1
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Abstract
Biosynthesis and secretion of the hypothalamic nonapeptide oxytocin largely depends on steroid hormones. Estradiol, corticosterone, and vitamin D seem to be the most prominent actors. Due to their lipophilic nature, systemic steroids are thought to be capable of crossing the blood-brain barrier, thus mediating central functions including neuroendocrine and behavioral control. The actual mode of action of steroids in hypothalamic circuitry is still unknown: Most of the oxytocinergic perikarya lack nuclear steroid receptors but express proteins suspected to be membrane receptors for steroids. Oxytocin expressing neurons contain enzymes important for intrinsic steroid metabolism. Furthermore, they produce and probably liberate specific steroid-binding globulins. Rapid responses to steroid hormones may involve these binding proteins and membrane-associated receptors, rather than classic nuclear receptors and genomic pathways. Neuroendocrine regulation, reproductive behaviors, and stress response seem to depend on these mechanisms.
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Affiliation(s)
| | - Scott D Ochs
- Dept. of Pharmacology, Via College of Osteopathic Medicine, Spartanburg, SC, USA
| | - Jack D Caldwell
- Dept. of Pharmacology, Via College of Osteopathic Medicine, Spartanburg, SC, USA
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2
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Nakata M, Gantulga D, Santoso P, Zhang B, Masuda C, Mori M, Okada T, Yada T. Paraventricular NUCB2/Nesfatin-1 Supports Oxytocin and Vasopressin Neurons to Control Feeding Behavior and Fluid Balance in Male Mice. Endocrinology 2016; 157:2322-32. [PMID: 27105386 DOI: 10.1210/en.2015-2082] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Nesfatin-1, derived from nucleobindin-2 (NUCB2), is expressed in the hypothalamus, including the paraventricular nucleus (PVN), an integrative center for energy homeostasis. However, precise role of the NUCB2/nesfatin-1 in PVN remains less defined. The present study aimed to clarify physiological and/or pathophysiological roles of endogenous NUCB2/nesfatin-1 in PVN by using adeno-associated virus vectors encoding short hairpin RNAs targeting NUCB2 in mice. PVN-specific NUCB2 knockdown primarily increased food intake and decreased plasma oxytocin level specifically in light phase, leading to increased body weight gain without affecting energy expenditure. Furthermore, high-salt diet increased the systolic blood pressure, plasma arginine vasopressin (AVP) and AVP mRNA expression in PVN, and all these changes were blunted by PVN-specific NUCB2 knockdown. These results reveal that the endogenous NUCB2/nesfatin-1 in PVN regulates PVN AVP and oxytocin and consequently the fluid and energy balance.
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Affiliation(s)
- Masanori Nakata
- Division of Integrative Physiology (M.N., D.G., P.S., B.Z., T.Y.), Jichi Medical University School of Medicine, Shimotsuke, Tochigi 329-0498, Japan; Department of Biochemistry and Molecular Biology (C.M., T.O.), Division of Gene Therapy, Research Center for Advanced Medical Technology, Nippon Medical School, Tokyo 113-8603, Japan; Metabolic and Obese Research Institute (M.M.), Maebashi, Gunma 371-0037, Japan; and Department of Developmental Physiology (T.Y.), Division of Adaptation Development, National Institute for Physiological Sciences, Okazaki, Aichi 444-8585, Japan
| | - Darambazar Gantulga
- Division of Integrative Physiology (M.N., D.G., P.S., B.Z., T.Y.), Jichi Medical University School of Medicine, Shimotsuke, Tochigi 329-0498, Japan; Department of Biochemistry and Molecular Biology (C.M., T.O.), Division of Gene Therapy, Research Center for Advanced Medical Technology, Nippon Medical School, Tokyo 113-8603, Japan; Metabolic and Obese Research Institute (M.M.), Maebashi, Gunma 371-0037, Japan; and Department of Developmental Physiology (T.Y.), Division of Adaptation Development, National Institute for Physiological Sciences, Okazaki, Aichi 444-8585, Japan
| | - Putra Santoso
- Division of Integrative Physiology (M.N., D.G., P.S., B.Z., T.Y.), Jichi Medical University School of Medicine, Shimotsuke, Tochigi 329-0498, Japan; Department of Biochemistry and Molecular Biology (C.M., T.O.), Division of Gene Therapy, Research Center for Advanced Medical Technology, Nippon Medical School, Tokyo 113-8603, Japan; Metabolic and Obese Research Institute (M.M.), Maebashi, Gunma 371-0037, Japan; and Department of Developmental Physiology (T.Y.), Division of Adaptation Development, National Institute for Physiological Sciences, Okazaki, Aichi 444-8585, Japan
