The effects of maternal zinc deficiency on myometrial contractility: an in vitro study

Aim: The aim of the study is to investigate the effects of zinc-supplemented or zinc-deficient diet on myometrial contractility during pregnancy. Material and Method: The patients were divided in four groups as Group 1 (n=5) fed with zinc-deficient diet, Group 2 (n=5) fed with zinc-supplemented diet, Group 3 (n=5) fed with normal diet, and Group 4 (n=5) as the control group and in vitro contractility study was conducted in the myometrial samples taken from these four groups, and intergroup comparison was performed for the results. The p<0.05 was accepted as significant. Results: In the evaluation of the contractility data, it was determined that the strength and period of contraction and also the frequencies increased in the zinc-supplemented group compared to the other groups. The difference was found to be significant only in frequency ( p<0.05). In the intergroup comparison, the frequency was found to be significantly higher in the zinc-supplemented group than all the other groups ( p<0.05). Conclusion: This in vitro finding can indicate the importance of zinc supplementation during pregnancy for postpartum bleeding.

Obstetric and Neonatal Outcomes Related To Intrapartum Hydration Strategies in Low-Risk Deliveries: An Observational Study

Background Effective myometrial contractility is important for successful labor, although little attention has been paid to the effect of managing intrapartum fluid intake. Ineffective myometrial contractility leads to prolonged labor, thus increasing obstetric and neonatal adverse outcomes. The risk of prolonged labor can be reduced by increasing the total volume of fluids administered during labor. Objective To determine the hydration strategies applied in nulliparous women undergoing low risk labor and their association with obstetric and neonatal outcomes. Methods A prospective cohort study was conducted in a Universitary Hospital. The study population included nulliparous women who presented in active labor or induced labor. Sample size was 147. In order to stratify women based on the hydration received, we set as a cut-off point the mean total volume administered per hour (300 ml/h). This enabled to compare obstetric, clinical, and neonatal outcomes in women who had received ≥ 300 mL/h o < 300 mL/h. The primary outcome was total length of labor. Secondary outcomes included maternal and neonatal outcomes. Results The study population comprised 148 nulliparous women, mean (DS) age 32.2 (4.4) years, mean (DS) gestational age of 39.4 (1.41) weeks. At admission, median (IQR) dilation was 2 (1–3) cm. Labor was induced in 65.5% (n = 97). Obstetric and neonatal outcomes were more favorable in women who received a ≥ 300 mL/h volume, with statistically significant median differences in the duration total duration of labor (526 vs 735 min; p < 0.001). Clinically relevant differences were also observed with respect to cesarean delivery (14.3% vs 18.7%), fever (5.5% vs 7.7%), weight loss at 24 hours (–2.3% vs − 3%) and at 48 hours (–5.7% vs − 6.3 %), incidence of weight loss > 7% at 48 hours (28.6% vs 39.8%), breastfeeding (94.6% vs 82.4%). Conclusions Higher fluid volume administered to nulliparous women during low-risk labor is associated with improved obstetric and neonatal outcomes.

PKA and AKIP1 interact to mediate cAMP-driven COX-2 expression: A potentially pivotal interaction in preterm and term labour

Previously, we showed that cAMP increased COX-2 expression in myometrial cells via MAPK. Here, we have extended these observations, using primary myometrial cell cultures to show that the cAMP agonist, forskolin, enhances IL-1β-driven COX-2 expression. We then explored the role of A-kinase interacting protein (AKIP1), which modulates the effect of PKA on p65 activation. AKIP1 knockdown reversed the effect of forskolin, such that its addition inhibited IL-1β-induced COX-2 mRNA expression and reduced the IL-1β-induced increase in nuclear levels of p65 and c-jun. Forskolin alone and with IL-1β increased IκBα mRNA expression suggesting that in the context of inflammation and in the presence of AKIP1, cAMP enhances p65 activation. AKIP1 knockdown reversed these changes. Interestingly, AKIP1 knockdown had minimal effect on the ability of forskolin to repress either basal OTR expression or IL-1β-stimulated OTR mRNA expression. AKIP1 was up-regulated by IL-1β, but not stretch and was repressed by cAMP. The mRNA expression of AKIP1 increased in early labour in tandem with an increase in COX-2 mRNA and protein. AKIP1 protein levels were also increased with inflammation and stretch-induced preterm labour. Our results identify a second important cAMP effector-switch occurring at term in human myometrium and suggest that a hitherto unrecognized interaction may exist between AKIP1, NFκB and AP-1. These data add to the proposition that cAMP acts as a key regulator of human myometrial contractility.

