Optimal starting dosing regimen of intravenous oxytocin for labor induction based on the population kinetic-pharmacodynamic model of uterine contraction frequency

BACKGROUND

Intravenous oxytocin is commonly used for labor induction. However, a consensus on the initial dosing regimen is lac with conflicting research findings and varying guidelines. This study aimed to develop a population kinetic-pharmacodynamic (K-PD) model for oxytocin-induced uterine contractions considering real-world data and relevant influencing factors to establish an optimal starting dosing regimen for intravenous oxytocin.

METHODS

This retrospective study included pregnant women who underwent labor induction with intravenous oxytocin at Peking University Third Hospital in 2020. A  population K-PD model was developed to depict the time course of uterine contraction frequency (UCF), and covariate screening identified significant factors affecting the pharmacokinetics and pharmacodynamics of oxytocin. Model-based simulations were used to optimize the current starting regimen based on specific guidelines.

RESULTS

Data from 77 pregnant women with 1095 UCF observations were described well by the K-PD model. Parity, cervical dilation, and membrane integrity are significant factors influencing the effectiveness of oxytocin. Based on the model-based simulations, the current regimens showed prolonged onset times and high infusion rates. This study proposed a revised approach, beginning with a rapid infusion followed by a reduced infusion rate, enabling most women to achieve the target UCF within approximately 30 min with the lowest possible infusion rate.

CONCLUSION

The K-PD model of oxytocin effectively described the changes in UCF during labor induction. Furthermore, it revealed that parity, cervical dilation, and membrane integrity are key factors that influence the effectiveness of oxytocin. The optimal starting dosing regimens obtained through model simulations provide valuable clinical references for oxytocin treatment.

Lippia origanoides essential oil induces tocolytic effect in virgin rat uterus and inhibits writhing in a dysmenorrhea mouse model

ETHNOPHARMACOLOGICAL RELEVANCE

The species Lippia origanoides Kunth, popularly known as "salva-de-marajó", is used in Brazilian traditional "quilombola" communities to treat menstrual cramps and uterine inflammation.

AIM OF THE STUDY

Evaluate the spasmolytic activity of Lippia origanoides essential oil (LOO) on experimental models of uterine conditions related to menstrual cramps and investigate its mechanism of action.

MATERIALS AND METHODS

Virgin rat-isolated uterus was mounted in the organ bath apparatus to evaluate the spasmolytic effect of LOO on basal tonus and contractions induced by carbachol, KCl, or oxytocin. We used pharmacological agents to verify the relaxation mechanism of LOO. The evaluation of uterine contractility in virgin rats, after treatment with LOO for three consecutive days, was carried out by the construction of a concentration-response curve with oxytocin or carbachol. The primary dysmenorrhea animal model was replicated with an injection of estradiol cypionate in female mice for three consecutive days, followed by intraperitoneal application of oxytocin.

RESULTS

LOO relaxed the rat uterus precontracted with 10^-2 IU/mL oxytocin (logEC₅₀ = 1.98 ± 0.07), 1 μM carbachol (logEC₅₀ = 1.42 ± 0.07) or 60 mM KCl (logEC₅₀ = 1.53 ± 0.05). It was also able relax uterus on spontaneous contractions (logEC₅₀ = 0.41 ± 0.05). Preincubation with glibenclamide, propranolol, phentolamine or L-NAME in contractions induced by carbachol did not alter significantly the relaxing effect of LOO. However, in the presence of 4-aminopyridine, CsCl or tetraethylammonium there was a reduction of LOO potency, whereas the blockers methylene blue, ODQ, aminophylline and heparin potentiated the LOO relaxing effect. Preincubation with LOO in a Ca²⁺ free medium at concentrations of 27 μg/mL or 81 μg/mL reduced the contraction induced by carbachol. The administration of LOO for 3 days did not alter uterus contractility. The treatment with LOO at 30 or 100 mg/kg intraperitoneally, or 100 mg/kg orally, inhibited writhing in female mice. The association of LOO at 10 mg/kg with nifedipine or mefenamic acid potentiated writhing inhibition in mice.

CONCLUSIONS

The essential oil of L. origanoides has tocolytic activity in rat isolated uterus pre-contracted with KCl, oxytocin, or carbachol. This effect is possibly related to the opening of potassium channels (K_ir, K_V, and K_Ca), cAMP increase, and diminution of intracellular Ca²⁺. This relaxant effect, probably, contributed to reduce the number of writhings in an animal model of dysmenorrhea being potentiated by nifedipine or mefenamic acid. Taken together, the results here presented indicate that this species has a pharmacological potential for the treatment of primary dysmenorrhea, supporting its use in folk medicine.

Uterotonic Effects of Aqueous and Methanolic Extracts of Lannea acida in Wistar Rats: An In Vitro Study

Lannea acida (Anacardiaceae), commonly called Kikié in the Noun division (West-Cameroon), is a tree whose bark is used locally to facilitate delivery. This study was aimed at evaluating the in vitro uterotonic effects of aqueous and methanol extracts of L. acida in Wistar rats. Uterine strips isolated from rats pretreated with 5 μg estradiol (48 h) were mounted in a single-organ bath containing aerated and thermostated De Jalon solution (37 °C). After equilibration, non-cumulative effects of L. acida extracts were recorded after application. The effect of the methanol extract (the most active extract) was monitored in the presence of atosiban (a competitive antagonist of oxytocin receptors), atropine (a specific type 3 muscarinic receptor antagonist), nifedipine (an L-type calcium channel antagonist), and 2-Aminoethoxydiphenyl borate (2-ADB, a specific antagonist of inositol 1,4,5-triphosphate receptors type 1), and in calcium-free medium containing EGTA to elucidate its mechanism of action. L. acida induced uterine contraction in a concentration-dependent manner with the methanol extract (1.506 ± 0.032 gf) being the most effective. Administration of atosiban (2 μmol/L) and atropine (1 μmol/L) reduced the contractile effect of L. acida. Complete inhibition was observed with nifedipine, 2-APB, and calcium-free medium containing EGTA. These results suggest that L. acida possesses uterotonic effects mediated through oxytocin receptors with mobilization of extracellular calcium.

Evaluating aminophylline and progesterone combination treatment to modulate contractility and labor-related proteins in pregnant human myometrial tissues

Progesterone (P4) and cyclic adenosine monophosphate (cAMP) are regarded as pro-quiescent factors that suppress uterine contractions during pregnancy. We previously used human primary cells in vitro and mice in vivo to demonstrate that simultaneously enhancing myometrial P4 and cAMP levels may reduce inflammation-associated preterm labor. Here, we assessed whether aminophylline (Ami; phosphodiesterase inhibitor) and P4 can reduce myometrial contractility and contraction-associated proteins (CAPs) better together than individually; both agents are clinically used drugs. Myometrial tissues from pregnant non-laboring women were treated ex vivo with Ami acutely (while spontaneous contracting) or throughout 24-h tissue culture (±P4); isometric tension measurements, PKA assays, and Western blotting were used to assess tissue contractility, cAMP action, and inflammation. Acute (1 h) treatment with 250 and 750 μM Ami reduced contractions by 50% and 84%, respectively, which was not associated with a directly proportional increase in whole tissue PKA activity. Sustained myometrial relaxation was observed during 24-h tissue culture with 750 μM Ami, which did not require P4 nor reduce CAPs. COX-2 protein can be reduced by 300 nM P4 but this did not equate to myometrial relaxation. Ami (250 μM) and P4 (100 and 300 nM) co-treatment did not prevent oxytocin-augmented contractions nor reduce CAPs during interleukin-1β stimulation. Overall, Ami and P4 co-treatment did not suppress myometrial contractions more than either agent alone, which may be attributed to low specificity and efficacy of Ami; cAMP and P4 action at in utero neighboring reproductive tissues during pregnancy should also be considered.

Quercetin affects uterine smooth muscle contractile activity in gilts

Quercetin is a polyphenolic flavonoid occurring in leaves, stems, flowers and fruits of many plants. In traditional Chinese medicine, it is used as a natural therapeutic agent with a broad spectrum of activities (antioxidant, neuroprotective, anti-inflammatory, anticancer, antibacterial and antiviral). Moreover, quercetin affects function of the reproductive tract, however the knowledge of this activity is still fragmentary. Therefore, this study aimed to determine the influence of quercetin on the contractile activity of the porcine myometrium collected from immature (n = 6), cyclic (n = 6) and early pregnant (n = 6) gilts. Strips of the myometrium (comprising longitudinal and circular layer) were resected from the middle part of the uterine horns and the isometric contractions were recorded. After 60-90 min of preincubation, the strips were stimulated with quercetin in increasing (10-13-10-1 M) concentrations and the changes in the tension amplitude and frequency of contractions were measured. Quercetin decreased (P<0.01-0.001) the amplitude of contractions at concentrations 10-11-10-1 M and 10-10-10-1 M in cyclic and early pregnant groups, respectively. The frequency of contractions decreased in all groups but was the highest (at concentrations 10-11-10-1 M; P<0.05-0.001) in the cyclic group and the lowest (at concentrations 10-5-10-1 M; P<0.01) in the immature group. The tension decreased only in the cyclic group after quercetin administration in high concentrations (10-6-10-1 M; P<0.05-0.01). The results indicate that quercetin causes relaxation of the porcine uterine smooth muscle but this activity is strongly related to the physiological status of the gilts.

Effect of maternal oxytocin on umbilical venous and arterial blood flows during physiological-based cord clamping in preterm lambs

BACKGROUND

Delayed umbilical cord clamping (UCC) after birth is thought to cause placental to infant blood transfusion, but the mechanisms are unknown. It has been suggested that uterine contractions force blood out of the placenta and into the infant during delayed cord clamping. We have investigated the effect of uterine contractions, induced by maternal oxytocin administration, on umbilical artery (UA) and venous (UV) blood flows before and after ventilation onset to determine whether uterine contractions cause placental transfusion in preterm lambs.

METHODS AND FINDINGS

At ~128 days of gestation, UA and UV blood flows, pulmonary arterial blood flow (PBF) and carotid arterial (CA) pressures and blood flows were measured in three groups of fetal sheep during delayed UCC; maternal oxytocin following mifepristone, mifepristone alone, and saline controls. Each successive uterine contraction significantly (p<0.05) decreased UV (26.2±6.0 to 14.1±4.5 mL.min-1.kg-1) and UA (41.2±6.3 to 20.7 ± 4.0 mL.min-1.kg-1) flows and increased CA pressure and flow (47.1±3.4 to 52.8±3.5 mmHg and 29.4±2.6 to 37.3±3.4 mL.min-1.kg-1). These flows and pressures were partially restored between contractions, but did not return to pre-oxytocin administration levels. Ventilation onset during DCC increased the effects of uterine contractions on UA and UV flows, with retrograde UA flow (away from the placenta) commonly occurring during diastole.

CONCLUSIONS

We found no evidence that amplification of uterine contractions with oxytocin increase placental transfusion during DCC. Instead they decreased both UA and UV flow and caused a net loss of blood from the lamb. Uterine contractions did, however, have significant cardiovascular effects and reduced systemic and cerebral oxygenation.

