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Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The effect of E. coli lipopolysaccharide (LPS) on sympathetic neuro-effector transmission was studied in the rabbit mesenteric artery. The experiments were performed on artery rings isolated 5 or 20 h after intravenous treatment with LPS or saline as well as on artery rings isolated from non-treated rabbits (for assessment of the effect of in vitro preincubation with LPS). In most experiments, neural elements in the arteries were stimulated electrically (10 V, 2 ms, 1-32 Hz). 2. Preincubation with LPS (10 micrograms ml-1) for 5 or 20 h had no effect on the contraction responses of endothelium-intact artery rings to electrical stimulation. In contrast, in vivo intravenous pretreatment with LPS (10 micrograms) led to an inhibition of the contraction; LPS elicited this effect when injected 20 h, but not 5 h, before the experiment. The effect of LPS was eliminated in artery rings isolated from animals receiving an inhibitor of protein synthesis (actinomycin D or cycloheximide) before treatment with LPS. LPS (injected 20 h before the experiment) had no effect on the concentration-response curves for exogenous noradrenaline and tyramine in endothelium-intact artery rings. 3. The inhibition of electrically induced contractions produced by LPS treatment in endothelium-intact artery rings was attenuated by atropine and yohimbine, but not by phentolamine. Yohimbine plus atropine restored the depressed contraction to the normal level. Clonidine and acetylcholine mimicked the effect of LPS in endothelium-intact artery rings isolated from saline-treated animals. 4. When steady-state contractions were induced by 5 min of stimulation at 16 Hz, acetylcholine or clonidine reduced the contraction in endothelium-denuded artery rings from both saline-treated rabbits and animals receiving LPS 20 h before the experiment. The reduction produced by acetylcholine or clonidine of the contraction in artery rings from LPS-treated rabbits was significantly greater than in artery rings from saline-treated animals.5. These results suggest that treatment of rabbits with LPS inhibits noradrenaline release from sympathetic nerve endings via increased sensitivity of both prejunctional inhibitory muscarinic receptors and x2-adrenoceptors in mesenteric arteries. They also suggest that the effect of LPS is independent of endothelial cells but linked to protein synthesis.
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PMID:Endotoxin impairs the response of rabbit mesenteric artery to electrical stimulation via a prejunctional mechanism. 133 42

Interleukin-1 receptor antagonist (IRA) is a secretory product of human monocytes or related cell lines that acts as a pure interleukin-1 (IL-1) antagonist in several bioassays. IRA administration was reportedly a life-saving intervention in rabbits injected with lethal doses of bacterial lipopolysaccharide (LPS). We report the inhibitory effect of IRA on three distinct types of vascular responses to IL-1 in rabbit isolated blood vessels. The rabbit isolated superior mesenteric artery, when precontracted with phenylephrine, relaxed in a sustained manner in less than 30 min following application of recombinant interleukin-1 beta (12-290 pM), and this was a prostaglandin (PG)-dependent and endothelium-independent process. IRA (human recombinant sequence; 0.9-15 nM) behaved as an antagonist of IL-1 alpha or IL-1 beta, based on the surmountability and the concentration dependence, but could only prevent the effect of IL-1, not reverse it. IRA had no direct effect on the preparation and did not influence the acute relaxing effect elicited by substance P or iloprost, a PGI2 mimetic. Exposure to IL-1 beta depressed the response to noradrenaline (NA) in several hours in rabbit aorta rings. The inhibitory effect of IL-1 beta was endothelium and prostaglandin independent, but was prevented by a treatment with NG-nitro-L-arginine (a nitric oxide synthesis inhibitor), cycloheximide, dexamethasone, or IRA. Using the residual NA-induced contraction as a quantification of the IL-1 agonist effect, IRA was a very potent antagonist of IL-1 beta but was not totally surmountable.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of interleukin-1 receptor antagonist on three types of responses to interleukin-1 in rabbit isolated blood vessels. 138 81