| | - Boyang Zhang
- Division of Integrative Physiology (M.N., D.G., P.S., B.Z., T.Y.), Jichi Medical University School of Medicine, Shimotsuke, Tochigi 329-0498, Japan; Department of Biochemistry and Molecular Biology (C.M., T.O.), Division of Gene Therapy, Research Center for Advanced Medical Technology, Nippon Medical School, Tokyo 113-8603, Japan; Metabolic and Obese Research Institute (M.M.), Maebashi, Gunma 371-0037, Japan; and Department of Developmental Physiology (T.Y.), Division of Adaptation Development, National Institute for Physiological Sciences, Okazaki, Aichi 444-8585, Japan
| | - Chiaki Masuda
- Division of Integrative Physiology (M.N., D.G., P.S., B.Z., T.Y.), Jichi Medical University School of Medicine, Shimotsuke, Tochigi 329-0498, Japan; Department of Biochemistry and Molecular Biology (C.M., T.O.), Division of Gene Therapy, Research Center for Advanced Medical Technology, Nippon Medical School, Tokyo 113-8603, Japan; Metabolic and Obese Research Institute (M.M.), Maebashi, Gunma 371-0037, Japan; and Department of Developmental Physiology (T.Y.), Division of Adaptation Development, National Institute for Physiological Sciences, Okazaki, Aichi 444-8585, Japan
| | - Masatomo Mori
- Division of Integrative Physiology (M.N., D.G., P.S., B.Z., T.Y.), Jichi Medical University School of Medicine, Shimotsuke, Tochigi 329-0498, Japan; Department of Biochemistry and Molecular Biology (C.M., T.O.), Division of Gene Therapy, Research Center for Advanced Medical Technology, Nippon Medical School, Tokyo 113-8603, Japan; Metabolic and Obese Research Institute (M.M.), Maebashi, Gunma 371-0037, Japan; and Department of Developmental Physiology (T.Y.), Division of Adaptation Development, National Institute for Physiological Sciences, Okazaki, Aichi 444-8585, Japan
| | - Takashi Okada
- Division of Integrative Physiology (M.N., D.G., P.S., B.Z., T.Y.), Jichi Medical University School of Medicine, Shimotsuke, Tochigi 329-0498, Japan; Department of Biochemistry and Molecular Biology (C.M., T.O.), Division of Gene Therapy, Research Center for Advanced Medical Technology, Nippon Medical School, Tokyo 113-8603, Japan; Metabolic and Obese Research Institute (M.M.), Maebashi, Gunma 371-0037, Japan; and Department of Developmental Physiology (T.Y.), Division of Adaptation Development, National Institute for Physiological Sciences, Okazaki, Aichi 444-8585, Japan
| | - Toshihiko Yada
- Division of Integrative Physiology (M.N., D.G., P.S., B.Z., T.Y.), Jichi Medical University School of Medicine, Shimotsuke, Tochigi 329-0498, Japan; Department of Biochemistry and Molecular Biology (C.M., T.O.), Division of Gene Therapy, Research Center for Advanced Medical Technology, Nippon Medical School, Tokyo 113-8603, Japan; Metabolic and Obese Research Institute (M.M.), Maebashi, Gunma 371-0037, Japan; and Department of Developmental Physiology (T.Y.), Division of Adaptation Development, National Institute for Physiological Sciences, Okazaki, Aichi 444-8585, Japan
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3
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Abstract
In this review, our knowledge, gleaned from a range of species, of what determines gestation length, how fetal maturation and birth are synchronized and how the uterotonic mechanisms are activated at birth are discussed. Accumulated data indicate that fetal glucocorticoids are involved in, but do not necessarily play a causative role in, the initiation of parturition in eutherian mammals generally. Present observations are consistent with a complex, positive regulatory interaction between estrogens, prostaglandins and oxytocin and are consistent with a role for prostaglandins as the final, common effector in myometrial activation. We are, however, left with the possibility that the initial mechanism for the timing of birth is encoded in the fetal genome and is closely linked to, and activated when, certain prerequisite developmental events have occurred in the fetus. Our understanding of these events in the sheep have led to its extensive use as an experimental model for the study of human clinical correlates of fetal maturation and development and the control of the initiation of parturition.
