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At least 649 records · Page 36Linked to original sources
PubMed1985

Effects of TMB-8, an intracellular calcium antagonist, and W-7, a calmodulin antagonist, on prostaglandin output from the guinea-pig uterus.

TMB-8, an intracellular Ca2+ antagonist, inhibited the A23187-induced increase in outputs of prostaglandin (PG) F-2 alpha and 6-keto-PGF-1 alpha from the guinea-pig uterus superfused in vitro. The high basal output of PGF-2 alpha from the Day-15 guinea-pig uterus was not inhibited by TMB-8, indicating that a maintained high intracellular free Ca2+ concentration is not necessary for maintaining this high output of PGF-2 alpha. W-7, a calmodulin antagonist, had similar actions except that PGF-2 alpha output from the Day-15 uterus was reduced 20-30 min after the W-7 treatment had stopped. Overall, these findings suggest that, in the guinea-pig, oestradiol acting on a progesterone-primed uterus causes a prolonged stimulation of endometrial phospholipase A-2 in the absence of a maintained high Ca2+ concentration, thus providing a continuous release of arachidonic acid for increased endometrial PGF-2 alpha synthesis during the last third of the oestrous cycle.

6-Ketoprostaglandin F1 alpha↗
PubMed1988

Effect of neonatal exposure to the antioestrogens nafoxidine and CI-628 upon the development of the uterus in the prepubertal rat.

Neonatal Sprague-Dawley rats were injected with the antioestrogens nafoxidine or CI-628 on Day 3 of life alone or in combination with oestradiol benzoate 24 h later. Oestrogen-stimulated glucose oxidation and cytoplasmic oestrogen binding sites of the uteri were assessed at 21-23 days of age. Neither antioestrogen antagonized the prepubertal uterine impairments produced by neonatal oestradiol treatment. Both antioestrogens administered alone produced deficits which mimicked those produced by neonatal oestrogenization. However, the agonist property of each antioestrogen was differentially expressed: treatment with CI-628 reduced prepubertal oestrogen binding sites in the uterus, but nafoxidine exposure decreased the sensitivity of the uterus to oestradiol stimulation of glucose oxidation. It is postulated that CI-628 directly affects the uterus to reduce production of oestrogen receptor protein, while nafoxidine affects the development of the uterine phosphogluconate oxidative pathway indirectly through impaired ovarian function. However, antioestrogens blocked the neonatal oestradiol-induced reduction in the oestrogen-stimulated production of actomyosin in the adult uterus. Therefore, while both CI-628 and nafoxidine are clearly agonists in the neonatal rat, each appears to exhibit cell-specific agonist and antagonist properties.

Actomyosin↗
PubMed1988

Platelet-activating factor in the rabbit uterus during early pregnancy.

Platelet-activating factor (PAF) concentrations were low in the non-pregnant, oestrous uterus (mean +/- s.e.m.: 2.2 +/- 1.2 pmol/g, n = 3). However, uterine PAF increased dramatically during pregnancy to a maximum of 37.8 +/- 4.90 pmol/g (n = 7) on Day 5. By Day 7, PAF concentrations in the uteri of pregnant rabbits had returned to levels similar to those found at oestrus. In contrast, uterine PAF in pseudopregnant rabbits peaked at 30.6 +/- 2.8 pmol/g (n = 8) on Day 4, declined to 20.5 +/- 2.4 pmol/g (n = 8) on Day 5 and then remained at that concentration through Day 7. Uterine PAF co-migrated with synthetic PAF (1-O-hexadecyl-2-acetyl-sn-glycero-phosphocholine) in both thin-layer and normal-phase high-performance liquid chromatography. PAF activity in the uterus during pregnancy and pseudopregnancy was found almost exclusively in the endometrium; little or no PAF was found in myometrium, uterine flushings or blastocysts. While no PAF was detected in blastocysts on Days 5 and 6 of pregnancy, the presence of the embryo appears to modulate biosynthesis and/or degradation of PAF by the uterus, since PAF decreased significantly in uterine tissue apposed to the implanting embryo (but not in similar areas between such attachment sites). Increased concentrations of PAF in the preimplantation rabbit uterus followed by a dramatic decrease on the day of blastocyst attachment suggest that this potent inflammatory autacoid may play a vital role in implantation.