An integrated study of metabolomics and transcriptomics to reveal the anti-primary dysmenorrhea mechanism of Akebiae Fructus

ETHNOPHARMACOLOGICAL RELEVANCE

Akebiae Fructus, a Tujia minority folk medicine and a well-known traditional Chinese medicine for soothing the liver, regulating Qi, promoting blood circulation and relieving pain, is widely used in the treatment of primary dysmenorrhea. However, little is known about its underlying mechanism.

AIM OF THE STUDY

To explore the effect of Akebiae Fructus on primary dysmenorrhea model induced by estradiol benzoate and oxytocin, and to provide better understanding of the mechanism of Akebiae Fructus for primary dysmenorrhea treatment.

MATERIALS AND METHODS

The primary dysmenorrhea mouse model was used in this study. Except for the control group and the normal administration group, the mice of other groups were subcutaneously injected with estradiol benzoate (10 mg/kg/d) for 10 consecutive days. From the 5th day of the ten-day model period, the positive control groups were given 0.075 g/kg ibuprofen and 7.5 g/kg Leonurus granule, the drug groups were given 0.2 g/kg, 0.4 g/kg, 0.8 g/kg Akebiae Fructus extract, the normal administration group was given 0.8 g/kg Akebiae Fructus extract, and the same volume saline was given in the control group. On the tenth day, oxytocin (10 U/kg) was peritoneally injected after estradiol benzoate injected 1 h. After the oxytocin injection, writhing behavior was observed for 30 min. Then the uterine tissue was collected to measure the level of PGF2α and PGE2, and for histological analysis and transcriptomics analysis. Meanwhile, plasma and urine samples were collected for metabolomic analysis.

RESULTS

Akebiae Fructus inhibited the writhing, decreased the PGF2α level and ameliorated the morphological changes. 32 potential metabolic biomarkers in plasma and 17 in urine were found for primary dysmenorrhea, and after Akebiae Fructus treatment, 25 metabolites in plasma and 14 in urine were restored. These altered metabolites were mainly involved in lipid, amino acid and organic acid metabolism. For the transcriptomic study, a total of 2244 differentially expressed genes (1346 up-regulated and 898 down-regulated) were obtained between the control and model group, and 148 differentially expressed genes (DEGs) were found related with Akebiae Fructus treatment of primary dysmenorrhea. Correlation analysis was carried out based on the transcriptomic and metabolomic data. 5 differentially expressed genes (Plpp3, Sgpp2, Arg1, Adcy8, Ak5) were found related with the enrichment metabolic pathways. The mechanism by which Akebiae Fructus ameliorates primary dysmenorrhea may account for the regulation of the gene expression to control the key enzymes in the sphingolipid metabolism, arginine and proline metabolism, glycerophospholipid metabolism and purine metabolism, inhibiting the abnormal secretion of PGF2α, alleviating the uterine contraction and reducing inflammation and pain.

CONCLUSIONS

Akebiae Fructus could effectively alleviate the symptoms of primary dysmenorrhea, regulate metabolic disorders, and control the related gene expression in primary dysmenorrhea. The study may provide clues for further study of Akebiae Fructus treatment on primary dysmenorrhea.

Relaxant Effects of the Aqueous Extract of Excoecaria grahamii (Euphorbiaceae) Leaves on Uterine Horn Contractility in Wistar Rats

In uterine smooth muscle, the effects of Excoecaria grahamii are not yet documented. To fill this gap, we investigated the pharmacological effect of Excoecaria grahamii on the contraction of the rat isolated uterine horns. The isolated segments were exposed to different concentrations of the aqueous extract of Excoecaria grahamii leaves and pharmacological drugs. The results showed that Excoecaria grahamii aqueous extract decreased the amplitude and frequency by concentration-related manner. IC50 values were 2.4 and 2.6, respectively, for amplitude and frequency. Our study revealed that the extract did not act through histamine H2-receptors or the nitric oxide pathway. It also inhibited uterine contractions induced by oxytocin and potassium chloride (KCl). These data suggest that Excoecaria grahamii active compound can be used for calming uterine contractions. The action of Excoecaria grahamii showed that it can be useful to fight against diseases which caused uterotonic effects. It can be useful to prevent preterm birth and pains caused by menstruations but further investigation is needed to clarify the mechanism action.

Chemical composition and uterine smooth muscle relaxant activity of essential oils from 10 kinds of blood-activating and stasis-resolving Chinese medicinal herbs

ETHNOPHARMACOLOGICAL RELEVANCE

Dysmenorrhea is one of the most common gynecological problems among menstruating females. Blood-activating and stasis-resolving herbs (BASRHs) have been employed to be the first choice for treating dysmenorrhea in China. Especially, the essential oils of some BASRHs have been confirmed to play important roles in the treatment of dysmenorrhea, but the constituents and uterine smooth muscle relaxant activity of some commonly used BASRH essential oils have not been fully assessed, and whether there are differences in the constituents and anti-dysmenorrhea effect among BASRH essential oils has not been evaluated.

AIM OF THE STUDY

This study aims to systematically investigate the chemical constituents of 10 BASRH essential oils and assess their uterine smooth muscle relaxant activity and the preliminary mechanism of the most effective essential oil.

MATERIALS AND METHODS

The chemical constituents of 10 BASRH essential oils were analyzed by Gas Chromatography-Mass Spectrometer. A rat model of dysmenorrhea in vitro was established to investigate the uterine smooth muscle relaxant activity of 10 kinds of essential oils. Rat isolated uterus strips were given different dose of 10 kinds of essential oils (0.04, 0.08, 0.16 mg/mL). The contractile responses were recorded with Power Lab recording system, and contractile tension, contractile frequency, and contractile activity were evaluated. The preliminary mechanism of the essential oil of the rhizomes of Curcuma phaeocaulis Valeton (CPEO) was assessed using a rat model of dysmenorrhea in vivo and in vitro, and rats were given the CPEO (15, 30, and 60 mg/kg) by gavage. The level of Ca2+ in uterine tissue of rats was determined by methyl thyme phenol blue colorimetric and Bradford methods. The effects of CPEO on extracellular Ca2+ influx and intracellular Ca2+ release were evaluated using the isolated uterus.

RESULTS

The results of Gas Chromatography-Mass Spectrometer analysis showed that more than 81 components (content: 1% max appearance) were identified. The main components of the 10 BASRH essential oils were found to be monoterpenoids, sesquiterpenoids, diterpenoids, aromatics, aliphatics, and phthalides. The study of in vitro smooth muscle relaxant activity demonstrated that all the essential oils except the essential oil of the roots of Cyathula officinalis K.C.Kuan markedly decrease the contractile activity, tension, and frequency (P < 0.05 or P < 0.01). Among these oils, CPEO has the most pronounced effect. Further in vivo studies indicated that CPEO can significantly decrease the level of Ca2+ in uterine tissue when compared with the model group (P < 0.05 or P < 0.01). In vitro studies indicated that CPEO can inhibit the extracellular Ca2+ influx and intracellular Ca2+ release in favor of uterine relaxation.

CONCLUSIONS

BASRH essential oils play an important role in inhibiting uterine smooth muscle contractions, and sesquiterpenoids and phthalides in BASRH essential oils are important active compounds for relaxing uterine smooth muscle. CPEO is a favorable candidate for developing anti-dysmenorrhea drugs.

The ontogeny of kisspeptin receptor in the uterine contractions in rats: Its possible role in the quiescence of non-pregnant and pregnant uteri

The objectives of this study were to investigate the effects of KISS1 94-121 fragment on the contractility of non-pregnant and pregnant rat uteri, and to determine the uterine and myometrial expressions of Kiss1r. Uterine muscle strips were obtained from non-pregnant Sprague-Dawley rats in oestrous phase and from pregnant rats on gestational days 5, 15, 18, 20 or 22. The in vitro contractility measurements were carried out in an isolated organ bath in the presence of KISS1 94-121. Experiments with 5-day pregnant tissues were also performed in the presence of kisspeptin-234 trifluoroacetate. The mRNA and protein expressions of Kiss1r were measured by RT-PCR and Western blot analysis, while localizations of receptors were defined by fluorescent immunohistochemistry. KISS1 94-121 induced a dose-dependent relaxation both in non-pregnant and pregnant intact and endometrium-denuded uteri. A gradual decrease was found in the uterine expressions of Kiss1r mRNA and protein towards the end of the gestational period, and it was further confirmed by the immunohistochemical results. The significant majority of Kiss1r is found in the myometrium, however the few endometrial Kiss1r also influences the uterine contractions. The relaxing effect of kisspeptin is continuously reduced towards the end of gestational period in parallel with the reduction of Kiss1r expression. Our results suggest a putative role of kisspeptin in the maintenance of uterine quiescence that may have significance in miscarriage or preterm contractions.

Acute Pulmonary Edema Induced by a Low Dose of Ritodrine Hydrochloride: A Case Report

OBJECTIVE

Acute pulmonary edema associated with ritodrine hydrochloride is a rare, life-threatening complication, and dose and duration of ritodrine use are closely associated with this pathology. We report a case of acute pulmonary edema associated with short-duration infusion of ritodrine hydrochloride in a patient with pectus excavatum as an underlying factor.

CASE REPORT

A 30-year-old healthy pregnant woman was treated with oral ritodrine for tocolysis between 31 and 35 weeks of pregnancy. At 36 weeks of gestation, she went into preterm labor, with premature rupture of the membrane and breech presentation, and received an infusion of ritodrine hydrochloride for a few hours. Although she was normotensive until labor onset, mild hypertension and proteinuria were recognized. Intraoperatively, a funnel-chest deformity was observed, and she developed postoperative pulmonary edema associated with dyspnea and wet cough and confirmed on chest radiography and arterial gas analysis, and recovered with supportive care.

CONCLUSION

Small-dose infusion of ritodrine hydrochloride might cause pulmonary edema in patients with underlying medical problems, including pectus excavatum.

Conflicting Nongenomic Effects of Progesterone in the Myometrium of Pregnant Rats

Recently, it has been suggested that progesterone affects the contractile activity of pregnant myometrium via nongenomic pathways; therefore, we aimed to clarify whether progesterone causes and/or inhibits pregnant myometrial contractions via nongenomic pathways. Our in vitro experiments using myometrial strips obtained from rats at 20 days of gestation revealed that progesterone caused myometrial contractions in a concentration- and time-dependent manner at concentrations up to 5 × 10-7 M; however, this effect decreased at concentrations higher than 5 × 10-5 M. Similarly, progesterone enhanced oxytocin-induced contractions up to 5 × 10-7 M and inhibited contractions at concentrations higher than 5 × 10-5 M. Conversely, progesterone did not enhance high-KCl-induced contractions but inhibited contractions in a concentration- and time-dependent manner at concentrations higher than 5 × 10-7 M. We also found that RU486 did not affect progesterone-induced contractions or the progesterone-induced inhibition of high-KCl-induced contractions; however, progesterone-induced contractions were blocked by calcium-free phosphate saline solution, verapamil, and nifedipine. In addition, FPL64176, an activator of L-type voltage-dependent calcium channels, enhanced high-KCl-induced contractions and rescued the decrease in high-KCl-induced contractions caused by progesterone. Together, these results suggest that progesterone exerts conflicting nongenomic effects on the contractions of pregnant myometrium via putative L-type voltage-dependent calcium channels.

