Ang II-induced contraction is impaired in the aortas of renovascular hypertensive animal model.

Abstract: Renin-angiotensin system plays a critical role in blood pressure control, and the abnormal activation of the AT1 receptor contributes to the development of renovascular hypertension. This study aimed to evaluate the underlying cellular signaling for AT1 receptor activation by Ang II and to compare this mechanism between aortas from 2K-1C and 2K rats. Effects of antagonists and inhibitors were investigated on Ang II-induced contractions in denuded or intact-endothelium aortas. The AT1 receptor antagonist abolished Ang II-induced contraction in 2K-1C and 2K rat aortas, while AT2 and Mas receptors antagonists had no effect. Endothelial nitric oxide synthase inhibition increased the maximal effect (Emax) of Ang II in 2K, which was not changed in 2K-1C aortas. It was associated with lower eNOS mRNA levels in 2K-1C. Endothelium removal increased the Emax of Ang II in 2K-1C and mainly in 2K rat aortas. Nox and COX inhibition did not alter Ang II-induced contraction in 2K and 2K-1C rat aortas. However, AT1 expression was higher in 2K-1C compared to 2K rat aortic rings, whereas expression of phosphorylated (active) IP3 receptors was lower in 2K-1C than in 2K rats. These results demonstrate that endothelium removal impairs Ang II-stimulated contraction in the aorta of 2K-1C rats, which is associated with the reduction of IP3 receptor phosphorylation and activation. In addition, eNOS plays a critical role in Ang II-induced contraction in 2K rat aortas. It is possible that the high Ang II plasma levels could desensitize AT1 receptor in 2K-1C rats, leading to impaired IP3 receptors activation.

New advances in the protective mechanisms of acidic pH after ischemia: Participation of NO.

BACKGROUND: It has been previously demonstrated that the maintenance of ischemic acidic pH or the delay of intracellular pH recovery at the onset of reperfusion decreases ischemic-induced cardiomyocyte death. OBJECTIVE: To examine the role played by nitric oxide synthase (NOS)/NO-dependent pathways in the effects of acidic reperfusion in a regional ischemia model. METHODS: Isolated rat hearts perfused by Langendorff technique were submitted to 40 min of left coronary artery occlusion followed by 60 min of reperfusion (IC). A group of hearts received an acid solution (pH = 6.4) during the first 2 min of reperfusion (AR) in absence or in presence of l-NAME (NOS inhibitor). Infarct size (IS) and myocardial function were determined. In cardiac homogenates, the expression of P-Akt, P-endothelial and inducible isoforms of NOS (P-eNOS and iNOS) and the level of 3-nitrotyrosine were measured. In isolated cardiomyocytes, the intracellular NO production was assessed by confocal microscopy, under control and acidic conditions. Mitochondrial swelling after Ca2+ addition and mitochondrial membrane potential (Δψ) were also determined under control and acidosis. RESULTS: AR decreased IS, improved postischemic myocardial function recovery, increased P-Akt and P-eNOS, and decreased iNOS and 3-nitrotyrosine. NO production increased while mitochondrial swelling and Δψ decreased in acidic conditions. l-NAME prevented the beneficial effects of AR. CONCLUSIONS: Our data strongly supports that a brief acidic reperfusion protects the myocardium against the ischemia-reperfusion injury through eNOS/NO-dependent pathways.

Frequency of Gene Polymorphisms in Admixed Venezuelan Women with Recurrent Pregnancy Loss: Microsomal Epoxy Hydroxylase (rs1051740) and Enos (rs1799983).

