Non-selective Cyclooxygenase Inhibitor Research Articles

Egg white-derived peptides prevent cardiovascular disorders induced by mercury in rats: Role of angiotensin-converting enzyme (ACE) and NADPH oxidase

The study aimed to investigate the effects of egg white hydrolysate (EWH) on vascular disorders induced by mercury (Hg). For this, male Wistar rats were treated for 60days: Untreated (saline, i.m.); Mercury (HgCl2, i.m., 1st dose 4.6μg/kg, subsequent doses 0.07μg/kg/day); Hydrolysate (EWH, gavage, 1g/kg/day); Hydrolysate-Mercury. Systolic (SBP) and diastolic (DBP) blood pressure measurement and vascular reactivity experiments in aorta were performed. We analyzed endothelial dependent and independent vasodilator responses and vasoconstrictor response to phenylephrine (Phe) in absence and presence of endothelium, a NOS inhibitor, a NADPH oxidase inhibitor, the superoxide dismutase, a non-selective COX inhibitor, a selective COX-2 inhibitor, an AT-1 receptors blocker. In situ superoxide anion production, SOD-1, NOX-4, p22phox, COX-2 and AT-1 mRNA levels and NOX-1 protein expression were performed in aorta while the determination of angiotensin converting enzyme (ACE) activity was measured in plasma. As results, EWH prevented the increase in SBP and Phe responses and the endothelial dysfunction elicited by Hg, which was related to decreased ACE activity and NOX activation by EWH and, subsequently, alleviated ROS production and improved NO bioavailability in aorta. In conclusion, EWH could be considered as alternative or complementary treatment tools for Hg-induced cardiovascular damage.

Central mediators of the zymosan-induced febrile response.

Zymosan is a fungal cell wall protein-carbohydrate complex that is known to activate inflammatory pathways through the Toll-like receptors and is commonly used to induce fever. Nevertheless, the central mediators that are involved in the zymosan-induced febrile response are only partially known. The present study evaluated the participation of prostaglandins, substance P, endothelin-1 (ET-1), and endogenous opioids (eOPs) in the zymosan-induced febrile response by using inhibitors and antagonists in male Wistar rats. Both nonselective (indomethacin) and selective (celecoxib) cyclooxygenase inhibitors reduced the febrile response induced by an intraperitoneal (i.p.) injection of zymosan. Indomethacin also blocked the increase in the prostaglandin E2 levels in the cerebrospinal fluid. An intracerebroventricular injection of the neurokinin-1, ETB, and μ-opioid receptor antagonists also reduced the febrile response induced by the i.p. injected zymosan. Moreover, the μ-opioid receptor antagonist CTAP also reduced the febrile response induced by intra-articular injection of zymosan. These results demonstrate that prostaglandins, substance P, ET-1, and eOPs are central mediators of the zymosan-induced febrile response.

Effectiveness of various non-steroidal anti-inflammatory drugs in pain management of patients with vertebral fracture: A comparative clinical study

Purpose: To study the effectiveness of various nonsteroidal anti-inflammatory drugs (NSAIDs) in patients with vertebral fractures. Methods: A total of 78 patients (17 males and 61 females) with a mean age of 69.5 years were included. The major inclusion criterion was an osteoporotic vertebral fracture between T7 and L3. The exclusion criteria included fractures above T7 and below L3; and other bone disorders such as disc herniation, spondylolisthesis, an infection, or a tumour. Pain intensity was assessed with the aid of a 10-point visual analogue scale (VAS). Bone mineral density (BMD) data, delay in reunion, and any other matter of significance, were discussed with the treating doctors and cross-checked with independent doctors. The NSAIDs given were non-selective cyclo-oxygenase (COX) inhibitors (naproxen, indomethacin and flurbiprofen) and selective COX 2 inhibitors (piroxicam, celecoxib, and rofecoxib). All data were compiled and appropriately analysed. Results: Some NSAIDs interfered with bone healing. No male required surgery, but two females taking naproxen, one taking flurbiprofen, and another taking celecoxib, required surgery. In terms of bone healing, non-union and delay in reunion were more evident in those taking naproxen, indomethacin or flurbiprofen than in those taking piroxicam, celecoxib, or rofecoxib. All T scores were lower than -2.5, indicating that all the patients were osteoporotic. Positive changes in T scores after 12 weeks were evident only in those taking rofecoxib, celecoxib, or piroxicam. VAS scores were also better in these patients. Conclusions: Celecoxib seems to be the best of the six NSAIDs in terms of both analgesia and bone health. The study recommends the use of celecoxib in patients with vertebral fractures. Keywords: Orthopaedic, NSAID, COX, Bone reunion, Analgesic activity, Pain management, T score

Inhibition of microsomal prostaglandin E-synthase-1 (mPGES-1) selectively suppresses PGE2 in an in vitro equine inflammation model.

