The Placental Function Beyond Pregnancy: Insights from Latin America.

Currently, more than 100,000 papers had been published studying the placenta in both physiological and pathological contexts. However, relevant health conditions affecting placental function, mostly found in low-income countries, should be evaluated deeper. This review will raise some - of what we think necessary - points of discussion regarding challenging topics not fully understood, including the paternal versus maternal contribution on placental genes imprinting, placenta-brain communication, and some environmental conditions affecting the placenta. The discussions are parts of an international effort to fulfil some gaps observed in this area, and Latin-American research groups currently evaluate that.

Piezo1 activation induces relaxation of the pudendal artery and corpus cavernosum.

Piezo1 channel is a sensor for shear-stress in the vasculature. Piezo1 activation induces vasodilation, and its deficiency contributes to vascular disorders, such as hypertension. In this study, we aimed to determine whether Piezo1 channel has a functional role in the dilation of pudendal arteries and corpus cavernosum (CC). For this, male Wistar rats were used, and the relaxation of the pudendal artery and CC was obtained using the Piezo1 activator, Yoda1, in the presence and absence of Dooku (Yoda1 antagonist), GsMTx4 (non-selective mechanosensory channel inhibitor) and L-NAME (nitric oxide synthase inhibitor). In the CC, Yoda1 was also tested in the presence of indomethacin (non-selective COX inhibitor) and tetraethylammonium (TEA, non-selective potassium channel inhibitor). The expression of Piezo1 was confirmed by Western blotting. Our data show that Piezo1 activation leads to the relaxation of the pudendal artery and CC as the chemical activator of Piezo1, Yoda1, relaxed the pudendal artery (47%) and CC (41%). This response was impaired by L-NAME and abolished by Dooku and GsMTx4 in the pudendal artery only. Indomethacin and TEA did not affect the relaxation induced by Yoda1 in the CC. Limited tools to explore this channel prevent further investigation of its underlying mechanisms of action. In conclusion, our data demonstrate that Piezo1 is expressed and induced the relaxation of the pudendal artery and CC. Further studies are necessary to determine its role in penile erection and if erectile dysfunction is associated with Piezo1 deficiency.

Severe Acute Respiratory Syndrome Coronavirus 2 Infection in Pregnancy. A Non-systematic Review of Clinical Presentation, Potential Effects of Physiological Adaptations in Pregnancy, and Placental Vascular Alterations.

In December 2019, the novel Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) rapidly spread to become a pandemic. To date, increasing evidence has described the potential negative impact of SARS-CoV-2 infection on pregnant women. Although the pathophysiology of coronavirus disease 2019 (COVID-19) is not entirely understood, there is emerging evidence that it causes a severe systemic inflammatory response associated with vascular alterations that could be of special interest considering some physiological changes in pregnancy. Additionally, these alterations may affect the physiology of the placenta and are associated with pregnancy complications and abnormal histologic findings. On the other hand, data about the vaccine against SARS-CoV-2 are limited, but the risks of administering COVID-19 vaccines during pregnancy appear to be minimal. This review summarizes the current literature on SARSCoV2 virus infection, the development of COVID-19 and its relationship with physiological changes, and angiotensin-converting enzyme 2 (ACE2) function during pregnancy. We have particularly emphasized evidence coming from Latin American countries.

O-Linked ß-N-Acetylglucosamine Modification: Linking Hypertension and the Immune System.

The O-linked ß-N-acetylglucosamine modification (O-GlcNAcylation) of proteins dynamically regulates protein function, localization, stability, and interactions. This post-translational modification is intimately linked to cardiovascular disease, including hypertension. An increasing number of studies suggest that components of innate and adaptive immunity, active players in the pathophysiology of hypertension, are targets for O-GlcNAcylation. In this review, we highlight the potential roles of O-GlcNAcylation in the immune system and discuss how those immune targets of O-GlcNAcylation may contribute to arterial hypertension.

Interleukin-10 in the Vasculature: Pathophysiological Implications.

