Preterm labour (PTL) is defined as labour before 37 completed weeks of gestation. Despite advances in medical research, PTL remains a major clinical problem. Preterm birth (PTB) rates range from approximately 5-18% worldwide. Importantly, PTB is the leading cause of childhood morbidity and mortality. PTL is difficult to predict and the aetiology is poorly understood but infection and inflammation are believed to be major factors. It has been suggested that the presence of intrauterine infection or inflammation may initiate the pathological, preterm activation of the inflammatory cascade associated with term labour. Therefore, PTL therapeutics should aim to inhibit these inflammatory pathways. Statins, 5-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors, are potent inhibitors of cholesterol biosynthesis, which act on the mevalonate pathway. In addition to their lipid-lowering effects, statins also have anti-inflammatory and anti-contraction properties. The hypothesis of this thesis was that statins will prevent PTB by reducing inflammation. The aims of this thesis were firstly to investigate the effect of the statins, simvastatin and pravastatin, on inflammation and contractility in a pregnant human myometrial cell line. Secondly, to determine whether simvastatin and/or pravastatin can prevent PTB or improve neonatal outcome in a lipopolysaccharide (LPS)-induced mouse model of PTB. Myometrial cells were either co-treated with LPS and simvastatin/pravastatin, pretreated with simvastatin/pravastatin or treated with simvastatin/pravastatin post-LPS stimulation. The effect of statin treatment on the mRNA expression and the release of inflammatory mediators was then investigated. Simvastatin treatment reduced LPS-induced inflammation by both lowering the expression of pro-inflammatory mediators and increasing the expression of anti-inflammatory mediators. Pravastatin treatment did not alter the expression of inflammatory mediators following LPS stimulation. The effect of simvastatin on the contraction of myometrial cells was investigated by embedding the cells in rat tail collagen to form gels. As these are smooth muscle cells, basal contraction was observed causing the gel size to reduce. When LPS was introduced, this caused the gels to contract further than the vehicle treated gels. Simvastatin attenuated the contraction of the myometrial cells, both alone and in the presence of LPS. These effects were reversed by the addition of mevalonate pathway metabolites, mevalonate and geranylgeranyl pyrophosphate (GG-PP) but not by farnesyl pyrophosphate (F-PP). Simvastatin also lowered levels of phosphorylated myosin light chain (pMLC) in the myometrial cells, which is essential for smooth muscle contraction. Again, this effect was abolished by mevalonate and GG-PP but not F-PP. It is hypothesised that simvastatin attenuated myometrial cell contraction by inhibiting Rho isoprenylation by GG-PP, preventing Rho-associated kinase (ROCK) activation, which then prevented the phosphorylation of MLC. A mouse model of intrauterine LPS-induced PTB was utilised to investigate the effect of statin treatment on PTB and fetal survival. Mice received an intraperitoneal injection of pravastatin (10μg) or simvastatin (20μg or 40μg) on gestational day (D)16. This was followed by ultrasound-guided intrauterine injection of LPS (1μg) on D17 and another pravastatin/simvastatin treatment two hours later. When mice were treated with LPS, 77.8% of mice delivered preterm. When mice received LPS and 20μg simvastatin, 50% delivered preterm. However, when mice were treated with LPS and 40μg simvastatin, 40% delivered preterm, more pups were born alive and uterine pro-inflammatory mRNA expression was downregulated. Conversely, pravastatin did not prevent PTB or improve the percentage of live born pups. In summary, simvastatin treatment exerted anti-inflammatory and anti-contraction effects on human myometrial cells in vitro. The anti-contractile properties were likely due to the inhibition of the Rho/ROCK pathway. Furthermore, in our LPS-induced mouse model of PTB, fewer mice delivered preterm with simvastatin treatment, simvastatin attenuated LPS-induced pup mortality and reduced uterine inflammatory gene expression. These results suggest that statin therapy may be a novel treatment for PTL.

<p>The effects of environmental contaminants in humans and animals are of great concern. Some contaminants are endocrine disruptors that may interfere with the endogenous hormonal signalling and disturb, for example, reproductive organs and functions.</p><p>Primary uterine myometrial cells originating from women and Baltic grey seals were exposed to some polychlorinated biphenyls (PCBs) and their metabolites. Even though human and Baltic grey seal myometrial cells responded differently to the tested PCBs, the results indicate that PCBs can influence myometrial cell proliferation <i>in vitro</i>.</p><p>The prevalence of uterine leiomyomas was investigated among 257 Baltic grey seals. Leiomyomas were only present in females older than 22 years, at a prevalence of 65%. Proliferation in leiomyoma cells was detected in individuals lacking ovarian proliferation support, suggesting the presence of an exogenous stimulant. By taking into account temporal alterations in the contaminant burden of the seals, PCB exposure was found to be associated with leiomyoma prevalence. In conclusion, PCB exposure may be related to uterine leiomyoma development and proliferation in Baltic grey seals <i>in vivo</i>.</p><p>Human endometrial endothelial cells (HEECs) were exposed to some endocrine disruptors, and the effects of the endocrine disruptors on cell proliferation and viability were studied. All evaluated endocrine disruptors decreased HEEC proliferation and most also decreased HEEC viability. Further studies revealed that the reduction in HEEC proliferation after exposure to o,p’-DDT was associated with differential expression of mRNA involved in proliferation, defence response, and lipid and cholesterol metabolism compared to untreated HEEC. </p><p>In conclusion, these studies suggest that endocrine disruptors affect cultured cells from the female reproductive tract of humans and grey seals, and may have deleterious effects on proliferation, viability, and genes involved in defence response, and lipid or cholesterol metabolism.</p>