Natural infection by mouse hepatitis virus (MHV) can affect interpretation of immunological studies in mice. MHV, a collective term describing a group of corona viruses, is found in natural infections in over 70% of laboratory mouse populations in the U.S.A. and Canada. Natural outbreaks of MHV in our animal colony afforded us the opportunity to study MHV-induced immunosuppression as well as the effects of MHV infection on neurotransmitter immunomodulation. Concanavalin A (Con A)-stimulated DNA synthesis by spleen T lymphocytes from MHV-infected mice was 20-50% that of non-infected mice. The MHV infection also altered neurotransmitter modulation of spleen T-lymphocyte activation. In contrast to noradrenaline ablation of Con A-activated DNA synthesis by spleen lymphocytes from non-infected mice, DNA synthesis by the infected group was not inhibited by noradrenaline or dibutyryl-cAMP. These effects of MHV infection were specific for spleen T lymphocytes since MHV infection did not alter Con A stimulation of thymocytes, lipopolysaccharide stimulation of spleen B lymphocytes, or noradrenaline inhibition of thymocyte and B-cell DNA synthesis. MHV infection also did not alter spleen T-lymphocyte subset proportions. Thus, MHV infection inhibits spleen T-lymphocyte activation and blocks in vitro catecholamine and cAMP regulation of spleen T-cell activation but does not affect activation of thymic cells or spleen B cells.
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PMID:Mouse hepatitis virus infection suppresses modulation of mouse spleen T-cell activation. 157

Interleukin-1-like immunoreactivity has earlier been demonstrated by immunohistochemistry in the noradrenaline-containing chromaffin cells of the rat adrenal gland [Schultzberg et al. (1989) Neuroscience 30, 805-810; Schultzberg et al. (1987) J. Neurosci. Res. 18, 184-189]. In this study, we examine the regulation, upon cholinergic stimulation, of the expression of the cytokine interleukin-1 alpha in the rat adrenal gland. Interleukin-1 alpha and interleukin-1 alpha mRNA levels in the adrenal gland are affected by systemic administration of the cholinergic agonists nicotine (0.5 mg/kg, i.p.) and carbachol (0.5 mg/kg, i.p.). Both drugs cause an increase in interleukin-1 alpha mRNA levels. In contrast to the increased mRNA levels, nicotine and carbachol reduce the interleukin-1 alpha protein level measured in the rat adrenal gland: nicotine by approximately 30%, 60 min after injection, and carbachol by approximately 55%, 30 min after injection. The interleukin-1 alpha protein level returns to control level 90 min after nicotine injection, and 120 min after carbachol injection. We thus found a large, constitutively expressed and inducible pool of interleukin-1 alpha in the rat adrenal gland, which appears to be sensitive to cholinergic stimulation and which may be responsible for some of the local and systemic effects of interleukin-1 alpha. Experiments with Escherichia coli lipopolysaccharide show that this substance, which induces interleukin-1 expression and secretion in macrophages, is also able to induce the expression of interleukin-1 alpha mRNA and interleukin-1 alpha in the adrenal gland when injected at the dose of 2 mg/kg, i.p.
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PMID:Interleukin-1 alpha expression is inducible by cholinergic stimulation in the rat adrenal gland. 164 Nov 33

1. The aim of this investigation was to study the relationship between contractile responsiveness, activation of the L-arginine pathway and tissue levels of guanosine 3':5'cyclic monophosphate (cylic GMP) in aortic rings removed from rats 4 h after intraperitoneal administration of bacterial endotoxin (E. coli. lipopolysaccharide, LPS, 20 mg kg-1). 2. LPS-treatment resulted in a reduction of the sensitivity and maximal contractile response to noradrenaline (NA). 3. Depression of the maximal contractile response was restored to control by 6-anilo-5,8-quinolinedione (LY 83583, 10 microM), which prevents activation of soluble guanylate cyclase. 4. Cyclic GMP levels in tissue from LPS-treated rats were 2 fold greater than cyclic GMP levels detected in tissue from control (saline-treated) rats. The LPS-induced increase in cyclic GMP content was observed both in the presence and absence of functional endothelium. 5. Addition of L-arginine 1 mM) to maximally contracted aortic rings produced significantly relaxation of rings from LPS-treated rats but not rings from control animals. In the LPS-treated group, addition of L-arginine was also associated with a significant increase in cyclic GMP content. L-Arginine had no effect on the cyclic GMP content of control rings. D-Arginine (1 mM) was without effect. 6. In rings from LPS-treated rats, NG-nitro-L-arginine methyl ester (L-NAME, 300 microM), an inhibitor of nitric oxide (NO) production, increased the contractile response to NA and prevented the LPS-induced increase in cyclic GMP content. In control rings, L-NAME increased the NA sensitivity only when the endothelium remained intact and reduced the cyclic GMP content of these rings to that of control endothelium-denuded rings. 7. These results demonstrate that LPS-induced hyporeactivity to NA occurs secondarily to activation of the L-arginine pathway and subsequent activation of soluble guanylate cyclase in vascular tissue. In addition they suggest that LPS induces the production of an NO-like relaxing factor in non-endothelial cells.
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PMID:Evidence that an L-arginine/nitric oxide dependent elevation of tissue cyclic GMP content is involved in depression of vascular reactivity by endotoxin. 167 81