Interleukin-10 (IL-10) is an important immunomodulatory cytokine, initially characterized as an anti-inflammatory agent released by immune cells during infectious and inflammatory processes. IL-10 exhibits biological functions that extend to the regulation of different intracellular signaling pathways directly associated with vascular function. This cytokine plays a vital role in vascular tone regulation by changing important proteins involved in vasoconstriction and vasodilation. Numerous investigations covered here have shown that therapeutic strategies inducing IL-10 exert anti-inflammatory, anti-hypertrophic, anti-hyperplastic, anti-apoptotic and antihypertensive effects. This non-systematic review summarizes the modulating effects mediated by IL-10 in vascular tissue, particularly on vascular tone, and the intracellular pathway induced by this cytokine. We also highlight the advances in IL-10 manipulation as a therapeutic target in different cardiovascular pathophysiologies, including the physiological implications in animals and humans. Finally, the review illustrates current and potential future perspectives of the potential use of IL-10 in clinical trials based on the clinical evidence.

Mitochondrial DNA and TLR9 activation contribute to SARS-CoV-2-induced endothelial cell damage.

BACKGROUND AND PURPOSE: Mitochondria play a central role in the host response to viral infection and immunity, being key to antiviral signaling and exacerbating inflammatory processes. Mitochondria and Toll-like receptor (TLR) have been suggested as potential targets in SARS-CoV-2 infection. However, the involvement of TLR9 in SARS-Cov-2-induced endothelial dysfunction and potential contribution to cardiovascular complications in COVID-19 have not been demonstrated. This study determined whether infection of endothelial cells by SARS-CoV-2 affects mitochondrial function and induces mitochondrial DNA (mtDNA) release. We also questioned whether TLR9 signaling mediates the inflammatory responses induced by SARS-CoV-2 in endothelial cells. EXPERIMENTAL APPROACH: Human umbilical vein endothelial cells (HUVECs) were infected by SARS-CoV-2 and immunofluorescence was used to confirm the infection. Mitochondrial function was analyzed by specific probes and mtDNA levels by real-time polymerase chain reaction (RT-PCR). Inflammatory markers were measured by ELISA, protein expression by western blot, intracellular calcium (Ca2+) by FLUOR-4, and vascular reactivity with a myography. KEY RESULTS: SARS-CoV-2 infected HUVECs, which express ACE2 and TMPRSS2 proteins, and promoted mitochondrial dysfunction, i.e. it increased mitochondria-derived superoxide anion, mitochondrial membrane potential, and mtDNA release, leading to activation of TLR9 and NF-kB, and release of cytokines. SARS-CoV-2 also decreased nitric oxide synthase (eNOS) expression and inhibited Ca2+ responses in endothelial cells. TLR9 blockade reduced SARS-CoV-2-induced IL-6 release and prevented decreased eNOS expression. mtDNA increased vascular reactivity to endothelin-1 (ET-1) in arteries from wild type, but not TLR9 knockout mice. These events were recapitulated in serum samples from COVID-19 patients, that exhibited increased levels of mtDNA compared to sex- and age-matched healthy subjects and patients with comorbidities. CONCLUSION AND APPLICATIONS: SARS-CoV-2 infection impairs mitochondrial function and activates TLR9 signaling in endothelial cells. TLR9 triggers inflammatory responses that lead to endothelial cell dysfunction, potentially contributing to the severity of symptoms in COVID-19. Targeting mitochondrial metabolic pathways may help to define novel therapeutic strategies for COVID-19.

High Levels of Tumor Necrosis Factor-Alpha Reduce Placental Aquaporin 3 Expression and Impair in vitro Trophoblastic Cell Migration.