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Affiliation(s)
- G Jenkin
- Department of Physiology, P.O. Box 13F, Monash University, Melbourne, Victoria 3800, Australia.
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4
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Murata T, Narita K, Honda K, Matsukawa S, Higuchi T. Differential regulation of estrogen receptor alpha and beta mRNAs in the rat uterus during pregnancy and labor: possible involvement of estrogen receptors in oxytocin receptor regulation. Endocr J 2003; 50:579-87. [PMID: 14614214 DOI: 10.1507/endocrj.50.579] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Oxytocin receptor (OTR) mRNA levels in the uterus dramatically increase in the near term human and rat. Estrogen is believed to be a potent stimulator of OTR mRNA expression. However, estrogen does not stimulate rat OTR mRNA expression on day 18 of pregnancy or in progesterone-treated rats. Thus, the regulation of uterine responsiveness to estrogen in the near term rat appears to be an important mediator of estrogen action. To determine the effect of altering uterine responsiveness to estrogen on OTR induction, uterine ERalpha and ER beta mRNA levels were examined by competitive RT-PCR in pregnant and parturient rats, progesterone-treated ovariectomized (OVX) virgin rats and OVX pregnant rats. In pregnant and parturient rats, OTR mRNA levels were highest at 2200-2230 h on day 21 of pregnancy (P21pm) and during labor when compared with other groups. ERalpha mRNA levels significantly increased during labor compared with days 15-21 of pregnancy. Compared with control animals, ERalpha mRNA levels decreased significantly in OVX virgin rats implanted with tubes containing progesterone for one week; 24 h following the removal of the progesterone tubes, ERalpha mRNA levels were found to be similar to control levels. Estrogen treatment following OVX on day 18 of pregnancy caused increased OTR mRNA levels, whereas ovariectomy alone increased ERbeta mRNA but not ERalpha mRNA. Results from the present study suggest that ERalpha and ERbeta mRNA expressions are differentially regulated in the rat uterus. Moreover, during spontaneous labor our findings appear to suggest that ERalpha plays a more prominent role than ERbeta in mediating estrogen action in the induction of uterine OTR mRNA before labor.
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Affiliation(s)
- Takuya Murata
- Department of Physiology, Fukui Medical University, Shimoaizuki, Matsuoka, Japan
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5
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Strakova Z, Copland JA, Lolait SJ, Soloff MS. ERK2 mediates oxytocin-stimulated PGE2 synthesis. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:E634-41. [PMID: 9575824 DOI: 10.1152/ajpendo.1998.274.4.e634] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Oxytocin (OT) induces PG synthesis by both uterine endometrial and amnion cells. We showed previously that CHO cells stably transfected with the rat oxytocin receptor (CHO-OTR cells) also synthesize PGE2 in response to OT. In the present work we have demonstrated that OTRs are coupled to both Gi and Gq/11, using immunoprecipitation of solubilized OTR complexes and ADP ribosylation. OT treatment caused the rapid phosphorylation of extracellular signal-regulated protein kinase 2 (ERK2 or p42MAPK), which was partially inhibited by pertussis toxin (PTX), consistent with OTR-Gi coupling. The PTX-insensitive portion of ERK2 phosphorylation was linked to Gq, as inhibitors of both phospholipase C (U-73122) and protein kinase C (GF-109203X) blocked OT-induced ERK2 phosphorylation. OT-stimulated c-fos expression was also mediated by ERK2 phosphorylation. The ERK-c-fos pathway has been shown to be associated with cell proliferation, but OT had no effect on [3H]thymidine uptake by CHO-OTR cells. However, inhibition of OT-induced ERK2 phosphorylation with an ERK kinase inhibitor (PD-98059) markedly reduced OT-stimulated PGE2 synthesis, pointing to the importance of ERK2 activation in OT action.