The mechanism of action of oxytocin antagonist nolasiban in ART in healthy female volunteers

RESEARCH QUESTION

What are the effects of the oxytocin receptor (OTR) antagonist nolasiban on uterine contractions, endometrial perfusion and endometrial mRNA expression?

DESIGN

Randomized, double-blind, parallel-group, mechanism-of-action study with nolasiban. Forty-five healthy, pre-menopausal women were treated with placebo, 900 mg or 1800 mg nolasiban on the day corresponding to blastocyst transfer. Ultrasonographic uterine contraction frequency and endometrial perfusion were assessed, and endometrial biopsies analysed by next-generation sequencing.

RESULTS

Both doses of nolasiban showed decreased contraction frequency and increased endometrial perfusion depending on the time point assessed. At 1800 mg, 10 endometrial genes (DPP4, CNTNAP3, CNTN4, CXCL12, TNXB, CTSE, OLFM4, KRT5, KRT6A, IDO2) were significantly differentially expressed (adjusted P < 0.05). Of these, OLFM4, DPP4 and CXCL12 were regulated in the same direction as genes involved in implantation during the window of implantation. In addition, three genes (DPP4, CXCL12 and IDO2) were associated with decidualization and endometrial receptivity.

CONCLUSIONS

These data expand our knowledge of the mechanism of action of nolasiban in increasing pregnancy rates after embryo transfer. The results suggest more marked effects of nolasiban 1800 mg compared with the 900 mg dose, supporting testing at higher doses in IVF patients.

The effect of an oxytocin washout period on blood loss at cesarean delivery

Objectives Prolonged oxytocin exposure may result in increased blood loss during delivery. Our objective was to determine whether an oxytocin rest period before cesarean delivery had an impact on blood loss. Methods We performed a retrospective cohort study of women who underwent primary cesarean delivery after oxytocin augmentation. The primary outcome was change between pre- and postoperative hematocrit (Hct) in women with less than 60-min oxytocin rest period (<60 min) and greater than 60-min rest period (>60 min). Results There was no difference in demographic characteristics (age, BMI, or gestational age at delivery) between the two groups. Women in the >60 min group had a higher cumulative dose and longer duration of oxytocin administration. There was no significant difference in change in Hct between the two groups when controlling for these factors. Conclusions We did not find a significant correlation between the duration of the oxytocin rest period and blood loss. Oxytocin washout periods of greater than 60 min may not result in decreased blood loss at cesarean delivery, and thus, women may not benefit from such oxytocin washout periods.

The Inhibitory Effect of Extra Virgin Olive Oil and Its Active Compound Oleocanthal on Prostaglandin-Induced Uterine Hypercontraction and Pain-Ex Vivo and In Vivo Study

Primary dysmenorrhea is a common occurrence in adolescent women and is a type of chronic inflammation. Dysmenorrhea is due to an increase in oxidative stress, which increases cyclooxygenase-2 (COX-2) expression, increases the concentration of prostaglandin F2α (PGF2α), and increases the calcium concentration in uterine smooth muscle, causing excessive uterine contractions and pain. The polyphenolic compound oleocanthal (OC) in extra virgin olive oil (EVOO) has been shown to have an anti-inflammatory and antioxidant effect. This study aimed to investigate the inhibitory effect of extra virgin olive oil and its active ingredient oleocanthal (OC) on prostaglandin-induced uterine hyper-contraction, its antioxidant ability, and related mechanisms. We used force-displacement transducers to calculate uterine contraction in an ex vivo study. To analyze the analgesic effect, in an in vivo study, we used an acetic acid/oxytocin-induced mice writhing model and determined uterus contraction-related signaling protein expression. The active compound OC inhibited calcium/PGF2α-induced uterine hyper-contraction. In the acetic acid and oxytocin-induced mice writhing model, the intervention of the EVOO acetonitrile layer extraction inhibited pain by inhibiting oxidative stress and the phosphorylation of the protein kinase C (PKC)/extracellular signal-regulated kinases (ERK)/ myosin light chain (MLC) signaling pathway. These findings supported the idea that EVOO and its active ingredient, OC, can effectively decrease oxidative stress and PGF2α-induced uterine hyper-contraction, representing a further treatment for dysmenorrhea.

Smooth muscle cell-specific TMEM16A deletion does not alter Ca2+ signaling, uterine contraction, gestation length, or litter size in mice†

Ion channels in myometrial cells play critical roles in spontaneous and agonist-induced uterine contraction during the menstrual cycle, pregnancy maintenance, and parturition; thus, identifying the genes of ion channels in these cells and determining their roles are essential to understanding the biology of reproduction. Previous studies with in vitro functional and pharmacological approaches have produced controversial results regarding the presence and role of TMEM16A Ca2+-activated Cl- channels in myometrial cells. To unambiguously determine the function of this channel in these cells, we employed a genetic approach by using smooth muscle cell-specific TMEM16A deletion (i.e. TMEM16ASMKO) mice. We found that myometrial cells from TMEM16ASMKO mice generated the same pattern and magnitude in Ca2+ signals upon stimulation with KCl, oxytocin, and PGF2α compared to the isogenic control myometrial cells. At the uterine tissue level, TMEM16A deletion also did not cause detectable changes in either spontaneous or agonist (i.e. KCl, oxytocin, and PGF2α)-induced contractions. Moreover, in vivo the TMEM16ASMKO mice gave birth at full term with the same litter size as genetically identical control mice. Finally, TMEM16A immunostaining in both control and TMEM16ASMKO mice revealed that this protein was highly expressed in the endometrial stroma, but did not co-localize with a smooth muscle specific marker MYH11. Collectively, these results unequivocally demonstrate that TMEM16A does not serve as a pacemaking channel for spontaneous uterine contraction, neither does it function as a depolarizing channel for agonist-evoked uterine contraction. Yet these two functions could underlie the normal gestation length and litter size in the TMEM16ASMKO mice.

Smooth muscle 22α deficiency impairs oxytocin-induced uterine contractility in mice at full-term pregnancy

Smooth muscle 22α (SM22α, namely Transgelin), as an actin-binding protein, regulates the contractility of vascular smooth muscle cells (VSMCs) by modulation of the stress fiber formation. However, little is known about the roles of SM22α in the regulation of uterine contraction during parturition. Here, we showed that contraction in response to oxytocin (OT) was significantly decreased in the uterine muscle strips from SM22α knockout (Sm22α-KO) mice, especially at full-term pregnancy, which may be resulted from impaired formation of stress fibers. Furthermore, serious mitochondrial damage such as the mitochondrial swelling, cristae disruption and even disappearance were observed in the myometrium of Sm22α-KO mice at full-term pregnancy, eventually resulting in the collapse of mitochondrial membrane potential and impairment in ATP synthesis. Our data indicate that SM22α is necessary to maintain uterine contractility at delivery in mice, and acts as a novel target for preventive or therapeutic manipulation of uterine atony during parturition.

Chlamydia muridarum infection differentially alters smooth muscle function in mouse uterine horn and cervix

Chlamydia trachomatis infection is a primary cause of reproductive tract diseases including infertility. Previous studies showed that this infection alters physiological activities in mouse oviducts. Whether this occurs in the uterus and cervix has never been investigated. This study characterized the physiological activities of the uterine horn and the cervix in a Chlamydia muridarum (Cmu)-infected mouse model at three infection time points of 7, 14, and 21 days postinfection (dpi). Cmu infection significantly decreased contractile force of spontaneous contraction in the cervix (7 and 14 dpi; P < 0.001 and P < 0.05, respectively), but this effect was not observed in the uterine horn. The responses of the uterine horn and cervix to oxytocin were significantly altered by Cmu infection at 7 dpi (P < 0.0001), but such responses were attenuated at 14 and 21 dpi. Cmu infection increased contractile force to prostaglandin (PGF_2α) by 53-83% in the uterine horn. This corresponded with the increased messenger ribonucleic acid (mRNA) expression of Ptgfr that encodes for its receptor. However, Cmu infection did not affect contractions of the uterine horn and cervix to PGE₂ and histamine. The mRNA expression of Otr and Ptger4 was inversely correlated with the mRNA expression of Il1b, Il6 in the uterine horn of Cmu-inoculated mice (P < 0.01 to P < 0.001), suggesting that the changes in the Otr and Ptger4 mRNA expression might be linked to the changes in inflammatory cytokines. Lastly, this study also showed a novel physiological finding of the differential response to PGE₂ in mouse uterine horn and cervix.

Pimpinella anisum extract attenuates spontaneous and agonist-induced uterine contraction in term-pregnant rats

ETHNOPHARMACOLOGY RELEVANCE

Pimpinella anisum is a well-known traditional medicinal herb which has been used in folk medicine as an antiulcer, anticancer, antibacterial and as a muscle relaxant.

AIM OF THE STUDY

This study was performed to explore the modulatory effects of Pimpinella anisum on term-pregnant rat uterine contractility and to investigate its possible underlying mechanisms.

MATERIAL AND METHODS

Intact uterine strips without endometrial layer were isolated from female term-pregnant Wistar rats (22 days of gestation) and mounted in a tissue bath apparatus for in vitro isometric force recording. The effects of different concentrations of Pimpinella anisum extract (PAE) (1, 3, 5, and 7 mg/mL) were examined on uterine contractions generated spontaneously or induced with oxytocin (5 nmol/L), Bay K8644 (1 μmol/L), and carbachol (10 μmol/L). In some experiments, PAE was applied on depolarized myometrium in the presence of high-KCl solution (60 mmol/L). The effect on Ca²⁺ release was also examined.

RESULTS

Application of PAE significantly reduced uterine contractions generated spontaneously or induced with oxytocin, Bay K8644, and carbachol in a concentration-dependent manner (n = 7; P < 0.01). In depolarized myometrium, PAE significantly reduced the tonic force induced by high-KCl solution (n = 7; P < 0.01). PAE prevented oxytocin-induced transient contraction in the entire absence of external calcium (n = 7; P < 0.01).

CONCLUSION

The present findings demonstrate the potentials of PAE to relax pregnant uterine contractions possibly by blocking Ca²⁺ entry via L-type calcium channels and inhibiting Ca²⁺ release from the internal store. The tocolytic effects of PAE may be a potential adjuvant against strong premature uterine contractions which threaten early pregnancy although clinical studies are required.