Placentas from preeclamptic women display augmented tumor necrosis factor-alpha (TNF-α) levels with reduced expression of aquaporin 3 (AQP3). However, whether TNF-α modulates AQP3 expression remains to be elucidated. We hypothesize that elevated levels of TNF-α reduce AQP3 expression and negatively impact trophoblastic cell migration. Spontaneously hypertensive rats (SHRs) and Wistar rats (14-16 weeks) were divided into hypertensive and normotensive groups, respectively. Systolic blood pressure (SBP) was measured, and animals mated. In a third group, pregnant SHRs were treated with a TNF-α antagonist, etanercept (0.8 mg/kg, subcutaneously) on days 0, 6, 12, and 18 of pregnancy. Placentas were collected on the 20th day of pregnancy. Human placental explants, from normotensive pregnancies, were incubated with TNF-α (5, 10, and 20 ng/ml) and/or etanercept (1 µg/ml). Swan 71 cells were incubated with TNF-α (10 ng/ml) and/or etanercept (1 µg/ml) and subjected to the wound healing assay. AQP3 expression was assessed by Western blot and TNF-α levels by ELISA. SBP (mmHg) was elevated in the hypertensive group, and etanercept treatment reduced this parameter. Placental TNF-α levels (pg/ml) were higher in the hypertensive group. AQP3 expression was reduced in the hypertensive group, and etanercept treatment reversed this parameter. Explants submitted to TNF-α exposition displayed reduced expression of AQP3, and etanercept incubation reversed it. Trophoblastic cells incubated with TNF-α showed decreased cell migration and reduced AQP3 expression, and etanercept incubation ameliorated it. Altogether, these data demonstrate that high TNF-α levels negatively modulate AQP3 in placental tissue, impairing cell migration, and its relationship in a pregnancy affected by hypertension.

COVID-19 and hypertension: Is there a role for dsRNA and activation of Toll-like receptor 3?

The virus responsible for the coronavirus disease of 2019 (COVID-19) is the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Evidences suggest that COVID-19 could trigger cardiovascular complications in apparently healthy patients. Coronaviruses are enveloped positive-strand RNA viruses acting as a pathogen-associated molecular pattern (PAMP)/ danger-associated molecular patterns (DAMP). Interestingly, Toll-like receptor (TLR) 3 recognize both PAMPs DAMPs and is activated by viral double-stranded RNA (dsRNA) leading to activation of TIR receptor domain-containing adaptor inducing IFN-ß (TRIF) dependent pathway. New evidence has shown a link between virus dsRNA and increased BP. Hence, we hypothesize that COVID-19 infection may be over activating the TLR3 through dsRNA, evoking further damage to the patients, leading to vascular inflammation and increased blood pressure, favoring the development of several cardiovascular complications, including hypertension.

Resistance mesenteric arteries display hypercontractility in the resolution time of Strongyloides venezuelensis infection.

The blood flow in the mesenteric region is crucial for nutrient absorption and immune response in the gastrointestinal tract. The presence of nematodes or their excreted/secreted products seems to provoke vascular dysfunction. However, it is unclear whether and how the intestinal nematodes with habitat in the intestinal niche could affect the mesenteric vascular resistance. In this study, male Wistar rats were infected with 2000 larvae of S. venezuelensis, and experiments were conducted at 0 (non-infected control), 10 or 30 days post-infection (DPI). Eggs were counted in rats' feces and adult worms recovered from the small intestine. Second- or third-order mesenteric arteries were extracted for concentration-response curves (CRC) to phenylephrine [PE; in the presence or absence of L-NAME or indomethacin] and acetylcholine. The number of eggs and adult worms were significantly higher in the 10 DPI group than those of 30 DPI group. Augmented PE-induced contraction was seen after 30 DPI compared to 10 DPI or control group. Hypercontractility to PE was partially prevented by L-NAME and wholly abolished by indomethacin incubation. Endothelium-dependent relaxation and endothelial nitric oxide synthase expression were unchanged among groups. COX-1 and COX-2 display a different pattern of expression over the infection. Hypercontractility observed in mesenteric resistance arteries in the resolution time of S. venezuelensis infection may represent systemic damage, which can generate significant cardiovascular and gastrointestinal repercussions.

Sex Differences in Molecular Mechanisms of Cardiovascular Aging.

