The Journal of pharmacology and experimental therapeutics
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J. Pharmacol. Exp. Ther. · Jan 2006
Inhibition of inducible nitric-oxide synthase expression by (5R)-5-hydroxytriptolide in interferon-gamma- and bacterial lipopolysaccharide-stimulated macrophages.
(5R)-5-Hydroxytriptolide (LLDT-8) is a novel analog of triptolide that has antiarthritic, hepatoprotective, and antiallogenic transplantation-rejective effects. In the present study, we report that LLDT-8 inhibited nitric oxide (NO) production and inducible nitric-oxide synthase (iNOS) expression in macrophages. LLDT-8 significantly attenuated NO production, in a dose-dependent manner, in primary peritoneal macrophages and a macrophage cell line of Raw 264.7 cells following stimulation with interferon (IFN)-gamma, lipopolysaccharide (LPS), and IFN-gamma plus LPS. ⋯ In IFN-gamma-stimulated Raw 264.7 cells, LLDT-8 suppressed the gene transcription of signal transducer and activator of transcription 1alpha and interferon regulatory factor (IRF)-1, but it displayed no apparent effect on IFN-gamma receptor level on cell surface. After LPS challenge, LLDT-8 further abrogated the expression of LPS receptor complex, including CD14, Toll-like receptor 4, and myeloid differentiation protein-2; decreased the LPS-induced phosphorylation of stress-activated protein kinase/c-Jun NH(2)-terminal kinase, extracellular signal-regulated kinase 1/2, and p38 mitogen-activated protein kinase (MAPK); retarded the degradation of IkappaBalpha; and ameliorated the DNA binding activity of nuclear factor-kappaB (NF-kappaB) to nuclear proteins that accounts for transcriptional regulation of iNOS. Taken together, these results suggest that LLDT-8 reduces NO production and iNOS expression by inhibiting IFN-gamma-triggered IRF-1 expression and LPS-triggered MAPK phosphorylation and NF-kappaB activation.
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J. Pharmacol. Exp. Ther. · Jan 2006
Activation of the adenosine A3 receptor in RAW 264.7 cells inhibits lipopolysaccharide-stimulated tumor necrosis factor-alpha release by reducing calcium-dependent activation of nuclear factor-kappaB and extracellular signal-regulated kinase 1/2.
Bacterial lipopolysaccharide (LPS) activates the immune system and promotes inflammation via Toll-like receptor (TLR) 4, which regulates the synthesis and release of tumor necrosis factor (TNF)-alpha and other inflammatory cytokines. Previous studies have shown that the nucleoside adenosine suppresses LPS-stimulated TNF-alpha release in human UB939 macrophages by activating an adenosine A(3) receptor (A(3)AR) subtype on these cells. In this study, we examined the mechanism(s) underlying A(3)AR-dependent inhibition of TNF-alpha release in a mouse (RAW 264.7) cell line. ⋯ Activation of the A(3)AR or inhibition of intracellular Ca(2+) release also reduced LPS-stimulated nuclear factor-kappaB (NF-kappaB) activation and extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation. Similar inhibition by A(3)AR was observed for LPS-stimulated inducible nitric-oxide synthase. These data support the contention that inhibition of LPS-stimulated release of inflammatory molecules, such as TNF-alpha and NO via the A(3)AR, involves suppression of intracellular Ca(2+)signaling, leading to suppression of NF-kappaB and ERK1/2 pathways.
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J. Pharmacol. Exp. Ther. · Jan 2006
Blockade of nuclear factor-kappaB signaling pathway and anti-inflammatory activity of cardamomin, a chalcone analog from Alpinia conchigera.
Nuclear factor-kappaB (NF-kappaB) and the signaling pathways that regulate its activity have become a focal point for intense drug discovery and development efforts. NF-kappaB regulates the transcription of a large number of genes, particularly those involved in immune, inflammatory, and antiapoptotic responses. In our search for NF-kappaB inhibitors from natural resources, we identified cardamomin, 2',4'-dihydroxy-6'-methoxychalcone, as an inhibitor of NF-kappaB activation from Alpinia conchigera Griff (Zingiberaceae). ⋯ However, this compound did not inhibit LPS-induced activation of extracellular signal-regulated kinase and stress-activated protein kinase/c-Jun NH(2)-terminal kinase, but significantly impaired activation of p38 mitogen-activated protein kinase. We also demonstrated that pretreatment of cardamomin rescued C57BL/6 mice from LPS-induced mortality in conjunction with decreased serum level of TNF-alpha. Together, cardamomin could be valuable candidate for the intervention of NF-kappaB-dependent pathological condition such as inflammation.
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J. Pharmacol. Exp. Ther. · Jan 2006
ARD-353 [4-((2R,5S)-4-(R)-(4-diethylcarbamoylphenyl)(3-hydroxyphenyl)methyl)-2,5-dimethylpiperazin-1-ylmethyl)benzoic acid], a novel nonpeptide delta receptor agonist, reduces myocardial infarct size without central effects.
A novel delta-receptor selective compound, ARD-353 [4-((2R,5S)-4-(R)-(4-diethylcarbamoylphenyl)(3-hydroxyphenyl)methyl)-2, 5-dimethylpiperazin-1-ylmethyl)benzoic acid], was evaluated for activity on infarct size in a rat model of acute myocardial infarction. ARD-353 was characterized as having delta receptor selectivity using radioligand binding and had no apparent selectivity between delta receptor subtypes as determined by [(3)H] cyclic [D-Pen(2),D-Pen(5)]enkephalin (delta(1)) and [(3)H]Deltorphin II (delta(2)) competition binding. ARD-353 also showed selective delta receptor agonist activity in mouse-isolated vas deferens. ⋯ The effects of ARD-353 on infarct size were blocked by the delta(1)-opioid selective antagonist 7-benzylidenenaltrexone, indicating a significant role for the delta(1)-opioid receptor in the cardioprotective mechanism of ARD-353. ARD-353 (0.3 mg/kg i.v.) produced significant protection when administered 5 min and 12 and 48 h before ischemic insult or when given immediately after the ischemic insult (at the start of reperfusion). Given the lack of central nervous system effects and beneficial efficacy in the rat model of myocardial ischemia, it is felt that ARD-353 is the first nonpeptide delta-receptor agonist with true potential for clinical use before surgically induced ischemia or in an emergency setting.
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J. Pharmacol. Exp. Ther. · Jan 2006
Increased superoxide anion production by interleukin-1beta impairs nitric oxide-mediated relaxation in resistance arteries.
The present study was designed to analyze the effect of long-term incubation with interleukin-1beta (IL-1beta) on endothelium-dependent relaxation in rat mesenteric resistance arteries. Vessels were incubated in culture medium with or without IL-1beta (10 ng/ml, 14 h). Changes in lumen diameter were recorded in a pressure myograph. ⋯ The impairment of ACh relaxation induced by IL-1beta was also partially reversed by the xanthine oxidase inhibitor allopurinol (1 mM) but not by either the NADPH oxidase inhibitor apocynin (0.3 mM) or the inducible NOS inhibitor N-3-aminomethylbenzylacetamidine (1 microM). However, all these inhibitors improved the impaired SNP response. The results of the present study demonstrate that long-term incubation with IL-1beta induces an impairment of the nitric oxide-mediated relaxation in mesenteric resistance arteries through the production of O(2)(.), mainly from xanthine oxidase.