Uterine receptor for oxytocin: Effects of estrogen

Soloff, Melvyn S.

doi:10.1016/s0006-291x(75)80080-5

Cited by 180 publications

(65 citation statements)

References 15 publications

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“…In the rat, the administration of an estrogen receptor antagonist during late pregnancy reduced uterine OT mRNA and protein causing a significant delay in parturition (Fang et al 1996). In addition, estrogen stimulates the synthesis of OTR (Soloff 1975). Thus, it is plausible that the expression and activity of uterine PLA 2 s was induced by both estradiol and OT.…”

Section: Discussionmentioning

confidence: 99%

Secretory and cytosolic phospholipase A2 activities and expression are regulated by oxytocin and estradiol during labor

Farina¹,

Billi²,

Leguizamón³

et al. 2007

Reproduction

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The release of arachidonic acid from membrane glycerophospholipids through the action of phospholipases (PLs) is the first step in the biosynthesis of prostaglandins (PGs). In reproductive tissues, the most important PLs are cytosolic PLA 2 (cPLA 2 ) and types IIA and V of the secretory isoform (sPLA 2 ). The aim of this work was to investigate the role of ovarian steroid hormones and oxytocin (OT) in the regulation of rat uterine PLA 2 activity and expression during pregnancy and labor. The activity of sPLA 2 increased near labor, whereas cPLA 2 activity augmented towards the end of gestation. The levels of sPLA 2 IIA and cPLA 2 mRNA showed an increase before labor (P!0.05, day 21), whereas sPLA 2 V mRNA was not regulated during pregnancy. The administration of atosiban (synthetic OT antagonist) together with tamoxifen (antagonist of estrogen receptors) was able to decrease cytosolic and secretory PLA 2 activities, diminish the expression of sPLA 2 IIA and cPLA 2 , as well as decrease PGF 2a production before the onset of labor (P!0.01). The ovarian steroid did not affect PLA 2 during pregnancy. Collectively, these findings indicate that in the rat uterus, both 17b-estradiol and OT could be regulating the activity and the expression of the secretory and the cytosolic isoforms of PLA 2 , thus controlling PGF 2a synthesis prior to the onset of labor. Reproduction (2007) 134 355-364

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Section: Discussionmentioning

confidence: 99%

Secretory and cytosolic phospholipase A2 activities and expression are regulated by oxytocin and estradiol during labor

Farina¹,

Billi²,

Leguizamón³

et al. 2007

Reproduction

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“…The particulate fraction sedimenting between 1,000g for 10min and 165,000g for 30min was prepared and assayed for PHI-oxytocin binding activity (Soloff, 1975a (Morgat, Hung, Cardinaud, Fromageot, Bockaert, Imbert & Morel, 1970) was synthesized by Schwarz-Mann and was reported to have full biological activity (452 iu per mg) in the rat isolated uterus assay (Sturmer, 1968;Fitzpatrick & Bently, 1968). More than 90% of the radioactivity migrated with authentic oxytocin upon thin layer chromatography oxytocin and the oxytocin antagonists ( Figure 2).…”

Section: Binding Assaymentioning

confidence: 99%

“…In view of the demonstration of specific binding sites for [3H]-oxytocin in the uterus of several species (Soloff, Swartz, Morrison & Saffran, 1973;Soloff, Swartz & Steinberg, 1974;Soloff, 1975a) it is possible to estimate the binding affinities of the oxytocin antagonists directly and to correlate the values with antagonist activity. Four of the most potent oxytocin antagonists have been examined in the present studies.…”

Section: Introductionmentioning

confidence: 99%

Uterine Receptors for Oxytocin: Correlation Between Antagonist Potency and Receptor Binding