Recurrent pregnancy loss (RPL) affects around 2% of women of reproductive age. Primary RPL is defined by ≥2 pregnancy losses and no normal birth delivery. In secondary RPL, the losses are after a normal pregnancy and delivery. Most cases have no clear aetiology, although primary cases are the most complex. Several gene single nucleotide polymorphisms (SNPs) have been associated with RPL. The frequency of some SNPs is increased in women suffering from RLP from Asian or Caucasian races; however, in admixed populations, the information on possible genetic links is scarce and contradictory. This study aimed to assess the frequency of two SNPs present in two different enzymes involved in medical conditions observed during pregnancy. It is a case-control study. Microsomal epoxy hydrolase (mEPH) is involved in detoxifying xenobiotics, is present in the ovaries, and is hormonally regulated. The endothelial nitric oxide synthase (NOS3) that forms nitric is involved in vascular tone. Two SNPs, rs1051740 (mEPH) and rs1799983 (NOS3), were assessed. The study included 50 controls and 63 primary RPL patients. The frequency of mutated alleles in both SNPs was significantly higher in patients (p < 0.05). Double-mutated homozygotes were encountered only in RPL patients (p < 0.05). Genetic polymorphisms rs1051740 and rs1799983 may be involved in primary RPL in the Venezuelan admix population. Genetic studies could provide crucial information on the aetiology of primary RPL.

Modulation of the activation of endothelial nitric oxide synthase and nitrosative stress biomarkers by aspirin triggered lipoxins: A possible mechanism of action of aspirin in the antiphospholipid syndrome.

PROBLEM: Antiphospholipid syndrome (APS) is characterized by the clinical manifestation of vascular thrombosis (VT) or pregnancy morbidity (PM) and antiphospholipid antibodies (aPL) that can modify the nitric oxide production. Low-dose aspirin is used in the prevention and treatment of diverse alterations of pregnancy. One of the mechanisms of action of aspirin is to induce the production of aspirin-triggered-lipoxins (ATL). The aim of this study was to evaluate the modulatory effect of ATL over the activation of endothelial nitric oxide synthase (eNOS) and nitrosative stress biomarkers induced by aPL. METHODS: We used polyclonal IgG and sera from women with aPL and PM/VT or VT only, and from women with PM only and positive for non-criteria aPL (SN-OAPS). In these sera, biomarkers of nitrosative stress (nitrites and nitrotyrosine) were measured. The protein expression of nitrotyrosine and the phosphorylation of eNOS (at Ser1177) were estimated in human umbilical vein endothelial cells (HUVECs) stimulated with polyclonal IgG with or without ATL. RESULTS: Women with SN-OAPS showed increased circulating levels of nitrites and nitrotyrosine. Likewise, polyclonal IgG from either SN-OAPS or VT patients stimulated nitrotyrosine expression in HUVECs. ATL decreased the nitrotyrosine expression induced by polyclonal IgG from the SN-OAPS group. ATL also recovered the reduced eNOS phosphorylation at Ser1177 in HUVECs stimulated with polyclonal IgG from women with PM/VT or SN-OAPS. CONCLUSIONS: Increased nitrosative stress present in serum of women with SN-OAPS is associated with IgG-mediated impaired endothelial NO synthesis in endothelial cells. ATL prevent these cellular changes.

Exercise-induced angiogenesis is attenuated by captopril but maintained under perindopril treatment in hypertensive rats.

Angiogenesis is an important exercise-induced response to improve blood flow and decrease vascular resistance in spontaneously hypertensive rats (SHR), but some antihypertensive drugs attenuate this effect. This study compared the effects of captopril and perindopril on exercise-induced cardiac and skeletal muscle angiogenesis. Forty-eight Wistar rats and 48 SHR underwent 60 days of aerobic training or were kept sedentary. During the last 45 days, rats were treated with captopril, perindopril or water (Control). Blood pressure (BP) measurements were taken and histological samples from the tibialis anterior (TA) and left ventricle (LV) muscles were analyzed for capillary density (CD) and vascular endothelial growth factor (VEGF), VEGF receptor-2 (VEGFR-2) and endothelial nitric oxide synthase (eNOS) protein level. Exercise increased vessel density in Wistar rats due to higher VEGFR-2 (+17%) and eNOS (+31%) protein level. Captopril and perindopril attenuated exercise-induced angiogenesis in Wistar rats, but the attenuation was small in the perindopril group, and this response was mediated by higher eNOS levels in the Per group compared to the Cap group. Exercise increased myocardial CD in Wistar rats in all groups and treatment did not attenuate it. Both exercise and pharmacological treatment reduced BP of SHR similarly. Rarefaction was found in TA of SHR compared to Wistar, due to lower levels of VEGF (-26%) and eNOS (-27%) and treatment did not avoid this response. Exercise prevented these reductions in control SHR. While rats treated with perindopril showed angiogenesis in the TA muscle after training, those rats treated with captopril showed attenuated angiogenesis (-18%). This response was also mediated by lower eNOS levels in Cap group compared with Per and control group. Myocardial CD was reduced in all sedentary hypertensive compared with Wistar and training restored the number of vessels compared with sedentary SHR. In conclusion, taken into account only the aspect of vessel growth, since both pharmacological treatments reduced BP in SHR, the result of the present study suggests that perindopril could be a drug of choice over captopril for hypertensive practitioners of aerobic physical exercises, especially considering that it does not attenuate angiogenesis induced by aerobic physical training in skeletal and cardiac muscles.