Cardiovascular disease (CVD) is still the leading cause of illness and death in the Western world. Cardiovascular aging is a progressive modification occurring in cardiac and vascular morphology and physiology where increased endothelial dysfunction and arterial stiffness are observed, generally accompanied by increased systolic blood pressure and augmented pulse pressure. The effects of biological sex on cardiovascular pathophysiology have long been known. The incidence of hypertension is higher in men, and it increases in postmenopausal women. Premenopausal women are protected from CVD compared with age-matched men and this protective effect is lost with menopause, suggesting that sex-hormones influence blood pressure regulation. In parallel, the heart progressively remodels over the course of life and the pattern of cardiac remodeling also differs between the sexes. Lower autonomic tone, reduced baroreceptor response, and greater vascular function are observed in premenopausal women than men of similar age. However, postmenopausal women have stiffer arteries than their male counterparts. The biological mechanisms responsible for sex-related differences observed in cardiovascular aging are being unraveled over the last several decades. This review focuses on molecular mechanisms underlying the sex-differences of CVD in aging.

Angiotensin (1-7)-attenuated vasoconstriction is associated with the Interleukin-10 signaling pathway.

AIMS: Angiotensin-1-7 [Ang-(1-7)] is an essential peptide of the renin-angiotensin system that promotes benefits modulating effects in different tissues. Similarly, interleukin-10 (IL-10) exhibits an immunomodulatory action on the vasculature. This study aimed to evaluate whether Ang-(1-7) levels attenuates vascular contractile response, mediated by IL-10-pathway (JAK1/STAT3/IL-10). MAIN METHODS: Aortas from male mice C57BL/6J and knockout for IL-10 (IL-10-/-) were incubated with Ang-(1-7) [10 µM] or vehicle, during 5 min, 1 h, 6 h, 12 h, and 24 h. Concentration-response curves to phenylephrine, western blotting, and flow cytometry analysis was performed to evaluate the contractile response, protein expression, and IL-10 levels, respectively. KEY FINDINGS: Incubation with Ang-(1-7) produced a time-dependent increase in Janus kinases 1 (JAK1) expression, as well as increased expression and activity of the signal transducer and activator of transcription 3 (STAT3) protein. However, this effect was not observed in knockout animals for IL-10. After 12 h of Ang-(1-7) treatment, arteries from control mice displayed decreased vascular reactivity to phenylephrine, but this effect was not observed in the absence of endogenous IL-10. Additionally, incubation with Ang-(1-7) augments IL-10 levels after 6 h, 12 h, and 24 h of incubation. SIGNIFICANCE: These results demonstrated the role of Ang-(1-7) in the IL-10 signaling pathway and its effects in the vascular contractility response. Thus, these findings suggest a new synergic action where Ang-(1-7) and IL-10 converge into a protective mechanism against vascular dysfunction.

Toll-Like Receptors Contribute to Sex Differences in Blood Pressure Regulation.

Toll-like receptors (TLRs) play an important role in the innate immune system, and recently, they have been shown to be involved in the regulation of blood pressure. The incidence of hypertension is higher in men, and it increases in postmenopausal women. In fact, premenopausal women are protected from cardiovascular disease compared with age-matched men, and it is well established that this protective effect is lost with menopause. However, the molecular mechanisms underlying this protection in women are unknown. Whether or not it could be related to differential activation of the innate immune system remains to be elucidated. This review focuses on (1) the differences between men and women in TLR activation and (2) whether TLR activation may influence the regulation of blood pressure in a sex-dependent manner.

The limited knowledge of placental damage due to neglected infections: ongoing problems in Latin America.