Animals↗
PubMed1990

Decidualization in the post-partum uterus of the mouse.

Unilaterally ovariectomized mice were allowed to complete one pregnancy before the second ovary was removed and sensitivity to decidualization was induced by hormone administration. The virgin uterine horn and the post-partum horn were stimulated to decidualize by the intraluminal injection of arachis oil. A greater decidual response was found in post-partum horns than in virgin horns. The foci of decidual induction in post-partum horns were regularly spaced reflecting the regular spacing of used and unused areas of the uterus. A focus of decidual induction occurred in 68% of the recently used uterine areas observed, i.e. areas associated with post-partum nodules. When compared with foci of decidualization in adjacent unused areas of the uterus, none of the decidualized used zones showed more decidual tissue, about half showed less decidual tissue and half showed the same amount of decidual tissue. The remaining 32% of used zones were not associated with foci of decidual induction. The results indicate that decidualization can be induced in recently used zones of the uterus using a non-traumatic method of induction, but that used zones are associated with less decidual tissue than unused zones of the post-partum uterus.

Animals↗
PubMed1991

Effect of melittin on prostaglandin production by guinea-pig uterus.

Melittin, an activator of phospholipase (PL) A-2, increased the outputs of prostaglandin (PG) F-2 alpha and 6-keto-PGF-1 alpha, but not of PGE-2, from Day-7 guinea-pig uterus superfused in vitro. Reducing the extracellular calcium concentration (by omitting calcium chloride from the superfusing fluid) partially inhibited the stimulatory effect of melittin on uterine PG production. TMB-8 (an intracellular calcium antagonist) completely prevented the stimulation of PGF-2 alpha and 6-keto-PGF-1 alpha output by melittin, although the production of both PGs tended to increase after stopping the melittin and TMB-8 treatments. TMB-8 also inhibited the increases in outputs of PGF-2 alpha, 6-keto-PGF-1 alpha and PGE-2 and prevented contraction of the uterus induced by exogenous PLA-2. Trifluoperazine (a calmodulin antagonist) had no inhibitory effect on the increases in outputs of PGF-2 alpha and 6-keto-PGF-1 alpha produced by melittin; it potentiated the stimulatory effect of melittin on 6-keto-PGF-1 alpha output and allowed melittin to increase PGE-2 output. When melittin was applied twice to the superfused uterus with an interval of 1 h between each treatment, partial refractoriness of the responses to melittin was seen: the magnitudes of the increases in PGF-2 alpha and 6-keto-PGF-1 alpha outputs were 40-50% less after the second treatment than after the first treatment. These results show that melittin stimulates the synthesis of PGF-2 alpha and PGI-2 (measured as 6-keto-PGF-1 alpha) in guinea-pig uterus by mechanisms which are calcium dependent.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Ketoprostaglandin F1 alpha↗
PubMed1993

Uptake of relaxin in the uterus and cervix of rats in vivo: influence of ovarian steroids and tolerance.