Preeclampsia association of placental nucleotide variations in eNOS, VEGFA, and FLT-1 genes in Latin American pregnant women.

INTRODUCTION: Preeclampsia is a leading cause of maternal and fetal morbidity in low- and middle-income countries, including those in Latin America. Placental vascular alterations are crucial in the pathophysiology of preeclampsia and few studies have evaluated nucleotide variations on genes associated with vascular regulation in the human placenta. This study aimed to evaluate whether placental nucleotide variations on eNOS, VEGFA, and FLT-1 genes are more frequently associated with preeclampsia in the Latin American population. METHODS: This case-control study included placental tissue from 88 controls and 82 cases that were genotyped through Taqman probes for eNOS, VEGFA, and FLT-1 genes. The intergroup comparisons were analyzed with the Mann-Whitney U test. Genotype and allele frequencies were compared by the X2 test. The association between the nucleotide variants with preeclampsia was evaluated through logistic regression analysis. RESULTS: A significant association was observed for VEGFA SNV rs2010963 (OR 1.95; CI 95% 1.13-3.37), after adjusting for population substructure. The allele combination T, G, G, C, C, C (rs2070744, rs1799983, rs2010963, rs3025039, rs699947 and rs4769613 respectively), showed a negative association with preeclampsia (OR 0.08; CI 95% 0.01-0.93). DISCUSSION: Placental SNV rs2010963 in the VEGFA gene was a risk factor for preeclampsia, while the allele combination T, G, G, C, C, C may represent potential protective factors for preeclampsia within Latin American women.

Sex differences in the participation of endothelial mediators and signaling pathways involved in the vasodilator effect of a selective GPER agonist in resistance arteries of gonadectomized Wistar rats.

AIM: Endothelial mechanisms underlying the vascular effects of estrogen modulated by the G protein-coupled estrogen receptor (GPER) are not well understood, especially in gonadal sex hormone deprivation. Thus, we investigated vascular function and endothelial signaling pathways involved in the selective activation of GPER in resistance arteries of gonadectomized rats. METHODS: Gonadectomy was performed in Wistar rats of both sexes. After 21 days, the animals were euthanized. Concentration-response curves were obtained by cumulative additions of G-1 in third-order mesenteric arteries. The vasodilatory effects of G-1 were evaluated before and after endothelium removal or incubation with pharmacological inhibitors. Tissue protein expression was measured by western blotting. Assays with 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate (DAF-FM) and 2',7' dichlorodihydrofluorescein-diacetate (H2DCF-DA) were performed in the arteries investigated. Immunolocalization was assessed by immunofluorescence. RESULTS: G-1 induced partially endothelium-dependent relaxation in both sexes. The three isoforms of the enzyme nitric oxide synthase contributed to the production and release of nitric oxide in both gonadectomized groups, but the role of inducible nitric oxide synthase is more expressive in males. The mechanistic pathway by which endothelial nitric oxide synthase is phosphorylated appears to differ between sexes, with the rapid signaling pathway phosphatidylinositol-3-kinase/protein kinase B/endothelial nitric oxide synthase (PI3k-Akt-eNOS) being identified for males and mitogen-activated protein kinase/extracellular signal-regulated kinase/endothelial nitric oxide synthase (MEK-ERK-eNOS) for females. The contribution of hydrogen peroxide as an endothelial relaxation mediator seems to be greater in females. CONCLUSION: These results provide new insights into the effects of estrogen-induced responses via GPER on vascular function in gonadal sex hormone deprivation.