Regulatory Influence of Galanin and GALR1/GALR2 Receptors on Inflamed Uterus Contractility in Pigs

Uterine inflammation is a very common and serious pathology in domestic animals, the development and progression of which often result from disturbed myometrial contractility. We investigated the effect of inflammation on the protein expression of galanin (GAL) receptor subtypes (GALR)1 and GALR2 in myometrium and their role in the contractile amplitude and frequency of an inflamed gilt uterus. The gilts of the E. coli and SAL groups received E. coli suspension or saline in their uteri, respectively, and only laparotomy was performed (CON group). Eight days later, the E. coli group developed severe acute endometritis and lowered GALR1 protein expression in the myometrium. Compared to the pretreatment period, GAL (10−7 M) reduced the amplitude and frequency in myometrium and endometrium/myometrium of the CON and SAL groups, the amplitude in both stripes and frequency in endometrium/myometrium of the E. coli group. In this group, myometrial frequency after using GAL increased, and it was higher than in other groups. GALR2 antagonist diminished the decrease in amplitude in myometrium and the frequency in endometrium/myometrium (SAL, E. coli groups) induced by GAL (10−7 M). GALR1/GALR2 antagonist and GAL (10−7 M) reversed the decrease in amplitude and diminished the decrease in frequency in both examined stripes (CON, SAL groups), and diminished the drop in amplitude and abolished the rise in the frequency in the myometrium (E. coli group). In summary, the inflammation reduced GALR1 protein expression in pig myometrium, and GALR1 and GALR2 participated in the contractile regulation of an inflamed uterus.

Role of beta-adrenergic receptor subtypes in pig uterus contractility with inflammation

Uterine inflammation is a very common and serious condition in domestic animals. To development and progression of this pathology often lead disturbances in myometrial contractility. Participation of β1-, β2- and β3-adrenergic receptors (ARs) in noradrenaline (NA)-influenced contractility of the pig inflamed uterus was studied. The gilts of SAL- and E.coli-treated groups were administered saline or E.coli suspension into the uterine horns, respectively. Laparotomy was only done in the CON group. Compared to the period before NA administration, this neurotransmitter reduced the tension, amplitude and frequency in uterine strips of the CON and SAL groups. In the E.coli group, NA decreased the amplitude and frequency, and these parameters were lower than in other groups. In the CON, SAL and E.coli groups, β1- and β3-ARs antagonists in more cases did not significantly change and partly eliminated NA inhibitory effect on amplitude and frequency, as compared to NA action alone. In turn, β2-ARs antagonist completely abolished NA relaxatory effect on these parameters in three groups. Summarizing, NA decreases the contractile amplitude and frequency of pig inflamed uterus via all β-ARs subtypes, however, β2-ARs have the greatest importance. Given this, pharmacological modulation of particular β-ARs subtypes can be used to increase inflamed uterus contractility.

Identification of mundulone and mundulone acetate as natural products with tocolytic efficacy in mono- and combination-therapy with current tocolytics