Inhibition of prostaglandin E2 (PGE2) production effectively limits inflammation in horses, however nonspecific prostaglandin blockade via cyclooxygenase (COX) inhibition elicits deleterious gastrointestinal side effects in equine patients. Thus, more selective PGE2 targeting therapeutics are needed to treat inflammatory disease in horses. One potential target is microsomal prostaglandin E-synthase-1 (mPGES-1), which is the terminal enzyme downstream of COX-2 in the inducible PGE2 synthesis cascade. This enzyme has yet to be studied in equine leukocytes, which play a pivotal role in equine inflammatory disease. The objective of this study was to determine if mPGES-1 is a PGE2-selective anti-inflammatory target in equine leukocytes. To evaluate this objective, leukocyte-rich plasma (LRP) was isolated from equine whole blood collected via jugular venipuncture of six healthy adult horses of mixed breeds and genders. LRP was primed with granulocyte-monocyte colony-stimulating factor (GM-CSF) and stimulated with lipopolysaccharide (LPS) in the presence or absence of an mPGES-1 inhibitor (MF63), a COX-2 inhibitor (NS-398), or a nonselective COX inhibitor (indomethacin). Following treatment, mPGES-1 and COX-2 mRNA and protein levels were measured via qPCR and western blot, respectively, and PGE2, thromboxane (TXA2) and prostacyclin (PGI2) levels were measured in cellular supernatants via ELISA. This study revealed that LPS significantly increased mPGES-1 mRNA, but not protein levels in equine LRP as measured by qPCR and western blot, respectively. In contrast, COX-2 mRNA and protein were coordinately induced by LPS. Importantly, treatment of LPS-stimulated leukocytes with indomethacin and NS-398 significantly reduced extracellular concentrations of multiple prostanoids (PGE2, TXA2 and PGI2), while the mPGES-1 inhibitor MF63 selectively inhibited PGE2 production only. mPGES-1 inhibition also preserved higher basal levels of PGE2 production when compared to either COX inhibitor, which might be beneficial in a clinical setting. In conclusion, this work identifies mPGES-1 as a key regulator of PGE2 production and a PGE2-selective target in equine leukocytes. This study demonstrates that mPGES-1 is a potentially safer and effective therapeutic target for treatment of equine inflammatory disease when compared to traditional non-steroidal anti-inflammatory drugs.

Diclofenac but not celecoxib improves endothelial function in rheumatoid arthritis: A study in adjuvant-induced arthritis

Background and aimsWe aimed at investigating the effect of celecoxib (COX-2 selective inhibitor) and diclofenac (non-selective COX inhibitor) on endothelial function, and at identifying the underlying mechanisms in adjuvant-induced arthritis (AIA). MethodsAt the first signs of AIA, diclofenac (5 mg/kg twice a day, i.p), celecoxib (3 mg/kg/day, i.p) or saline (Vehicle) was administered for 3 weeks. Endothelial function was studied in aortic rings relaxed with acetylcholine (Ach) with or without inhibitors of NOS, arginase, EDHF and superoxide anions (O2−°) production. Aortic expression of eNOS, Ser1177-phospho-eNOS, COX-2, arginase-2, p22phox and p47phox was evaluated by Western blotting analysis. Arthritis scores, blood pressure, glycaemia and serum ADMA levels were measured. ResultsDiclofenac and celecoxib significantly reduced arthritis score to the same extent (p<0.05). As compared to vehicle-treated AIA, celecoxib did not change whereas diclofenac improved endothelial function (p<0.05) through increased EDHF production, decreased arginase activity and expression, decreased superoxide anions production and expression of p22phox and p47phox. Diclofenac but not celecoxib significantly enhanced blood pressure and serum ADMA levels. Glycaemia was unchanged by both treatments. ConclusionsOur study reveals that the effect of NSAIDs on endothelial function cannot be extrapolated from their impact on arthritis severity and suggest that changes in blood pressure and plasma ADMA levels may not be useful to predict CV risk of NSAIDs in RA.