Relationship between the El Niño-Southern Oscillation and yield and sugar content of wine grapes grown in Santana do Livramento, RS, Brazil / Relações entre El Niño-Oscilação Sul, e produtividade e acúmulo de açúcares em uvas cultivadas em Santana do Livramento, RS, Brasil

The El Niño-Southern Oscillation (ENSO) is a well-known source of interannual variability in the climate of Santana do Livramento, Campanha Gaúcha, Brazil. It affects the agronomic responses of several crops grown in the region. Analysis of a dataset comprising observations of grape yield and sugar content in 11 white and 17 red grape cultivars over the last 3 decades revealed some patterns. In the long term (several years or decades), yield and sugar content showed a negative relationship, that is, larger crop loads resulted in lower sugar content at harvest. However, a number of calculations and principal component analyses showed that annual yield and sugar content fluctuations in the short term can be better explained by considering as reference points only the results obtained for each crop one and two years before. Based on these simple calculations, there was a clear separation between El Niño and La Niña events. In the vineyards of this region, La Niña events typically tend to result in higher grape yields and sugar content at harvest, while the opposite is true for El Niño, which tend to produce lower grape yields and sugar content at harvest. The results of neutral events are typically closer to those of El Niño events.(AU)

O El Niño-Oscilação Sul (ENSO) é uma fonte conhecida de variabilidade interanual no clima de Santana do Livramento, Campanha Gaúcha, Brasil, que afeta as respostas agronômicas de diversas culturas agrícolas cultivadas na região. A análise de um conjunto de dados que compreende observações de produtividade e teores de açúcar em uvas de videiras de 11 cultivares brancas e 17 cultivares tintas ao longo de quase 3 décadas revelou alguns padrões. No longo prazo (vários anos ou décadas), a produtividade e o teor de açúcar mostraram correlação negativa - maiores cargas de fruto resultaram em menores teores de açúcar na colheita. No entanto, alguns cálculos e análises de componentes principais permitiram definir que as oscilações da produtividade anual e do teor anual de açúcar no curto prazo podem ser melhor explicadas se for considerando apenas os resultados de um e dois anos anteriores de cada safra como pontos de referência. Seguindo esses cálculos, pôde-se notar uma clara separação entre eventos de El Niño e eventos de La Niña. Nos vinhedos desta região, os eventos de La Niña tipicamente tendem a resultar tanto em maior produtividade quanto em maior teor de açúcar na colheita. Em contraste, eventos de El Niño tipicamente tendem a causar menor produtividade e menor teor de açúcar na colheita. Anos neutros tipicamente apresentam resultados mais próximos aos eventos de El Niño.(AU)

Role of Nitric Oxide in the Cardiovascular System of South American Rattlesnakes (Crotalus durissus).

AbstractUnderstanding the basis of vascular tonus regulation is fundamental to comprehending cardiovascular physiology. In the present study, we used the recently developed decerebrate rattlesnake preparation to investigate the role of nitric oxide (NO) in the control of vascular tonus in a squamate reptile. This preparation allowed multiple concomitant cardiovascular parameters to be monitored, while avoiding the deleterious effect of anesthetic drugs on autonomic modulation. We observed that both systemic and pulmonary circuits were clearly responsive to NO signaling. NO increased vascular conductance in the systemic and pulmonary systems. Vasodilation by NO of the systemic circulation was compensated by cardiovascular alterations involving venous return, cardiac output, and cardiac shunt adjustments. The cardiac shunt seemed to be actively used for hemodynamic adjustments via modulation of the pulmonary artery constriction. N(ω)-nitro-L-arginine methyl ester injection demonstrated that NO contributes to modulating resting vasodilation in the systemic circuit. In contrast, NO-mediated vasodilation did not have an important role in the pulmonary circulation in inactive decerebrated snakes at 25°C. These responses vary importantly from those described for anesthetized snakes.

