Effects of combined use of sildenafil citrate (Viagra) and 17beta-estradiol on ovine coronary and uterine hemodynamics

The Effect of Vaginal Sildenafil on The Outcome of Assisted Reproductive Technology Cycles in Patients with Repeated Implantation Failures: A Randomized Placebo-Controlled Trial

Background

The aim of this study was to investigate the effects of vaginal sildenafil on the outcome of patients with at least two unsuccessful in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) attempts.

Materials and Methods

In this randomized placebo-controlled trial study, a total of 66 infertile women aged ≤38 years, with a history of normal ovarian reserve, two prior consecutive failed IVF/ICSI attempts, human chorionic gonadotropin (hCG) day endometrial thickness <7 mm in all prior IVF/ICSI cycles, normal endometrial appear- ance by either hysteroscopy, hysterosonography, or hysterosalpingography enrolled in this study. The conventional gonadotropin-releasing hormone (GnRH) protocol was used for ovarian stimulation. The patients were randomly divided into three groups: vaginal sildenafil (suppository-100 mg/daily), vaginal placebo/sildenafil (suppository-100 mg/daily), and vaginal placebo (suppository). Each patient underwent colour Doppler ultrasound on day 14 of their previous cycle to investigate any abnormalities in the uterus and adnexa. Endometrial thickness, echo pattern, uterine artery resistance, and pulsatility indices were recorded pre- and post-treatment. The primary outcome measures were implantation, chemical and clinical pregnancy rates. For data analysis, SPSS version 20 software was used. In all tests, the significance level was considered less than 0.05.

Results

There was no significant difference between three groups in endometrial thickness on the hCG injection day. The chemical pregnancy in women who received sildenafil (alone or in combination with placebo) showed a two-fold increase in comparison to the placebo group. This increase was clinically meaningful, but according to sample size, it was statistically non-significant. The results of our study showed that the implantation was higher in women who received placebo/sildenafil compared to the other groups. The abortion rate was not statistically significant among the groups.

Conclusion

Vaginal sildenafil may conceivably improve chemical pregnancy rates in repeated IVF failure patients. Further randomized clinical trials using oral or vaginal sildenafil with higher sample size are recommended (Registra- tion number: NCT03192709).

Estrogen regulation of cardiac cAMP-L-type Ca2+ channel pathway modulates sex differences in basal contraction and responses to β2AR-mediated stress in left ventricular apical myocytes

Backgrounds/Aim

Male and female hearts have many structural and functional differences. Here, we investigated the role of estrogen (E2) in the mechanisms of sex differences in contraction through the cAMP-L-type Ca²⁺channel pathway in adult mice left ventricular (LV) apical myocytes at basal and stress state.

Methods

Isolated LV apical myocytes from male, female (Sham) and ovariectomised mice (OVX) were used to investigate contractility, Ca²⁺ transients and L-type Ca²⁺ channel (LTCC) function. The levels of β₂AR, intracellular cAMP, phosphodiesterase (PDE 3 and PDE 4), RyR2, PLB, SLN, and SERCA2a were compared among the experimental groups.

Results

We found that (1) intracellular cAMP, I_CaL density, contraction and Ca²⁺ transient amplitudes were larger in Sham and OVX + E2 myocytes compared to male and OVX. (2) The mRNA expression of PDE 3 and 4 were lower in Sham and OVX + E2 groups compared with male and OVX groups. Treatment of myocytes with IBMX (100 μM) increased contraction and Ca²⁺ transient amplitude in both sexes and canceled differences between them. (3) β₂AR-mediated stress decreased cAMP concentration and peak contraction and Ca²⁺ transient amplitude only in male and OVX groups but not in Sham or OVX + E2 groups suggesting a cardioprotective role of E2 in female mice. (4) Pretreatment of OVX myocytes with GPR30 antagonist G15 (100 nM) abolished the effects of E2, but ERα and ERβ antagonist ICI 182,780 (1 μM) did not. Moreover, activation of GPR30 with G1 (100 nM) replicated the effects of E2 on cAMP, contraction and Ca²⁺ transient amplitudes suggesting that the acute effects of E2 were mediated by GPR30 via non-genomic signaling. (5) mRNA expression of RyR2 was higher in myocytes from Sham than those of male while PLB and SLN were higher in male than Sham but no sex differences were observed in the mRNA of SERCA2a.

Conclusion

Collectively, these results demonstrate that E2 modulates the expression of genes related to the cAMP-LTCC pathway and contributes to sex differences in cardiac contraction and responses to stress. We also show that estrogen confers cardioprotection against cardiac stress by non-genomic acute signaling via GPR30.

