Contribution of cyclooxygenase-1-dependent prostacyclin synthesis to bradykinin-induced dermal extravasation.

BACKGROUND: Non-allergic angioedema is a potentially life-threatening condition caused by accumulation of bradykinin and subsequent activation of bradykinin type 2 receptors (B2). Since COX activity plays a pivotal role in B2 signaling, the aim of this study was to determine which prostaglandins are the key mediators and which COX, COX-1 or COX-2, is predominantly involved. METHODS: We used Miles assays to assess the effects of inhibitors of COX, 5-lipoxygenase, epoxyeicosatrienoic acid generation, cytosolic phospholipase A2α and a variety of prostaglandin receptor antagonists on bradykinin-induced dermal extravasation in C57BL/6 and COX-1-deficient mice (COX-1-/-). In addition, the prostacyclin metabolite 6-keto-PGF1α was quantified by ELISA in subcutaneous tissue from C57BL/6 and human dermal microvascular endothelial cells. In the latter, 6-keto-PGF1α was also quantified and identified by LC-MS/MS. RESULTS: Unspecific COX inhibition by ibuprofen and diclofenac significantly reduced B2-mediated dermal extravasation in C57BL/6 but not COX-1-/-. Likewise, inhibition of cytosolic phospholipase A2α showed similar effects. Furthermore, extravasation in COX-1-/- was generally lower than in C57BL/6. Of the prostaglandin antagonists used, only the prostacyclin receptor antagonist RO1138452 showed a significant reduction of dermal extravasation. Moreover, 6-keto-PGF1α concentrations were increased after bradykinin treatment in subcutaneous tissue from C57BL/6 as well as in human dermal microvascular endothelial cells and this increase was abolished by diclofenac. CONCLUSION: Our findings suggest that COX-1-dependent prostacyclin production is critically involved in dermal extravasation after activation of B2 in small dermal blood vessels. Targeting prostacyclin production and/or signaling appears to be a suitable option for acute treatment of non-allergic angioedema.

Targeting cyclooxygenase enzyme for the adjuvant COVID-19 therapy.

Despite vigorous efforts, the COVID-19 pandemic continues to take a toll on the global health. The contemporary therapeutic regime focused on the viral spike proteins, viral 3CL protease enzyme, immunomodulation, inhibition of viral replication, and providing a symptomatic relief encouraged the repurposing of drugs to meet the urgency of treatment. Similarly, the representative drugs that proved beneficial to alleviate SARS-CoV-1, MERS-CoV, HIV, ZIKV, H1N1, and malarial infection in the past presented a sturdy candidature for ameliorating the COVID-19 therapeutic doctrine. However, most of the deliberations for developing effective pharmaceuticals proved inconsequential, thereby encouraging the identification of new pathways, and novel pharmaceuticals for capping the COVID-19 infection. The COVID-19 contagion encompasses a burst release of the cytokines that increase the severity of the infection mainly due to heightened immunopathogenicity. The pro-inflammatory metabolites, COX-2, cPLA2, and 5-LOX enzymes involved in their generation, and the substrates that instigate the origination of the innate inflammatory response therefore play an important role in intensifying and worsening of the tissue morbidity related to the coronavirus infection. The deployment of representative drugs for inhibiting these overexpressed immunogenic pathways in the tissues invaded by coronaviruses has been a matter of debate since the inception of the pandemic. The effectiveness of NSAIDs such as Aspirin, Indomethacin, Diclofenac, and Celecoxib in COVID-19 coagulopathy, discouraging the SARS viral replication, the inflammasome deactivation, and synergistic inhibition of H5N1 viral infection with representative antiviral drugs respectively, have provided a silver lining in adjuvant COVID-19 therapy. Since the anti-inflammatory NSAIDs and COXIBs mainly function by reversing the COX-2 overexpression to modulate the overproduction of pro-inflammatory cytokines and chemokines, these drugs present a robust treatment option for COVID-19 infection. This commentary succinctly highlights the various claims that support the status of immunomodulatory NSAIDs, and COXIBs in the adjuvant COVID-19 therapy.