The effects of environmental contaminants in humans and animals are of great concern. Some contaminants are endocrine disruptors that may interfere with the endogenous hormonal signalling and disturb, for example, reproductive organs and functions. Primary uterine myometrial cells originating from women and Baltic grey seals were exposed to some polychlorinated biphenyls (PCBs) and their metabolites. Even though human and Baltic grey seal myometrial cells responded differently to the tested PCBs, the results indicate that PCBs can influence myometrial cell proliferation in vitro. The prevalence of uterine leiomyomas was investigated among 257 Baltic grey seals. Leiomyomas were only present in females older than 22 years, at a prevalence of 65%. Proliferation in leiomyoma cells was detected in individuals lacking ovarian proliferation support, suggesting the presence of an exogenous stimulant. By taking into account temporal alterations in the contaminant burden of the seals, PCB exposure was found to be associated with leiomyoma prevalence. In conclusion, PCB exposure may be related to uterine leiomyoma development and proliferation in Baltic grey seals in vivo. Human endometrial endothelial cells (HEECs) were exposed to some endocrine disruptors, and the effects of the endocrine disruptors on cell proliferation and viability were studied. All evaluated endocrine disruptors decreased HEEC proliferation and most also decreased HEEC viability. Further studies revealed that the reduction in HEEC proliferation after exposure to o,p’-DDT was associated with differential expression of mRNA involved in proliferation, defence response, and lipid and cholesterol metabolism compared to untreated HEEC. In conclusion, these studies suggest that endocrine disruptors affect cultured cells from the female reproductive tract of humans and grey seals, and may have deleterious effects on proliferation, viability, and genes involved in defence response, and lipid or cholesterol metabolism.

$\beta\sb2$-Adrenoceptor ($\beta\sb2$-AR) agonists, such as terbutaline, are used as tocolytic agents in the treatment of preterm labor. $\beta$-Adrenoceptor stimulation relaxes myometrium through specific receptors coupled through Gs to adenylyl cyclase (AC) that catalyzes the conversion of ATP to cAMP. The purpose of this study was to compare $\beta$-adrenoceptors and cAMP production in cultured human leukocytes and myometrial cells, and to determine the importance of $\beta$-adrenoceptors and cAMP production in isoproterenol-induced myometrial relaxation. $\sp{125}$I-iodopindolol was used to assess $\beta$-adrenoceptor affinity and number cAMP levels were analyzed before and after stimulation by isoproterenol, AlF$\sb4\sp-$, forskolin, and PGE$\sb1$. Isometric recording was used to examine myometrium contraction and relaxation. $\beta$-adrenoceptors in leukocytes and myometrial cells have similar $\sp{125}$I-iodopindolol binding affinity and B$\rm\sb{MAX}$. Both tissues can be stimulated by isoproterenol, but have reserve adenylyl cyclase activity not stimulated by $\beta$-ARs. Cultured human myometrial cells have higher basal AC activity and lower isoproterenol coupled cAMP production than leukocytes. The rank order of $\beta$-adrenoceptor agonist potencies in leukocytes is: isoproterenol $>$ terbutaline $>$ ritodrine. Myometrial cells could not be stimulated by terbutaline or ritodrine. This indicates that the intrinsic activity of $\beta$-adrenoceptor coupled cAMP production is different in these two tissues. Prolonged exposure to 200 nM terbutaline results in a decrease in both $\beta$-adrenoceptor number and isoproterenol-coupled cAMP production in cultured leukocytes and myometrial cells. Signal transduction factors, such as adenylyl cyclase and the PGE$\sb1$ pathway, are not affected by the down-regulation process. Isoproterenol relaxes term myometrium through $\beta\sb2$-ARs without a change in cAMP production. Cultured leukocytes do not completely reflect the activity of $\beta$-adrenoceptor coupled cAMP production to myometrial cultured cells. In myometrium, the presence of $\beta$-ARs does not guarantee stimulation of cAMP production, and cAMP is not an accurate index of myometrial relaxation at the end of pregnancy. While leukocytes may accurately reflect changes in myometrial $\beta$-adrenoceptors, postreceptor differences suggest that they are not a reasonable indicator of myometrial response to $\beta$-AR stimulation.