Preoperative flurbiprofen axetil administration for acute postoperative pain: a meta-analysis of randomized controlled trials.

Non-steroidal anti-inflammatory drugs have been shown to effectively decrease postoperative pain and reduce opioid requirements. Flurbiprofen axetil is an injectable non-selective cyclooxygenase inhibitor that has a high affinity for inflammatory tissues to achieve targeted drug therapy and prolonged duration of action. This meta-analysis examined the use of preoperative flurbiprofen axetil and its impact on postoperative analgesia. An electronic literature search of the Library of PubMed, Cochrane CENTRAL, and EMBASE databases was conducted in Feb 2016. Searches were limited to randomized controlled trials. The primary outcome was pain scores. The secondary outcomes included cumulative postoperative opioid consumption and opioid-related adverse effects. A total of nine RCT studies involving 457 patients were included in this study. Compared to patients without perioperative flurbiprofen axetil, patients treated with preoperative flurbiprofen axetil had lower pain scores at 2h (SMD -1.00; 95% CI -1.57 to -0.43, P=0.0006), 6h (SMD -1.22; 95% CI -2.01 to -0.43; P=0.002), 12h (SMD -1.19; 95% CI -2.10 to -0.28; P=0.01), and 24h (SMD -0.79; 95% CI -1.31 to -0.27; P=0.003) following surgery. Preoperative flurbiprofen axetil had no significant effect on postoperative opioid consumption (SMD -13.11; 95% CI -34.56 to 8.33; P=0.23). There was no significant difference between the groups with regard to adverse effects. Compared to patients with postoperative flurbiprofen axetil, however, preoperative flurbiprofen axetil resulted in decreased pain score only at 2h after operation. Preoperative use of flurbiprofen axetil will result in significantly lower postoperative pain scores, but no difference in nausea, vomiting, and opioid consumption compared to those who did not receive flurbiprofen axetil. However, more homogeneous and well-designed clinical studies are necessary to determine whether preoperative flurbiprofen axetil administration has more efficacy than that given at the end of surgery.

Trypanosoma cruzi: Inhibition of infection of human monocytes by aspirin

Cell invasion by Trypanosoma cruzi and its intracellular replication are essential for progression of the parasite life cycle and development of Chagas disease. Prostaglandin E2 (PGE2) and other eicosanoids potently modulate host response and contribute to Chagas disease progression. In this study, we evaluated the effect of aspirin (ASA), a non-selective cyclooxygenase (COX) inhibitor on the T. cruzi invasion and its influence on nitric oxide and cytokine production in human monocytes. The pretreatment of monocytes with ASA or SQ 22536 (adenylate-cyclase inhibitor) induced a marked inhibition of T. cruzi infection. On the other hand, the treatment of monocytes with SQ 22536 after ASA restored the invasiveness of T. cruzi. This reestablishment was associated with a decrease in nitric oxide and PGE2 production, and also an increase of interleukin-10 and interleukin-12 by cells pre-treated with ASA. Altogether, these results reinforce the idea that the cyclooxygenase pathway plays a fundamental role in the process of parasite invasion in an in vitro model of T. cruzi infection.

Do nitric oxide synthase and cyclooxygenase contribute to sweating response during passive heating in endurance-trained athletes?

The aim of our study was to determine if habitual endurance training can influence the relative contribution of nitric oxide synthase (NOS) and cyclooxygenase (COX) in the regulation of sweating during a passive heat stress in young adults. Ten trained athletes and nine untrained counterparts were passively heated until oral temperature (as estimated by sublingual temperature, Tor) increased by 1.5°C above baseline resting. Forearm sweat rate (ventilated capsule) was measured at three skin sites continuously perfused with either lactated Ringer's solution (Control), 10 mmol/L NG‐nitro‐L‐arginine methyl ester (L‐NAME, non‐selective NOS inhibitor), or 10 mmol/L ketorolac (Ketorolac, non‐selective COX inhibitor) via intradermal microdialysis. Sweat rate was averaged for each 0.3°C increase in Tor. Sweat rate at the L‐NAME site was lower than Control following a 0.9 and 1.2°C increase in Tor in both groups (all P ≤ 0.05). Relative to the Control site, NOS‐inhibition reduced sweating similarly between the groups (P = 0.51). Sweat rate at the Ketorolac site was not different from the Control at any levels of Tor in both groups (P > 0.05). Nevertheless, a greater sweat rate was measured at the end of heating in the trained as compared to the untrained individuals (P ≤ 0.05). We show that NOS contributes similarly to sweating in both trained and untrained individuals during a passive heat stress. Further, no effect of COX on sweating was measured for either group. The greater sweat production observed in endurance‐trained athletes is likely mediated by factors other than NOS‐ and COX‐dependent mechanisms.