Anti-inflammatory and anti-virus potential of poxytrins, especially protectin DX.

Poxytrins (Pufa Oxygenated Trienes) are dihydroxy derivatives from polyunsaturated fatty acids (PUFA) with adjacent hydroxyl groups to a conjugated triene having the specific E,Z,E geometry. They are made by the double action of one lipoxygenase or the combined actions of two lipoxygenases, followed by reduction of the resulting hydroperoxides with glutathione peroxidase. Because of their E,Z,E conjugated triene, poxytrins may inhibit inflammation associated with cyclooxygenase (COX) activities, and reactive oxygen species (ROS) formation. In addition of inhibiting COX activities, at least one poxytrin, namely protectin DX (PDX) from docosahexaenoic acid (DHA), has also been reported as able to inhibit influenza virus replication by targeting its RNA metabolism.

Vascular activity of infusion and fractions of Cymbopogon citratus (DC) Stapf. in human arteries.

ETHNOPHARMACOLOGICAL RELEVANCE: Cymbopogon citratus (DC.) Stapf has been traditionally used mainly for inflammatory diseases and hypertension. However, the mechanisms underlying its vascular activity remain to be fully characterized and the fractions responsible for its cardiovascular activity are still unknown. AIM OF THE STUDY: In this study, we aimed to assess the vascular activity of Cymbopogon citratus in human arteries and to study the role of cyclooxygenase in its vasorelaxant effects. MATERIALS AND METHODS: Vascular effects of leaves infusion and three fractions (phenolic acids, flavonoids and tannins) were studied using distal segments of human internal thoracic arteries harvested from patients undergoing coronary revascularization, which were mounted as rings in tissue organ baths and maintained at 37 °C in Krebs Henseleit buffer. The effect on basal vascular tone, the effect on the noradrenaline-induced contraction and the vasorelaxant effects were assessed. The role of cyclooxygenase was evaluated with indomethacin. RESULTS: Our results showed a mild effect on the basal vessel tone of the infusion. A significant inhibition on the adrenergic-mediated vasoconstriction was observed for the infusion (0.0002 mg/mL) and the flavonoid fraction (0.2 mg/mL), despite a potentiation was observed in some conditions. A vasorelaxant effect was observed for both the infusion (6.46% of maximal relaxation) and the tannin fraction (26.91% of maximal relaxation, P < 0.05 vs. infusion). Incubation with indomethacin (10 µM) elicited a decrease in the vasorelaxation to the infusion (P < 0.05). CONCLUSIONS: These results suggest that cyclooxygenase may be involved in the vasorelaxation to the infusion of Cymbopogon citratus and that tannins are the compound fraction mainly responsible for this vasorelaxation.

Periapical bone response to bacterial lipopolysaccharide is shifted upon cyclooxygenase blockage.

OBJECTIVES: Infection, inflammation and bone resorption are closely related events in apical periodontitis development. Therefore, we sought to investigate the role of cyclooxygenase (COX) in osteoclastogenesis and bone metabolism signaling in periapical bone tissue after bacterial lipopolysaccharide (LPS) inoculation into root canals. METHODOLOGY: Seventy two C57BL/6 mice had the root canals of the first molars inoculated with a solution containing LPS from E. coli (1.0 mg/mL) and received selective (celecoxib) or non-selective (indomethacin) COX-2 inhibitor. After 7, 14, 21 and 28 days the animals were euthanized and the tissues removed for total RNA extraction. Evaluation of gene expression was performed by qRT-PCR. Statistical analysis was performed using analysis of variance (ANOVA) followed by post-tests (α=0.05). RESULTS: LPS induced expression of mRNA for COX-2 (Ptgs2) and PGE2 receptors (Ptger1, Ptger3 and Ptger4), indicating that cyclooxygenase is involved in periapical response to LPS. A signaling that favours bone resorption was observed because Tnfsf11 (RANKL), Vegfa, Ctsk, Mmp9, Cd36, Icam, Vcam1, Nfkb1 and Sox9 were upregulated in response to LPS. Indomethacin and celecoxib differentially modulated expression of osteoclastogenic and other bone metabolism genes: celecoxib downregulated Igf1r, Ctsk, Mmp9, Cd36, Icam1, Nfkb1, Smad3, Sox9, Csf3, Vcam1 and Itga3 whereas indomethacin inhibited Tgfbr1, Igf1r, Ctsk, Mmp9, Sox9, Cd36 and Icam1. CONCLUSIONS: We demonstrated that gene expression for COX-2 and PGE2 receptors was upregulated after LPS inoculation into the root canals. Additionally, early administration of indomethacin and celecoxib (NSAIDs) inhibited osteoclastogenic signaling. The relevance of the cyclooxygenase pathway in apical periodontitis was shown by a wide modulation in the expression of genes involved in both bone catabolism and anabolism.