Soloff

1976

British J Pharmacology

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“…This increased uterine responsiveness to oxytocin occurs in parallel with an increase in the number of uterine oxytocin binding sites in rats [3,21], humans [4], rabbits [13,14] and cows [5]. Corresponding increases in uterine oxytocin receptor (OTR) mRNA expression in late pregnancy and parturition have been reported in rats [11,12,19], humans [9], cows [8] and sheep [24,25].Estrogen stimulates the number of uterine oxytocin binding sites [3,20,22] and OTR mRNA expression in ovariectomized (OVX) virgin rats [11,12]. However, injection of estrogen does not stimulate oxytocin receptor mRNA expression in late pregnant rats or progesterone-primed OVX virgin rats, but is effective only after ovariectomy and removal of progesterone, respectively [17].…”

mentioning

confidence: 92%

Changes in Uterine Receptor mRNAs for Oxytocin and Estrogen in the Pseudopregnant Rat

Murata

Narita

Higuchi

2008

The Journal of Veterinary Medical Science

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ABSTRACT. This study examined the uterine oxytocin-(OTR) and estrogen-(ER) receptor mRNA levels during and after pseudopregnancy (PSP) in rats. An increased OTR mRNA level was observed from day 14 of PSP, and the maximal level was attained during the following proestrus. The levels of ERα mRNA were low during PSP and significantly increased during the following estrus. The level of ERβ mRNA was significantly decreased during proestrus and then returned to the values observed during days 7-14 of PSP by estrus. These results suggest i) suppression of ERα mRNA during the luteal phase and that ii) the changes in OTR, ERα and ERβ mRNA levels during proestrus and estrus following PSP are similar to those during the normal estrous cycle. KEY WORDS: estrogen receptor, oxytocin receptor, pseudopregnancy.J. Vet. Med. Sci. 70(11): 1253-1256, 2008 Oxytocin (OT) was initially isolated as a neurohypophysial hormone that stimulates contraction of the myometrium and myoepithelium to facilitate parturition and milk ejection, respectively, and is considered to mediate various reproductive functions in the ovary, uterus and brain. In the uterus, the near-term myometrium is extremely sensitive to oxytocin. This increased uterine responsiveness to oxytocin occurs in parallel with an increase in the number of uterine oxytocin binding sites in rats [3,21], humans [4], rabbits [13,14] and cows [5]. Corresponding increases in uterine oxytocin receptor (OTR) mRNA expression in late pregnancy and parturition have been reported in rats [11,12,19], humans [9], cows [8] and sheep [24,25].Estrogen stimulates the number of uterine oxytocin binding sites [3,20,22] and OTR mRNA expression in ovariectomized (OVX) virgin rats [11,12]. However, injection of estrogen does not stimulate oxytocin receptor mRNA expression in late pregnant rats or progesterone-primed OVX virgin rats, but is effective only after ovariectomy and removal of progesterone, respectively [17]. These results suggest that in addition to the increase in serum estrogen level near term in rats, regulation of the uterine responsiveness to estrogen is important for understanding the role of estrogen in the uterus. The actions of estrogen are mediated through estrogen receptors [1], and two types of estrogen receptor (ER), ERα and ERβ, have been cloned from the human uterus [6] and rat prostate [10], respectively.In the rat uterus at the end of pregnancy and during labor, the ERα mRNA level gradually increases simultaneously with the OTR mRNA level, while the ERβ mRNA level does not show any significant changes; during this period, there is a positive correlation between the ERα and OTR mRNA levels [16]. However, while the OTR mRNA level is increased during proestrus and then decreased during estrus in the estrous cycle, the ERα and ERβ mRNA levels decrease during proestrus and return to the levels observed during diestrus at estrus [15,16]. This indicates apparent reciprocal changes between OTR and ER (ERα and ERβ) mRNA levels during proestrus and estrus. Furthermore, injection of 17...

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Uterine receptor for oxytocin: Effects of estrogen

Cited by 180 publications

References 15 publications

Secretory and cytosolic phospholipase A2 activities and expression are regulated by oxytocin and estradiol during labor

Secretory and cytosolic phospholipase A2 activities and expression are regulated by oxytocin and estradiol during labor

Uterine Receptors for Oxytocin: Correlation Between Antagonist Potency and Receptor Binding

Changes in Uterine Receptor mRNAs for Oxytocin and Estrogen in the Pseudopregnant Rat

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