Copper induces damage, oxidative stress and cell death in endothelium of chronic intoxicated Wistar rats / El cobre induce daño, estrés oxidativo y muerte celular en el endotelio de ratas Wistar intoxicadas

SUMMARY: Reactive Oxygen Species (ROS) are part of the functional balance of various systems, they can generate cellular damage by oxidative stress associated with disease processes such as atherosclerosis, cardiovascular disease, diabetes, and aging. Some studies report that copper induces damage to the endothelium, which could be associated with cardiovascular pathologies. This study was an experimental comparative, prospective, longitudinal, and controlled clinical trial in a murine animal model. Twenty-four male Wistar rats were included, the distribution of the groups was time-depending chronic exposition to copper, and a control group. Results show gradual alterations in the groups treated with copper: areas with loss of the endothelium, signs of disorganization of smooth muscle fibers in the tunica media, as well as areas with the fragmentation of the elastic sheets. A significant statistical difference was observed in the active- Caspase-3 analysis expression in the aortic endothelium and endothelium of the capillaries and arterioles of the lung between the control group vs 300 ppm of copper. Expression of eNOS was detected in the endothelium of the aorta and vessels of the lung. Our study shows histological changes in the walls of the great vessels of intoxicated rats with copper, and the increment of inflammatory cells in the alveoli of the study model, mainly at a high dose of copper exposition. These results will be useful to understand more about the mediators involved in the effect of copper over endothelium and cardiovascular diseases in chronic intoxication in humans.

RESUMEN: Las Especies Reactivas de Oxígeno (ROS) son parte del equilibrio funcional de varios sistemas, pueden generar daño celular por estrés oxidativo asociado a procesos patológicos como aterosclerosis, enfermedades cardiovasculares, diabetes y envejecimiento. Algunos estudios informan que el cobre induce daños en el endotelio, lo que podría estar asociado a patologías cardiovasculares. Este estudio fue un ensayo clínico experimental comparativo, prospectivo, longitudinal y controlado en un modelo animal murino. Se incluyeron veinticuatro ratas Wistar macho, la distribución de los grupos fue la exposición crónica al cobre en función del tiempo y un grupo de control. Los resultados muestran alteraciones graduales en los grupos tratados con cobre: áreas con pérdida del endotelio, signos de desorganización de las fibras musculares lisas en la túnica media, así como áreas con la fragmentación de las láminas elásticas. Se observó una diferencia estadística significativa en la expresión del análisis de caspasa-3 activa en el endotelio aórtico y el endotelio de los capilares y arteriolas del pulmón entre el grupo de control frente a 300 ppm de cobre. Se detectó expresión de eNOS en el endotelio de la aorta y los vasos del pulmón. Nuestro estudio muestra cambios histológicos en las paredes de los grandes vasos de ratas intoxicadas con cobre, y el incremento de células inflamatorias en los alvéolos del modelo de estudio, principalmente a una alta dosis de exposición de cobre. Estos resultados serán útiles para comprender más sobre los mediadores involucrados en el efecto del cobre sobre el endotelio y las enfermedades cardiovasculares en la intoxicación crónica en humanos.

Decreased NO production in endothelial cells exposed to plasma from ME/CFS patients.

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating disease characterized by severe and persistent fatigue. Along with clinical studies showing endothelial dysfunction (ED) in a subset of ME/CFS patients, we have recently reported altered ED-related microRNAs in plasma from affected individuals. Inadequate nitric oxide (NO), mainly produced by the endothelial isoform of nitric oxide synthase (eNOS) in endothelial cells (ECs), is a major cause of ED. In this study, we hypothesized that plasma from that cohort of ME/CFS patients induces eNOS-related ED in vitro. To test this, we cultured human umbilical vein endothelial cells (HUVECs) in the presence of plasma from either ME/CFS patients (ME/CFS-plasma, n = 11) or healthy controls (HC-plasma, n = 12). Then, we measured the NO production in the absence and presence of tyrosine kinase and G protein-coupled receptors agonists (TKRs and GPCRs, respectively), well-known to activate eNOS in ECs. Our data showed that HUVECs incubated with ME/CFS-plasma produced less NO either in the absence or presence of eNOS activators compared to ones in presence of HC-plasma. Also, the NO production elicited by bradykinin, histamine, and acetylcholine (GPCRs agonists) was more affected than the one triggered by insulin (TKR agonist). Finally, inhibitory eNOS phosphorylation at Thr495 was higher in HUVECs treated with ME/CFS-plasma compared to the same treatment with HC-plasma. In conclusion, this study in vitro shows a decreased NO production in HUVECs exposed to plasma from ME/CFS patients, suggesting an unreported role of eNOS in the pathophysiology of this disease.