Variability in the Analgesic Response to Ibuprofen Is Associated With Cyclooxygenase Activation in Inflammatory Pain.

The mechanisms underlying interindividual variability in analgesic efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) are not well understood. Therefore, we performed pain phenotyping, functional neuroimaging, pharmacokinetic/pharmacodynamic assessments, inflammation biomarkers, and gene expression profiling in healthy subjects who underwent surgical extraction of bony impacted third molars and were treated with ibuprofen (400 mg; N = 19) or placebo (N = 10). Analgesic efficacy was not associated with demographic or clinical characteristics, ibuprofen pharmacokinetics, or the degree of cyclooxygenase inhibition by ibuprofen. Compared with partial responders to ibuprofen (N = 9, required rescue medication within the dosing interval), complete responders (N = 10, no rescue medication) exhibited greater induction of urinary prostaglandin metabolites and serum tumor necrosis factor-α and interleukin 8. Differentially expressed genes in peripheral blood mononuclear cells were enriched for inflammation-related pathways. These findings suggest that a less pronounced activation of the inflammatory prostanoid system is associated with insufficient pain relief on ibuprofen alone and the need for additional therapeutic intervention.

Periapical bone response to bacterial lipopolysaccharide is shifted upon cyclooxygenase blockage

Abstract Objectives: Infection, inflammation and bone resorption are closely related events in apical periodontitis development. Therefore, we sought to investigate the role of cyclooxygenase (COX) in osteoclastogenesis and bone metabolism signaling in periapical bone tissue after bacterial lipopolysaccharide (LPS) inoculation into root canals. Methodology: Seventy two C57BL/6 mice had the root canals of the first molars inoculated with a solution containing LPS from E. coli (1.0 mg/mL) and received selective (celecoxib) or non-selective (indomethacin) COX-2 inhibitor. After 7, 14, 21 and 28 days the animals were euthanized and the tissues removed for total RNA extraction. Evaluation of gene expression was performed by qRT-PCR. Statistical analysis was performed using analysis of variance (ANOVA) followed by post-tests (α=0.05). Results: LPS induced expression of mRNA for COX-2 (Ptgs2) and PGE2 receptors (Ptger1, Ptger3 and Ptger4), indicating that cyclooxygenase is involved in periapical response to LPS. A signaling that favours bone resorption was observed because Tnfsf11 (RANKL), Vegfa, Ctsk, Mmp9, Cd36, Icam, Vcam1, Nfkb1 and Sox9 were upregulated in response to LPS. Indomethacin and celecoxib differentially modulated expression of osteoclastogenic and other bone metabolism genes: celecoxib downregulated Igf1r, Ctsk, Mmp9, Cd36, Icam1, Nfkb1, Smad3, Sox9, Csf3, Vcam1 and Itga3 whereas indomethacin inhibited Tgfbr1, Igf1r, Ctsk, Mmp9, Sox9, Cd36 and Icam1. Conclusions: We demonstrated that gene expression for COX-2 and PGE2 receptors was upregulated after LPS inoculation into the root canals. Additionally, early administration of indomethacin and celecoxib (NSAIDs) inhibited osteoclastogenic signaling. The relevance of the cyclooxygenase pathway in apical periodontitis was shown by a wide modulation in the expression of genes involved in both bone catabolism and anabolism.

