muscularis. RT-PCR analysis indicated that both M2 and M3 receptor transcripts were expressed within the proximal and distal rat vagina. Carbachol dose-dependently (10−7–10−4 M) contracted the rat vaginal muscularis with a greater maximal contractile response in the proximal vagina ( P < 0.01) compared with the distal vagina. The contractile responses of the rat vaginal muscularis to carbachol were dose dependently inhibited by the M3 antagonist para-fluoro-hexahydrosiladefenidol, and a pKB of 7.78 and 7.95 was calculated for the proximal and distal vagina, respectively. Inositol phosphate production was significantly increased in both regions of the vagina following 20-min exposure to 50 μM carbachol with higher levels detected in the proximal vagina compared with the distal ( P < 0.05). Preliminary experiments indicated the presence of M2 and M3 receptors in the human vaginal muscularis as well as contraction of human vaginal muscularis to carbachol, indicating that our animal studies are relevant to human tissue. Our results provide strong evidence for the functional significance of M3 receptor expression in the vaginal muscularis.

Conceptus development in vivo, endometrial and conceptus protein release in vitro following blastocyst transfer to ewes induced to ovulate at 28 days post-partum

1993 ◽  
Vol 5 (2) ◽  
pp. 191 ◽  
Author(s):  
JM Wallace ◽  
RP Aitken ◽  
MA Cheyne
Keyword(s):  
Binding Sites ◽  
Post Partum ◽  
Oxytocin Receptor ◽  
Blastocyst Transfer ◽  
Receptor Density ◽  
Conceptus Development ◽  
Uterine Environment ◽  
Transfer Procedures

The use of laparoscopic insemination to deposit semen into the tip of the uterine horn ensures fertilization in ewes induced to ovulate at 3-5 weeks post-partum. Acceptable pregnancy rates are achieved if embryos from post-partum donors are transferred to a normal uterine environment yet embryos rarely survive when transferred or returned to a post-partum uterus. Blastocyst transfer procedures were developed to test whether the post-partum uterus can support conceptus development during the period of rapid growth coincident with the maternal recognition of pregnancy. In Experiment 1, the efficiency of the blastocyst transfer procedure was determined using control ewes > 150 days post-partum. Eight of nine recipient ewes established pregnancies and 75% of blastocysts survived to term. In Experiment 2, blastocysts were transferred to control (n = 12) or post-partum (n = 10) recipients that had been induced to ovulate 28 days after lambing during the breeding season. Conceptus development was assessed 96 h after blastocyst transfer on Day 15 of the cycle. At this time, conceptus mass in the seven post-partum ewes which remained pregnant was generally lower than in the 11 corresponding control ewes. Conceptus and endometrial tissues were cultured separately for a further 24 h in vitro in the presence of [3H]leucine to determine production of oTP-1 and the pregnancy-specific endometrial protein p70 respectively. Oxytocin binding sites were measured in endometrial tissue. Following 96 h culture in a post-partum uterus the conceptus retained its competence to synthesize and secrete ovine trophoblast protein 1 (oTP-1) in vitro. However, despite normal oTP-1 production the conceptus tissue failed to completely suppress endometrial oxytocin receptor binding. The negative correlation between p70 production and oxytocin receptor density implies a possible role for this protein in the suppression of oxytocin receptor synthesis required to prevent luteolysis in pregnant ewes.

scholarly journals Translational Regulation of Angiotensin Type 1a Receptor Expression and Signaling by Upstream AUGs in the 5′ Leader Sequence

2004 ◽  
Vol 279 (44) ◽  
pp. 45322-45328 ◽  
Author(s):  
Hong Ji ◽  
Yinghua Zhang ◽  
Wei Zheng ◽  
Zheng Wu ◽  
Sunghou Lee ◽  
...  
Keyword(s):  
Inositol Phosphate ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Inhibitory Effect ◽  
Leader Sequence ◽  
Receptor Expression ◽  
Exon 2 ◽  
Upstream Augs ◽  
Angiotensin Type

Rat angiotensin type 1a receptor (AT1aR) is regulated by four upstream AUGs present in the 5′ leader sequence (5′-LS). Disruption of all four upstream AUGs (QM) results in 2–3-fold higher levels of angiotensin type 1 receptor (AT1R) densities in transiently transfected rat aortic smooth muscle cells (A10 cells) and stably transfected Chinese hamster ovary cells. Cells expressing QM have 5-fold higher levels of angiotensin II-induced inositol phosphate production than wild type (WT). Polysome analysis showed that QM mRNA is present in heavier fractions than the WT transcript, and 5.7-fold more AT1R protein is produced byin vitrotranslation from QM transcripts compared with WT transcripts. The AT1aR comprises 3 exons. Exon 3 (E3) encodes the entire open reading frame and 3′-untranslated region. Exons 1 and 2 (E1 and E2) and 52 nucleotides of E3 encode the 5′-LS. The AUGs in both exons contribute to the inhibitory effect on AT1R expression but not to the same degree. Disruption of the AUGs in exon 2 (DM2) relieves half of the inhibition, whereas disruption of the AUGs in exon 1 (DM1) is without effect. Disruption of the AUGs in exon 2 results in levels of receptor expression and translation that are indistinguishable from the alternative splice variant E1,3, which we previously showed was more efficiently translated than the E1,2,3 transcript. Individual mutations revealed that only the fourth AUG increased AT1R translation. In conclusion, all four AUGs present in the 5′-LS function cumulatively to suppress AT1aR expression and signaling by inhibiting translation. These data also show that both AUGs in E2 contribute to the inhibitoryciselement present in this alternatively spliced exon.