The placenta works as a selective barrier, protecting the fetus from potential infections that may affect the maternal organism during pregnancy. In this review, we will discuss several challenging infections that are common within Latin American countries and that may affect the maternal-fetal interface and pose risks to fetal development. Specifically, we will focus on emerging infectious diseases including the arboviruses, malaria, leishmaniasis, and the bacterial foodborne disease caused by Shiga toxin-producing Escherichia coli. We will also highlight some topics of interest currently being studied by research groups that comprise an international effort aimed at filling the knowledge gaps in this field. These topics address the relationship between exposure to microorganisms and placental abnormalities, congenital anomalies, and complications of pregnancy. ABBREVIATIONS: ADE: antibody-dependent enhancement; CCL2: monocyte chemoattractant protein-1; CCL3: macrophage inflammatory protein-1 α; CCL5: chemokine (C-C motif) ligand 5; CHIKV: chikungunya virus; DCL: diffuse cutaneous leishmaniasis; DENV: dengue virus; Gb3: glycolipid globotriaosylceramyde; HIF: hypoxia-inducible factor; HUS: hemolytic uremic syndrome; IFN: interferon; Ig: immunoglobulins; IL: interleukin; IUGR: intrauterine growth restriction; LCL: localized cutaneous leishmaniasis; LPS: lipopolysaccharid; MCL: mucocutaneous leishmaniasis; NO: nitric oxide; PCR: polymerase chain reaction; PGF: placental growth factor; PM: placental malaria; RIVATREM: Red Iberoamericana de Alteraciones Vasculares em transtornos del Embarazo; sVEGFR: soluble vascular endothelial growth factor receptor; STEC: shiga toxin-producing Escherichia coli; stx: shiga toxin protein; TNF: tumor necrosis factor; TOAS: T cell original antigenic sin; Var2CSA: variant surface antigen 2-CSA; VEGF: vascular endothelial growth factor; VL: visceral leishmaniasis; WHO: world health organization; YFV: yellow fever virus; ZIKV: Zika virus.

O-GlcNAc impairs endothelial function in uterine arteries from virgin but not pregnant rats: The role of GSK3ß.

Increased O-Linked ß-N-acetylglucosamine (O-GlcNAc) is observed in several pathologies, and unbalanced O-GlcNAcylation levels favor endothelial dysfunction. Whether augmented O-GlcNAc impacts the uterine artery (UA) function and how it affects the UA during pregnancy remains to be elucidated. We hypothesized that glucosamine treatment increases O-GlcNAc, leading to uterine artery dysfunction and this effect is prevented by pregnancy. Pregnant (P) and non-pregnant (NP) Wistar rats were treated with glucosamine (300 mg/kg; i.p.) for 21 days. Concentration response-curves (CRC) to acetylcholine (in the presence or absence of L-NAME) and sodium nitroprusside were performed in UAs. In NP rats, glucosamine treatment increased O-GlcNAc expression in UAs accompanied by decreased endothelium-dependent relaxation, which was abolished by L-NAME. Endothelial nitric oxide synthase (eNOS) activity and total Akt expression were decreased by glucosamine-treatment in NP rats. Further, NP rats treated with glucosamine displayed increased glycogen synthase kinase 3 beta (GSK3ß) activation and O-GlcNAc-transferase (OGT) expression in the UA. P rats treated with glucosamine displayed decreased O-GlcNAc in UAs and it was accompanied by improved relaxation to acetylcholine, whereas eNOS and GSK3ß activity and total Akt and OGT expression were unchanged. Sodium nitroprusside-induced relaxation was not changed in all groups, indicating that glucosamine treatment led to endothelial dysfunction in NP rats. The underlying mechanism is, at least in part, dependent on Akt/GSK3ß/OGT modulation. We speculate that during pregnancy, hormonal alterations play a protective role in preventing O-GlcNAcylation-induced endothelial dysfunction in the UAs.

The role of xenobiotic-metabolizing enzymes in the placenta: a growing research field.