The influence of oestradiol benzoate and progesterone treatment and of tolerance to relaxin on the uptake of 125I-labelled porcine relaxin by reproductive tissues was investigated in anaesthetized female rats. In ovary-intact rats, 125I-labelled relaxin uptake increased with time in reproductive tissues and in tissues concerned with metabolism and excretion. Administration of 50 micrograms unlabelled porcine relaxin before injection of 125I-labelled relaxin significantly reduced uptake of 125I-labelled relaxin into the uterus and cervix, but had no effect on uptake of 125I-labelled relaxin into other tissues, indicating that specific uptake of relaxin was occurring in the uterus and cervix. In ovariectomized rats, treatment with oestradiol benzoate or oestradiol benzoate plus progesterone for 1 day did not significantly increase uterine or cervical 125I-labelled relaxin uptake compared with corn oil-treated rats, but induced a significant increase in uterine uptake of 125I-labelled relaxin after treatment for 2 days. Induction of tolerance to relaxin by i.v. infusion of a high dose of relaxin significantly reduced uterine and cervical uptake of 125I-labelled relaxin at 3 h after termination of infusion compared with saline-infused rats. By 12 h after termination of infusion, 125I-labelled relaxin uptake in the uterus and cervix was similar in saline-infused rats and in rats given an infusion of relaxin. Infusion of glibenclamide (20 mg kg-1) did not influence uterine or cervical uptake of 125I-labelled relaxin; however, treatment with phentolamine (10 mg kg-1) significantly reduced 125I-labelled relaxin uptake in uterus, bladder and jejunum. This study demonstrates that steroid hormone treatment and tolerance modulate relaxin uptake in reproductive tissues.

Animals↗
PubMed1994

Effect of parathyroid hormone-related protein (PTHrP) on the contractility of the myometrium and localization of PTHrP in the uterus of pregnant rats.

The effect of parathyroid hormone-related protein (PTHrP) on the contractility of uterine segments taken from pregnant rats and the localization of PTHrP in the uterus during pregnancy were investigated. PTHrP(1-34) had a potent inhibitory effect on spontaneous contractions of the longitudinal layer of uterine myometrium taken from rats at day 4 of pregnancy (IC50 1.6 nmol l-1). In low calcium De Jalon's solution, it also decreased base-line tension (IC50 1.5 nmol l-1) in a concentration-dependent manner. The effect of PTHrP(1-34) on uterine motility decreased as pregnancy progressed until day 13, after which PTHrP(1-34) had no measurable effect on uterine contractility. In contrast, PTHrP(1-34) had no effect on the contractions of the circular smooth muscle of the uterus at any stage of pregnancy. PTHrP(50-69) had no effect on the contractility of either muscle layer of the myometrium. A temporal pattern of staining for PTHrP in the uterus of pregnant rats was observed, and the changes in the staining patterns in the endometrium and myometrium were different in each layer. These data suggest that PTHrP may have at least two distinct roles in the uterus, a relaxing action on longitudinal muscle that depends on the hormonal state of the rat and a novel effect either intraluminally or within the endometrial layer.

Animals↗
PubMed1996

Nitric oxide synthase isoforms in the rat uterus: differential regulation during pregnancy and labour.

Production of nitric oxide in the uterus is increased during pregnancy and decreased during delivery. In this study the isoform of nitric oxide synthase which may be responsible for the changes in nitric oxide production was investigated in relation to pregnancy and delivery. Monoclonal antibodies were used to measure changes in neuronal nitric oxide synthase (NOS I), macrophage nitric oxide synthase (NOS II) and endothelial cell nitric oxide synthase (NOS III) protein in the rat uterus by densitometric scanning of specific bands. Results show that: (1) NOS II protein concentrations in the uterus were substantially increased during pregnancy and were decreased during delivery, both at term and preterm (induced by RU486); (2) NOS III protein was present at all stages examined but the concentrations were unchanged; (3) NOS I was present in the rat uterus during the nonpregnant stage but not during pregnancy and delivery. The changes in uterine NOS II protein concentrations during pregnancy and delivery were further confirmed by the changes in the Ca(2+)-independent, but not Ca(2+)-dependent, nitric oxide synthase activity. Therefore, an increase in NOS II, thus in nitric oxide production during pregnancy, may play a role in maintaining uterine quiescence.

Animals↗
PubMed1998

Role of mast cells in oestradiol effects on the uterus of ovariectomized rats.