The role of potassium channels in the endothelial dysfunction induced by periodontitis.

OBJECTIVE: Periodontitis is associated with endothelial dysfunction, which is clinically characterized by a reduction in endothelium-dependent relaxation. However, we have previously shown that impairment in endothelium-dependent relaxation is transient. Therefore, we evaluated which mediators are involved in endothelium-dependent relaxation recovery. MATERIAL AND METHODS: Rats were subjected to ligature-induced experimental periodontitis. Twenty-one days after the procedure, the animals were prepared for blood pressure recording, and the responses to acetylcholine or sodium nitroprusside were obtained before and 30 minutes after injection of a nitric oxide synthase inhibitor (L-NAME), cyclooxygenase inhibitor (Indomethacin, SC-550 and NS- 398), or calcium-dependent potassium channel blockers (apamin plus TRAM- 34). The maxilla and mandible were removed for bone loss analysis. Blood and gingivae were obtained for C-reactive protein (CRP) and myeloperoxidase (MPO) measurement, respectively. RESULTS: Experimental periodontitis induces bone loss and an increase in the gingival MPO and plasmatic CRP. Periodontitis also reduced endothelium-dependent vasodilation, a hallmark of endothelial dysfunction, 14 days after the procedure. However, the response was restored at day 21. We found that endothelium-dependent vasodilation at day 21 in ligature animals was mediated, at least in part, by the activation of endothelial calcium-activated potassium channels. CONCLUSIONS: Periodontitis induces impairment in endothelial-dependent relaxation; this impairment recovers, even in the presence of periodontitis. The recovery is mediated by the activation of endothelial calcium-activated potassium channels in ligature animals. Although important for maintenance of vascular homeostasis, this effect could mask the lack of NO, which has other beneficial properties.

The role of potassium channels in the endothelial dysfunction induced by periodontitis

Abstract Objective: Periodontitis is associated with endothelial dysfunction, which is clinically characterized by a reduction in endothelium-dependent relaxation. However, we have previously shown that impairment in endothelium-dependent relaxation is transient. Therefore, we evaluated which mediators are involved in endothelium-dependent relaxation recovery. Material and methods: Rats were subjected to ligature-induced experimental periodontitis. Twenty-one days after the procedure, the animals were prepared for blood pressure recording, and the responses to acetylcholine or sodium nitroprusside were obtained before and 30 minutes after injection of a nitric oxide synthase inhibitor (L-NAME), cyclooxygenase inhibitor (Indomethacin, SC-550 and NS- 398), or calcium-dependent potassium channel blockers (apamin plus TRAM- 34). The maxilla and mandible were removed for bone loss analysis. Blood and gingivae were obtained for C-reactive protein (CRP) and myeloperoxidase (MPO) measurement, respectively. Results: Experimental periodontitis induces bone loss and an increase in the gingival MPO and plasmatic CRP. Periodontitis also reduced endothelium-dependent vasodilation, a hallmark of endothelial dysfunction, 14 days after the procedure. However, the response was restored at day 21. We found that endothelium-dependent vasodilation at day 21 in ligature animals was mediated, at least in part, by the activation of endothelial calcium-activated potassium channels. Conclusions: Periodontitis induces impairment in endothelial-dependent relaxation; this impairment recovers, even in the presence of periodontitis. The recovery is mediated by the activation of endothelial calcium-activated potassium channels in ligature animals. Although important for maintenance of vascular homeostasis, this effect could mask the lack of NO, which has other beneficial properties.

Non-steroidal Anti-inflammatory Drugs in Newborns and Infants.

