Relaxin and progesterone are myometrial inhibitors in the ovariectomized non-pregnant mini-pig

Porter, D. G.; Watts, Alice D.

doi:10.1530/jrf.0.0760205

Cited by 18 publications

(11 citation statements)

References 14 publications

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“…From these results, we speculate that PR in the myometrium is upregulated by high plasma levels of oestradiol-17b during oestrus in order to prepare for the progesterone regulation via PR at following stages of the oestrous cycle/pregnancy. Increasing and high levels of progesterone have been shown to provide a quiescent uterus with low myometrial activity (Porter & Watts 1986, Ding et al 1994 and to decrease PR levels (Batra & Iosif 1989, Bouchard 1999, which was supported by our present results with low PR levels at d 19 of early pregnant sows (group 5, experiment B) compared with high PR levels at prooestrus in cyclic sows (experiment A).…”

Section: Discussionsupporting

confidence: 87%

Immunohistochemical studies on the progesterone receptor (PR) in the sow uterus during the oestrous cycle and in inseminated sows at oestrus and early pregnancy

Sukjumlong¹,

Dalin²,

Sahlin³

et al. 2005

Reproduction

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Physiological changes in the sow uterus involve the regulation by progesterone and its receptor proteins (PR). Therefore, the aim of the present study was to investigate the localization of PR during different stages of the oestrous cycle and in inseminated sows during early pregnancy by use of immunohistochemistry. Uterine samples were collected from cyclic and inseminated sows at different stages of the oestrous cycle and early pregnancy. The samples were fixed in 10% formaldehyde and embedded in paraffin. Immunohistochemistry was done by use of a mouse monoclonal antibody to PR. The highest PR immunostaining in the surface epithelium was observed at oestrus/5 -6 h after artificial insemination (AI) and early dioestrus/70 h after AI. In the glandular epithelium, the highest level of PR was found at oestrus with the lowest at late dioestrus/d 19. Higher levels of PR were observed in inseminated groups compared with cyclic sows. In the myometrium, a high level of PR was found at oestrus, while stromal PR cells were constantly present throughout the oestrous cycle and at different stages of early pregnancy. In conclusion, this study shows that the immunopresence of PR in the sow uterus differed between uterine compartments at the same reproductive stage. Differences were also found for some uterine compartments between cyclic and inseminated/early pregnant sows. The relatively consistent immunostaining of PR in the stroma strengthens a stromal role in the regulation of physiological activities in the sow uterus during the oestrous cycle as well as early pregnancy.

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Section: Discussionsupporting

confidence: 87%

Immunohistochemical studies on the progesterone receptor (PR) in the sow uterus during the oestrous cycle and in inseminated sows at oestrus and early pregnancy

Sukjumlong¹,

Dalin²,

Sahlin³

et al. 2005

Reproduction

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“…A pilot study was first conducted using the group A rats. Myometrial RNA was extracted from tissues obtained on GDs 6,8,10,12,14,15,17,19,21,and 22; during labor on GD 23 (n ¼ 4 per day); and on Postpartum Days (PDs) 1 and 4 (n ¼ 4 per day) and was provided by Dr. Oksana Shynlova and Prof. Stephen Lye (Samuel Lunenfeld Research Institute). This enabled us to identify key stages of gestation for further analysis at both the transcriptional and the translational level, with a larger sample size per stage using group B rats.…”

Section: Experimental Designmentioning

confidence: 99%

“…In vitro studies show that porcine relaxin inhibits contractile activity in the nonpregnant (NP) and pregnant rat until midpregnancy, but that the myometrium is completely refractory to the inhibitory effect of relaxin by Gestational Day (GD) 19 [5,6]. In NP ovariectomized rats and pigs, relaxin primarily reduces frequency rather than amplitude of spontaneous intrauterine pressure cycles (IUPCs) [7,8]. Ovariectomized pregnant rats have a significantly greater frequency of IUPCs and reduced myometrial quiescence from mid to late gestation, an effect that is reversed by relaxin treatment [9].…”

Section: Introductionmentioning

confidence: 99%

Decreased Expression of the Rat Myometrial Relaxin Receptor (RXFP1) in Late Pregnancy Is Partially Mediated by the Presence of the Conceptus1