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Affiliation(s)
- Z Strakova
- Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston 77555-1062, USA
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6
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Sugimoto Y, Yamasaki A, Segi E, Tsuboi K, Aze Y, Nishimura T, Oida H, Yoshida N, Tanaka T, Katsuyama M, Hasumoto K, Murata T, Hirata M, Ushikubi F, Negishi M, Ichikawa A, Narumiya S. Failure of parturition in mice lacking the prostaglandin F receptor. Science 1997; 277:681-3. [PMID: 9235889 DOI: 10.1126/science.277.5326.681] [Citation(s) in RCA: 460] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Mice lacking the gene encoding the receptor for prostaglandin F2alpha (FP) developed normally but were unable to deliver normal fetuses at term. Although these FP-deficient mice showed no abnormality in the estrous cycle, ovulation, fertilization, or implantation, they did not respond to exogenous oxytocin because of the lack of induction of oxytocin receptor (a proposed triggering event in parturition), and they did not show the normal decline of serum progesterone concentrations that precedes parturition. Ovariectomy at day 19 of pregnancy restored induction of the oxytocin receptor and permitted successful delivery in the FP-deficient mice. These results indicate that parturition is initiated when prostaglandin F2alpha interacts with FP in ovarian luteal cells of the pregnant mice to induce luteolysis.
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Affiliation(s)
- Y Sugimoto
- Department of Physiological Chemistry, Faculty of Pharmaceutical Sciences, Kyoto University, Kyoto 606, Japan
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7
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Arslan A, Zingg HH. Regulation of COX-2 gene expression in rat uterus in vivo and in vitro. PROSTAGLANDINS 1996; 52:463-81. [PMID: 8979307 DOI: 10.1016/s0090-6980(96)00125-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Prostaglandins are involved in mediating several important processes in mammalian reproduction, including the initiation of parturition. In the present study, we examined the expression in the rat uterus of two-rate limiting enzymes involved in prostaglandin production, cyclooxygenase (COX) 1 and 2. Expression of the COX-2 gene in the pregnant rat uterus gave rise to a single mRNA transcript of approximately 4.4 kb. COX-2 mRNA levels increased 3.5 fold between day 7 of pregnancy and the onset of parturition on day 22. In contrast, COX-1 mRNA levels remained constant during the same period. To investigate factors involved in mediating the regulation of COX-1 and COX-2 gene expression, rat endometrial stromal and epithelial cell lines, were used. In the stroma-derived cell line, CUS-V2, COX-2 gene expression was demonstrated by reverse transcriptase/polymerase chain reaction (RT-PCR) and by immunocytochemistry. In these cells, COX-2 gene expression was inducible by the cytokines interleukin-1 beta and tumor necrosis factor alpha, but not by interleukin-6. The two former cytokines also induced prostaglandin F2 alpha production. In contrast, COX-1 gene expression was constitutive in this cell line. In the endometrial epithelium-derived cell line, CUE-P both COX-1 and COX-2 genes were expressed in a constitutive fashion. In conclusion, the present in vivo and in vitro data indicate that decidual COX-2, but not COX-1, gene expression is regulated during pregnancy and implicate specific cytokines as possible inducers within the decidua.