Safety trial of tadalafil administered for the treatment of preeclampsia

Purpose: The aim of this study is to evaluate the safety of clinical usage of tadalafil in women with preeclampsia.Materials and methods: Maternal, fetal, and neonatal adverse events were closely examined in eight preeclampsia patients receiving tadalafil treatment.Results: There were no maternal adverse events associated with 10 mg/day of tadalafil. Even at 20 mg/day, only grade 1 headaches in two cases and grade 1 palpitation in one case were observed, which resolved spontaneously within 3 days. At a dose of 40 mg/day, there was only one case of grade 1 headache. All these adverse events were grade 1 and spontaneously resolved within 3 days. There were no fetal adverse events. All observed neonatal adverse events were thought to be caused by prematurity and not related to tadalafil.Conclusion: This study shows that tadalafil treatment for preeclampsia is deemed sufficiently tolerable. Although there was a dose-dependent increase in maternal adverse events, all the adverse events were mild and deemed to be safe for the mother and fetus at all dosages.

Effects of the Catechol and Methoxy Metabolites of 17β-Estradiol on Nitric Oxide Production by Ovine Uterine Artery Endothelial Cells

Nitric oxide (NO) production is essential to facilitate rises in uterine blood flow (UBF) during pregnancy. It has been proposed that the metabolites of E₂β, 2-hydroxyestradiol (2-OHE₂), 4-hydroxyestradiol (4-OHE₂), 2-methoxyestradiol (2-ME₂), and 4-methoxyestradiol (4-ME₂) play a role in mediating vasodilation and rises in UBF during pregnancy. We previously showed that the E₂β metabolites stimulate prostacyclin production in pregnancy-derived ovine uterine artery endothelial cells (P-UAECs); however, it is unknown whether the E₂β metabolites also induce NO production. Herein, UAECs derived from nonpregnant and pregnant ewes were used to test the hypothesis that E₂β metabolites stimulate NO production in a pregnancy-specific manner. Specific estrogen receptor (ER) and adrenergic receptor (AR) antagonists were used to determine the roles of ERs or ARs in E₂β metabolite-induced NO production. E₂β and its metabolites increased total nitric oxide metabolites (NOx) levels (NO₂ + NO₃) in P-UAECs, but not in NP-UAECs. Pretreatment with combined 1 µmol/L 1,3-bis(4-hydroxyphenyl)-4-methyl-5-[4-(2-piperidinylethoxy)phenol]-1H-pyrazole dihydrochloride (MPP; ER-α antagonist) and 1 µmol/L 4-[2-phenyl-5,7-bis(trifluoromethyl)pyrazolo[1,5-a]pyrimidin-3-yl]phenol (PHTPP; ER-β antagonist) inhibited the rises in NOx levels stimulated by E₂β and 2-ME₂, but had no effect on 2-OHE₂-, 4-OHE₂-, or 4-ME₂-stimulated rises in NOx levels. Pretreatment with yohimbine (α₂-AR antagonist) and propranolol (β_2,3-AR antagonist) inhibited the rises in NOx levels stimulated by 2-OHE₂, but not by E₂β, 4-OHE₂, 2-ME₂, or 4-ME₂. These data demonstrate that E₂β metabolites stimulate NO synthesis via ERs or ARs in UAECs in a pregnancy-specific manner, suggesting that these metabolites contribute to rises in vasodilation and UBF during pregnancy.

Utero-placental perfusion Doppler indices in growth restricted fetuses: effect of sildenafil citrate

OBJECTIVE

To assess efficacy and tolerability of sildenafil citrate on utero-placental blood flow and fetal growth in pregnancies complicated by fetal growth restriction (FGR).

METHODS

From March 2015, a randomized controlled trial of 54 patients at 24 weeks or more complicated by FGR and abnormal Doppler indices were randomly allocated 1:1 into an intervention arm (receive sildenafil citrate, 50 mg) or a control arm (receive placebo). The primary outcomes were changes occurred in the Doppler parameters 2 h following drug administration.

RESULTS

Baseline characteristics were similar between groups. Significant difference was observed in the Delta uterine and umbilical Doppler indices among sildenafil group as compared to placebo group (p < 0.001). Middle cerebral Doppler indices, however, decreased significantly after sildenafil, which could be the result of shifting more blood to improve the utero-placental perfusion. No difference regarding Delta cerebro-placental ratio among both groups (p = 0.979). Sildenafil was also associated with pregnancy prolongation (p = .0001), increased gestational age at delivery (p = .004), improved neonatal weight (p = .0001), and less admission to neonatal intensive care unit (p = .03). No adverse effects reported in both treatment arms.

CONCLUSION

Sildenafil citrate, by its vasodilator effect, can improve utero-placental blood flow in pregnancies complicated by FGR and abnormal Doppler.

CLINICAL TRIAL

gov Registry: NCT02362399.