Gestational and Hormonal Effects on Magnesium Sulfate's Ability to Inhibit Mouse Uterine Contractility

Magnesium sulfate is used as a tocolytic, but clinical efficacy has been seriously questioned. Our objective was to use controlled ex vivo conditions and known pregnancy stages, to investigate how 2 key factors, hormones and gestation, affect magnesium's tocolytic ability. We hypothesized that these factors could underlie the varying clinical findings around magnesium's efficacy. Myometrial strips were obtained from nonpregnant (n = 10), mid-pregnant (n = 12), and term-pregnant (n = 11) mouse uterus. The strips were mounted in organ baths superfused with oxygenated physiological saline at pH 7.4 and 37 °C. The effect of different concentrations of MgSO₄ (2-20 mM) was examined on spontaneous and oxytocin-induced (0.5-1 nM) contractions. Contractile properties (amplitude, frequency, and area under the curve) were measured before and after application of magnesium. Magnesium sulfate had a dose-dependent inhibitory effect on both spontaneous and oxytocin-induced contractions but was less effective in the presence of oxytocin. In spontaneous contractions, magnesium was more potent as gestation progressed (P < .0001). In the presence of oxytocin, however, there were no significant gestational differences in its effects on contraction. The rapid onset and reversal of magnesium's effects suggest an extracellular action on calcium entry. Taken together, we conclude that magnesium's actions are influenced by both gestational state and hormones, such that, at least in mice, it is least effective in early gestation with oxytocin present and most effective at term in the absence of oxytocin. That magnesium is least effective preterm and oxytocin decreases its effectiveness throughout gestation, may explain its disappointing clinical effects as a tocolytic.

Regulation effect and mechanism of Sheng-Hua-Tang on female reproductive system: From experimental transcriptomic analysis to clinical applications

ETHNOPHARMACOLOGICAL RELEVANCE

Sheng-Hua-Tang (SHT) is commonly used to treat female illnesses, especially postpartum conditioning. However, its effects and mechanisms on female reproductive system remain unclear. The aim of the present study was to investigate the effect of SHT on female brain-ovary-uterus axis from bench to clinic.

MATERIALS AND METHODS

Mice were administrated SHT (200 mg/kg) orally for seven consecutive days. Brain, ovary, and uterus tissues were then collected for microarray analysis. A nationwide database analysis and a pilot randomized, open-label clinical trial were further applied to evaluate the clinical application and effects of SHT on postpartum women.

RESULTS

Microarray analysis showed that oral administration of SHT induced a cascade reaction of gene expression, with 17, 883, and 1592 genes were significantly regulated by SHT in brain, ovary, and uterus, respectively. Population-based analysis of one million subjects in Taiwan's National Health Insurance Research Database between 1997 and 2013 showed that SHT was commonly used in menstrual disorders in female population, especially dysmenorrhea, abnormal uterine bleeding, and variation of menstrual cycle. Clinical trial on postpartum women showed that oral administration SHT for one week alleviated uterine contraction pain and breast swelling pain. Furthermore, Mmp2, Mmp3, Mmp9, Mmp11, Mmp15, Oxtr, Plrl, and Tph2 gene expression affected by SHT in mice were correlated with clinical effects of SHT in human subjects.

CONCLUSION

This report provided the scientific evidences of mechanisms and clinical efficacies of SHT. Moreover, our findings might afford insights for clinical doctors in terms of SHT prescription.

Paeonol alleviates primary dysmenorrhea in mice via activating CB2R in the uterus

BACKGROUND AND PURPOSE

Primary dysmenorrhea is the most common gynaecologic problem in menstruating women and is characterized by spasmodic uterine contraction and pain symptoms associated with inflammatory disturbances. Paeonol is an active phytochemical component that has shown anti-inflammatory and analgesic effects in several animal models. The aim of this study was to explore whether paeonol is effective against dysmenorrhea and to investigate the potential mechanism of cannabinoid receptor signalling.

EXPERIMENTAL APPROACH

Dysmenorrhea was established by injecting oestradiol benzoate into female mice. The effects of paeonol on writhing time and latency, uterine pathology and inflammatory mediators were explored. Isolated uterine smooth muscle was used to evaluate the direct effect of paeonol on uterine contraction.

KEY RESULTS

The oral administration of paeonol reduced dysmenorrhea pain and PGE2 and TNF-α expression in the uterine tissues of mice, and paeonol was found to be distributed in lesions of the uterus. Paeonol almost completely inhibited oxytocin-, high potassium- and Ca²⁺-induced contractions in isolated uteri. Antagonists of CB2R (AM630) and the MAPK pathway (U0126), but not of CB1R (AM251), reversed the inhibitory effect of paeonol on uterine contraction. Paeonol significantly blocked L-type Ca²⁺ channels and calcium influx in uterine smooth muscle cells via CB2R. Molecular docking results showed that paeonol fits well with the binding site of CB2R.

CONCLUSIONS AND IMPLICATIONS

Paeonol partially acts through CB2R to restrain calcium influx and uterine contraction to alleviate dysmenorrhea in mice. These results suggest that paeonol has therapeutic potential for the treatment of dysmenorrhea.

Effects of Intermittent and Continuous Oxytocin Exposure on Myometrial Contractile Activity in Term-Pregnant Rats In Vitro

Continuous oxytocin exposure to augment labor contractions may cause receptor desensitization and further reduce the uterine response to oxytocin, resulting in an increased risk of uterine atony. This study aimed to investigate and compare the uterine response to continuous and intermittent oxytocin stimulation. We hypothesized that intermittent brief episodes of oxytocin separated by recovery periods rather than continuous oxytocin application improves subsequent uterine contractions. Myometrial strips were isolated from term-pregnant rats (22 days of gestation; n = 11), mounted in tissue bath chambers, and exposed to continuous oxytocin (5 nM) for 2 h or 6 repeated episodes of 10-min oxytocin exposure (5 nM) separated by 10 min of recovery period in Krebs solution. Contractile parameters (force amplitude, frequency, and integral force) significantly decreased during continuous oxytocin exposure compared with control (n = 11; P < 0.01). Interestingly, myometrial contractility significantly increased during subsequent short intermittent oxytocin exposure which was sustained for 6 h compared with control or continuous exposure (n = 11; P < 0.01). Brief intermittent oxytocin stimulations resulted in better uterine response and improved contractile force than continuous exposure, which may be attributed to attenuation of receptor desensitization or recovery of oxytocin receptor function following intermittent exposure. These findings would help maintain adequate strong contractions to avoid postpartum bleeding.

Mercury affects uterine myogenic activity even without producing any apparent toxicity in rats: Involvement of calcium-signaling cascades

BACKGROUND

Mercury is an established environmental toxicant reported to cause reproductive disorders in women, however, its direct action on myometrial activity is yet to be understood. Earlier we have reported the underlying mechanism of mercury-induced myometrial contractions following in vitro exposure; however, no such information on the effect of mercury on myometrial activity following in vivo exposure is available, therefore, the present study was undertaken.

OBJECTIVE

Present study was designed to evaluate the effect of mercury on myometrial activity following in vivo exposure of rats and unravel the possible underlying mechanism.

METHODS

Female Wistar rats were orally exposed to mercury (5, 50 and 500 μg/L in drinking water) for 28 days to investigate the toxicodynamics of mercuric chloride (HgCl₂)-induced alterations in myometrial activity. Response of the isolated myometrial strips to different spasmogens was recorded using polyphysiograph. Blood and uterine calcium, mercury, iron and zinc levels were estimated by atomic absorption spectrophotometry. Blood biochemicals and serum hormonal profiles (estradiol, progesterone) were also determined.

RESULTS

No systemic toxicity of mercury was observed in any of the treatment groups (5, 50 and 500 μg/L) in terms of alterations in body weight, organ weights, blood biochemical parameters including hormonal profile. Interestingly, mercury at 5 μg/L concentration significantly increased the receptor-dependent (PGF_2α-induced) and receptor-independent (CaCl₂-induced and high K⁺-depolarizing solution-induced) myometrial contractions and it was coupled with corresponding increase in the uterine calcium levels. However, mercury at higher dose levels (50 and 500 μg/L) did not significantly alter the myometrial response.

CONCLUSION

Our results evidently suggest that mercury at low level (5 μg/L) produced detrimental effect on myometrial activity by altering calcium entry into the smooth muscle and/or the release of calcium from intracellular stores without causing any apparent systemic toxicity in rats.

In utero hypoxia altered Ang II-induced contraction via PKCβ in fetal cerebral arteries

Cerebral circulation is important in fetal brain development, and angiotensin II (Ang II) plays vital roles in regulation of adult cerebral circulation. However, functions of Ang II in fetal cerebral vasculature and influences of in utero hypoxia on Ang II-mediated fetal cerebral vascular responses are largely unknown. This study investigated the effects and mechanisms of in utero hypoxia on fetal middle cerebral arteries (MCA) via Ang II. Near-term ovine fetuses were exposed to in utero hypoxia, and fetal MCA responses to Ang II were tested for vascular tension, calcium transient, and molecular analysis. Ang II caused significant dose-dependent contraction in control fetal MCA. Ang II-induced MCA constriction was decreased significantly in hypoxic fetuses. Neither losartan (AT1R antagonist, 10-5 mol/L) nor PD123,319 (AT2R antagonist, 10-5 mol/L) altered Ang II-mediated contraction in fetal MCA. Phenylephrine-mediated constriction was also significantly weaker in hypoxic fetuses. Bay K8644 caused similar contractions between the two groups. Protein expression of L-type voltage-dependent calcium channels was unchanged. There were no differences in caffeine-mediated vascular tension or calcium transients. Contraction induced by PDBu (PKC agonist) was obviously weaker in hypoxic MCA. Protein expression of PKCβ was reduced in the hypoxic compared with the control, along with no differences in phosphorylation levels. The results showed that fetal MCA was functionally responsive to Ang II near term. Intrauterine hypoxia reduced the vascular agonist-mediated contraction in fetal MCA, probably via decreasing PKCβ and its phosphorylation, which might play protective effects on fetal cerebral circulation against transient hypoxia.

Marantodes pumilum (Blume) Kuntze (Kacip Fatimah) stimulates uterine contraction in rats in post-partum period

ETHNOPHARMACOLOGICAL RELEVANCE

Marantodes pumilum (Blume) Kuntze has traditionally been used to firm the uterus after delivery, however scientific evidences behind this claim is still lacking.

AIMS OF STUDY

To demonstrate Marantodes pumilum leaves aqueous extract (MPE) has an effect on uterine contraction after delivery and to elucidate the molecular mechanisms involved.

METHODS

Day-1 post-delivery female rats were given MPE (100, 250 and 500 mg/kg/day) orally for seven consecutive days. A day after the last treatment (day-8), rats were sacrificed and uteri were harvested and subjected for ex-vivo contraction study using organ bath followed by protein expression and distribution study by Western blotting and immunohistochemistry techniques, respectively. The proteins of interest include calmodulin-CaM, myosin light chain kinase-MLCK, sarcoplasmic reticulum Ca²⁺-ATPase (SERCA), G-protein α and β (Gα and Gβ), inositol-triphosphate 3-kinase (IP3K), oxytocin receptor-OTR, prostaglandin (PGF)2α receptor-PGFR, muscarinic receptor-MAChR and estrogen receptor (ER) isoforms α and β. Levels of estradiol and progesterone in serum were determined by enzyme-linked immunoassay (ELISA).