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Affiliation(s)
- A Arslan
- Department of Medicine, Royal Victoria Hospital, Montreal, Quebec, Canada
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8
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Rhee JW, Longo LD, Pearce WJ, Bae NH, Valenzuela GJ, Ducsay CA. Effect of chronic hypoxia on myometrial responsiveness in the pregnant rat. THE AMERICAN JOURNAL OF PHYSIOLOGY 1996; 270:E477-82. [PMID: 8638696 DOI: 10.1152/ajpendo.1996.270.3.e477] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Mechanisms involving the timing of normal parturition are not well understood in most animal species. To gain a greater understanding of the mechanisms, we employed hypoxia to perturb the normal system of parturition. The present study was designed to investigate the effects of chronic hypoxia on myometrial contractility in the near-term pregnant rat. Rats were exposed to room air (control) or to continuous hypoxia (10.5% O2) either from experimental days 19 through 21 (2-day exposure) or from experimental days 15 through 21 (6-day exposure). On day 21, blood was collected for hormone assays, and the uterine horns were collected from each dam. One horn was snap-frozen in liquid nitrogen for oxytocin (OT) receptor analysis, and the other was used for in vitro assessment of myometrial contractile responses to cumulative doses of OT or arginine vasopressin (AVP). Hypoxic exposure resulted in approximately 60% reduction of the maximal myometrial contractile response to OT and a significant reduction in OT binding sites from 256.9 +/- 34.9 to 84.9 +/- 21.3 fmol/mg protein (P<0.01). In contrast, the contractile response to AVP was unaffected after exposure to chronic hypoxia (P> 0.05). Additionally, we observed no difference in the plasma concentrations of estrogen, progesterone, and corticosterone. We conclude that chronic hypoxia decreased the effectiveness of OT-specific contractile mechanisms, at least partially through a decrease in OT binding sites.
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Affiliation(s)
- J W Rhee
- Department of Physiology, Loma Linda University, School of Medicine, California 92350, USA
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9
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Wu WX, Myers DA, Nathanielsz PW. Changes in estrogen receptor messenger ribonucleic acid in sheep fetal and maternal tissues during late gestation and labor. Am J Obstet Gynecol 1995; 172:844-50. [PMID: 7892873 DOI: 10.1016/0002-9378(95)90009-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
OBJECTIVE Our purpose was to investigate whether there is an increase in messenger ribonucleic acid for estrogen receptor in critical maternal or fetal tissues in the last third of pregnancy and during labor in sheep. STUDY DESIGN Estrogen receptor messenger ribonucleic acid was measured by Northern hybridization analysis in fetal-placental and maternal uterine tissues during the last third of pregnancy and during spontaneous or cortisol-induced labor in sheep. Statistical differences were assessed with two-way analysis of variance. RESULTS No estrogen receptor messenger ribonucleic acid was observed in amnion or chorion in any animal studied. There were no gestational age related changes in estrogen receptor messenger ribonucleic acid in any tissues between 100 and 145 days' gestation. During spontaneous and cortisol-induced labor estrogen receptor messenger ribonucleic acid increased significantly (p < 0.05) in myometrium, endometrium, and cervix. No increase was observed in the fetal placental cotyledon and mesometrium. Estrogen receptor messenger ribonucleic acid was markedly decreased (p < 0.05) in myometrium and endometrium after fetal adrenalectomy. CONCLUSION An increase in estrogen receptor messenger ribonucleic acid in association with labor may contribute part of the mechanism by which estrogens exert their influence on the process of parturition.
