Browsing Theses by Subject "Labour"
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The influence of the hormonal milieu on eicosanoid and cytokine production in tissues from the female reproductive tract.In the human uterus prostaglandins (PG) PGE2, PGD2, PGI2, PGF2¿ and Thromboxane A2 (TXA2), also termed prostanoids, are synthesised and deactivated to 15-keto PGE2, J2 metabolites, 6-keto-PGF1¿, 15-keto PGF2¿ and TXB2 respectively. However, not all metabolites have been analysed simultaneously within the same tissue. The primary objective of this thesis was to determine full uterine prostanoid profiles in human non-pregnancy, pregnancy and parturition, to better understand these processes and find suitable tocolytic targets. In addition, ten cytokines in human cervico-vaginal fluid (CVF) were measured according to interval to labour to test their suitability as labour onset predictors, with a view to developing a test to determine women at risk of preterm labour. Prostanoid analysis was carried out in endometrium (n=9) and myometrium (n=15- 16) donated by non-pregnant women and lower segment myometrium obtained from pregnant women (before (n=14) and after labour onset (n=7)) by liquid chromatography coupled with electrospray ionisation mass spectrometry (LC/ESIMS/ MS). Cytokines produced by CVF collected from pregnant donors (20-41 weeks gestation, n=2-10) were investigated using Enzyme-Linked Immunosorbent Assay (ELISA) or Luminex®. Human endometrium produced greater concentrations of TXB2, PGE2 and PGF2¿ than myometrium in vitro (p<0.05). Fifteen prostanoids were detected in human myometrium. Production of 6-keto-PGF1¿, PGE1 and PGF1¿ increased whilst 15- keto PGE2 and PGJ2 decreased at term pregnancy (37-41 weeks gestation) versus non-pregnancy (p<0.05). Myometrium from parturient donors synthesised TXB2 and PGE2 more abundantly than the non-labouring equivalent. Cytokine concentration was greatest in CVF sampled the week before labour, in particular Interleukin-6 (IL-6), Macrophage Inflammatory Protein-1¿ (MIP-1¿) and Monocyte Chemotactic Protein-1 (MCP-1) (p<0.05). Endometrial TXB2, PGE2 and PGF2¿ could aid in proliferation of glandular epithelium prior to ovulation. Prostacyclin may facilitate prolongation of pregnancy to term and thromboxane could contribute to uterine stimulation during labour. Cervical dilation may be influenced by PGE2 in lower segment myometrium. MCP- 1, MIP-1¿ and IL-6 could mark a short interval to labour onset.
The influence of the hormonal milieu on functional prostaglandin and oxytocin receptors and their downstream signal pathways in isolated human myometrium.Although prostaglandins (PG) and oxytocin are crucial mediators of uterine contractility, their receptor-mediated effects during the menstrual cycle, pregnancy and labour are not fully understood. The aim of this thesis was to elucidate the functional expression of EP, FP, TP and oxytocin receptors in isolated human myometrium relative to myocyte mRNA and signal transduction pathways. Myometrial samples were obtained from consenting non-pregnant and pregnant donors. Functional techniques were used to determine isometric muscle contractions. Primary uterine myocytes and fibroblasts were cultured at term to identify stimulated changes in calcium (Ca2+), cyclic adenosine monophosphate (cAMP) and mRNA. Myometrial strips exhibited spontaneous contractions, which were most active midcycle under oestrogenic conditions. At this time intrinsic contractility and responsiveness to uterotonins decreased towards the fundus. PGE2 produced bellshaped responses with predominant utero-relaxant effects mediated via the EP2 subtype. Although activity was partially restored by PGE2 through EP3/1 receptors, tissue excitation was more pronounced at FP, TP and oxytocin receptors. Despite high FP mRNA expression, the lower segment uterus was particularly responsive to U46619 and oxytocin at term pregnancy. Even so, Ca2+ mobilisation by oxytocin was greater via principal release from intracellular stores. Incubations with atosiban, progesterone and a rho-kinase inhibitor reduced oxytocin-stimulated Ca2+ transients. EP2 also attenuated oxytocic effects but this appeared to be mediated through cAMP rather than Ca2+ signalling pathways. With advancing labour, intrinsic myogenic activity declined in parallel with oxytocin desensitisation. However, TP-induced contractions were continued in the lower parturient uterus. These findings demonstrate that PG and oxytocin receptor expression are regulated in a hormone-dependent temporal and spatial manner. EP2-mediated cAMP formation appears to promote uterine quiescence, whilst TP receptors may control muscle tonus during parturition. These receptors and their messenger systems represent effective tocolytic targets for uterine hypercontractile disorders, such as dysmenorrhoea and preterm labour.