RESULTS

Ex-vivo contraction study revealed the force of uterine contraction increased with increasing doses of MPE. In addition, expression of CaM, MLCK, SERCA, Gα, Gβ, IP3K, OTR, PGF2α, MAChR, Erα and ERβ in the uterus increased with increasing doses of MPE. Serum analysis indicate that estradiol levels decreased while progesterone levels remained low at day-8 post-partum in rats receiving 250 and 500 mg/kg/day MPE.

CONCLUSIONS

These findings support the claims that MPE help to firm the uterus and pave the way for its use as a uterotonic agent after delivery.

Application of N-Dodecyl l-Peptide to Enhance Serum Stability while Maintaining Inhibitory Effects on Myometrial Contractions Ex Vivo

N-Alkylation and N-acylation of the prostaglandin-F_2α allosteric modulator l-PDC31 were performed to install various alkyl, PEG and isoprenoid groups onto the l-enantiomer of the peptide. Among the different bio-conjugates studied, the N-dodecyl analog reduced prostaglandin-F_2α-induced mouse myometrium contractions ex vivo. Furthermore, N-dodecyl-l-PDC31 exhibited improved stability in a mouse serum assay, likely due to protection from protease degradation by the lipid chain.

Bryophyllum pinnatum enhances the inhibitory effect of atosiban and nifedipine on human myometrial contractility: an in vitro study

BACKGROUND

The herbal medicine Bryophyllum pinnatum has been used as a tocolytic agent in anthroposophic medicine and, recently, in conventional settings alone or as an add-on medication with tocolytic agents such as atosiban or nifedipine. We wanted to compare the inhibitory effect of atosiban and nifedipine on human myometrial contractility in vitro in the absence and in the presence of B. pinnatum press juice (BPJ).

METHODS

Myometrium biopsies were collected during elective Caesarean sections. Myometrial strips were placed under tension into an organ bath and allowed to contract spontaneously. Test substances alone and at concentrations known to moderately affect contractility in this setup, or in combination, were added to the organ bath, and contractility was recorded throughout the experiments. Changes in the strength (measured as area under the curve (AUC) and amplitude) and frequency of contractions after the addition of all test substances were determined. Cell viability assays were performed with the human myometrium hTERT-C3 and PHM1-41 cell lines.

RESULTS

BPJ (2.5 μg/mL), atosiban (0.27 μg/mL), and nifedipine (3 ng/mL), moderately reduced the strength of spontaneous myometrium contractions. When BPJ was added together with atosiban or nifedipine, inhibition of contraction strength was significantly higher than with the tocolytics alone (p = 0.03 and p < 0.001, respectively). In the case of AUC, BPJ plus atosiban promoted a decrease to 48.8 ± 6.3% of initial, whereas BPJ and atosiban alone lowered it to 70.9 ± 4.7% and to 80.9 ± 4.1% of initial, respectively. Also in the case of AUC, BPJ plus nifedipine promoted a decrease to 39.9 ± 4.6% of initial, at the same time that BPJ and nifedipine alone lowered it to 78.9 ± 3.8% and 71.0 ± 3.4% of initial. Amplitude data supported those AUC data. The inhibitory effects of BPJ plus atosiban and of BPJ plus nifedipine on contractions strength were concentration-dependent. None of the test substances, alone or in combination, decreased myometrial cell viability.

CONCLUSIONS

BPJ enhances the inhibitory effect of atosiban and nifedipine on the strength of myometrial contractions, without affecting myometrium tissue or cell viability. The combination treatment of BPJ with atosiban or nifedipine has therapeutic potential.

Tocolytic activity assessment of the methanol leaf extract of Justicia flava Vahl (Acanthaceae) on mouse myometrial contractility and preliminary mass spectrometric determination of secondary metabolites

ETHNOPHARMACOLOGICAL RELEVANCE

The leaves of Justicia flava are traditionally used in the South of Nigeria to prevent preterm births.

AIM OF THE STUDY

In this study, the activity of the methanol leaf extract of J. flava (JF) was investigated on uterine contractility in non-pregnant and pregnant isolated mouse tissues.

MATERIAL AND METHODS

The effects on spontaneous, oxytocin, and KCl-induced contractions were determined. The effects in calcium-free media were also determined. Possible mechanisms of activity were investigated using receptor and channel modulators. Mass spectrometric analysis was additionally performed on the leaf extract to identify secondary metabolites.

RESULTS

JF was observed to inhibit spontaneous, oxytocin and high KCl-induced uterine contractility. JF also inhibited contractions in Ca²⁺-free media. JF was found to exert its inhibitory effect via interaction with inositol triphosphate and ryanodine receptors and also through modulation of K⁺- channels. Lignans and alkaloids were identified with the lignans being the most abundant in JF.

CONCLUSION

JF has been shown to potently inhibit uterine contractions in non-pregnant and pregnant isolated mouse uterus. The inhibitory activity of JF has been shown to occur via blockade of extracellular and intracellular calcium entry and these effects may be due to the lignans identified in - JF. JF has therefore been shown in this study to be a lead plant in the discovery of new drugs with uterine inhibitory activity.

Effect of neonatal exposure to endosulfan on myometrial adaptation during early pregnancy and labor in rats

Proper myometrial adaptation during gestation is crucial for embryo implantation, pregnancy maintenance and parturition. Previously, we reported that neonatal exposure to endosulfan alters uterine development and induces implantation failures. The present work investigates the effects of endosulfan exposure on myometrial differentiation at the pre-implantation period, and myometrial activation during labor. Newborn female rats were s.c. injected with corn oil (vehicle) or 600 μg/kg/day of endosulfan (Endo600) on postnatal days (PND) 1, 3, 5 and 7. On PND90, the rats were mated to evaluate: i) the myometrial differentiation on gestational day 5 (GD5, pre-implantation period), by assessment myometrial histomorphology, smooth muscle cells (SMCs) proliferation, and expression of proteins involved in myometrial adaptation for embryo implantation (steroid receptors, Wnt7a and Hoxa10); ii) the timing of parturition and myometrial activation during labor by determining the uterine expression of contraction-associated genes (oxytocin receptor, OTXR; prostaglandin F₂α receptor, PTGFR and connexin-43, Cx-43). Endosulfan decreased the thickness of both myometrial layers, with a concomitant decrease in the collagen remodeling. Blood vessels relative area in the interstitial connective tissue between muscle layers was also decreased. Endo600 group showed lower myometrial proliferation in association with a downregulation of Wnt7a and Hoxa10. Although in all females labor occurred on GD23, the exposure to endosulfan altered the timing of parturition, by inducing advancement in the initiation of labor. This alteration was associated with an increased uterine expression of OTXR, PTGFR and Cx-43. In conclusion, neonatal exposure to endosulfan produced long-term effects affecting myometrial adaptation during early pregnancy and labor. These alterations could be associated with the aberrant effects of endosulfan on the implantation process and the timing of parturition.

Calcium Channels, Rho-Kinase, Protein Kinase-C, and Phospholipase-C Pathways Mediate Mercury Chloride-Induced Myometrial Contractions in Rats

Adverse effects of mercury on female reproduction are reported; however, its effect on myogenic activity of uterus and mechanism thereof is obscure. Present study was undertaken to unravel the mechanistic pathways of mercuric chloride (HgCl₂)-induced myometrial contraction in rats. Isometric tension in myometrial strips of rats following in vitro exposure to HgCl₂ was recorded using data acquisition system-based physiograph. HgCl₂ produced concentration-dependent (10 nM-100 μM) uterotonic effect which was significantly (p < 0.05) reduced in Ca²⁺-free solution and inhibited in the presence of nifedipine (1 μM), a L-type Ca²⁺ channel blocker, thus suggesting the importance of extracellular Ca²⁺ and its entry through L-type calcium channels in HgCl₂-induced myometrial contractions in rats. Cumulative concentration-response curve of HgCl₂ was significantly (p < 0.05) shifted towards right in the presence of Y-27632 (10 μM), a Rho-kinase inhibitor, suggesting the involvement of Ca²⁺-sensitization pathway in mediating HgCl₂-induced myometrial contraction. HgCl₂-induced myometrial contraction was also significantly (p < 0.05) inhibited in the presence of methoctramine or para-fluoro-hexahydro-siladifenidol, a selective M₂ and M₃ receptor antagonists, respectively, which evidently suggest that mercury also interacts with M₂ and M₃ muscarinic receptors to produce myometrial contractions. U-73122 and GF-109203X, the respective inhibitors of PLC and PKC-dependent pathways, downstream to the receptor activation, also significantly (p < 0.05) attenuated the uterotonic effect of HgCl₂ on rat uterus. Taken together, present study evidently reveals that HgCl₂ interacts with muscarinic receptors and activates calcium signaling cascades involving calcium channels, Rho-kinase, protein kinase-C, and phospholipase-C pathways to exert uterotonic effect in rats. Graphical Abstract Graphical abstract depicting the mechanism of mercury-induced myometrial contraction in rats. M receptor: Muscarinic receptor; PIP2: phospho-inositol bisphosphate; PLC: phospholipase-C; DAG: diacyl glycerol; IP3: inositol triphosphate; IP3R: inositol triphosphate receptor; PKC; protein kinase-C; MLCP: myosin light chain phosphatise; MYPT: myosin phosphatase; SR: sarco-endoplasmic reticulum.

Does nifedipine improve outcomes of embryo transfer?: Interim analysis of a randomized, double blinded, placebo-controlled trial

BACKGROUND

Implantation failure is the main factor affecting the success rate of in vitro fertilization (IVF) procedures. Studies have reported that uterine contractions (UC) at the time of embryo transfer (ET) were inversely related to implantation and pregnancy rate, hence reducing the success of IVF treatments. Various pharmacological agents, with the exception of calcium channel blockers, have been investigated to improve ET outcomes by reducing UC. Thus, a double-blinded randomized, placebo-controlled trial was conducted to determine whether nifedipine, a calcium channel blocker with potent smooth muscle relaxing activity and an excellent safety profile, can improve the outcome of patients undergoing ET treatments.

METHODS

Ninety-three infertile women were recruited into 1 of 2 groups: placebo (n = 47) or nifedipine 20 mg (n = 46). Study participants were admitted 30 minutes prior to ET and given either tablet after their baseline vital signs were recorded. They then underwent ET and were observed for adverse events for another 30 minutes post-ET. Follow up of the participants' outcomes was conducted via electronic medical records. The primary outcomes are implantation and clinical pregnancy rates. Secondary outcomes include any maternal or fetal adverse events, miscarriage, pregnancy, live births, and neonatal outcomes. Resulting data were then analyzed using t test, Pearson chi-square test, and Fisher exact test to compare outcomes between the 2 groups.

RESULTS

No statistical differences in the implantation rate (42.6% vs 39.1%, P = .737, rate ratio 0.868, 95% confidence interval [CI]: 0.379-1.986) and the clinical pregnancy rate (23.4% vs 26.1%, P = .764, rate ratio 1.155, 95% CI: 0.450-2.966) were detected between the placebo and the treatment groups. In addition, no statistical significance between the placebo and the treatment groups for any secondary outcomes were detected.

CONCLUSIONS

This double blinded, randomized, and placebo-controlled trial demonstrated that the single use of 20 mg nifedipine given 30 minutes before embryo transfer did not improve the implantation rate or the clinical pregnancy rate of the infertility treatment. Further studies are required to demonstrate the clinical benefits and risks of nifedipine usage in embryo transfer.