Currently, there are a lack of FDA-approved tocolytics for the management of preterm labor. We previously observed that the isoflavones mundulone and mundulone acetate (MA) inhibit intracellular Ca2+-regulated myometrial contractility. Here, we further probed the potential of these natural products to be small molecule leads for discovery of novel tocolytics by: (1) examining uterine-selectivity by comparing concentration-response between human primary myometrial cells and a major off-target site, aortic vascular smooth muscle cells (VSMCs), (2) identifying synergistic combinations with current clinical tocolytics to increase efficacy or and reduce off-target side effects, (3) determining cytotoxic effects and (4) investigating the efficacy, potency and tissue-selectivity between myometrial contractility and constriction of fetal ductus arteriosus (DA), a major off-target of current tocolytics. Mundulone displayed significantly greater efficacy (Emax = 80.5% vs. 44.5%, p=0.0005) and potency (IC50 = 27 μM and 14 μM, p=0.007) compared to MA in the inhibition of intracellular-Ca2+ from myometrial cells. MA showed greater uterine-selectivity, compared to mundulone, based on greater differences in the IC50 (4.3 vs. 2.3 fold) and Emax (70% vs. 0%) between myometrial cells compared to aorta VSMCs. Moreover, MA demonstrated a favorable in vitro therapeutic index of 8.8, compared to TI = 0.8 of mundulone, due to its significantly (p<0.0005) smaller effect on the viability of myometrial (hTERT-HM), liver (HepG2) and kidney (RPTEC) cells. However, mundulone exhibited synergism with two current tocolytics (atosiban and nifedipine), while MA only displayed synergistic efficacy with only nifedipine. Of these synergistic combinations, only mundulone + atosiban demonstrated a favorable TI = 10 compared to TI=0.8 for mundulone alone. While only mundulone showed concentration-dependent inhibition of ex vivo mouse myometrial contractions, neither mundulone or MA affected mouse fetal DA vasoreactivity. The combination of mundulone and atosiban yielded greater tocolytic efficacy and potency on term pregnant mouse and human myometrial tissue compared to single-drugs. Collectively, these data highlight the difference in uterine‐selectivity of Ca2+‐mobilization, effects on cell viability and tocolytic efficacy between mundulone and MA. These natural products could benefit from medicinal chemistry efforts to study the structural activity relationship for further development into a promising single- and/or combination-tocolytic therapy for management of preterm labor.

Effects of Solvents, Emulsions, Cosolvents, and Complexions on Ex Vivo Mouse Myometrial Contractility

A great need exists to develop tocolytic and uterotonic drugs that combat poor, labor-related maternal and fetal outcomes. A widely utilized method to assess novel compounds for their tocolytic and uterotonic efficacy is the isometric organ bath contractility assay. Unfortunately, water-insoluble compounds can be difficult to test using the physiological, buffer-based, organ bath assay. Common methods for overcoming solubility issues include solvent variation, cosolvency, surfactant or complexion use, and emulsification. However, these options for drug delivery or formulation can impact tissue function. Therefore, the goal of this study was to evaluate the ability of common solvents, surfactants, cosolvents, and emulsions to adequately solubilize compounds in the organ bath assay without affecting mouse myometrial contractility. We found that acetone, acetonitrile, and ethanol had the least effect, while dimethylacetamide, ethyl acetate, and isopropanol displayed the greatest inhibition of myometrial contractility based on area under the contractile curve analyses. The minimum concentration of surfactants, cosolvents, and human serum albumin required to solubilize nifedipine, a current tocolytic drug, resulted in extensive bubbling in the organ bath assay, precluding their use. Finally, we report that an oil-in-water base emulsion containing no drug has no statistical effect beyond the control (water), while the drug emulsion yielded the same potency and efficacy as the freely solubilized drug.

The Myometrium in Pregnant Women with Obesity

: Obesity is a worldwide public health problem, affecting at least one-third of pregnant women. One of the main problems of obesity during pregnancy is the resulting high rate of cesarean section. The leading cause of this higher frequency of cesarean sections in obese women, compared with that in nonobese women, is an altered myometrial function that leads to lower frequency and potency of contractions. In this article, the disruptions of myometrial myocytes were reviewed in obese women during pregnancy that may explain the dysfunctional labor. The myometrium of obese women exhibited lower expression of connexin43, a lower function of the oxytocin receptor, and higher activity of the potassium channels. Adipokines, such as leptin, visfatin, and apelin, whose concentrations are higher in obese women, decreased myometrial contractility, perhaps by inhibiting the myometrial RhoA/ROCK pathway. The characteristically higher cholesterol levels of obese women alter myometrial myocyte cell membranes, especially the caveolae, inhibiting oxytocin receptor function, and increasing the K+ channel activity. All these changes in the myometrial cells or their environment decrease myometrial contractility, at least partially explaining the higher rate of cesarean of sections in obese women.