The role of mast cells and their main secretory products in the effects of oestradiol on the uterus was investigated. Ovariectomized rats were treated with a single injection of oestradiol (10 micrograms per rat, i.m.) or vehicle together with drugs affecting the activity of mast cells, cromoglycate (10 mg per rat, i.m.), which diminishes the degranulation of mast cells, or compound 48/80 (0.5 mg per rat, i.m.), which enhances this process. Oestradiol or vehicle was also administered with two important secretory products of mast cells, heparin (0.4 mg per rat, i.m.) or histamine (2 mg per rat, i.m.). All drugs were injected simultaneously with oestradiol (first injection) and then every 6 h until the animals were killed. Observations were performed at 24, 36 and 48 h after oestradiol or vehicle injection. The condition of mast cells was determined by the percentage of degranulated mast cells in sections stained with toluidine blue. Oestradiol-induced effects in the uterus were estimated by the mitotic index, proliferating cell nuclear antigen-labelling index, DNA content, volumes of cells, nuclei and nucleoli in the luminal epithelium, glandular epithelium and stroma cells of the endometrium. Cromoglycate treatment resulted in a decrease in both mast cell degranulation and all examined oestradiol effects in the uterus at all periods of observation. Compound 48/80 increased mast cell degranulation and expression of one aspect of oestradiol effects on the volumes of cell compartments. Histamine or heparin led to a marked increase in the cell, nucleus and nucleolus volumes in all uterine structures. However, heparin produced a depression in proliferation, whereas histamine had a weak transient stimulating action on this process. No effects of the protocols were found in the absence of oestradiol treatment. These results suggest that mast cells are involved in the realization of oestrogen action, including the stimulation of cell growth and proliferation in the uterus, and that the effect of mast cells is mediated by both histamine and heparin.

Analysis of Variance↗
PubMed2001

Immunohistochemical study of the distribution of adrenergic and peptidergic innervation in the equine uterus and the cervix.

Little is known about neurogenic regulation of uterine contractility in mares. The present study investigated the distribution of adrenergic and peptidergic nerves in the mare uterus. Samples from the uterine horn, body and cervix were collected from 18 cyclic mares for immunohistochemistry. The uterus was well supplied with adrenergic nerves. A large number of tyrosine hydroxylase- and dopamine beta-hydroxylase-immunoreactive nerve bundles and fibres were present in the myometrium and endometrium in all regions of the uterus and cervix. These adrenergic nerve bundles and fibres travelled parallel to the muscle layers and were often associated with blood vessels. The density of peptidergic nerves was less than that of adrenergic nerves, but the pattern of distribution was similar. Neuropeptide Y-immunoreactive nerve fibres were the most abundant, whereas vasoactive intestinal polypeptide- and calcitonin gene-related peptide-immunoreactive nerve fibres were less frequently seen. Substance P-immunoreactive nerve fibres were the most sparse. Peptidergic nerves were distributed among the smooth muscle layers and near endometrial glands and were often associated with blood vessels in all regions of the uterus. The density of peptidergic nerve fibres was similar in the uterine horn and body but was slightly denser in the cervix. These findings indicate that uterine innervation may have an important role in controlling reproductive functions in mares.

Animals↗
PubMed2003

Global gene profiling analysis of mouse uterus during the oestrous cycle.

Many genes related to the cyclic changes of the uterus during the oestrous cycle have been identified using a one-by-one approach. In the present study, cDNA microarray technology was applied to investigate the global profile of gene expression of mouse uterus at the oestrous and dioestrous stages. At a certain stage of the oestrous cycle, the uteri of mature CD-1 mice (n=10) were removed, pooled and snap-frozen in liquid nitrogen. Total RNA was extracted to synthesize cDNA probes for microarray assay. By screening 8192 mouse genes and expressed sequence tags (ESTs), 51 upregulated and 51 downregulated genes were identified in oestrous uterus, of which 62 are well characterized and 40 are ESTs. The known genes were assigned to various gene categories according to their main function. The microarray was performed three times with three independent sets of uterine tissue pools. The results of northern blot analysis for small proline-rich protein 2 (Sprr2), 17beta-hydroxysteroid dehydrogenase type 2 (17betaHSD-2), high mobility group 2 (Hmg2), mitotic checkpoint component 2 (Mad2) and an EST AW555366 mRNA were consistent with that of microarray analysis. In situ hybridization was performed to localize the transcript of the EST AW555366. Most of the upregulated genes encode secreted immune-related proteins, proteinases and their inhibitors, indicating their potential involvement in sperm viability as well as capacitation. The downregulated genes mainly encode cell cycle-related factors, implying the active proliferation of uterus at dioestrus.