Is Aspirin Still the Cornerstone of Antiplatelet Therapy in Patients With Coronary Artery Disease? An Historical and Practical Narrative Review

Aspirin is an irreversible and non-selective inhibitor of cyclo-oxygenase. It represents the cornerstone of antiplatelet therapy and is used in secondary prevention of cardiovascular disease. Disagreement over the optimal maintenance dosage still exists; in America and Europe the most used doses of aspirin are 81 mg and 100 mg daily, respectively. There is also debate on the formulation and route of administration of the loading dose. The latest studies advise chewable and non-enteric coated aspirin; intravenous administration represents an alternative for unconscious or shocked patients. Aspirin hypersensitivity is characterized by the onset of respiratory, mucocutaneous, and systemic symptoms. It is marginally considered, but its prevalence is significant. International cardiologic guidelines only report the possibility of desensitizing intolerant patients or, alternatively, administering one single antiplatelet agent. Desensitization can induce a temporary tolerance to the drug and consists of the administration of sequential and incremental doses of aspirin. Rapid desensitization protocols have proven to be safe and effective in the vast majority of cases, and they should be included in the management of these patients. New studies are being carried out comparing aspirin with other antiplatelet agents, and the results will be available shortly.

Aluminum exposure at human dietary levels promotes vascular dysfunction and increases blood pressure in rats: A concerted action of NAD(P)H oxidase and COX-2.

Aluminum (Al) is a non-essential metal and a significant environmental contaminant and is associated with a number of human diseases including cardiovascular disease. We investigated the effects of Al exposure at doses similar to human dietary levels on the cardiovascular system over a 60day period. Wistar male rats were divided into two major groups and received orally: 1) Low aluminum level - rats were subdivided and treated for 60days as follows: a) Untreated - ultrapure water; b) AlCl3 at a dose of 8.3mg/kg bw for 60days, representing human Al exposure by diet; and 2) High aluminum level - rats were subdivided and treated for 42days as follows: C) Untreated - ultrapure water; d) AlCl3 at 100mg/kg bw for 42days, representing a high level of human exposure to Al. Effects on systolic blood pressure (SBP) and vascular function of aortic and mesenteric resistance arteries (MRA) were studied. Endothelium and smooth muscle integrity were evaluated by concentration-response curves to acetylcholine (ACh) and sodium nitroprusside. Vasoconstrictor responses to phenylephrine (Phe) in the presence and absence of endothelium and in the presence of the NOS inhibitor L-NAME, the potassium channels blocker TEA, the NAD(P)H oxidase inhibitor apocynin, superoxide dismutase (SOD), the non-selective COX inhibitor indomethacin and the selective COX-2 inhibitor NS 398 were analyzed. Vascular reactive oxygen species (ROS), lipid peroxidation and total antioxidant capacity, were measured. The mRNA expressions of eNOS, NAD(P)H oxidase 1 and 2, SOD1, COX-2 and thromboxane A2 receptor (TXA-2 R) were also investigated. Al exposure at human dietary levels impaired the cardiovascular system and these effects were almost the same as Al exposure at much higher levels. Al increased SBP, decreased ACh-induced relaxation, increased response to Phe, decreased endothelial modulation of vasoconstrictor responses, the bioavailability of nitric oxide (NO), the involvement of potassium channels on vascular responses, as well as increased ROS production from NAD(P)H oxidase and contractile prostanoids mainly from COX-2 in both aorta and mesenteric arteries. Al exposure increased vascular ROS production and lipid peroxidation as well as altered the antioxidant status in aorta and MRA. Al decreased vascular eNOS and SOD1 mRNA levels and increased the NAD(P)H oxidase 1, COX-2 and TXA-2 R mRNA levels. Our results point to an excess of ROS mainly from NAD(P)H oxidase after Al exposure and the increased vascular prostanoids from COX-2 acting in concert to decrease NO bioavailability, thus inducing vascular dysfunction and increasing blood pressure. Therefore, 60-day chronic exposure to Al, which reflects common human dietary Al intake, appears to pose a risk for the cardiovascular system.