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Affiliation(s)
- W X Wu
- Department of Physiology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853-6401
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10
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Uguru MO, Okwuasaba FK, Ekwenchi MM, Uguru VE. Oxytocic and oestrogenic effects ofMonechma ciliatum methanol extractin vivo andin vitro in rodents. Phytother Res 1995. [DOI: 10.1002/ptr.2650090107] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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11
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Zingg HH, Rozen F, Chu K, Larcher A, Arslan A, Richard S, Lefèbvre D. Oxytocin and oxytocin receptor gene expression in the uterus. RECENT PROGRESS IN HORMONE RESEARCH 1995; 50:255-73. [PMID: 7740160 DOI: 10.1016/b978-0-12-571150-0.50015-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- H H Zingg
- Laboratory of Molecular Endocrinology, Royal Victoria Hospital, McGill University, Montreal, Quebec, Canada
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12
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Melin P. Oxytocin antagonists in preterm labour and delivery. BAILLIERE'S CLINICAL OBSTETRICS AND GYNAECOLOGY 1993; 7:577-600. [PMID: 8252818 DOI: 10.1016/s0950-3552(05)80449-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Evidence has been gained that an oxytocin receptor antagonist given by intravenous infusion effectively stops uterine contractions in threatened as well as in actual preterm labour. The findings suggest that the increase of oxytocin receptors is aetiologically important in uncomplicated preterm labour. Oxytocin antagonists could therefore be an attractive alternative to currently used drugs by virtue of their high specificity and lack of serious side-effects. Their use in prophylactic and maintenance therapy may be greater when modified analogues have been developed that allow non-parenteral therapy.
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Affiliation(s)
- P Melin
- Ferring Research Institute AB, Malmö, Sweden
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13
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Eden RD, Sokol RJ, Sorokin Y, Cook HJ, Sheeran G, Chik L. The mammary stimulation test--a predictor of preterm delivery? Am J Obstet Gynecol 1991; 164:1409-17; discussion 1417-9. [PMID: 2048587 DOI: 10.1016/0002-9378(91)91418-v] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Clinical risk identification for preterm delivery, the major cause of perinatal morbidity and mortality, remains problematic. To test the hypothesis that a provocative test for uterine contractility at the beginning of the third trimester would reliably identify patients destined to be delivered before and at term, we designed the mammary stimulation test. Uterine contractions in response to nipple stimulation at a mean of 28.6 weeks' gestation, were evaluated in 94 gravid patients at risk for preterm delivery. The mammary stimulation test, the results of which were not used for clinical management, was positive in 50% of patients tested and had a sensitivity of 84% and a positive predictive value of 34% (chi 2 = 11.15, p less than 0.01). Ninety-four percent of patients predicted to be delivered at term actually were delivered at term (negative predictive value). Furthermore, no patients with a negative mammary stimulation test were delivered within 1 month of testing or were delivered of infants weighing less than 2000 gm. Discriminant analysis indicated that the mammary stimulation test provided information beyond that available from clinical risk factors alone. A cost analysis suggested that the use of the mammary stimulation test could reduce the cost of ambulatory uterine activity monitoring by nearly 50%. If these findings can be validated in additional samples, the mammary stimulation test may be useful in prematurity prevention programs.
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Affiliation(s)
- R D Eden
- Department of Obstetrics and Gynecology, Wayne State University, Detroit, Michigan
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14
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Evans RG, Rice GE, Olley JE. Studies of the effects of subacute treatment with N-(cyclopropylmethyl)-19-isopentylnororvinol (M320) on timing of parturition in the rat. Br J Pharmacol 1988; 95:777-82. [PMID: 3207993 PMCID: PMC1854236 DOI: 10.1111/j.1476-5381.1988.tb11704.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
1. Administration of 10 micrograms kg-1 of the long lasting potent kappa- and weaker mu-opioid agonist N-(cyclopropylmethyl)-19-isopentylnororvinol (M320) twice daily from day 20 of gestation prolonged the internal gestation period of the rat and retarded the development of the offspring in the perinatal period. 2. The capacities of myometrial, placental and cervical tissues to produce prostaglandin E2 (PGE2) were not affected by M320 treatment. 3. During the period in which parturition normally occurred in saline-treated rats, foetal pituitary levels of immunoreactive oxytocin (ir-OXY) but not immunoreactive arginine-vasopressin (ir-AVP) were greater in M320-compared to saline-treated animals. Following the completion of parturition, foetal pituitary ir-OXY and ir-AVP levels continued to rise in saline-treated rats, but fell dramatically in rats treated subacutely with M320. 4. These data indicate that subacute treatment with M320 may inhibit foetal oxytocin release at term. This foetal OXY release may be a stimulus for the initiation of labour.