Changes in progesterone and oestrogen receptor mRNA and protein and oxytocin receptors in endometrium of ewes after intrauterine injection of ovine trophoblast interferon

1993 ◽  
Vol 10 (2) ◽  
pp. 185-192 ◽  
Author(s):  
M A Mirando ◽  
J P Harney ◽  
Y Zhou ◽  
T F Ogle ◽  
T L Ott ◽  
...  
Keyword(s):  
Oestrogen Receptor ◽  
Inositol Phosphate ◽  
Oxytocin Receptor ◽  
Secretory Proteins ◽  
Type I ◽  
Oestrogen Receptors ◽  
Receptor Mrna ◽  
Oxytocin Receptors ◽  
Highly Correlated

ABSTRACT This study determined whether twice-daily intrauterine injections of ovine conceptus secretory proteins (oCSP) containing type-I trophoblast interferon (25 μg/uterine horn) from day 11 to day 15 post-oestrus (oestrus = day 0) could alter the binding capacities of endometrial receptors for oxytocin, progesterone and oestrogen in cyclic ewes when compared with control ewes receiving serum protein (SP) injections. Injections of oCSP on days 11–15 post-oestrus decreased concentrations of oestrogen receptors (P<0·06), oestrogen receptor mRNA (P<0·05) and progesterone receptors (P<0·08) in endometrium on day 16 when compared with SP-infused control ewes, which were undergoing corpus luteum regression on days 14–16. Injection of oCSP also decreased the number (P<0·10) and affinity (P<0·06) of oxytocin receptors. Inositol phosphate formation induced in the endometrium on day 16 by 100 nm oxytocin in vitro was highly correlated with the concentration (r≥0·93, P<0·001) and Kd (r= –0·91, P<0·01) of oxytocin receptors in SP-infused ewes, but was not as highly correlated with concentration (r≤0·83, P<0·06) and Kd (r≤ –0·40, P>0·40) of oxytocin receptors in oCSP-infused ewes. This indicates that oCSP disrupted the relationship between oxytocin receptor binding and oxytocin-induced activation of its second messenger system. These results indicate that antiluteolytic type-I trophoblast interferon may prevent oxytocininduced luteolytic pulsatile secretion of prostaglandin F2α during maternal recognition of pregnancy in sheep, by reducing the synthesis and affinity of endometrial oxytocin receptors. Inhibition of other components of the oxytocin receptor—phospholipase C system by ovine trophoblast interferon may also be involved in reducing endometrial responsiveness to oxytocin. Ovine trophoblast interferon may inhibit the synthesis of endometrial oestrogen receptors to inhibit responsiveness to oxytocin during early pregnancy in ewes.

Absence of the oxytocin-induced prostaglandin F2α secretory response in uterus from ovariectomized ewes and activation of the response in vitro

1995 ◽  
Vol 145 (2) ◽  
pp. 299-305 ◽  
Author(s):  
E L Sheldrick ◽  
H C Flick-Smith ◽  
D E Bendall ◽  
A P F Flint
Keyword(s):  
Inositol Phosphate ◽  
Prostaglandin F2α ◽  
Binding Activity ◽  
Control Medium ◽  
Fresh Tissue ◽  
Short Term Exposure ◽  
Before And After ◽  
Prostaglandin F ◽  
Prostaglandin H

Abstract Oxytocin-induced prostaglandin F2α (PGF2α) responses were measured in explants of uterus from ovariectomized ewes on the day of tissue collection or after culture for 72 h in the presence or absence of oestradiol-17β (100 nmol/l). Oxytocin receptor binding activity was 210 ±47 fmol [3H]oxytocin bound per mg protein in fresh tissue and 89 ± 24 and 90 ± 17 fmol/mg in tissue cultured with control medium or with oestradiol respectively (means ± s.e.m.). PGF2α production during the hour following oxytocin administration to freshly collected tissue was 272 ± 77 ng/g/h compared with 193 ± 35 ng/g/h in the absence of oxytocin. These rates were 2789 ± 1085 and 353 ± 135 ng/g/h after culture for 72 h in control medium and 2022 ± 496 and 342 ± 134 ng/g/h after culture with oestradiol. Thus oestradiol had no effect on the culture-induced maturation of the PGF2α response. Short-term exposure to arachidonic acid (66 μmol/l) did not increase PGF2α production in fresh tissue but significantly increased basal but not oxytocin-induced PGF2α production after 72 h in culture (P<0·05). There was an absence of oxytocin-induced inositol phosphate turnover in fresh tissue but after culture concentrations of inositol mono-, bis- and trisphosphates were all significandy increased by oxytocin (P<0·005). Antisera directed against G-protein α sub-units αi3, αo, αq, α11 and the common β subunit, and prostaglandin H-synthase-1 detected proteins that were present before and after culture. Oestradiol had no effect on the presence or apparent concentrations of these proteins. Journal of Endocrinology (1995) 145, 299–305

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