Nonsteroidal antiinflammatory drugs (NSAIDs) and acetaminophen are used in young infants and newborns for pain and fever control, patent ductus closure, prevention of intraventricular hemorrhage, and potentially for prevention of retinopathy of prematurity. These drugs inhibit cyclooxygenase 1 (COX-1), COX-2, and peroxidases, thus, blocking prostaglandin (PG) synthesis. PGs are eicosanoids that regulate several physiologic, pathologic, and cellular processes, including vasomotor tone, platelet aggregation, sensitization of neurons to pain, and many molecular events critical to physiologic homeostasis. NSAIDs inhibit caspases and cell death. Increasing knowledge of these molecular entities may allow targeted drug development to prevent or minimize neonatal morbidities.

Investigating Cyclooxygenase Inhibition in a Rat Pulmonary Contusion Model: A Laboratory Study Finding No Improvement with Ibuprofen.

Minimal advances have been made in the management of pulmonary contusions (PCs). The purpose of this study was to evaluate the impact of cyclooxygenase inhibition on outcomes following PC in a rat model. PC was induced in anesthetized adult rats. Ibuprofen was given to the treatment group (TG) and water was given to the control group (CG). Lung injury was assessed with pulse oximetry, arterial blood gases, CT, and histopathologic examination. Inflammation was measured with both serum and bronchoalveolar lavage (BAL) levels of tumor necrosis factor α and interleukin-6. Rats in the TG did not differ from rats in the CG with respect to oxygenation. Pathologic examination demonstrated a trend toward more inflammatory infiltrate in the CG, yet the sizes of the contusions were larger in the TG. The CG trended toward decreased levels of interleukin-6 in the serum and BAL at both three and seven days. While BAL levels of tumor necrosis factor α were increased in the TG at three days compared to the CG, they trended toward a reduced amount at seven days. Our data do not support cyclooxygenase inhibition for treatment to decrease the respiratory compromise associated with PC in this model of rat PCs.

AR-12 suppresses dengue virus replication by down-regulation of PI3K/AKT and GRP78.

Dengue virus (DENV) infection has become a public health issue of worldwide concern and is a serious health problem in Taiwan, yet there are no approved effective antiviral drugs to treat DENV. The replication of DENV requires both viral and cellular factors. Targeting host factors may provide a potential antiviral strategy. It has been known that up-regulation of PI3K/AKT signaling and GRP78 by DENV infection supports its replication. AR-12, a celecoxib derivative with no inhibiting activity on cyclooxygenase, shows potent inhibitory activities on both PI3K/AKT signaling and GRP78 expression levels, and recently has been found to block the replication of several hemorrhagic fever viruses. However the efficacy of AR-12 in treating DENV infection is still unclear. Here, we provide evidence to show that AR-12 is able to suppress DENV replication before or after virus infection in cell culture and mice. The antiviral activities of AR-12 are positive against infection of the four different DENV serotypes. AR-12 significantly down-regulates the PI3K/AKT activity and GRP78 expression in DENV infected cells whereas AKT and GRP78 rescue are able to attenuate anti-DENV effect of AR-12. Using a DENV-infected suckling mice model, we further demonstrate that treatment of AR-12 before or after DENV infection reduces virus replication and mice mortality. In conclusion, we uncover the potential efficacy of AR-12 as a novel drug for treating dengue.

Cutaneous blood flow during intradermal NO administration in young and older adults: roles for calcium-activated potassium channels and cyclooxygenase?