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Affiliation(s)
- R G Evans
- Department of Pharmacology, Monash University, Clayton, Victoria, Australia
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15
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Engstrøm T, Atke A, Vilhardt H. Oxytocin receptors and contractile response of the myometrium after long term infusion of prostaglandin F2 alpha, indomethacin, oxytocin and an oxytocin antagonist in rats. REGULATORY PEPTIDES 1988; 20:65-72. [PMID: 2832879 DOI: 10.1016/0167-0115(88)90058-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Binding of [3H]oxytocin to isolated myometrial plasma membranes was not affected by the presence of prostaglandin (PG)F2 alpha or E2 in the incubation medium. Long-term treatment with PGF2 alpha or indomethacin had no effect on oxytocin receptor concentrations and dissociation constants of myometrial plasma membranes nor on maximal contractility or KM values of isolated uterine strips exposed to oxytocin. Infusion of oxytocin for 5 days in non-pregnant rats resulted in a decrease in oxytocin receptor concentrations in myometrial plasma membranes whereas the binding affinity to oxytocin was unaffected. Isolated uterine strips from similarly treated rats showed a reduced maximal contractile response to oxytocin and an elevated KM value, possibly indicating an influence of oxytocin on the coupling between receptor occupancy and contractility. Treatment for 5 days with desamino1-[D-Tyr(O-ethyl)2-Thr4-Orn8] oxytocin (an oxytocin antagonist) increased the concentration of myometrial oxytocin receptors. In addition KD values of these receptors were elevated. The present results indicate that prolonged exposure to oxytocin leads to a down-regulation of the myometrial receptor concentration, which is not caused by ligand-receptor interaction in itself. The concerted effect of oxytocin and prostaglandins on myometrial contraction does not appear to involve modulation of the oxytocin receptor by prostaglandins.
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Affiliation(s)
- T Engstrøm
- Department of Medical Physiology C, University of Copenhagen, Denmark
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16
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Chan WY. Enhanced prostaglandin synthesis in the parturient rat uterus and its effects on myometrial oxytocin receptor concentrations. PROSTAGLANDINS 1987; 34:889-902. [PMID: 2835792 DOI: 10.1016/0090-6980(87)90069-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We measure oxytocin (OT) responsiveness and prostaglandins (PGs) synthesis in uteri of 19, 20, 21 and 22-day pregnant and 2-day postpartum rats to determine whether the enhanced OT sensitivity and PG synthesis in the parturient uterus is the result of a higher cyclooxygenase activity. We also investigated the effects of suppression of PG synthesis on OT responsiveness and OT receptor in 22-day and 23-day pregnant rats. PG productions (PGE2, PGF2 alpha, 6-keto-PGF1 alpha and TXB2 in microsomal fractions were quantitated by radio- immunoassays (RIAs). OT receptor concentrations were measured in plasma membrane fractions by radioligand-receptor binding assays. Naproxen sodium was used to inhibit endogenous PG synthesis. We found a close temporal relationship between enhanced OT responsiveness and increased uterine PGE2 alpha synthesis, but no significant difference in cyclooxygenase activities among the microsomes prepared from uteri of different gestational ages. Suppression of PG synthesis attenuated OT responsiveness and markedly reduced OT binding sites, from 242 to 78 fmol/mg protein. There was no change in the binding affinity. These findings suggest that PG stimulates OT receptor formation which leads to enhanced OT responsiveness. The increase in PG production is not mediated by a higher cyclooxygenase activity.
