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A V Sirotkin, P Sanislo, H-J Schaeffer, I Florkovičová, J Kotwica, J Bulla and L Hetényi

, androstenedione, estradiol, oxytocin, inhibin A, inhibin B, insulin-like growth factor-I (IGF-I), transforming growth factor-2β (TGF-2β) and an IGF-binding protein (IGFBP-3) by these cells. The involvement of a PKA-dependent pathway in mediating TPO action was

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Meghan M White and Willis K Samson

osmolality . PNAS 90 10380 – 10384 . Blackburn RE Samson WK Fulton RJ Stricker EM Verbalis JG 1995 Central oxytocin and atrial natriuretic peptide receptors mediate osmotic inhibition of salt appetite in rats . American Journal of

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Greisa Vila, Michaela Riedl, Michael Resl, Aart Jan van der Lely, Leo J Hofland, Martin Clodi and Anton Luger

F 2001 The oxytocin receptor system: structure, function, and regulation . Physiological Reviews 81 629 – 683 . Hosoda H Kangawa K 2008 The autonomic nervous system regulates gastric ghrelin secretion in rats . Regulatory Peptides

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DM Sloboda, JP Newnham and Challis JR

Synthetic glucocorticoids have become an important clinical tool with which to advance fetal lung maturation in women at risk of early preterm birth, and this has succeeded in reducing neonatal mortality and morbidity from respiratory distress syndrome. Although previous studies have shown that glucocorticoids have deleterious consequences on fetal development, there is little information regarding the effects of clinically relevant repeated maternal doses of glucocorticoids on fetal growth and hypothalamic-pituitary-adrenal (HPA) function. We hypothesised that repeated prenatal exposure to increased concentrations of glucocorticoids would alter fetal growth and HPA axis development. Pregnant ewes were injected with betamethasone (0.5 mg/kg) or vehicle at 104, 111 and 118 days of gestation (term 150 days). Animals were sacrificed at 125 and 146 days of gestation, at which time fetal weights were recorded. Maternal and fetal blood samples were gathered and fetal tissue collected. Maternal oestradiol concentrations were significantly greater than those in controls at 125 days of gestation, but were not different at 146 days. Maternal plasma progesterone concentrations were similar between groups at both 125 and 146 days of gestation. Weight at birth was significantly reduced by 23% at 125 days and 19% at 146 days of gestation (P<0.05) after exposure to glucocorticoid. Cord plasma ACTH concentrations were not significantly different between groups at day 125, but were significantly increased in day 146 fetuses of ewes that had received betamethasone (P<0.05). Cord plasma cortisol concentrations followed the same trend, although differences were not statistically significant. Cord plasma corticosteroid binding capacity (CBC) was significantly increased at 125 days of gestation in fetuses of betamethasone-treated animals (P<0.05), but not at 146 days of gestation. To examine the mechanisms regulating the increase in cord plasma ACTH of 146-day fetuses, we used in situ hybridisation to determine the distribution and levels of mRNA encoding key pituitary and hypothalamic neuropeptides of the HPA axis. In pituitaries of 146-day fetuses, there were no significant differences in the regional pattern of distribution or amounts of pro-opiomelanocortin (POMC) mRNA between betamethasone-treated animals and controls, in either the pars intermedia or the inferior and superior regions of the pars distalis. Neither prohormone convertase (PC)-1 nor PC-2 mRNA levels in pituitaries of 146-day fetuses were significantly different between treatment groups. After maternal betamethasone, immunoreactive ACTH peptide content in the fetal pars distalis was not different but glucocorticoid receptor (GR) mRNA levels in the pars distalis were increased significantly (P<0.05). No significant difference in distribution pattern or concentrations of corticotrophin-releasing hormone (CRH) mRNA, GR mRNA, oxytocin mRNA and pre-proenkephalin mRNA were found in hypothalami from fetuses at 146 days of gestation after betamethasone treatment. We conclude that antenatal betamethasone given to pregnant sheep in a manner similar to that used in human obstetric practice results in reduced weight at birth at 125 and 146 days, and altered basal cord levels of plasma ACTH and corticosteroid binding capacity, but these changes are not reflective of changes in steady state concentrations of POMC and CRH mRNA in the fetal pituitary or hypothalamus.

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László Szidonya, Miklós Cserző and László Hunyady

. Terrillon S Durroux T Mouillac B Breit A Ayoub MA Taulan M Jockers R Barberis C Bouvier M 2003 Oxytocin and vasopressin V1a and V2 receptors form constitutive homo- and heterodimers during biosynthesis . Molecular Endocrinology 17 677

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Qinglei Li, Fermin Jimenez-Krassel, Anilkumar Bettegowda, James J Ireland and George W Smith

& Fortune 1992 ). Induction of oxytocin mRNA expression by luteinized bovine GC can be blocked by progesterone receptor antagonists in vitro ( Lioutas et al. 1997 , Jo et al. 2002 ). Given widespread reports of a role for progesterone

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Christian Vollmer, Ingo Schwartges, Silke Naber, Christopher Beck, Inge Bauer and Olaf Picker

). Although the relation between increased vasopressin plasma levels and the effect of the V 1A receptors might indicate an effect of vasopressin, we cannot exclude the effect of other possible ligands, e.g. oxytocin, on the receptor. However, vasopressin has

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Mone Zaidi, Maria I New, Harry C Blair, Alberta Zallone, Ramkumarie Baliram, Terry F Davies, Christopher Cardozo, James Iqbal, Li Sun, Clifford J Rosen and Tony Yuen

://doi.org/10.1074/jbc.M112.365049 ) 10.1074/jbc.M112.365049 Colucci S Colaianni G Mori G Grano M Zallone A 2002 Human osteoclasts express oxytocin receptor . Biochemical and Biophysical Research Communications 297 442 – 445 . ( https

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Willis K Samson, Gina L C Yosten, Jaw-Kang Chang, Alastair V Ferguson and Meghan M White

blood collected into heparinized tubes. Samples were maintained on ice and then centrifuged (3000  g , 4 °C, 30 min) to allow collection of plasma for subsequent determination of vasopressin (AVP) and oxytocin (OT) levels by RIA ( Samson 1985 , Samson

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A L Griffiths, K M Marshall, J Senior, C Fleming and D F Woodward

, oxytocin receptor expression ( Fang et al. 1996 ), prostaglandin receptor expression ( Matsumoto et al. 1997 ) and connexin-43, the gap junction protein ( Petrocelli & Lye 1993 ). During labour, gap junctions are abundant in the mouse myometrium ( Dahl