Nitric oxide (NO) increases cutaneous blood flow; however, the underpinning mechanism(s) remains to be elucidated. We hypothesized that the cutaneous blood flow response during intradermal administration of sodium nitroprusside (SNP, a NO donor) is regulated by calcium-activated potassium (KCa) channels and cyclooxygenase (COX) in young adults. We also hypothesized that these contributions are diminished in older adults given that aging can downregulate KCa channels and reduce COX-derived vasodilator prostanoids. In 10 young (23 ± 5 yr) and 10 older (54 ± 4 yr) adults, cutaneous vascular conductance (CVC) was measured at four forearm skin sites infused with 1) Ringer (Control), 2) 50 mM tetraethylammonium (TEA), a nonspecific KCa channel blocker, 3) 10 mM ketorolac, a nonspecific COX inhibitor, or 4) 50 mM TEA + 10 mM ketorolac via intradermal microdialysis. All skin sites were coinfused with incremental doses of SNP (0.005, 0.05, 0.5, 5, and 50 mM each for 25 min). During SNP administration, CVC was similar at the ketorolac site (0.005-50 mM, all P > 0.05) relative to Control, but lower at the TEA and TEA + ketorolac sites (0.005-0.05 mM, all P < 0.05) in young adults. In older adults, ketorolac increased CVC relative to Control during 0.005-0.05 mM SNP administration (all P < 0.05), but this increase was not observed when TEA was coadministered (all P > 0.05). Furthermore, TEA alone did not modulate CVC during any concentration of SNP administration in older adults (all P > 0.05). We show that during low-dose NO administration (e.g., 0.005-0.05 mM), KCa channels contribute to cutaneous blood flow regulation in young adults; however, in older adults, COX inhibition increases cutaneous blood flow through a KCa channel-dependent mechanism.

Vascular Endothelium-Dependent and Independent Actions of Oleanolic Acid and Its Synthetic Oleanane Derivatives as Possible Mechanisms for Hypotensive Effects.

PURPOSE: Plant-derived oleanolic acid (OA) and its related synthetic derivatives (Br-OA and Me-OA) possess antihypertensive effects in experimental animals. The present study investigated possible underlying mechanisms in rat isolated single ventricular myocytes and in vascular smooth muscles superfused at 37°C. METHODS: Cell shortening was assessed at 1 Hz using a video-based edge-detection system and the L-type Ca2+ current (ICaL) was measured using the whole-cell patch-clamp technique in single ventricular myocytes. Isometric tension was measured using force transducer in isolated aortic rings and in mesenteric arteries. Vascular effects were measured in endothelium-intact and denuded vessels in the presence of various enzyme or channel inhibitors. RESULTS: OA and its derivatives increased cell shortening in cardiomyocytes isolated from normotensive rats but had no effect in those isolated from hypertensive animals. These triterpenes also caused relaxation in aortic rings and in mesenteric arteries pre-contracted with either phenylephrine or KCl-enriched solution. The relaxation was only partially inhibited by endothelium denudation, and also partly inhibited by the cyclooxygenase (COX) inhibitor indomethacin, with no additional inhibitory effect of the NO synthase inhibitor, N-ω-Nitro-L-arginine. A combination of both ATP-dependent channel inhibition by glibenclaminde and voltage-dependent K+ channel inhibition by 4-aminopyridine was necessary to fully inhibit the relaxation. CONCLUSION: These data indicate that the effects of OA and its derivatives are mediated via both endothelium-dependent and independent mechanisms suggesting the involvement of COX in the endothelium-dependent effects and of vascular muscle K+ channels in the endothelium-independent effects. Finally, our results support the view that the antihypertensive action of OA and its derivatives is due to a decrease of vascular resistance with no negative inotropic effect on the heart.

Investigation of cyclooxygenase and signaling pathways involved in human platelet aggregation mediated by synergistic interaction of various agonists.