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Affiliation(s)
- W Y Chan
- Department of Pharmacology, Cornell University Medical College, New York, New York 10021
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17
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Gall MA, Day BN. Induction of parturition in swine with prostaglandin F2α, estradiol benzoate and oxytocin. Theriogenology 1987; 27:493-505. [PMID: 16726254 DOI: 10.1016/0093-691x(87)90237-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/1985] [Accepted: 10/03/1986] [Indexed: 11/28/2022]
Abstract
Pregnant sows and gilts were administered either 0, 2.5, 5, 10 or 20 mg prostaglandin F(2)alpha (PGF(2)alpha) intramuscularly on Day 112 or 113 of gestation at 0800 h in an effort to induce parturition. The average interval from PGF(2)alpha injection to farrowing was 55.1 +/- 5.7, 29.4 +/- 3.1, 32.1 +/- 4.6, 27.8 +/- 1.8 and 26.9 +/- 1.1 h for 0, 2.5, 5, 10 and 20 mg, respectively. All PGF(2)alpha treatments increased (P < 0.01) over controls the number of sows farrowing 23 to 33 h after injection. The average gestation length was significantly shorter in treated gilts; however, no detrimental effect on pig performance or pig survivability was observed. A second trial evaluated the effect of a 10-mg dose of PGF(2)alpha on the induction of parturition in sows in order to obtain a majority of sows farrowing within normal working hours (0700 to 1700 h). The interval from injection to farrowing was decreased (P < 0.05) by PGF(2)alpha treatment (66.2 +/- 5.3 vs 28.1 +/- 2.2 h). Fifty-seven percent (P < 0.05) of PGF(2)alpha-treated sows farrowed between 0700 and 1700 h as compared to 13.6% for control sows. A third trial was conducted to examine a sequential treatment of PGF(2)alpha and oxytocin to control the time of parturition more precisely. Sows receiving only 10 mg of PGF(2)alpha farrowed on an average 31.1 +/- 1.4 h after injection. The injection of 40 IU oxytocin 24 to 28 h after PGF(2)alpha decreased (P < 0.05) the interval from PGF(2)alpha to farrowing (28.1 +/- 0.9 h). The addition of oxytocin increased (P < 0.05) the number of sows farrowing within 3 h of injection (33 vs 86% for PGF(2)alpha and PGF(2)alpha + oxytocin treatments, respectively). A fourth trial was designed to determine if the addition of exogenous estradiol benzoate (EB) to a sequential treatment of PGF(2)alpha and oxytocin would improve the predictability and synchronization of the induced parturition. Sows were assigned to receive either saline, 10 mg PGF(2)alpha + 40 IU oxytocin or 10 mg PGF(2)alpha + 5 mg EB + 40 IU oxytocin. The addition of EB reduced (P < 0.01) the variance in the interval from oxytocin to farrowing and added precision to the predicted time of induced parturition.
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Affiliation(s)
- M A Gall
- Department of Animal Science University of Missouri Columbia, MO 65211 USA
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Bunce GE, Wilson GR, Mills CF, Klopper A. Studies on the role of zinc in parturition in the rat. Biochem J 1983; 210:761-7. [PMID: 6409077 PMCID: PMC1154287 DOI: 10.1042/bj2100761] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
1. Pregnant rats were fed either low (less than 1 p.p.m.) Zn or control (40 p.p.m. Zn) diets from day 10 of gestation. They were killed at intervals during the last 96 h preceding the normal time for onset of parturition, and differences in plasma progesterone, oestradiol-17 beta and ovarian 20 alpha-hydroxysteroid dehydrogenase were assessed. 2. Gestation was prolonged in Zn-deficient rats. 3. Although the preparturient decline in plasma progesterone began at the same time in all groups, at term, plasma progesterone concentration in Zn-deficient rats remained significantly higher than in normal females. 4. Induction of ovarian 20 alpha-hydroxysteroid dehydrogenase activity was delayed by about 8 h by Zn deficiency. This delay was not observed if prostaglandin F2 alpha was injected previously. 5. The results suggest a Zn-dependent step(s) in uterine synthesis and/or release of prostanoids.
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The Role of Oxytocin in Parturition. ACTA ACUST UNITED AC 1983. [DOI: 10.1016/b978-0-12-153204-8.50014-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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