Impact of combined treatment with nimesulide and cisplatin on oral carcinoma cells.

BackgroundDespite significant advances in diagnosis and therapy, the rate of survival of patients with oral cancers still remains poor as an appropriate treatment has not been found yet, due to side effects of chemo/radiotherapy.AimThis study aimed to identify molecular mechanisms of cell death of oral cancer cells caused by treatment with a nonselective Cox-2 inhibitor in combination with a low-dose chemotherapeutic drug.MethodsSquamous cell carcinoma (SCC) cells SCC9 and SCC25 were subjected to mono- and combination therapy with nimesulide and cisplatin. Fluorescence-activated cell sorting (FACS), immunohistochemistry, high-pressure liquid chromatography (HPLC), microarray gene chips, and isobaric tags for a relative and absolute quantitation (iTRAQ) system were used.ResultsIncreased numbers of apoptotic and necrotic SCC9/SCC25 cells were detected after combined exposure. ATP levels and the energy charge of SCC9 cells were significantly decreased after both individual and combined treatment. We detected and quantified a responsible gene, keratin 6a, and 540 relevant proteins. In SCC25 cells, ATP levels significantly decreased only after combination therapy. After combined treatment of SCC9 cells, significant upregulation of Histon-H2A/H2B/H4 was found, with a local discovery false rate of 0.003 for Histon-H2A and 0.0027 for Histon-H2B, respectively.ConclusionCompared to the single-drug treatment, combined treatment of the oral cancer cells with nimesulide and cisplatin increases and induces necrosis and apoptosis through different pathways. A significant effect of the cytoplasmic increase was also observed in histones of cell lines SCC9 and SCC25 that were previously treated with combined nimesulide and cisplatin therapy.

Abstract 1349: NSAIDs: Multiple roles in multiple environments

Abstract Non steroidal drugs are mainly known for their activities and use as anti-inflammatory, antipyretic compounds. But, in recent observations, they are exposed to use as an effective alternative compounds to prevent or stimulate different metabolic activities and help in preventing various neoplastic progression. They have specific role in controlling estrogen metabolism during breast cancer progression. Sometimes, they are used as an apoptotic induction in various cancers. Their role in hypoxia induced proliferation is also showing promising results. Different NSAIDs will help to induce the activities of various tumor suppressor genes. As chronic inflammation increases the risk for various cancers, therefore, it is important to eliminate inflammation through anti-Inflammatory compounds where NSAIDs are playing a vital role. Most of them are acting to prevent inflammation either via selective or non-selective COX based mechanism. The non-selective COX inhibitor sulindac and the COX-2 selective inhibitor etodolac etc. have been shown to prevent the formation and cause regression of adenomas in patients with familial polyposis. Unfortunately, COX-1 and/or COX-2 inhibition and depletion of physiologically important prostaglandins is associated with gastrointestinal, renal and cardiovascular toxicities that limit the use of NSAIDs and COX-2 inhibitors for cancer chemoprevention In this particular study, we are using various NSAIDs in a radiation-induced estogren treated breast cancer model to establish their role in differential expression of various cancer related genes selected from different cell cycle pathways microarray. Selection of biomarkers from these altered genes will help to develop a valid strategy for cancer prevention through precision based molecular targeted therapy. Supported by Office of Academic Affairs, Honors Program, COBI, Hostos-CUNY, NY, USA (DR) and Tarapacá University, Arica, Chile (GMC). Citation Format: Gloria M. Calaf, Debasish Roy. NSAIDs: Multiple roles in multiple environments [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1349. doi:10.1158/1538-7445.AM2017-1349

Selective cyclooxygenase inhibition by SC-560 improves hepatopulmonary syndrome in cirrhotic rats.