Introduction: The placenta is a temporary and unique organ that allows for the physical connection between a mother and fetus; this organ regulates the transport of gases and nutrients mediating the elimination of waste products contained in the fetal circulation. The placenta performs metabolic and excretion functions, on the basis of multiple enzymatic systems responsible for the oxidation, reduction, hydrolysis, and conjugation of xenobiotics. These mechanisms give the placenta a protective role that limits the fetal exposure to harmful compounds. During pregnancy, some diseases require uninterrupted treatment even if it is detrimental to the fetus. Drugs and other xenobiotics alter gene expression in the placenta with repercussions for the fetus and mother's well-being.Areas covered: This review provides a brief description of the human placental structure and function, the main drug and xenobiotic transporters and metabolizing enzymes, placenta-metabolized substrates, and alterations in gene expression that the exposure to xenobiotics may cause.Expert opinion: Research should be focused on the identification and validation of biological markers for the assessment of the harmful effects of some drugs in pregnancy, including the evaluation of polymorphisms and methylation patterns in chorionic villous samples and/or amniotic fluid.

Double-stranded RNA and Toll-like receptor activation: a novel mechanism for blood pressure regulation.

Toll-like receptors (TLRs), such as TLR4 and 9, recognize pathogen-associated molecular pattern (PAMPs) and danger-associated molecular patterns (DAMPs) and are associated with increased blood pressure (BP). TLR3, residing in the endosomal compartment, is activated by viral double-stranded RNA (dsRNA) leading to activation of TIR receptor domain-containing adaptor inducing IFN-ß (TRIF) dependent pathway. Besides foreign pathogens, the immune system responds to endogenous markers of cellular damage such as mitochondrial dsRNA (mtdsRNA). New evidence has shown a link between dsRNA and increased BP. Moreover, TLR3 activation during pregnancy was demonstrated to develop preeclampsia-like symptoms in both rats and mice. Hence, we hypothesize that the dsRNA derived from viral nucleic acids or cellular damage (mtdsRNA) will increase the inflammatory state through activation of TLR3, contributing to vascular dysfunction and increased BP. Therefore, inhibition of TLR3 could be a therapeutic target for the treatment of hypertension with potential improvement in vascular reactivity and consequently, a decrease in BP.

Placental structure in gestational diabetes mellitus.

The placenta is a transitory organ, located between the mother and the foetus, which supports intrauterine life. This organ has nutritional, endocrine and immunologic functions to support foetal development. Several factors are related to the correct functioning of the placenta including foetal and maternal blood flow, appropriate nutrients, expression and function of receptors and transporters, and the morphology of the placenta itself. Placental morphology is crucial for understanding the pathophysiology of the organ as represents the physical structure where nutrient exchange occurs. In pathologies of pregnancy such as diabetes mellitus in humans and animal models, several changes in the placental morphology occur, related mainly with placental size, hypervascularization, higher branching capillaries of the villi and increased glycogen deposits among others. Gestational diabetes mellitus is associated with modifications in the structure of the human placenta including changes in the surface area and volume, as well as histological changes including an increased volume of intervillous space and terminal villi, syncytiotrophoblast number, fibrinoid areas, and glycogen deposits. These modifications may result in functional changes in this organ thus limiting the wellbeing of the developing foetus. This review gives an overview of recurrent morphological changes at macroscopic and histological levels seen in the placenta from gestational diabetes in humans and animal models. This article is part of a Special Issue entitled: Membrane Transporters and Receptors in Pregnancy Metabolic Complications edited by Luis Sobrevia.

Interleukin 1-beta is Linked to Chronic Low-Grade Inflammation and Cardiovascular Risk Factors in Overweight Adolescents.

AIM: We hypothesized that IL-1ß concentrations are augmented in overweight adolescents, who do not display metabolic syndrome. Additionally, we aimed to correlate the IL-1ß concentrations with several established risk factors for CVD. METHODS: Overweight or control subjects, aging from 14-18 years, were classified according to their adjusted body mass index and evaluated for biochemical and anthropometric parameters. The proinflammatory cytokine IL-1ß was assessed in the serum. RESULTS: Increased body fat percentage, waist circumference, triglycerides, total cholesterol, Very Low-Density Lipoprotein (VLDL) cholesterol, Low-Density Lipoprotein (LDL) cholesterol, Castelli I index, IL-1ß, and IL-8 levels, were observed in overweight adolescents. No differences were observed in systolic blood pressure, diastolic blood pressure, glucose or High-Density Lipoprotein (HDL) cholesterol. Positive correlations between IL-1ß with anthropometric and or biochemical parameters were found. CONCLUSION: In conclusion, increased IL-1ß levels correlate to dyslipidemic factors and may further support low-grade inflammation. IL-1ß may further predict the early onset of cardiovascular disease in this population, taking into consideration its important regulatory role.

