2-phenyl-4-4-5-5-tetramethylimidazoline-1-oxyl-3-oxide and Disease-Models--Animal

Necrotizing enterocolitis (NEC) is the most common life-threatening gastrointestinal disease encountered in the premature infant. It has been shown that the intercellular reactive oxygen species (ROS) generation activated by lipopolysaccharide involved in the nuclear factor kappa B (NF-κB) activation and pathogenesis of NEC. Here, we report that an antioxidant peptide from tuna backbone protein (APTBP) reduces the inflammatory cytokines transcription and release. APTBP directly scavenges the free radical through 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO) assay. In addition, APTBP reduces the intracellular ROS level, exhibiting an antioxidant activity within cells. Remarkably, gavage with APTBP attenuates the phenotype of NEC in the mice model. Mechanically, the NF-κB activation, together with the expression of inflammatory cytokines are decreased significantly when intracellular ROS are eliminated by APTBP. Therefore, our findings demonstrated that an antioxidant peptide, APTBP, ameliorates inflammation in NEC through attenuating ROS-NF-κB axis.

Topics: Animals; Animals, Newborn; Biphenyl Compounds; Cyclic N-Oxides; Cytokines; Disease Models, Animal; Enterocolitis, Necrotizing; Humans; Imidazoles; Inflammation; Intestinal Mucosa; Lipopolysaccharides; Mice; NF-kappa B; Peptides; Picrates; Rats; Reactive Oxygen Species; Tuna

Pain consists of sensory and affective components. Although the neuronal mechanisms underlying the sensory component of pain have been studied extensively, those underlying its affective component are only beginning to be elucidated. Previously, we showed the pivotal role of the ventral part of the bed nucleus of the stria terminalis (vBNST) in the negative affective component of pain. Here, we examined the role of glutamate-nitric oxide (NO) signaling in the affective component of pain in rats using a conditioned place aversion (CPA) test. Intra-vBNST injection of either CNQX (an AMPA receptor antagonist) or MK-801 (an NMDA receptor antagonist) dose-dependently attenuated intraplantar formalin-induced CPA (F-CPA) without reducing nociceptive behaviors. In vivo microdialysis showed that extracellular oxidative NO metabolites (NOx) levels were significantly increased by intraplantar formalin injection. Intra-vBNST injection of NPLA (a selective neuronal NO synthase (nNOS) inhibitor), c-PTIO (a NO scavenger), or ZL006 (a postsynaptic density-95 (PSD-95)-nNOS interaction inhibitor) dose-dependently suppressed F-CPA without attenuating nociceptive behaviors. Intra-vBNST injection of NOR3 (a NO donor) produced CPA in a dose-dependent manner in the absence of noxious stimulation. Furthermore, whole-cell patch-clamp electrophysiology in the vBNST slices revealed that NOR3 induced depolarization of hyperpolarization-activated cation current (I

Topics: Animals; Conditioning, Operant; Cyclic N-Oxides; Disease Models, Animal; Excitatory Postsynaptic Potentials; Formaldehyde; Free Radical Scavengers; Hydroxylamines; Imidazoles; Male; Membrane Potentials; Neurons; Nitric Oxide Synthase Type I; Nitro Compounds; Pain; Pain Management; Pain Measurement; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Septal Nuclei; Signal Transduction

Hemolysis and consequent release of cell-free hemoglobin (CFHb) impair vascular nitric oxide (NO) bioavailability and cause oxidative and inflammatory processes. Hydroxyurea (HU), a common therapy for sickle cell disease (SCD), induces fetal Hb production and can act as an NO donor. We evaluated the acute inflammatory effects of intravenous water-induced hemolysis in C57BL/6 mice and determined the abilities of an NO donor, diethylamine NONOate (DEANO), and a single dose of HU to modulate this inflammation. Intravenous water induced acute hemolysis in C57BL/6 mice, attaining plasma Hb levels comparable to those observed in chimeric SCD mice. This hemolysis resulted in significant and rapid systemic inflammation and vascular leukocyte recruitment within 15 minutes, accompanied by NO metabolite generation. Administration of another potent NO scavenger (2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) to C57BL/6 mice induced similar alterations in leukocyte recruitment, whereas hemin-induced inflammation occurred over a longer time frame. Importantly, the acute inflammatory effects of water-induced hemolysis were abolished by the simultaneous administration of DEANO or HU, without altering CFHb, in an NO pathway-mediated manner. In vitro, HU partially reversed the Hb-mediated induction of endothelial proinflammatory cytokine secretion and adhesion molecule expression. In summary, pathophysiological levels of hemolysis trigger an immediate inflammatory response, possibly mediated by vascular NO consumption. HU presents beneficial anti-inflammatory effects by inhibiting rapid-onset hemolytic inflammation via an NO-dependent mechanism, independently of fetal Hb elevation. Data provide novel insights into mechanisms of hemolytic inflammation and further support perspectives for the use of HU as an acute treatment for SCD and other hemolytic disorders.