Uterine contractility changes in a perfused swine uterus model induced by local anesthetics procaine, lidocaine, and ropivacaine

Background

Local anesthetics (LAs) are increasingly used as therapeutics due to their multiple molecular effects. They may be potential agents also in gynecology and reproductive medicine. The objective of this study was to investigate the contractility response of the perfused swine uterus to different concentrations of the LAs procaine, lidocaine, and ropivacaine.

Methods and findings

In an extracorporeal perfusion model with fresh swine uteri, effects of administered boli of these three LAs in concentrations of 0.1 mg/mL, 0.5 mg/mL and 1.0 mg/mL on uterine contractility and peristalsis were assessed using an intrauterine double-chip micro-catheter. A dose-dependent increase in intrauterine pressure (IUP) in the isthmus and corpus uteri was observed after the administration of the ester-LA procaine 0.1, 0.5, and 1.0%, which was not seen with lower concentrations, or buffer solution. An increase-decrease curve was found after increasing concentrations of the amide-LA lidocaine and ropivacaine, with an IUP plateau with 0.1 and 0.5%, and a decrease with 1% (p<0.01). All reactions were seen in both the isthmus and corpus uteri. The difference of the contractility pattern between ester- and amide-LA at 1% concentration was significant.

Conclusion

LAs dose-dependently modulate contractility in non-pregnant swine uteri. The amid-LAs lidocaine and ropivacaine reduce contractility in higher concentrations and may be used as therapeutics in disorders with increased uterine contractility, as dysmenorrhoea, endometriosis, and infertility. The multiple molecular effects of LAs may explain these effects. This in-vitro pilot study in vitro provides initial data for designing further studies to transfer the results onto humans.

Do chlorinated insecticides (aldrin and DDT) or products of their transformations (dieldrin and DDE) impair signal transfer from regulators (oxytocin and relaxin) of bovine myometrium motility in vitro?

Aldrin, dieldrin, and DDT are chlorinated insecticides that are unintentionally widespread in the environment. It was previously shown that all of the aforementioned compounds increased secretion of ovarian oxytocin (OT), which is a potent uterotonic agent. However, only DDT and its metabolite (DDE) promoted, while aldrin and dieldrin inhibited basal and OT-stimulated myometrial contractions in cows. Therefore, the aim of this study was to determine the effect of these treatments on the reception and further transmission of the OT-signal for myometrial contractions and on the levels of contractile-associated integral proteins (caveolin; CAV) and gap junction proteins (GAPs). Moreover, their effect on reception of signal for the relaxation of myometrium was also studied. Myometrial strips or cells from non-pregnant (8-12 days of oestrous cycle) or late pregnant (5-8 months) cows were incubated with the studied compounds at environmentally relevant dose (10 ng/ml), which was chosen according to the previous studies. DDT and DDE increased the CAV protein level, while dieldrin decreased the GAPs level. None of the studied compounds affected mRNA expression of the OT receptor and expression of the second messengers (DAG, IP3, PKC, MLCK). Oppositely, DDE and dieldrin decreased mRNA expression of the relaxin (RLX) receptor. Changes in the amount of contractile-associated integral proteins may be involved in the molecular mechanism underlying the adverse effects of the studied insecticides on myometrial motility. Admittedly, none of the studied compounds impaired the reception or further intracellular transmission of the OT signal to promote contractions during the oestrous cycle, while they showed potential to impair the transmission the signal between cells as well as to diminish the effects of one of the primary inhibitor (RLX) of myometrial contractions during gestation.

The expected labor progression after labor augmentation with oxytocin: A retrospective cohort study

OBJECTIVE

To describe labor progression patterns with oxytocin for augmentation in women who achieve vaginal delivery; and to determine how long one should wait with effective uterine contraction before labor arrest can be diagnosed.

DESIGN

Population-based retrospective cohort study.

POPULATION

The final sample involved 8,988 women with singleton gestation, term live birth, vertex presentation, no previous cesarean section, vaginal delivery, and neonatal Apgar score at 5 minutes at 7 or higher, and complete information on oxytocin augmentation in 2005-2007.

METHODS

Linear interpolation was used from the vaginal exam records for each woman to estimate the cervical dilation when oxytocin was started and the highest dose was first reached by parity. We used survival methods to estimate quartiles of the traverse time distributions of cervical dilation.

MAIN OUTCOME MEASURES

Duration of labor under oxytocin augmentation.

RESULTS

When oxytocin was just started, it took a long time to observe cervical dilation. The 50th(95th) centiles of the time interval from 4 to 5 cm, 5 to 6 cm, and 6 to 10 cm dilation were 2.9(8.8) hr, 1.7(5.8) hr, and 2.1(6.0) hr in nulliparas; and 3.1(10.1) hr, 1.9(8.0) hr, and 1.7(6.2) hr in multiparas. After effective uterine contractions were achieved under oxytocin, labor progressed much faster. The corresponding values were 0.7(2.4)hr, 0.5(1.5)hr, and 0.5(1.5)hr in nulliparas; and 0.6(1.9)hr, 0.4(1.1)hr, and 0.4(0.9)hr in multiparas. Low- and high-dose oxytocin regimens had similar effects on labor.

CONCLUSION

When oxytocin is just started for labor augmentation in early first stage, it may take up to 10 hours for the cervix to dilate by 1 cm. Once effective uterine contractions are achieved and the cervix is dilated more than 5 cm, cervical dilation to the next centimeter occurs within 2 hrs in both nulliparas and multiparas in 95% of the cases. High- and low-dose oxytocin had a similar impact on labor progression in augmented labor.

Prostaglandin D2 evokes potent uterine contraction via the F prostanoid receptor in postpartum rats

Prostaglandin (PG) D₂, a prostanoid known to have hypotensive effect, can evoke increased in vitro prepartum myometrial contraction resulting from up-regulation of the F prostanoid (FP) receptor. The present study further determined postpartum rat uterine responses to PGD₂ to evaluate the possibility of the prostanoid becoming a therapeutic for postpartum uterine atony, a major cause of postpartum hemorrhage that can lead to maternal morbidity. In vitro and in vivo postpartum uterine responses to PGD₂ were determined and compared to those of prepartum rats. Here we show that in postpartum myometrial strips PGD₂ did evoke a contraction sensitive to FP receptor antagonism. Interestingly, this response was not only to a greater extent than that of prepartum rats, but also comparable with the contraction obtained with PGF_2α, a therapeutic for postpartum uterine atony but contradicted in conditions including hypertension. Indeed, PGD₂ was also found to cause increases of basal uterine contraction under in vivo conditions. Western blots revealed that the expression of FP receptors in postpartum myometrium was higher than that of prepartum rats. Moreover, we noted that the amount of PGD₂ produced in postpartum uteri, although lower than that of prepartum rats, was increased compared to non-pregnant conditions. These results thus demonstrate that due to a further up-regulation or high expression of myometrial FP receptors, PGD₂ can evoke potent uterine contraction postpartum, and hence the prostanoid, which is naturally synthesized in uterine tissues, could be a potential therapeutic for postpartum uterine atony, especially in settings, such as hypertension.

Extracts of compound Muniziqi granule suppressed uterus contraction and ameliorated oxytocin-induced primary dysmenorrhea

ETHNOPHARMACOLOGICAL RELEVANCE

Compound Muniziqi granule (CMG) is usually used as a traditional Uighur medicine to treat acne, chloasma, skin inflammation, primary dysmenorrhea (PDM), and menopausal syndrome. However, there are no sufficient data to support the clinic uses of CMG in PDM.

AIM OF THE STUDY

This work aims to examine the effect of CMG as a treatment for PDM and reveal its possible therapeutic mechanism.

MATERIALS AND METHODS

In vivo and in vitro mouse PDM models were utilized in this study. The mouse uterine contraction was induced by oxytocin after progynova or estradiol benzoate pretreatment. CMG, alkaloid extracts from seeds of Peganum harmala (AEP), and 10% and 95% ethanol extracts from seeds of Nigella glandulifera (EEN10 and EEN95) were given to mice in three doses by gavage. The writhing times within 30 min after oxytocin treatment were recorded to evaluate the analgesic effect, and the glutathione peroxidase (GSH-Px), malondialdehyde (MDA), 6-keto-prostaglandin F_1α (6-k-PGF_1α), prostaglandin F_2α (PGF_2α), thromboxane B2 (TXB₂), and nitric oxide (NO) levels in uterine tissues and PGF_2α and MDA in serum were determined. The effects (contractile curve) of CMG, AEP, EEN10, and EEN95 on uterus contraction induced by oxytocin in isolated mouse uterus were recorded.

RESULTS

In contrast to the control group, CMG, AEP, N10, and N95 could display analgesic activities dose dependently by reducing the writhing response of the PDM model mice. CMG, AEP, EEN10, and EEN95 could also remarkably decrease the level of PGF_2α, 6-k-PGF_1α, TXB₂, NO and MDA in uterine tissues and PGF_2α and MDA in serum, whereas the activity of GSH-Px in uterine tissues was increased. Furthermore, CMG, AEP, EEN10, and EEN95 could significantly inhibit the frequency and amplitude of isolated uterus induced by oxytocin in a concentration-dependent manner.

CONCLUSIONS

CMG exhibited a significant protective effect on experimental PDM. The mechanisms are probably associated with abating lipid peroxidation and over-inflammatory reaction, and alleviating the contraction of isolated mouse uterus. The seeds of P. harmala and N. glandulifera in the CMG may play an important role in exerting protective effects on PDM. This study provides pre-clinic proof to the use of CMG in clinical practice of PDM.

Role of the serotonergic pathway in uterotonic activity of Ananas comosus (L.) Merr. - An in vitro and in vivo study

BACKGROUND

Ananas comosus (L.) Merr. has been used as a traditional medicine in inducing abortion in many countries. Our previous in vitro experiments showed that the aqueous fraction (F4) of A. comosus extract stimulated the rat and human uterine contractions.

PURPOSE

The aim of this study was to identify the bioactive compound and further investigate the molecular mechanism of F4 induced contraction and the in vivo uterotonic effect of F4.

MATERIALS AND METHODS

Organ bath studies were employed to compare the stimulatory effect of F4 in non and late pregnant uterine tissue followed by isolation of protein from late pregnant uterine tissue for the western blot analysis. The PhysioTel transmitter was implanted in pregnant SD rats to measure the changes in intrauterine pressure (IUP). Analyses of the crude extract and active principle in F4 was performed using LC-HRMS.

RESULTS

Ripe F4 in a similar manner as serotonin produced a greater stimulatory response in late pregnant than non-pregnant uterine tissue without significant change in potency; ripe F4 also increased ERK phosphorylation which eventually led to a significant increase of the final product, MMP-13. In pregnant rats (E18), oral ripe F4 (1.5 g.100 g^-1 body weight) and ergometrine (1 mg) did not stimulate the uterine contraction probably due to the low level of estradiol and as a consequence low 5-HT receptors at the time of administration. In contrast, in postpartum rats, oral administration of F4 and ergometrine produced a significant increase in maximal IUP to 4.3 and 4.9 folds of basal IUP respectively. Contrary to the folklore use, unripe F4 did not stimulate the uterine activity during pregnancy and postpartum. Bioassay guided fractionation identified serotonin as a major bioactive compound in ripe F4.