Animals↗
PubMed2006

Reduced nitric oxide synthase and cyclo-oxygenase activity in the uterus of non-obese diabetic mice.

A functional interaction between progesterone, Th2 cytokines and a suitable balance between nitric oxide and prostaglandins in the uterus is considered to have a major role in the success of embryo implantation and pregnancy. Non-obese diabetic (NOD) mice offer a suitable model to study the modulatory role of Th1 cytokines on uterus signalling and function, since at the prediabetic stage they develop a spontaneous Th1 autoimmune response against exocrine glands similar to Sjögren's syndrome. Vasoactive intestinal peptide (VIP) is a vasoactive neuro- and immunopeptide that promotes Th2 profiles and contributes to the smooth muscle relaxation and vasodilation. The aim of the present study was to investigate the activities of nitric oxide synthase and cyclo-oxygenase and the effect of VIP in the uterus of NOD mice with an emerging Th1 cytokine response. We present evidence of a reduced basal and VIP-stimulated activity of both enzymes in the uterus of NOD mice compared with normal BALB/c mice in proestrus. An altered functional interaction between both enzymes is also present in NOD mice at the time when increased levels of serum interleukin (IL)-12 and tumour necrosis factor-alpha but not interferon (IFN)-gamma or IL-10 were detected. We conclude that signalling alterations in uteri of NOD mice are simultaneous to the onset of a systemic Th1 cytokine response.

Animals↗
PubMed2006

Expression and regulation of stanniocalcin 1 and 2 in rat uterus during embryo implantation and decidualization.

Stanniocalcin-1 (STC-1) is a recently discovered polypeptide hormone, while stanniocalcin-2 (STC-2) is a subsequently identified homologue of stanniocalcin-1. Although previous studies have shown that both STC-1 and -2 are involved in various physiological processes, such as ion transport, reproduction and development, their expression in the uterus and roles in implantation and early pregnancy are unclear. Here we have investigated the expression and regulation of both STC-1 and STC-2 in rat uterus during early pregnancy under various physiological conditions. We show that only basal levels of STC-1 and STC-2 mRNA were detected in the uterus from day one (D1) to day five (D5) of pregnancy. STC-2 immunostaining was gradually increased in the glandular epithelium from day two (D2), with a peak occurring on D5. High levels of both STC-1 and STC-2 mRNA were observed in the stoma cells at the implantation site on day six (D6) of pregnancy, whereas their immunostaining signals were also significant in the luminal epithelium. Basal levels of both STC-1 and STC-2 mRNA and STC-1 immunostaining were detected in the uterus with delayed implantation. After the delayed implantation was terminated by estrogen treatment, both STC-1 and STC-2 mRNA signals were significantly induced in the stroma underlying the luminal epithelium at the implantation site, and STC-2 immunostaining was also observed in the luminal epithelium surrounding the implanting blastocyst. Embryo transfer experiments further confirmed that STC-1 and STC-2 expression at the implantation sites was induced by the implanting blastocyst. Both STC-1 mRNA and immunostaining were seen in the decidualized cells from day seven (D7) to day nine (D9) of pregnancy. STC-2 mRNA was also found in the whole decidua from D7 to D9 of pregnancy; STC-2 protein, however, was strictly localized to the primary deciduas on D7 and D8, with a weak expression in the whole deciduas on D9. Consistent with the normal pregnancy process, strong STC-1 and STC-2 mRNA signals were detected in the decidualized cells under artificial decidualization, whereas only basal levels of STC-1 mRNA and immunostaining were observed in the control horn. These data suggest, for the first time, that STC-1 together with STC-2 may play important roles in the processes of implantation and decidualization in the rat.