ObjectiveHepatopulmonary syndrome (HPS) is characterized by hypoxia in patients with chronic liver disease. The mechanism of HPS includes pulmonary vasodilatation, inflammation, and angiogenesis. Prostaglandins synthesized by cyclooxygenases (COX) participate in vascular responsiveness, inflammation and angiogenesis, which can be modulated by COX inhibitors. We therefore evaluated the impact of COX inhibition in rats with common bile duct ligation (CBDL)-induced liver cirrhosis and HPS.MethodsCirrhotic rats were randomly allocated to receive non-selective COX inhibitor (indomethacin), selective COX-1 inhibitor (SC-560), or COX-2 inhibitor (celecoxib) for 14 days. After that, hemodynamic parameters, severity of hypoxia and intrapulmonary shunts, liver and renal biochemistry parameters, histological finding and protein expressions were evaluated.ResultsNon-selective COX inhibition by indomethacin improved hepatic fibrosis and pulmonary inflammation in cirrhotic rats with HPS. It also decreased mean arterial blood pressure, portal pressure, and alleviated hypoxia and intrapulmonary shunts. However, indomethacin increased mortality rate. In contrast, selective COX inhibitors neither affected hemodynamics nor increased mortality rate. Hypoxia was improved by SC-560 and celecoxib. In addition, SC-560 decreased intrapulmonary shunts, attenuated pulmonary inflammation and angiogenesis through down-regulating COX-, NFκB- and VEGF-mediated pathways.ConclusionSelective COX-1 inhibitor ameliorated HPS by mitigating hypoxia and intrapulmonary shunts, which are related to anti-inflammation and anti-angiogenesis.

Case Report: Nicolau syndrome due to etofenamate injection.

Nicolau syndrome, also known as embolia cutis medicomentosa, is a rare complication characterized by tissue necrosis that occurs after injection of drugs. The exact pathogenesis is uncertain, but there are several hypotheses, including direct damage to the end artery and cytotoxic effects of the drug. Severe pain in the immediate postinjection period and purplish discoloration of the skin with reticulate pigmentary pattern is characteristic of this syndrome. Diagnosis is mainly clinical and there is no standard treatment for the disease. Etofenamate is a non-steroidal anti-inflammatory drug and a non-selective cyclooxygenase inhibitor. Cutaneous adverse findings caused by etofenamate are uncommon. Herein, we present a case with diagnosis of Nicolau syndrome due to etofenamate injection, which is a rare occurrence.

Relaxation induced by the nitric oxide donor and cyclooxygenase inhibitor NCX2121 in renal hypertensive rat aortas

There is an imbalance between contractile and relaxing endothelial factors in hypertension which induces vascular dysfunction. It involves cyclooxygenase (COX) due to production of vasoconstrictor agonists such as thromboxane A2 (TXA2). In this work we used the NO-NSAID vasodilator compound NCX2121 that has nitric oxide (NO) in its structure and the non-selective COX inhibitor indomethacin. This class of pro-drug has been demonstrated hypotensive effect in animal models of hypertension without alteration in the arterial pressure of normotensive rats. It has been pointed a direct vasodilator effect of NO-NSAIDS which mechanism remains unclear. This study aimed to evaluate the cellular mechanisms involved in the NCX2121-induced relaxation in renal hypertensive two kidney-one clip (2K-1C) rat aorta with intact endothelium and denuded aortas. Our data demonstrated that NO was directly released from the compound NCX2121 in the cytosol of the vascular smooth muscle cells. The relaxation induced by NCX2121 was similar in 2K-1C and normotensive two kidney (2K). It was impaired by the endothelium removal and NO-Synthase (NOS) inhibition in both rat aorta groups. The inhibition of the main NO target, soluble guanylyl-cyclase (sGC) with ODQ, abolished NCX2121-induced relaxation in denuded aorta. The expression of COX-1 and COX-2 as well the produced stable analog of Thromboxane A2 (TXA2) were higher in 2K-1C than in 2K. NCX2121 decreased the augmented production of TXA2 in 2K-1C rat aortas. In intact-endothelium aorta, ODQ impaired the relaxation induced by NCX2121 in 2K but it had no effect in 2K-1C rat aorta. Taken together, our results show that NCX2121-induced relaxation is due to the direct NO release inside the vascular smooth muscle cells and sGC activation in denuded aortas, whereas in intact endothelium aortas, NCX2121-induced relaxation could be due to eNOS activation and inhibition of prostanoids production. In addition, relaxation-induced by NCX2121 is not greater in normotensive than in hypertensive rat aortas because COX activity is higher in 2K-1C than in 2K rat aortas.