CONCLUSIONS

Our data clearly indicate that the uterotonic effect of ripe F4 is mediated via the serotonergic pathway and suggest that serotonin rich diet may increase the peripheral serotonin and implicate in diverse physiological functions, including uterine motility.

The effects of apelin on myometrium contractions in pregnant rats

Apelin, which is a new hormone, is secreted especially in the brain by hypothalamus as well as by many other organs like the stomach, fat tissue, and the heart. For apelin, whose possible effects on many bodily functions like the endocrine system, cardiovascular system and metabolic activities are still under investigation, the reproductive system is also an important target area. The purpose of the present study was to investigate the effects of plasma apelin levels in rats that were in diestrus, pregnancy and lactation periods, and to examine its possible effects on myometrium contractions of pregnant rats and non-pregnant rats that were in diestrus period.  The plasma apelin concentrations in female adult Wistar rats were determined with the ELISA method in the diestrus period, and on the 12th, 18th, and 21st days of the pregnancy, and on the 2nd and 10th days of lactation (n=7 for each group). In addition, the effect of apelin at 0.01, 0.1, 1 and 10 μM doses on isometric contractions in the rat uterus on the 21st day of pregnancy and in diestrus period was tested by using isolated organ bath. This protocol was repeated under conditions that were pre-treated with protein kinase C inhibitor in calcium-free medium, and the possible effect of apelin on contractions and the mechanisms that might mediate this effect were investigated. When plasma apelin levels were compared with the rats in diestrus period, the apelin concentrations in the 21-day pregnancy group were high at a significant level (p&lt;0.05); and low at a significant level in the 2-day lactation group (p&lt;0.05). In myometrium contraction trials, it was observed that apelin induced the contractions. Apelin increased the frequency of the myometrium contractions at a significant level when applied at 1 μM and 10 μM concentrations (p&lt;0.05 and p&lt;0.001). Only after the apelin application at 10 μM concentration did the amplitude of the contractions increase at a significant level (p&lt;0.01). In the myometrium of the rats that were on the 21st day of pregnancy, the frequency of the contractions was statistically significant at 0.1 μM, 1 μM and 10 μM doses (p&lt;0.01). In addition, the amplitude of the contractions increased at a statistically significant level at 1 μM and 10 μM dose application (p&lt;0.05 and p&lt;0.01, respectively). The apelin application induced the contractions in calcium-free medium. When apelin was applied after the pre-application with protein kinase C inhibitor, no contractions were observed. The present study showed that apelin levels were increased at the end of pregnancy in rats, and the hormone induced the uterus contractions. This effect does not occur with protein kinase C inhibitor and in calcium-free medium, which shows that protein kinase C pathway might play a role in these mechanism.  These findings show that apelin might be an endogenous peptide that plays a role on uterine contractions at birth in rats.

Acute tocolysis for uterine tachysystole or suspected fetal distress

BACKGROUND

Uterine tachysystole (more than 5 contractions per 10 minutes in 2 consecutive intervals) is common during labour, particularly with use of labour-stimulating agents. Tachysystole may reduce fetal oxygenation by interrupting maternal blood flow to the placenta during contractions. Reducing uterine contractions may improve placental blood flow, improving fetal oxygenation. This review aimed to evaluate the use of tocolytics to reduce or stop uterine contractions for improvement of the condition of the fetus in utero. This new review supersedes an earlier Cochrane Review on the same topic.

OBJECTIVES

To assess the effects of the use of acute tocolysis during labour for uterine tachysystole or suspected fetal distress, or both, on fetal, maternal and neonatal outcomes.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) (2 February 2018), and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) evaluating acute tocolysis for uterine tachysystole, intrapartum fetal distress, or both.

DATA COLLECTION AND ANALYSIS

We used standard methods expected by Cochrane.

MAIN RESULTS

We included eight studies (734 women), conducted in hospital settings, predominantly in high-income countries (USA, Austria, Uruguay). Two trials were conducted in upper and lower middle-income countries (South Africa, Sri Lanka). The hospital facilities all had the capacity to perform caesarean section. Overall, the studies had a low risk of bias, except for methods to maintain blinding. All of the trials used a selective beta₂ (ß₂)-adrenergic agonist in one arm, however the drug used varied, as did the comparator. Limited information was available on maternal outcomes.Selective ß₂-adrenergic agonist versus no tocolytic agent, whilst awaiting emergency deliveryThere were two stillbirths, both in the no tocolytic control group (risk ratio (RR) 0.23, 95% confidence interval (CI) 0.01 to 4.55; 2 studies, 57 women; low-quality evidence). One had gross hydrocephalus and the second occurred with vaginal delivery after waiting 55 minutes for caesarean section. The decision for caesarean section delivery was an inclusion criterion in both studies so we could not assess this as an outcome under this comparison. Abnormal fetal heart trace is probably lower with tocolytic treatment (RR 0.28, 95% CI 0.08 to 0.95; 2 studies, 43 women; moderate-quality evidence). The effects on the number of babies with Apgar score below seven were uncertain (low-quality evidence).Intravenous (IV) atosiban versus IV hexoprenaline (1 study, 26 women) One infant in the hexoprenaline group required > 24 hours in the neonatal intensive care unit (NICU) following a forceps delivery (RR 0.33, 95% CI 0.01 to 7.50; low-quality evidence). There were no fetal or neonatal mortalities and no Apgar scores below seven. There was one caesarean delivery in the IV hexoprenaline group (RR 0.33, 95% CI 0.01 to 7.50; low-quality evidence), and one case of abnormal fetal heart score in the atosiban group (RR 3.00, 95% CI 0.13 to 67.51; very low-quality evidence).IV fenoterol bromhydrate versus emergency delivery (1 study, 390 women) No data were reported for perinatal death, severe morbidity or fetal or neonatal mortality. IV fenoterol probably increases the risk of caesarean delivery (RR 1.12, 95% CI 1.04 to 1.22; moderate-quality evidence). Fenoterol may have little or no effect on the risk of Apgar scores below seven (RR 1.28, 95% CI 0.35 to 4.68; low-quality evidence).IV hexoprenaline versus no tocolytic agent, whilst awaiting emergency delivery (1 study, 37 women) No data were reported for perinatal death or severe morbidity. There were two fetal deaths in the no tocolytic control group (RR 0.23, 95% CI 0.01 to 4.55; low-quality evidence). The rate of caesarean delivery was not reported. There were two babies with Apgar scores below seven in the control group and none in the hexoprenaline group (RR 0.24, 95% CI 0.01 to 4.57; 35 women; low-quality evidence).Subcutaneous terbutaline versus IV magnesium sulphate (1 study, 46 women)No data were reported for perinatal death, severe morbidity or fetal or neonatal mortality. The decision for caesarean section was an inclusion criterion, so we could not assess this. The effects on abnormal fetal heart trace are uncertain (very low-quality evidence).Subcutaneous terbutaline with continuation of oxytocic infusion versus cessation of oxytocic infusion without tocolytic agent (1 study, 28 women) No data were reported for perinatal death, severe morbidity or fetal or neonatal mortality. There may be little or no difference in the rates of caesarean delivery in the subcutaneous terbutaline (8/15) and control groups (4/13) (RR 1.73, 95% CI 0.68 to 4.45; low-quality evidence). There were no cases of Apgar scores below seven or abnormal fetal heart trace.Subcutaneous terbutaline versus no tocolytic agent, whilst awaiting emergency delivery (1 study, 20 women) No data were reported for perinatal death or severe morbidity. There were no fetal or neonatal mortalities. The decision for caesarean section was an inclusion criterion, so we could not assess this. There were two babies with Apgar scores below seven in the control group and none in the terbutaline group (RR 0.17, 95% CI 0.01 to 3.08; low-quality evidence).IV terbutaline versus IV nitroglycerin (1 study, 110 women)No data were reported for perinatal death or severe morbidity or fetal or neonatal mortality. There may be little or no difference in the rates of caesarean delivery between the IV terbutaline (30/57) and control groups (29/53) (RR 0.96, 95% CI 0.68 to 1.36; low-quality evidence). There were no cases of Apgar scores below seven.

AUTHORS' CONCLUSIONS

There is insufficient evidence to determine the effects of tocolytics for uterine tachysystole or suspected fetal distress during labour. The clinical significance for some of the improvements in measures of fetal well-being with tocolytics is unclear. The sample sizes were too small to detect effects on neonatal morbidity, mortality or serious adverse effects. The majority of studies are from high-income countries in facilities with access to caesarean section, which may limit the generalisability of the results to lower-resource settings, or settings where caesarean section is not available.Further well-designed and adequately powered RCTs are required to evaluate clinically relevant indicators of maternal and neonatal morbidity and mortality.

Glyphosate affects the secretion of regulators of uterine contractions in cows while it does not directly impair the motoric function of myometrium in vitro

The effects of pure glyphosate and its most popular product (brand name: Roundup) on the secretion of hormones involved in the regulation of myometrial contractions as well as their direct effects on myometrial contractions were examined. Myometrial strips as well as uterine and ovarian cells were taken from cows during the oestrous cycle and they were treated with both compounds at concentrations from their environmental range. Glyphosate stimulated the secretion of oestradiol from granulosa cells while both herbicides increased and decreased oxytocin (OT) and progesterone secretion from luteal cells respectively. However only Roundup stimulated mRNA expression of the precursor of OT. Both compounds decreased the secretion of prostaglandins from endometrial cells while they exerted no effect on the basal and OT-stimulated force of myometrial contractions. The studied herbicides did not directly impair the motoric function of the myometrium. However our data indicate the potential of these compounds to disturb the secretory functions of the ovaries and uterus which can lead to the deregulation of uterine contractions and to the impairment of fertilisation or to difficulties in the maintenance of gestation.

How do Spondias mombin L (Anacardiaceae) leaves extract increase uterine smooth muscle contractions to facilitate child birth in parturient women?

Background

Spondias mombin L. (Anacardiaceae) leaves were used in Togolese folk to treat dystocia, expel placenta and manage post-partum hemorrhage during child birth.

Objectives

This study aimed to establish how the extract of S. mombin leaves increase uterine smooth muscle contractions relevant to its traditional use to facilitate child birth.

Methods

Tests were performed on uterus muscle strips from Sprague-Dawley rats. Central portion of uterine horns were dissected, cleaned of surrounding fat and loose connective tissue, and cut longitudinally into strips which were placed in the organ bath for isometric tension record in presence of different substances.

Results

S. mombin leaves extract increased uterine spontaneous contractions. This effect was reduced by indomethacin (2 × 10-6 M), yohimbine (2 × 10-6 M) and 2-aminoethoxydiphenyl borate (2-APB) (5 × 10-5 M), but not by atropine (3.45 × 10-8 M) and cholesterol (2.5 mg/ml).