Animals↗
PubMed2000

Mechanism of relaxant response to papaverine on the smooth muscle of non-pregnant rat uterus.

In the present paper, we examined a mechanism of the papaverine induced relaxation in the smooth muscle of non-pregnant rat uterus. The hyperosmotic 65 mM KCl (H-65K+)-or oxytocin-induced contraction in the uterus was inhibited by an addition of papaverine in a concentration-dependent manner. Papaverine did not increase both cAMP and cGMP contents in the uterus in the presence of H-65K+ or oxytocin. In fura 2 loaded muscles, papaverine did not affect an increase of [Ca2+]i level by high K+ or oxytocin. In permeabilized muscles, papaverine had no effect on the Ca2+-induced contraction. H-65K+ and oxytocin increased the rate of oxygen consumption 1.8 and 1.5 times higher than that in the resting condition, respectively. The increase of oxygen consumption in the H-65K+ or oxytocin was significantly inhibited by papaverine (1-100 microM). These results suggested that papaverine inhibits smooth muscle contraction mainly by inhibition of mitochondrial respiration in rat uterus as well as guinea pig ileum, which shows a highly spontaneous activity and a highly metabolic dependency of a contraction.

Animals↗
PubMed1999

Differential immunolocalization of estrogen receptor alpha and beta in rat ovary and uterus.

In order to investigate the localization of estrogen receptor (ER) alpha and ERbeta in the reproductive organs in the rat, polyclonal antibodies were raised to each specific amino acid sequence. The Western blot with anti-ERalpha antibody showed a 66 kDa band in rat ovary and uterus, while that with anti-ERbeta antibody detected a 55 kDa band in rat ovary, uterus and prostate. The ligand-independent nuclear localization of the two receptors was verified by immunocytochemistry. By immunohistochemistry, the nuclei of glandular and luminal epithelial cells in the uterus were stained with anti-ERalpha antibody, whereas only the nuclei of glandular epithelium cells were stained with anti-ERbeta antibody. In rat ovary, positive signals were shown with anti-ERbeta antibody in the nuclei of granulosacells. No specific immunostaining was observed with anti-ERalpha antibody. Although ERbeta was immunostained at the proestrous, metestrous and diestrous stages, the immunoreactivity of ERbeta was hardly detected at the estrous stage in rat ovary. Thus, we show differential expression of ERalpha and ERbeta in rat uterus and ovary at the protein level, which may provide a clue for understanding the roles of the two receptors in reproductive organs.

Amino Acid Sequence↗
PubMed1985

Increase in plasminogen activator in the involuting uterus of the postpartum rat.

Plasminogen activator (PA) activity in the rat uterus was measured at fixed intervals post partum in order to determine whether this serine protease increases during the acute remodelling of tissue which occurs in the involuting uterus. Plasminogen activator activity was measured by an indirect method based on the hydrolysis of the chromogenic substrate S-2251 by PA-generated plasmin. At the time of parturition the control level of PA activity was 0.033 +/- 0.018 (S.D.) mumol/4 mg uterine wet weight per 30 min. This activity increased fourfold to a peak of 0.131 +/- 0.036 at 3 days post partum, and then it declined steadily towards the control level during the next 7 days. Concomitantly, uterine weight decreased to 25% of the control weight by 3 days post partum, and it continued to decrease until day 15. In the 30 days post partum during which PA activity was monitored there was no significant change in plasmin inhibitors in the uterine extracts. The results suggest a correlation between PA activity and the process of tissue remodelling which occurs during involution of the rat uterus. This increase in PA might serve to activate a latent collagenase since the measured peak in PA activity happens to coincide with a reported increase in collagenolytic activity in the involuting rat uterus.

Animals↗
PubMed1990

Influence of oestrogen and progesterone on macrophage distribution in the mouse uterus.