Nitric oxide regulates adhesiveness, invasiveness, and migration of anoikis-resistant endothelial cells

Anoikis is a type of apoptosis that occurs in response to the loss of adhesion to the extracellular matrix (ECM). Anoikis resistance is a critical mechanism in cancer and contributes to tumor metastasis. Nitric oxide (NO) is frequently upregulated in the tumor area and is considered an important player in cancer metastasis. The aim of this study was to evaluate the effect of NO on adhesiveness, invasiveness, and migration of anoikis-resistant endothelial cells. Here, we report that anoikis-resistant endothelial cells overexpress endothelial nitric oxide synthase. The inhibition of NO release in anoikis-resistant endothelial cells was able to decrease adhesiveness to fibronectin, laminin, and collagen IV. This was accompanied by an increase in cell invasiveness and migration. Furthermore, anoikis-resistant cell lines displayed a decrease in fibronectin and collagen IV protein expression after L-NAME treatment. These alterations in adhesiveness and invasiveness were the consequence of MMP-2 up-regulation observed after NO release inhibition. The decrease in NO levels was able to down-regulate the activating transcription factor 3 (ATF3) protein expression. ATF3 represses MMP-2 gene expression by antagonizing p53-dependent trans-activation of the MMP-2 promoter. We speculate that the increased release of NO by anoikis-resistant endothelial cells acted as a response to restrict the MMP-2 action, interfering in MMP-2 gene expression via ATF3 regulation. The up-regulation of nitric oxide by anoikis-resistant endothelial cells is an important response to restrict tumorigenic behavior. Without this mechanism, invasiveness and migration potential would be even higher, as shown after L-NAME treatment.

Identification of genetic risk factors associated with ischaemic stroke in young Mexican patients.

BACKGROUND: Numerous polymorphisms in candidate genes coding for haemostatic system proteins have been proposed as risk factors for thrombosis. METHODS: We performed a case-control study of consecutive ischaemic stroke survivors aged ≤45 years, treated at our neurology department from 2006 to 2014. Polymerase chain reaction-restriction fragment length polymorphism identified the following polymorphisms: Thr325Ile and Ala147Thr in TAFI, 4G/5G in PAI-1, PLA1/A2 in platelet glycoprotein IIb/IIIa, Glu298Asp in eNOS, and C677T in 5,10-MTHFR. A multivariate logistic regression analysis was performed to evaluate the independent risk of stroke. RESULTS: 204 cases and 204 age- and sex-matched controls were included in the study. Clinical and genetic variables associated with ischaemic stroke were hypertension (P=.03), tobacco use (P=.02), and the polymorphisms Glu298Asp (genotype: P=.001, allele frequency: P=.001) and C677T (genotype: P=.01); the Ala147Thr, Thr325IIe, 4G/5G, and PLA1/A2 mutations were not associated with ischaemic stroke. The 298Asp (P=.03) and T (P=.01) alleles, hypertension (P=.03), tobacco use (P=.01) and family history of stroke (P=.04) were identified as independent risk factors. CONCLUSION: The polymorphisms Glu298Asp and C677T, affecting the eNOS and 5,10-MTHFR enzymes, respectively, and smoking, hypertension, and family history of stroke were associated with ischaemic stroke in young Mexican patients; this was not the case for the Thr325Ile, Ala147Thr, 4G/5G, and PLA1/A2 polymorphisms of the genes coding for fibrinolytic proteins and platelet receptors.

Chronic mercury exposure induces oxidative stress in female rats by endothelial nitric oxide synthase uncoupling and cyclooxygenase-2 activation, without affecting oestrogen receptor function.