Molecular pathways of oestrogen receptors and β-adrenergic receptors in cardiac cells: Recognition of their similarities, interactions and therapeutic value

Oestrogen receptors (ERs) and β-adrenergic receptors (βARs) play important roles in the cardiovascular system. Moreover, these receptors are expressed in cardiac myocytes and vascular tissues. Numerous experimental observations support the hypothesis that similarities and interactions exist between the signalling pathways of ERs (ERα, ERβ and GPR30) and βARs (β₁ AR, β₂ AR and β₃ AR). The recently discovered oestrogen receptor GPR30 shares structural features with the βARs, and this forms the basis for the interactions and functional overlap. GPR30 possesses protein kinase A (PKA) phosphorylation sites and PDZ binding motifs and interacts with A-kinase anchoring protein 5 (AKAP5), all of which enable its interaction with the βAR pathways. The interactions between ERs and βARs occur downstream of the G-protein-coupled receptor, through the G_αs and G_αi proteins. This review presents an up-to-date description of ERs and βARs and demonstrates functional synergism and interactions among these receptors in cardiac cells. We explore their signalling cascades and the mechanisms that orchestrate their interactions and propose new perspectives on the signalling patterns for the GPR30 based on its structural resemblance to the βARs. In addition, we explore the relevance of these interactions to cell physiology, drugs (especially β-blockers and calcium channel blockers) and cardioprotection. Furthermore, a receptor-independent mechanism for oestrogen and its influence on the expression of βARs and calcium-handling proteins are discussed. Finally, we highlight promising therapeutic avenues that can be derived from the shared pathways, especially the phosphatidylinositol-3-OH kinase (PI3K/Akt) pathway.

Sildenafil citrate for the management of fetal growth restriction and oligohydramnios

Fetal growth restriction (FGR) and preeclampsia are the major causes of neonatal morbidity and mortality, which affect up to 8% of all pregnancies. The pathogenesis in FGR is an abnormal trophoblastic invasion leading to compromised uteroplacental circulation. However, in spite of this understanding and identification of high-risk patients, the management options are limited. There are some new studies which have demonstrated the role of sildenafil citrate in improving vasodilatation of small myometrial vessels and therefore improvement in amniotic fluid index, fetal weight, and even uterine and umbilical artery Doppler patterns. We report here the case of a 31-year-old female with infertility and preconceptional thin endometrium responding well to sildenafil citrate, followed by conception. However, she presented with an early-onset FGR at 26 weeks of gestation, and again after treatment with sildenafil citrate, showed improvement in amniotic fluid index and fetal weight, finally resulting in delivery of a full-term healthy baby with uneventful neonatal course.

Erectile properties of the Rho-kinase inhibitor SAR407899 in diabetic animals and human isolated corpora cavernosa

Background

RhoA-Rho kinase complex contributes to keep the cavernosus smooth muscle contracted and its inhibition is considered a potential strategy for the therapy of erectile dysfunction (ED).

Methods

We compared the effects of SAR407899, the Rho-kinase inhibitor Y-27632 and the PDE5 inhibitor sildenafil for their ability to relax corpus cavernosum strips contracted with phenylephrine in healthy and diabetic animals. Strips were obtained from WKY, spontaneous hypertensive (SHR), control CD, and diabetic CD rats, humans, control and diabetic rabbits. Diabetes was induced by streptozotocin or alloxan injection. In vivo penile erection (length) induced by drugs was measured in conscious rabbits.

Results

SAR407899 dose-dependently relaxed the pre-contracted corpora cavernosa in all species, with similar potency and efficacy in healthy vs diabetic rats, WKY vs SHR rats, healthy vs diabetic rabbits (IC₅₀ range from 0.05 to 0.29 μM, Emax range 89 to 97%). In the presence of the NO-synthase (NOS) inhibitor, L-NAME, the SAR407899 response did not decrease in any of the species or experimental conditions. The effect was confirmed in human strips where sildenafil was significantly less potent and effective, with IC₅₀ respectively 0.13 and 0.51 μM; Emax 92 and 43%. Unlike SAR407899, the potency and efficacy of sildenafil and Y27632 were significantly reduced by diabetes and L-NAME. In vivo, SAR407899 dose-dependently induced rabbit penile erection, with greater potency and longer duration of action than sildenafil. Sildenafil, but not SAR407899, was less effective in alloxan-induced diabetes.

Conclusion

The induction of penile erection by SAR407899, unlike that by sildenafil, is largely independent of e-NO activity. This suggests its use in erectile dysfunction for diabetic and hypertensive patients where e-NO activity is impaired.

Evidence for altered placental blood flow and vascularity in compromised pregnancies

The placenta is the organ that transports nutrients, respiratory gases, and wastes between the maternal and fetal systems. Consequently, placental blood flow and vascular development are essential components of normal placental function and are critical to fetal growth and development. Normal fetal growth and development are important to ensure optimum health of offspring throughout their subsequent life course. In numerous sheep models of compromised pregnancy, in which fetal or placental growth, or both, are impaired, utero-placental blood flows are reduced. In the models that have been evaluated, placental vascular development also is altered. Recent studies found that treatments designed to increase placental blood flow can 'rescue' fetal growth that was reduced due to low maternal dietary intake. Placental blood flow and vascular development are thus potential therapeutic targets in compromised pregnancies.