Vodstrcil

Shynlova

Verlander

et al. 2010

Biology of Reproduction

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The actions of relaxin are mediated by relaxin family peptide receptor 1 (Rxfp1). In pregnant mice, myometrial Rxfp1 expression decreases at term, coinciding with the highest level of circulating relaxin. This down-regulation in Rxfp1 in reproductive tissues has not been investigated in other pregnant animals, nor are the regulatory mechanisms known. In the present study, we examined Rxfp1 gene and protein expression in the nonpregnant, pregnant, and postpartum rat uterus. The potential effects of local conceptus-derived factors on Rxfp1 expression were then examined in unilaterally pregnant rats. Immunoreactive RXFP1 was predominantly detected in the circular smooth muscle layer in the myometrium and in the decidualized endometrium. Rxfp1 was expressed in the rat myometrium from early to midgestation at levels similar to those in nonpregnant rat myometrium, with a significant reduction in expression at both the transcriptional and translational levels during late gestation. In unilaterally pregnant rats, myometrial Rxfp1 was higher in the nongravid compared to the gravid uterine horn, demonstrating a local negative influence of the fetal-placental unit on Rxfp1 expression. In summary, the down-regulation in myometrial Rxfp1 expression at the end of gestation in the rat is partially mediated by the fetal-placental unit and is indicative of a functional withdrawal of relaxin. This may represent a novel mechanism for the activation of spontaneous uterine contractions at labor in this species.

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“…Relaxin, a peptide hormone produced mainly in the ovary, has several target tissues, including the myometrium on which it exerts a relaxant effect (rat : Sawyer et al, 1953;Bradshaw et al, 1981;mouse: Wiqvist, 1959;man: Szlachter et al, 1980;guinea-pig: Porter, 1972; mini-pig: Porter & Watts, 1986). It was recently reported that porcine relaxin specifically depressed the plateau component of the action potential in the myometrium of the pregnant and oestrogen-treated rat, thereby inhibiting the contraction (Chamley & Parkington, 1984).…”

Section: Introductionmentioning

confidence: 99%

Effects of porcine relaxin on contraction, membrane response and cyclic AMP content in rat myometrium in comparison with the effects of isoprenaline and forskolin

Osa

Inoue

Okabe

1991

British J Pharmacology

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1 The longitudinal muscle from the uterus of oestrogen-treated rats was quiescent in Mg-free Krebs solution. Electrical stimulation generated phasic contraction, which was depressed to 35% and 18% by 50 mu and 150 mu porcine relaxin, respectively. 2 The phasic contractions were more strongly depressed to 26% by 50 mu relaxin in solution containing 0.6 mm Mg, and the depression lasted for more than 4 h after the removal of relaxin. During the persisting depression, raising the external Ca to 7.5 mm did not restore the contraction, but the contraction was restored by removal of Mg. 3 The depression of the phasic contraction by relaxin, examined in Mg-free solution, was enhanced and reduced by pretreatment of the tissue with 0.6 mm Mg and 0.6 mm Mn, respectively, for about 15min. In contrast, the depression of contraction by isoprenaline or forskolin was enhanced by pretreatment with either Mg or Mn. 4 The cellular content of cyclic AMP was measured in Krebs solution containing 0.6 mm Mg. The values were 1.24 (pmolmg-' protein) in control solution, and 2.31 and 1.56 when the tissues were treated with 150 mu relaxin and 10-9 M isoprenaline, respectively. 5 The cyclic AMP production in response to 10-7M forskolin measured in Mg-free solution was enhanced when the tissue was pretreated with either 0.6mm Mg or Mn for 15min. The cyclic AMP production in response to 100mu relaxin was increased when the tissue was pretreated with 0.6mm Mg, and was unchanged by pretreatment with Mn. The cyclic AMP production in response to 10-9M isoprenaline was unchanged by pretreatment with the divalent cations. 6 The membrane potential of the muscle was -60.8mV in Krebs solution containing 0.3mm Mg, and electrical stimulation induced an action potential which consisted of spike and plateau components. Application of 150mu relaxin reduced the duration of the plateau; the contractions were progressively depressed. The resting membrane potential and membrane resistance were unchanged by application of 150 mu relaxin. The membrane was hyperpolarized by 2.8 mV, accompanied by a decrease in membrane resistance, when I0-9 M isoprenaline was applied. 7 Although there were several differences between the effects of relaxin and isoprenaline, it is probable that some process, which is cyclic AMP-dependent, accelerated by Mg and depressed by Mn, is involved in the depressant action of relaxin on contraction.

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Relaxin and progesterone are myometrial inhibitors in the ovariectomized non-pregnant mini-pig

Cited by 18 publications

References 14 publications

Immunohistochemical studies on the progesterone receptor (PR) in the sow uterus during the oestrous cycle and in inseminated sows at oestrus and early pregnancy

Immunohistochemical studies on the progesterone receptor (PR) in the sow uterus during the oestrous cycle and in inseminated sows at oestrus and early pregnancy

Decreased Expression of the Rat Myometrial Relaxin Receptor (RXFP1) in Late Pregnancy Is Partially Mediated by the Presence of the Conceptus1

Effects of porcine relaxin on contraction, membrane response and cyclic AMP content in rat myometrium in comparison with the effects of isoprenaline and forskolin

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