Macrophages are constituents of all normal connective tissue including the murine uterus. Macrophages have been identified previously in endometrium and myometrium of pregnant and non-pregnant murine uterus using antibodies against macrophages. In the current study immunohistochemical analysis of murine uterus demonstrated that there were not significant quantitative differences in uterine macrophages between the diestrous, pro-oestrous and oestrous stages. However, distributional changes occurred during the oestrous cycle. Macrophages were evenly distributed throughout uterine tissue during dioestrus, while, during pro-oestrus and oestrus, their concentration was highest in the subepithelial stroma. Because the oestrous cycle is hormonally regulated, we asked whether or not oestrogen and/or progesterone might influence macrophage distribution. Ovariectomy, which eliminates cyclical production of oestrogen and progesterone, resulted in a significant decrease in both the relative and the absolute number of uterine macrophages within 6 days. Injections of progesterone or oestrogen to ovariectomized mice resulted in restoration of uterine macrophage numbers. Injection of oestrogen plus progesterone in a regimen known to prepare the uterus for receptivity for blastocyst implantation increased the number of macrophages to levels which were consistently higher than those seen during oestrus. Moreover, following hormone administration macrophages were more concentrated in the subepithelial stroma, a distributional pattern which was most evident following injection of both hormones. The results suggest that both oestrogen and progesterone promote quantitative and distributional changes in the uterine macrophage population.

Animals↗
PubMed1998

Temporal expression and cellular localization of a gastrin-releasing peptide-related gene in ovine uterus during the oestrous cycle and pregnancy.

Synthesis of both mRNA and peptide for gastrin-releasing peptide (GRP) has been demonstrated in the pregnant endometrium of sheep and women. However, it is not known whether GRP is synthesized in the sheep uterus during the oestrous cycle. Furthermore the cellular site of GRP mRNA synthesis in the uterus has not been determined. Therefore we examined the synthesis of GRP and determined the cellular location of GRP peptide and mRNA in sheep uterus taken at different times during the oestrous cycle (duration 17 days) and pregnancy (duration 145 days). Northern blot analysis of RNA isolated from ovine endometrium revealed low or no GRP mRNA at days 4, 10, 12 and 14 of the oestrous cycle and a 24-fold rise in GRP mRNA (normalized to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA) between days 14 and 16. A similar pattern was observed during early pregnancy, with a 12-fold rise in GRP mRNA:GAPDH mRNA between days 17 and 20 of pregnancy. Levels of GRP peptide were determined by RIA and found to be low in endometrium isolated at days 4, 10, 12 and 14 of the oestrous cycle (1.0-1.6 pmol/g) and 4 to 5-fold higher at day 16. In situ hybridization localized GRP synthesis to the epithelial cells of the uterine glands at day 16 of the oestrous cycle and at days 17, 20, 40 and 50 of pregnancy. At day 140 of pregnancy diffuse hybridization to cells of the myometrium was also observed. Immunohistochemistry localized GRP peptide to the apical cytoplasm of uterine glandular epithelial cells at day 16 of the oestrous cycle. For samples obtained at day 20 of pregnancy, the area surrounding the glands also showed moderately strong staining. Further staining in the glandular lumen and the stromal tissue surrounding the glands was apparent at day 140 of pregnancy. No GRP immunoreactivity could be detected in the peripheral plasma during the oestrous cycle or the first 20 days of pregnancy. Sizing chromatography of GRP immunoreactivity extracted from endometrial tissue taken at day 10 of the oestrous cycle revealed two peaks that co-eluted with GRP(1-27) and GRP(18-27). However, during luteolysis and oestrus the major peak of GRP immunoreactivity extracted from endometrial tissue was larger than GRP(1-27) and similar to that seen previously in the gravid ovine endometrium. These studies demonstrate that a peptide similar to, but larger than, GRP is a major product of the glandular epithelium of the ovine uterus during the luteal regression phase of the oestrous cycle and post-blastocyst implantation in pregnancy and provide further evidence that GRP-related peptides have important regulatory roles in uterine function.

Animals↗