Conclusion

The pharmacological justification for the traditional use of S. mombin leaves to treat dystocia and expel placenta was that its hydro-ethanolic extract induced prostaglandins release, α2-adrenoceptors stimulation, calcium release from internal stores and lifted inhibitory effect of cholesterol on uterine contractions in order to increase uterine smooth muscle contractions.

Selenoprotein N Was Required for the Regulation of Selenium on the Uterine Smooth Muscle Contraction in Mice

Selenium (Se) is an essential micronutrient affecting various aspects of health. The balance of the Se concentration has an important protective and promoter effect on physiological function in inducing muscular disorders in smooth muscle. Selenoprotein N (SelN) is closely related to Ca²⁺ release. The present study aimed to determine the effects and mechanism of action of dietary Se on uterine smooth muscle contraction via SelN using a mouse model. Quantitative polymerase chain reaction (qPCR) analysis was performed to detect mRNA levels. Western blotting was performed to detect protein levels. The results of the immunohistochemical analysis showed that Se had an effect on the uterine smooth muscle. The Se-supplement increased the release of Ca²⁺, Ca²⁺-calmodulin (CaM) expression, myosin light chain kinase (MLCK) expression, and myosin light chain (MLC) phosphorylation but did not affect ROCK and RhoA in uterine smooth muscle. Furthermore, the lack of Se showed an opposite impact. The effects of Se regulation were closely related to SelN. The interference of mouse SelN was performed on the uterine smooth muscle cell. Additionally, the results displayed the regulation of Se on the release of Ca²⁺, CaM expression, MLCK expression, and MLC phosphorylation were significant inhibited, and there was no effect on ROCK and RhoA. In conclusion, Se played an important role in regulating the process of contraction in uterine smooth muscle with SelN.

Chlorinated insecticides (toxaphene and endrin) affect oxytocin, testosterone, oestradiol and prostaglandin secretion from ovarian and uterine cells as well as myometrial contractions in cow in vitro

We examined the direct effects of toxaphene and endrin, chlorinated insecticides that are widespread in the environment, on myometrial contractions and on the secretion of hormones involved in regulating these contractions. Granulosa, luteal, endometrial and myometrial cells, and myometrial strips from non-pregnant cows were incubated with both insecticides at environmentally relevant doses. Toxaphene inhibited and endrin stimulated the secretion of testosterone and oestradiol from granulosa cells. Toxaphene also inhibited and endrin stimulated the expression of the mRNA encoding the precursor of oxytocin (OT), as well OT secretion in luteal cell cultures. Moreover, endrin increased OT secretion from granulosa cells. Neither insecticide exerted an effect on progesterone secretion from luteal cells. Only toxaphene decreased the secretion of prostaglandins (PGF2 and PGE2) from endometrial cells. Meanwhile, only endrin decreased basal myometrial contractions, which was accompanied by inhibition of PGF2 secretion from the myometrium. Both endrin and toxaphene also decreased the force of the OT-stimulated myometrial contractions, whereas only toxaphene inhibited the stimulatory effect of OT on the force of myometrial contractions. In contrast to endrin, toxaphene decreased synthesis and secretion of one of the primary stimulators of myometrial contractions (OT) and indirectly inhibited OT signal reception in the myometrium by reducing E2 secretion. Both insecticides decreased OT-stimulated myometrial contractions; therefore, they may inhibit further transmission of the OT signal. Moreover, endrin inhibited basal myometrial contractions, potentially resulting from reduced PGF2 secretion from the myometrium. Our data indicate the potential of these insecticides to disturb the course of the oestrous cycle or fertilisation.

EFFECT OF PEPTIDOGLYCANE OF STAPHYLOCOCCUS AUREUS CELL WALL ON THE MECHANISM OF REGULATION OF CONTRACTILE ACTIVITY OF RAT MYOMETRIUM BY ADENYLATE CYCLASE SYSTEM

The revue deals with the role of each component of adenylate cyclase regulatory system in the rat myometrial contractile activity modulation by the peptidoglycane of Staphylococcus aureus. Noradrenalin and salbutamol were used to investigate peptidoglycane impact on the myometrial β-adrenergic receptors. It was shown that inhibited by these substances myometrial contractility increased to the initial level after peptidoglycane application. The same effect we observed under the cAMP level elevation by forscolin. Peptidoglycan’ s ability to strengthen contractions was inhibited by the 8-brom-cAMP and papaverine application. Stimulation of Gs-protein by the cholera toxin didn’t influence on the peptidoglycane effect while the blocking of Gi/o-protein by the pertussis toxin caused stopping it’s manifestation. We concluded that the modulating effect of peptidoglycane implemented via Gi/o-protein activation, which causes adenilatcyclase desensitization.

Retosiban Prevents Stretch-Induced Human Myometrial Contractility and Delays Labor in Cynomolgus Monkeys

Context

Stretch of the myometrium promotes its contractility and is believed to contribute to the control of parturition at term and to the increased risk of preterm birth in multiple pregnancies.

Objective

To determine the effects of the putative oxytocin receptor (OTR) inverse agonist retosiban on (1) the contractility of human myometrial explants and (2) labor in nonhuman primates.

Design

Human myometrial biopsies were obtained at planned term cesarean, and explants were exposed to stretch in the presence and absence of a range of drugs, including retosiban. The in vivo effects of retosiban were determined in cynomolgus monkeys.

Results

Prolonged mechanical stretch promoted myometrial extracellular signal-regulated kinase (ERK)1/2 phosphorylation. Moreover, stretch-induced stimulation of myometrial contractility was prevented by ERK1/2 inhibitors. Retosiban (10 nM) prevented stretch-induced stimulation of myometrial contractility and phosphorylation of ERK1/2. Moreover, the inhibitory effect of retosiban on stretch-induced ERK1/2 phosphorylation was prevented by coincubation with a 100-fold excess of a peptide OTR antagonist, atosiban. Compared with vehicle-treated cynomolgus monkeys, treatment with oral retosiban (100 to 150 days of gestational age) reduced the risk of spontaneous delivery (hazard ratio = 0.07, 95% confidence interval 0.01 to 0.60, P = 0.015).

Conclusions

The OTR acts as a uterine mechanosensor, whereby stretch increases myometrial contractility through agonist-free activation of the OTR. Retosiban prevents this through inverse agonism of the OTR and, in vivo, reduced the likelihood of spontaneous labor in nonhuman primates. We hypothesize that retosiban may be an effective preventative treatment of preterm birth in high-risk multiple pregnancies, an area of unmet clinical need.

Safety of Cimetidine in Obstetric Patients

Cimetidine has been suggested as a new approach to the prevention of the acid pulmonary aspiration syndrome in obstetric anaesthesia. In 20 patients in labour cimetidine 200 mg intravenously did not prolong labour or alter the pattern or strength of uterine contractions. The fetal heart rate did not show any alteration in rate or pattern and it was confirmed that cimetidine crosses the placenta. These findings suggest that further studies of cimetidine in obstetric patients would be safe.

Monosodium glutamate impairs the contraction of uterine visceral smooth muscle ex vivo of rat through augmentation of acetylcholine and nitric oxide signaling pathways

The aim of the study was to examine the toxic effects of Monosodium glutamate (MSG), an extensively used food additive, on the contraction of uterine visceral smooth muscle (UVSM) in rat and to elucidate the probable neurocrine mechanism involved in it. MSG produced significant potentiation of the force and inhibition of frequency of uterus recorded ex vivo in chronic MSG exposure and in single dose acute experiments. MSG also produced significant potentiation of force of acetylcholine induced contraction and no alterations in atropine induced contraction of uterus. Further, MSG produced significant increase in force and frequency of contraction of neostigmine incubated uterus. We have found significant potentiation of the post pause force of contraction of uterus when MSG was applied in adrenaline incubated uterus. MSG also produced significant decrease in frequency of contraction of sodium nitroprusside incubated uterus; increase in frequency of N-ω-Nitro-l-Arginine Methyl Ester incubated uterus and no significant changes in frequency of contraction of methylene blue incubated uterus. These results indicate that MSG potentiates the force of contraction of UVSM predominantly by augmenting the activity of cholinergic intrinsic efferents and inhibits the frequency of contraction probably by augmenting the activity of nitrergic efferents. In conclusion, MSG potentiates the force and inhibits the frequency of contraction of UVSM, and the MSG induced effect is probably mediated through the augmentation of acetylcholine and nitric oxide signaling pathways.

Hemostasis and uterine contraction promoting effect of the extract from drugs in the Zi-Yin-Tiao-Jing granule, a traditional Chinese compound preparation

ETHNOPHARMACOLOGICAL RELEVANCE

Zi-Yin-Tiao-Jing granule (ZG) is a traditional Chinese medicine compound preparation for perimenopausal dysfunctional uterine bleeding. It is made from 9 Chinese crude drugs based on a modified traditional Chinese prescription recorded in Fu Qingzhu Nvke as Guben Zhibeng Tang.

AIM OF THE STUDY

This study aimed to investigate the hemostasis and uterine contraction promoting effect of quality controlled ZG extract on animals as a preclinical study.

MATERIALS AND METHODS

ZG extract was quality controlled by determining the contents of asperosaponin Ⅵ and tetrahydroxystilbene glucoside (TSG) with high-performance liquid chromatography (HPLC) and the contents of total tannins, total saponins and total flavonoids with ultraviolet spectrophotometry (UV). Bleeding time, clotting time, prothrombin time (PT), activated partial thromboplastin time (APTT) and fibrinogen (FIB) content were assayed to test the hemostasis effect of ZG extract on sixty healthy female Kunming mice. In addition, ten healthy female Sprague-Dawley rats were used to test the effect of ZG extract on uterine contractions in vitro with the BL-420 Biological Function Experiment System.

RESULTS

The ZG extract contained 0.81mgg^-1 asperosaponin Ⅵ, 0.15mgg^-1 TSG, 1.98mgg^-1 total tannins, 1.83mgg^-1 total saponins, and 4.09mgg^-1 total flavonoids. Compared with placebo, the ZG extract shortened the bleeding time at a dosage of 1.2gkg^-1 and 2.4gkg^-1, and shortened the clotting time at 0.6gkg^-1, 1.2gkg^-1 and 2.4gkg^-1 in mice (P < 0.01). It also decurtated the APTT at a dosage of 0.6gkg^-1 (P < 0.05) and raised the content of FIB in the plasma at a dosage of 2.4gkg^-1 (P < 0.05). However, the PT showed no changes after the administration of ZG extract (P > 0.05). In addition, ZG extract at the doses of 1.8mgmL^-1, 3.6mgmL^-1, and 5.4mgmL^-1 increased the amplitude and motoricity of uterine contractions of rats (P < 0.05 or P < 0.01) but maintained the frequency as unchanged.

CONCLUSIONS

The ZG extract was quality controllable by assaying for asperosaponin Ⅵ, TSG, total tannins, total saponins and total flavonoids. It could promote the hemostasis of mice in vivo, as well as the uterine contractions of rats in vitro. Therefore, it may be a promising preparation for clinical treatment of perimenopausal dysfunctional uterine bleeding.