Increased expression of STAT3 and SOCS3 in placenta from hyperglycemic rats.

Signal transducer and activator of transcription 3 (STAT3) is a transcription factor that is activated by interleukin (IL)-6 and IL-10 that generate nearly opposing responses. The suppressor of cytokine signaling 3 (SOCS3) is the negative regulator of STAT3 and plays an important role in the negative regulation of the inflammatory process. Evidence has shown the importance of STAT3 and SOCS3 during implantation and normal pregnancy. However, little is known about the relationship of both factors under hyperglycemic condition. The aim of this study was to evaluate the placenta regions exhibiting immunopositivity for STAT3 and SOCS3 in hyperglycemic rats, as well as correlate these proteins with IL-10 and IL-6 levels. It was observed increased expression of STAT3 at the labyrinth (approximately 47% of increase compared to control) and junctional zone (approximately 32% of increase compared to control) from hyperglycemic placentas. Similar results were observed to SOCS3 (approximately 71% -labyrinth- and 53% -junctional zone- of increase compared to control). The levels of IL-10 were augmented at hyperglycemic placentas (approximately 1.5 fold of increase) and they were positively correlated with the increase of STAT3 at the labyrinth and SOCS at junctional zone. Therefore, under hyperglycemic conditions, the relation between STAT3 and SOCS3 was changed, leading to unbalance of the cytokine profile.

Equilin displays similar endothelium-independent vasodilator potential to 17ß-estradiol regardless of lower potential to inhibit calcium entry.

Conjugated equine estrogens (CEE) have been widely used by women who seek to relieve symptoms of menopause. Despite evidence describing protective effects against risk factors for cardiovascular diseases by naturally occurring estrogens, little is known about the vascular effects of equilin, one of the main components of CEE and not physiologically present in women. In this regard, the present study aims to compare the vascular effects of equilin in an experimental model of hypertension with those induced by 17ß-estradiol. Resistance mesenteric arteries from female spontaneously hypertensive rats (SHR) were used for recording isometric tension in a small vessel myograph. As effectively as 17ß-estradiol, equilin evoked a concentration-dependent relaxation in mesenteric arteries from female SHRs contracted with KCl, U46619, PDBu or ET-1. Equilin-induced vasodilation does not involve classical estrogen receptor activation, since the estrogen receptor antagonist (ICI 182,780) failed to inhibit relaxation in U46619-precontracted mesenteric arteries. Vasorelaxation was not affected by either endothelium removal or by inhibiting the release or action of endothelium-derived factors. Incubation with L-NAME (NOS inhibitor), ODQ (guanylyl cyclase inhibitor) or KT5823 (inhibitor of protein kinase G) did not affect equilin-induced relaxation. Similarly, indomethacin (COX inhibitor) or blockage of potassium channels with tetraethylammonium, glibenclamide, 4-aminopyridine, or ouabain did not affect equilin-induced relaxation. Inhibitors of adenylyl cyclase SQ22536 or protein kinase A (KT5720) also had no effects on equilin-induced relaxation. While 17ß-estradiol inhibited calcium (Ca2+) -induced contractions in high-K+ depolarization medium in a concentration-dependent manner, equilin induced a slight rightward-shift in the contractile responses to Ca2+. Comparable pattern of responses were observed in the concentration-response curves to (S)-(-)-Bay K 8644, a L-type Ca2+ channel activator. Equilin was unable to block the transitory contraction produced by caffeine-induced Ca2+ release from intracellular stores. In conclusion, equilin blocks L-type Ca2+ channels less effectively than 17ß-estradiol. Despite its lower effectiveness, equilin equally relaxes resistance mesenteric arteries by blocking Ca2+ entry on smooth muscle.