Topics: Anemia, Sickle Cell; Animals; Cell Movement; Cyclic N-Oxides; Disease Models, Animal; Free Radical Scavengers; Hemoglobins; Hemolysis; Humans; Hydrazines; Hydroxyurea; Imidazoles; Inflammation; Leukocytes; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Nitric Oxide; Nitric Oxide Donors; Primary Cell Culture; Tumor Necrosis Factor-alpha; Viscosity; Water

Cannabinoid compounds usually produce biphasic effects in the modulation of emotional responses. Low doses of the endocannabinoid anandamide (AEA) injected into the dorsolateral periaqueductal gray matter (dlPAG) induce anxiolytic-like effects via CB1 receptors activation. However, at higher doses the drug loses this effect, in part by activating Transient Receptor Potential Vanilloid Type 1 (TRPV1). Activation of these latter receptors could induce the formation of nitric oxide (NO). Thus, the present study tested the hypothesis that at high doses AEA loses it anxiolytic-like effect by facilitating, probably via TRPV1 receptor activation, the formation of NO. Male Wistar rats received combined injections into the dlPAG of vehicle, the TRPV1 receptor antagonist 6-iodo-nordihydrocapsaicin or the NO scavenger carboxy-PTIO (c-PTIO), followed by vehicle or AEA, and were submitted to the elevated plus maze (EPM) or the Vogel conflict test (VCT). A low dose (5pmol) of AEA produced an anxiolytic-like effect that disappeared at higher doses (50 and 200pmol). The anxiolytic-like effects of these latter doses, however, were restored after pre-treatment with a low and ineffective dose of c-PTIO in both animal models. In addition, the combined administration of ineffective doses of 6-iodo-nordihydrocapsaicin (1nmol) and c-PTIO (0.3nmol) produced an anxiolytic-like response. Therefore, these results support the hypothesis that intra-dlPAG injections of high doses of AEA lose their anxiolytic effects by favoring TRPV1 receptors activity and consequent NO formation, which in turn could facilitate defensive responses.

Topics: Animals; Anxiety; Arachidonic Acids; Cannabinoid Receptor Agonists; Capsaicin; Cyclic N-Oxides; Disease Models, Animal; Drinking; Drug Interactions; Endocannabinoids; Free Radical Scavengers; Imidazoles; Male; Maze Learning; Microinjections; Nitric Oxide; Periaqueductal Gray; Polyunsaturated Alkamides; Rats; Rats, Wistar; Reaction Time; TRPV Cation Channels

Cystathionine-beta-synthase (CBS) catalyzes the rate-limiting step in the transsulfuration pathway for the metabolism of homocysteine (Hcy) in the kidney. Our recent study demonstrates that ischemia-reperfusion reduces the activity of CBS leading to Hcy accumulation in the kidney, which in turn contributes to renal injury. CBS is also capable of catalyzing the reaction of cysteine with Hcy to produce hydrogen sulfide (H(2)S), a gaseous molecule that plays an important role in many physiological and pathological processes. The aim of the present study was to examine the effect of ischemia-reperfusion on CBS-mediated H(2)S production in the kidney and to determine whether changes in the endogenous H(2)S generation had any impact on renal ischemia-reperfusion injury. The left kidney of Sprague-Dawley rat was subjected to 45-min ischemia followed by 6-h reperfusion. The ischemia-reperfusion caused lipid peroxidation and cell death in the kidney. The CBS-mediated H(2)S production was decreased, leading to a significant reduction in the renal H(2)S level. The activity of cystathionine-gamma-lyase, another enzyme responsible for endogenous H(2)S generation, was not significantly altered in the kidney upon ischemia-reperfusion. Partial restoration of CBS activity by intraperitoneal injection of the nitric oxide scavenger, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide not only increased renal H(2)S levels but also alleviated ischemia-reperfusion-induced lipid peroxidation and reduced cell damage in the kidney tissue. Furthermore, administration of an exogenous H(2)S donor, NaHS (100 microg/kg), improved renal function. Taken together, these results suggest that maintenance of tissue H(2)S level may offer a renal protective effect against ischemia-reperfusion injury.

Topics: Animals; Apoptosis; Cyclic N-Oxides; Cystathionine beta-Synthase; Cystathionine gamma-Lyase; Disease Models, Animal; Free Radical Scavengers; Homeostasis; Homocysteine; Hydrogen Sulfide; Imidazoles; Kidney; Male; Nitric Oxide; Rats; Rats, Sprague-Dawley; Reperfusion Injury