In the present study, the mechanism(s) of synergistic interaction of various platelet mediators such as arachidonic acid (AA) when combined with 5-hydroxytryptamine (5-HT) or adenosine diphosphate (ADP) on human platelet aggregation were examined. The results demonstrated that 5-HT had no or negligible effect on aggregation but it did potentiate the aggregation response of AA. Similarly, the combination of subeffective concentrations of ADP and AA exhibited noticeable rise in platelet aggregation. Moreover, the observed synergistic effect of AA with 5-HT on platelets was inhibited by different cyclooxygenase (COX) inhibitors, namely ibuprofen and celecoxib, with half maximal inhibitory effect (IC50) values of 18.0 ± 1.8 and 15.6 ± 3.4 µmol/L, respectively. Interestingly, the synergistic effect observed for AA with 5-HT was, also, blocked by the 5-HT receptor blockers cyproheptadine (IC50=22.0 ± 7 µmol/L), ketanserin (IC50=152 ± 23 µmol/L), phospholipase C (PLC) inhibitor (U73122; IC50=6.1 ± 0.8 µmol/L), and mitogen activated protein kinase (MAPK) inhibitor (PD98059; IC50=3.8 ± 0.5 µmol/L). Likewise, the synergism of AA and ADP was, also, attenuated by COX inhibitors (ibuprofen; IC50=20 ± 4 µmol/L and celecoxib; IC50=24 ± 7 µmol/L), PLC inhibitor (U73122; IC50=3.7 ± 0.3 µmol/L), and MAPK inhibitor (PD98059; IC50=2.8 ± 1.1 µmol/L). Our observed data demonstrate that the combination of subthreshold concentrations of agonists amplifies platelet aggregation and that these synergistic effects largely depend on activation of COX/thromboxane A2, receptor-operated Ca(2+) channels, Gq/PLC, and MAPK signaling pathways. Moreover, our data revealed that inhibition of COX pathways by using both selective and/or non-selective COX inhibitors blocks not only AA metabolism and thromboxane A2 formation, but also its binding to Gq receptors and activation of receptor-operated Ca(2+) channels in platelets. Overall, our results show that PLC and MAPK inhibitors proved to inhibit the synergistic activation of platelets by several/multiple agonists.

Acetylcholine produces contraction mediated by cyclooxigenase pathway in arterial vessels in the marine fish (Isacia conceptionis).

Preliminary studies showed that dorsal artery contraction mediated by acetylcholine (ACh) is blocked with indomethacin in intertidal fish (G. laevifrons). Our objective was to characterize the cholinergic pathway in several artery vessels of the I. conceptionis. Afferent and efferent branchial, dorsal and mesenteric arteries were dissected of 6 juvenile specimens, isometric tension studies were done using doses response curves (DRC) for Ach (10(-13) to 10(-3) M), and cholinergic pathways were obtained by blocking with atropine or indomethacin. CRC to ACh showed a pattern of high sensitivity only in efferente branchial artery and low sensibility in all vessels. Furthermore, these contractions were blocked in the presence of atropine and indomethacin in all vessels. Our results corroborate previous results observed in intertidal species that contraction induced by acetylcholine is mediated by receptors that activate a cyclooxygenase contraction pathway.

Acetylcholine produces contraction mediated by cyclooxigenase pathway in arterial vessels in the marine fish (Isacia conceptionis) / Função vascular nas artérias do peixe marinos Isacia conceptionis

Preliminary studies showed that dorsal artery contraction mediated by acetylcholine (ACh) is blocked with indomethacin in intertidal fish (G. laevifrons). Our objective was to characterize the cholinergic pathway in several artery vessels of the I. conceptionis. Afferent and efferent branchial, dorsal and mesenteric arteries were dissected of 6 juvenile specimens, isometric tension studies were done using doses response curves (DRC) for Ach (10–13 to 10–3 M), and cholinergic pathways were obtained by blocking with atropine or indomethacin. CRC to ACh showed a pattern of high sensitivity only in efferente branchial artery and low sensibility in all vessels. Furthermore, these contractions were blocked in the presence of atropine and indomethacin in all vessels. Our results corroborate previous results observed in intertidal species that contraction induced by acetylcholine is mediated by receptors that activate a cyclooxygenase contraction pathway.

Estudos preliminares mostraram que a contração da artéria dorsal mediada por acetilcolina (ACh) é bloqueada com indometacina em peixes marinhos (G. laevifrons). Nosso objetivo foi caracterizar a via colinérgica em várias artérias de I. conceptionis. Artérias aferentes e eferentes branquiais, dorsais e mesentéricas foram dissecadas de 6 espécimes juvenis. Os estudos de tensão isométrica foram feitos utilizando-se a curva dose - resposta (CDR) para Ach (10–13 a 10–3M), e identificaram-se as vias colinérgicas, bloqueando com atropina e indometacina. CRC para ACh mostrou um padrão de alta sensibilidade na artéria eferentes branquiais e baixa sensibilidade em todos os vasos sanguineos. Essas contrações foram bloqueadas na presença de atropina e indometacina em todas as artérias avaliadas. Nossos resultados confirmam que a contração induzida por acetilcolina é mediada por receptores muscarínicos que ativam ciclo-oxigenase.