Anti-Proliferative Effects of Piroxicam and Nimesulide on A431 Human Squamous Carcinoma Cell Line

Background: Skin cancer is one of the most common types of cancer worldwide and non-steroidal anti-inflammatory drugs (NSAIDs) have been proposed for prevention and treatment of a variety of cancers. Objectives: In this study we aimed to evaluate the cytotoxic effects of piroxicam (a non-selective cyclooxygenase (COX) inhibitor) and nimesulide (a highly selective COX-2 inhibitor) on A431 human squamous carcinoma cell line. Methods: Squamous carcinoma cell line (A431) was cultured in RPMI medium containing 10% FBS and penicillin-streptomycin at 37°C and 5% CO2. Cells were treated with different concentrations of piroxicam and nimesulide (100 - 1000 µmol/L) for 24, 48 and 72 hours (h). Anti-proliferative effects were determined using MTT colorimetric assay. Results: Piroxicam and nimesulide reduced cell viability in a time and concentration dependent manner. The most cytotoxic effect was produced in 72 hours incubation time. The IC50 value of nimesulide was significantly lower than piroxicam in 24 and 72 hours, but not in 48 hours treatment duration. Conclusions: This study demonstrates that the administration of a highly selective COX-2 inhibitor could probably be more effective than a non-selective NSAID in reducing cancer cells proliferation and that COX-2 can possibly play an important role in skin cancer development.

Effects of indomethacin on prostanoid synthesis and vasomotor responsiveness in endothelium-denuded abdominal and thoracic aortas of Wistar rats

ABSTRACTIn endothelium-denuded abdominal (but not thoracic) aortas of rats, the nonselective cyclooxygenase (COX) inhibitor, indomethacin, suppressed contractions evoked by α-adrenergic agonists hypothetically mediated by prostanoids. We aimed to identify these non-endothelial-derived contractile prostanoids released by α-adrenergic receptors activation. Endothelium-denuded abdominal and thoracic aortas of Wistar rats were used for biochemical and functional analyses. Western blot analysis showed that COX-1 and COX-2 protein levels were respectively equivalent in endothelium-denuded abdominal and thoracic aortas. Enzyme immunoassay data supported direct evidence of phenylephrine-stimulated release of prostanoids (PGI2, PGE2, and PGF2α) by thoracic and abdominal aortas without endothelium, and their almost complete inhibition by 1 μM indomethacin. Isometric force measurements established that 10 μM indomethacin—but no lower concentrations—inhibited the contractions evoked by phenylephrine in endothelium-denuded abdominal aorta. In this preparation, 10 μM indomethacin also depressed the contractions provoked by angiotensin II and high K+ (80 mM). In fact, indomethacin (up to 1 mM) caused concentration-dependent reductions in all abovementioned contractile responses. In endothelium-denuded thoracic aortas, however, only 1 mM indomethacin significantly depressed the contractile activity stimulated by either phenylephrine, angiotensin II, or high K+. Hence, there was a clear quantitative difference in response to indomethacin between abdominal and thoracic aortas without endothelium. Altogether, the results indicate that prostanoids induced by phenylephrine in abdominal and thoracic aortas were derived from non-endothelial COX-mediated metabolism; notably, the decrease in prostanoid synthesis could not account for the inhibition of vasoconstrictor responses by indomethacin: Through COX-independent actions, indomethacin inhibited aortic smooth muscle contractility.

The Role of Cyclooxygenase Enzymes in the Effects of Losartan and Lisinopril on the Contractions of Rat Thoracic Aorta.

It was suggested that prostaglandins which are synthesized by cyclooxygenase (COX) enzymes contribute to the actions of angiotensin-converting enzyme (ACE) inhibition and angiotensin AT1 receptor antagonism and there is an interaction between ACE signaling pathway and COX enzymes. We aim to investigate the role of COX enzymes in the effects of losartan, an angiotensin II (Ang II) receptor antagonist or lisinopril, an ACE inhibitor, on the contractions of rat thoracic aorta in isolated tissue bath. Responses of losartan (10-6, 10-5, 10-4 M), lisinopril (10-6, 10-5, 10-4 M), and non-selective COX inhibitor dipyrone (10-4, 7 × 10-4, 2 × 10-3 M) alone to the contractions induced by phenylephrine (Phe) (10-7 M), potassium chloride (KCl) (6 × 10-2 M), Ang II (10-8 M) and responses of losartan or lisinopril in combination with dipyrone to the contractions induced by Phe or KCl were recorded. When used alone, dipyrone and losartan inhibited Phe, KCl, and Ang II-induced contractions, whereas lisinopril inhibited only Phe and Ang II-induced contractions. Inhibition of COX enzymes (COX-3, COX-3 + COX-1, COX-1+ COX-2 + COX-3 by dipyrone 10-4, 7 × 10-4, 2 × 10-3 M, respectively) augmented the relaxant effects of losartan or lisinopril. Also, dipyrone potentiated the effect of lisinopril on KCl-induced contractions. We suggest that dipyrone increases the smooth-muscle relaxing effects of losartan or lisinopril and that COX enzyme inhibition may have a role in the enhancement of this relaxation.