Mercury has been shown to be a significant health risk factor and is positively associated with cardiovascular diseases. Evidence reveals that men are more likely to develop cardiovascular diseases than women during reproductive age. However, the effects of mercury in females remain poorly investigated, despite the finding that female hormones demonstrate a cardioprotective role. In the present study, we evaluated whether chronic mercury chloride exposure could alter blood pressure and vascular function of the female rat aorta. Ten-week-old female Wistar rats were divided into two groups: control (vehicle) and mercury treated (first dose of 4.6 µg/kg, subsequent daily doses of 0.07 µg/kg), im. Mercury treatment did not modify systolic blood pressure (SBP) but increased vascular reactivity due to the reduction of nitric oxide bioavailability associated with the increase in reactive oxygen species from endothelial nitric oxide synthase (eNOS) uncoupling. Furthermore, increased participation of the cyclooxygenase-2 pathway occurred through an imbalance in thromboxane 2 and prostacyclin 2. However, the oestrogen signalling pathway was not altered in either group. These results demonstrated that chronic exposure to mercury in females induced endothelial dysfunction and, consequently, increased aortic vascular reactivity, causing vascular damage to the female rat aorta and representing a risk of cardiovascular diseases.

Metastatic Melanoma Progression Is Associated with Endothelial Nitric Oxide Synthase Uncoupling Induced by Loss of eNOS:BH4 Stoichiometry.

Melanoma is the most aggressive type of skin cancer due to its high capability of developing metastasis and acquiring chemoresistance. Altered redox homeostasis induced by increased reactive oxygen species is associated with melanomagenesis through modulation of redox signaling pathways. Dysfunctional endothelial nitric oxide synthase (eNOS) produces superoxide anion (O2-•) and contributes to the establishment of a pro-oxidant environment in melanoma. Although decreased tetrahydrobiopterin (BH4) bioavailability is associated with eNOS uncoupling in endothelial and human melanoma cells, in the present work we show that eNOS uncoupling in metastatic melanoma cells expressing the genes from de novo biopterin synthesis pathway Gch1, Pts, and Spr, and high BH4 concentration and BH4:BH2 ratio. Western blot analysis showed increased expression of Nos3, altering the stoichiometry balance between eNOS and BH4, contributing to NOS uncoupling. Both treatment with L-sepiapterin and eNOS downregulation induced increased nitric oxide (NO) and decreased O2• levels, triggering NOS coupling and reducing cell growth and resistance to anoikis and dacarbazine chemotherapy. Moreover, restoration of eNOS activity impaired tumor growth in vivo. Finally, NOS3 expression was found to be increased in human metastatic melanoma samples compared with the primary site. eNOS dysfunction may be an important mechanism supporting metastatic melanoma growth and hence a potential target for therapy.

Angiotensin II type 1 receptor is involved in hypertension and vascular alterations caused by environmental toxicant hexachlorobenzene.

Environmental hexachlorobenzene (HCB) increases blood pressure (BP) in female rats, causing alterations in arterial structure and function. Here we study the role of Angiotensin II receptor type 1 (AT1) in HCB-induced hypertension through the use of AT1 antagonist losartan. HCB-treated male rats showed a 22.7% increase in BP which was prevented by losartan. Losartan blocked HCB-induced changes in arterial morphology (decreased aorta cell number and increased wall thickness). Losartan also prevented HCB-induced alterations in artery relaxation by acetylcholine and nitroprusside but not the reduction in the maximum contraction by phenylephrine. Losartan rescued arterial molecular alterations caused by HCB (i.e. an increase in TGF-ß1 and AT1 expression and a decrease in eNOS expression and nitrite levels) and reduced hydrogen sulfide plasma concentration. In conclusion: in this work we demonstrate that AT1 activity is involved in HCB effects on the vascular system leading to hypertension.

Honeymoon Period in Newborn Rats With CDH Is Associated With Changes in the VEGF Signaling Pathway.