The ambidextrous cyclooxygenase: an enduring target.

With the discovery of COX, pain has not been treated in a relentless manner. Numbers of drugs with fewer side effects were discovered and are used successfully for treatment of pain. With new research coming into being since the discovery of COX, it was established that COX can be targeted not only for treatment of pain but for curing various diseases like cancer, Alzheimer's, Parkinson's disease, Glaucoma etc. With the sighting of COX-3, another isoform of COX, new diseases are being targeted for better treatment.

Pharmacogenomics of cyclooxygenases.

Cyclooxygenases (COX-1 and COX-2) are key enzymes in several physiopathological processes. Many adverse drugs reactions to NSAIDs are attributable to COX-inhibition. The genes coding for these enzymes (PTGS1 and PTGS2) are highly variable, and variations in these genes may underlie the risk of developing, or the clinical evolution of, several diseases and adverse drug reactions. We analyze major variations in the PTGS1 and PTGS2 genes, allele frequencies, functional consequences and population genetics. The most salient clinical associations of PTGS gene variations are related to colorectal cancer and stroke. In many studies, the SNPs interact with NSAIDs use, dietary or environmental factors. We provide an up-to-date catalog of PTGS clinical associations based on case-control studies and genome-wide association studies, and future research suggestions.

Effects of centrally injected glucagon-like peptide-2 on gastric mucosal blood flow in rats: possible mechanisms.

"Glucagon-like peptide-2" (GLP-2) is a peptide that is released from the enteroendocrine L cells in response to food in the gastrointestinal tract. Peripheral injection of GLP-2 has been shown to increase gastrointestinal blood flow, but effects of central GLP-2 on any vascular bed has not been studied yet. The aim of this study is to investigate the effects of various doses of intracerebroventricularly (i.c.v.)-injected GLP-2 on gastric mucosal blood flow (GMBF) and contribution of calcitonin gene related peptide (CGRP), nitric oxide synthase-nitric oxide (NOS-NO) and cyclooxygenase-prostaglandin (COX-PG) systems to the possible effect. The gastric chamber technique was used to determine GMBF. Urethane anesthesia was used throughout the recording procedure. Male Wistar rats were treated with GLP-2 (100, 150 ve 200ng/10µl; i.c.v.) or saline (10µl; i.c.v.) in order to find out the effective dose of i.c.v. GLP-2 on GMBF. Then, CGRP receptor antagonist CGRP-(8-37) (10µg/kg; s.c.), NOS inhibitor NG-nitro-l-arginine methyl ester (l-NAME; 30mg/kg; s.c.) or COX inhibitor indomethacin (5mg/kg; i.p.) was injected before the effective dose of i.c.v. GLP-2. GMBF was measured continuously for 35min following GLP-2 and recorded every fifth minute. Non-parametric Kruskal-Wallis test was used for statistical analysis. Differences were considered to be significant at p<0.05. GMBF increased rapidly following 100ng GLP-2 injection and did not fall to the basal levels during 35min. Other doses of i.c.v. GLP-2 did not produce any significant difference in GMBF. CGRP receptor antagonist, CGRP-(8-37) (10µg/kg; s.c.) and COX inhibitor indomethacin (5mg/kg; i.p.) significantly prevented the increase in GMBF due to GLP-2 (100ng; i.c.v.), while l-NAME (30mg/kg; s.c.) was ineffective. None of the drugs produced a significant change in GMBF when administered alone. Thus we suggest that, i.c.v. GLP-2 increases GMBF and CGRP and endogenous prostaglandins but not NO, contribute to this effect.