Mechanisms underlying sodium nitroprusside-induced tolerance in the mouse aorta: Role of ROS and cyclooxygenase-derived prostanoids

AimsTo determine the role of reactive oxygen species (ROS) on sodium nitroprusside (SNP)-induced tolerance. Additionally, we evaluated the role of ROS on NF-κB activation and pro-inflammatory cytokines production during SNP-induced tolerance. Main methodsTo induce in vitro tolerance, endothelium-intact or -denuded aortic rings isolated from male Balb-c mice were incubated for 15, 30, 45 or 60min with SNP (10nmol/L). Key findingsTolerance to SNP was observed after incubation of endothelium-denuded, but not endothelium-intact aortas for 60min with this inorganic nitrate. Pre-incubation of denuded rings with tiron (superoxide anion (O2−) scavenger), and the NADPH oxidase inhibitors apocynin and atorvastatin reversed SNP-induced tolerance. l-NAME (non-selective NOS inhibitor) and l-arginine (NOS substrate) also prevented SNP-induced tolerance. Similarly, ibuprofen (non-selective cyclooxygenase (COX) inhibitor), nimesulide (selective COX-2 inhibitor), AH6809 (prostaglandin PGF2α receptor antagonist) or SQ29584 [PGH2/thromboxane TXA2 receptor antagonist] reversed SNP-induced tolerance. Increased ROS generation was detected in tolerant arteries and both tiron and atorvastatin reversed this response. Tiron prevented tolerance-induced increase on O2– and hydrogen peroxide (H2O2) levels. The increase onp65/NF-κB expression and TNF-α production in tolerant arteries was prevented by tiron. The major new finding of our study is that SNP-induced tolerance is mediated by NADPH-oxidase derived ROS and vasoconstrictor prostanoids derived from COX-2, which are capable of reducing the vasorelaxation induced by SNP. Additionally, we found that ROS mediate the activation of NF-κB and the production of TNF-α in tolerant arteries. SignificanceThese findings identify putative molecular mechanisms whereby SNP induces tolerance in the vasculature.

The cessation of the long-term exposure to low doses of mercury ameliorates the increase in systolic blood pressure and vascular damage in rats

This study aimed to verify whether a prolonged exposure to low-level mercury promotes haemodynamic disorders and studied the reversibility of this vascular damage. Rats were divided into seven groups: three control groups received saline solution (im) for 30, 60 or 90 days; two groups received HgCl2 (im, first dose, 4.6μg/kg, subsequent doses 0.07μg/kg/day) for 30 or 60 days; two groups received HgCl2 for 30 or 60 days (im, same doses) followed by a 30-day washout period. Systolic blood pressure (SBP) was measured, along with analysis of vascular response to acetylcholine (ACh) and phenylephrine (Phe) in the absence and presence of endothelium, a nitric oxide (NO) synthase inhibitor, an NADPH oxidase inhibitor, superoxide dismutase, a non-selective cyclooxygenase (COX) inhibitor and an AT1 receptor blocker. Reactive oxygen species (ROS) levels and antioxidant power were measured in plasma. HgCl2 exposure for 30 and 60 days: a) reduced the endothelium-dependent relaxation; b) increased the Phe-induced contraction and the contribution of ROS, COX-derived vasoconstrictor prostanoids and angiotensin II acting on AT1 receptors to this response while the NO participation was reduced; c) increased the oxidative stress in plasma; d) increased the SBP only after 60 days of exposure. After the cessation of HgCl2 exposure, SBP, endothelium-dependent relaxation, Phe-induced contraction and the oxidative stress were normalised, despite the persistence of the increased COX-derived prostanoids. These results demonstrated that long-term HgCl2 exposure increases SBP as a consequence of vascular dysfunction; however, after HgCl2 removal from the environment the vascular function ameliorates.