Background: Patients with congenital diaphragmatic hernia (CDH) have a short postnatal period of ventilatory stability called the honeymoon period, after which changes in pulmonary vascular reactivity result in pulmonary hypertension. However, the mechanisms involved are still unknown. The aim of this study was to evaluate mechanical ventilation's effect in the honeymoon period on VEGF, VEGFR-1/2 and eNOS expression on experimental CDH in rats. Materials and Methods: Neonates whose mothers were not exposed to nitrofen formed the control groups (C) and neonates with left-sided defects formed the CDH groups (CDH). Both were subdivided into non-ventilated and ventilated for 30, 60, and 90 min (n = 7 each). The left lungs (n = 4) were evaluated by immunohistochemistry of the pulmonary vasculature (media wall thickness), VEGF, VEGFR-1/2 and eNOS. Western blotting (n = 3) was performed to quantify the expression of VEGF, VEGFR-1/2 and eNOS. Results: CDH had lower biometric parameters than C. Regarding the pulmonary vasculature, C showed a reduction in media wall thickness with ventilation, while CDH presented reduction with 30 min and an increase with the progression of the ventilatory time (honeymoon period). CDH and C groups showed different patterns of VEGF, VEGFR-1/2 and eNOS expressions. The receptors and eNOS findings were significant by immunohistochemistry but not by western blotting, while VEGF was significant by western blotting but not by immunohistochemistry. Conclusion: VEGF, its receptors and eNOS were altered in CDH after mechanical ventilation. These results suggest that the VEGF-NO pathway plays an important role in the honeymoon period of experimental CDH.

Protective effect of Sika Deer bone polypeptide extract on dexamethasone-induced osteoporosis in rats

BACKGROUND: Osteoporosis attacks approximately 10% of the population worldwide. Sika Deer (Cervus nippon), one of China's precious traditional medicinal animals, has been widely recorded in ancient Chinese medical books and claimed for centuries to have numerous medical benefits including bone strengthening. This study aimed to find the use of Sika Deer bone in treating osteoporosis according to traditional records and to investigate the protective effect of Sika Deer bone polypeptide extract on glucocorticoidinduced osteoporosis (GIOP) in rats. RESULTS: Sika Deer bone polypeptide extract could increase serum Ca2+ and BGP, decrease serum P3+, ALP, PTH, and CT, but had no effect on serum NO in rats with GIOP. The immunohistochemical iNOS results of the rats' distal femur were negative in each group. Besides the model group, the eNOS color reaction in osteoblasts was strongly positive in the other three groups. CONCLUSIONS: Sika Deer bone polypeptide extract can improve pathological changes in the microstructure and stimulate the expression of eNOS in osteoblasts. The protective effect on bone might be mediated by eNOS-dependent NO generation.

Nitric oxide determines the development of actinomycetoma by Nocardia brasiliensis in eNOS knockout C57BL/6 mice.

Mycetoma is a chronic human infectious disease that produces severe deformation frequently in the lower extremities. Etiological agents include fungi (eumycetoma) and bacteria (actinomycetoma) that produce similar clinical and microscopic changes. The clinical appearance includes swelling, abscesses, ulcers, scars and sinuses that drain purulent material with microbe microcolonies. The pathogenesis of actinomycetoma has been studied mainly in rodents. Using this approach, it was found that Nocardia brasiliensis produces proteases that may play a role in tissue damage, as well as immunosuppressive molecules, such as brasilicardin A. Nitric oxide (NO) is a molecule with biological activities depending on its local concentration. Its effect on killing intracellular bacteria such as Mycobacterium tuberculosis has been known for decades. NO plays an important role in innate and adaptive immunity. It can promote or suppress some biological activities despite its short half-ife. NO is produced by three different nitric oxide synthases (NOS). We used the genetic blockade of eNOS in C57BL/6 mice to demonstrate the role of NO in actinomycetoma development. Inflammation and actinomycetoma were prevented in genetically modified mice infected with N. brasiliensis. T cell proliferation was increased in these rodents, and antibody production, IL-6 and IL-10 expression were similar and TNF-α was lower.

The role of vascular endothelial protein tyrosine phosphatase on nitric oxide synthase function in diabetes: from molecular biology to the clinic.

Endothelial nitric oxide synthase (eNOS) and receptor-type vascular endothelial protein tyrosine phosphatase (VE-PTP) are one of the majors signaling pathways related to endothelial health in diabetes. Several reports have shown that the inhibition of VE-PTP can lead the nitric oxide production, although repeated studies showed that VE-PTP regulated the eNOS exclusive at Ser1177 in indirect-manner. A recent, exciting paper (Siragusa et al. in Cardiovasc Res, 2020. https://doi.org/10.1093/cvr/cvaa213 ), showing that VE-PTP regulates eNOS in a direct-manner, dephosphorylating eNOS at Tyr81 and indirect at Ser1177 and the effects of a VE-PTP inhibitor, AKB-9778, in the blood pressure from diabetic patients.