Chronic tissue ischemia due to defective vascular perfusion is a hallmark feature of peripheral artery disease for which minimal therapeutic options exist. We have reported that sodium nitrite therapy exerts cytoprotective effects against acute ischemia/reperfusion injury in both heart and liver, consistent with the model of bioactive NO formation from nitrite during ischemic stress. Here, we test the hypothesis that chronic sodium nitrite therapy can selectively augment angiogenic activity and tissue perfusion in the murine hind-limb ischemia model. Various therapeutic doses (8.25-3,300 mug/kg) of sodium nitrite or PBS were administered. Sodium nitrite significantly restored ischemic hind-limb blood flow in a time-dependent manner, with low-dose sodium nitrite being most effective. Nitrite therapy significantly increased ischemic limb vascular density and stimulated endothelial cell proliferation. Remarkably, the effects of sodium nitrite therapy were evident within 3 days of the ischemic insult demonstrating the potency and efficacy of chronic sodium nitrite therapy. Sodium nitrite therapy also increased ischemic tissue nitrite and NO metabolites compared to nonischemic limbs. Use of the NO scavenger carboxy PTIO completely abolished sodium nitrite-dependent ischemic tissue blood flow and angiogenic activity consistent with nitrite reduction to NO being the proangiogenic mechanism. These data demonstrate that chronic sodium nitrite therapy is a recently discovered therapeutic treatment for peripheral artery disease and critical limb ischemia.

Topics: Animals; Arteries; Cyclic N-Oxides; Cytoprotection; Disease Models, Animal; Endothelium, Vascular; Free Radical Scavengers; Hindlimb; Imidazoles; Ischemia; Male; Mice; Mice, Inbred C57BL; Neovascularization, Physiologic; Nitric Oxide; Peripheral Vascular Diseases; Sodium Nitrite

Nitric oxide (NO) is a widespread, potent, biological mediator that has many physiological and pathophysiological roles. Research in the field of NO appears to have followed a straightforward path, and the findings have been progressive: NO and cyclic GMP are involved in vasodilatation; glycerol trinitrate relaxes vascular smooth muscles by bioconversion to NO; mammalian cells synthesize NO; and last, NO mediates vasodilatation by stimulating the soluble guanylate cyclase (sGC), a heterodimeric (alpha/beta) haem protein that converts GTP to cGMP2-4. Here we report the discovery of a regulatory site on sGC. Using photoaffinity labelling, we have identified the cysteine 238 and cysteine 243 region in the alpha1-subunit of sGC as the target for a new type of sGC stimulator. Moreover, we present a pyrazolopyridine, BAY 41-2272, that potently stimulates sGC through this site by a mechanism that is independent of NO. This results in antiplatelet activity, a strong decrease in blood pressure and an increase in survival in a low-NO rat model of hypertension, and as such may offer an approach for treating cardiovascular diseases.

Topics: Amino Acid Sequence; Animals; Antihypertensive Agents; Binding Sites; Blood Pressure; Cyclic N-Oxides; Cysteine; Disease Models, Animal; Enzyme Activation; Female; Guanylate Cyclase; Heme; Humans; Imidazoles; In Vitro Techniques; Indazoles; Molecular Sequence Data; Nitric Oxide; Photoaffinity Labels; Platelet Aggregation Inhibitors; Pyrazoles; Pyridines; Rats; Solubility

Methamphetamine (METH) is a neurotoxic psychostimulant that produces catecholaminergic brain damage by producing oxidative stress and free radical generation. The role of oxygen and nitrogen radicals is well documented as a cause of METH-induced neurotoxic damage. In this study, we have obtained evidence that METH-induced neurotoxicity is the resultant of interaction between oxygen and nitrogen radicals, and it is mediated by the production of peroxynitrite. We have also assessed the effects of inhibitors of neuronal nitric oxide synthase (nNOS) as well as scavenger of nitric oxide and a peroxynitrite decomposition catalyst. Significant protective effects were observed with the inhibitor of nNOS, 7-nitroindazole (7-NI), as well as by the selective peroxynitrite scavenger or decomposition catalyst, 5,10,15,20-tetrakis(2,4,6-trimethyl-3,5-sulfonatophenyl)porphyrinato iron III (FeTPPS). However, the use of a nitric oxide scavenger, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO), did not provide any significant protection against METH-induced hyperthermia or peroxynitrite generation and the resulting dopaminergic neurotoxicity. In particular, treatment with FeTPPS completely prevented METH-induced hyperthermia, peroxynitrite production, and METH-induced dopaminergic depletion. Together, these data demonstrate that METH-induced dopaminergic neurotoxicity is mediated by the generation of peroxynitrite, which can be selectively protected by nNOS inhibitors or peroxynitrite scavenger or decomposition catalysts.

Topics: 3,4-Dihydroxyphenylacetic Acid; Analysis of Variance; Animals; Chromatography, High Pressure Liquid; Corpus Striatum; Cyclic N-Oxides; Disease Models, Animal; Dopamine; Dopamine Uptake Inhibitors; Drug Administration Schedule; Drug Interactions; Electrochemistry; Free Radical Scavengers; Homovanillic Acid; Imidazoles; Indazoles; Male; Methamphetamine; Mice; Mice, Inbred C57BL; Models, Biological; Neuroprotective Agents; Neurotoxicity Syndromes; Nitric Oxide; Peroxynitrous Acid; Tyrosine