1. Thermal responses to verapamil (5 mg/kg per hr) were investigated in pyrogen (lipopolysaccharide Escherichia coli) or noradrenaline (NA) treated rabbits. 2. The compound reduced the pyretic, metabolic and vasoconstricting activity of pyrogen. 3. On the other hand, verapamil did not significantly affect NA-induced hyperthermia. 4. Possible mechanisms responsible for the thermoregulatory activity of verapamil are discussed.
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PMID:The effect of verapamil on the thermoregulatory responses produced by endotoxin or noradrenaline in rabbits. 176 Nov 98

1. The modulation of the spontaneous increase in contractile responses to des-Arg9-bradykinin (des-Arg9-BK) of rabbit aortic strips incubated in vitro was studied. Rapid hypotensive responses to exogenous kinins were also measured in rabbits anaesthetized 5 h following pretreatment. 2. Continuous exposure to the protein synthesis inhibitors cycloheximide (71 microM) or anisomycin (3.8 microM) profoundly inhibited the sensitization to des-Arg9-BK in incubated aortic strips. However, temporary (3 h) inhibition of protein synthesis in vitro followed by further incubation (3 h) of tissues without inhibitor, paradoxically enhanced both the maximal contractile responses to des-Arg9-BK (1.7 microM) and the apparent affinity of the kinin without affecting contractions to noradrenaline (NA, 100 nM) at 6.5 h. 3. The stimulatory activity of the short treatment (pulse) with cycloheximide was abolished in the presence of dexamethasone sodium phosphate (100 microM throughout the incubation). The function of receptors for kinins did not appear to be altered directly by the steroid treatment. 4. Interleukin-1 beta (IL-1 beta), applied at low concentrations (100-250 pg ml-1) on aortic strips between 3 h and 6.5 h of incubation time, mimicked the selective stimulatory effect of the cycloheximide pulse on responses to des-Arg9-BK. Higher concentrations of IL-1 beta (0.5-5 ng ml-1) did not further amplify the responses to des-Arg9-BK but decreased the contractile responses to NA. 5. The modulation by IL-1 beta of vascular sensitivity to des-Arg9-BK and to NA was prevented by blockade of protein synthesis. 6. The induction in vivo by IL-1 beta (5 micrograms kg-1) or by cycloheximide (10 mg kg-1) of cardiovascular responsiveness to des-Arg9-BK was demonstrated with a blood pressure assay of exogenous kinins or with tissues isolated ex vivo 5 h after pretreatment of animals. Evidence of active disposition of cycloheximide in vivo was also obtained. 7. We propose the production of endogenous IL-1 as a possible mechanism for the enhancement of responsiveness to des-Arg9-BK observed in tissues pulsed with a protein synthesis inhibitor and for the inducing effect of cycloheximide or E. coli lipopolysaccharide in vivo. These results suggest that effects mediated by the BK1 receptor for kinins are potentially present in pathological conditions associated with IL-1 production.
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PMID:Pulse exposure to protein synthesis inhibitors enhances vascular responses to des-Arg9-bradykinin: possible role of interleukin-1. 187 45

1. The effects on blood pressure and on pressor responses to noradrenaline (NA), of NG-monomethyl-L-arginine (L-NMMA) and NG-nitro-L-arginine methyl ester (L-NAME), inhibitors of the L-arginine/nitric oxide pathway, were investigated in anaesthetized rats receiving an infusion of bacterial endotoxin (E. coli lipopolysaccharide, LPS). 2. Infusion of LPS (10 mg kg-1 h-1) for 50 min had no effect on mean arterial blood pressure (MABP) but induced a reduction in responsiveness to noradrenaline (100 ng-1 micrograms kg-1). L-NMMA (30 mg kg-1), but not D-NMMA, caused an increase in MABP of approximately 30 mmHg and restored responses to NA. This effect was reversed by L- but not D-arginine (100 mg kg-1). 3. In LPS-treated rats, blood pressure responses to NA were only marginally increased by the cyclooxygenase inhibitor, indomethacin (5 mg kg-1). L-NAME (1 mg kg-1) caused a similar increase in MABP and restored pressor responses to NA both in the presence and absence of indomethacin. 4. Co-infusion of vasopressin (100 ng kg-1, for 10 min) with LPS (10 mg kg-1 h-1) in order to reproduce the hypertensive effect of L-NMMA and L-NAME increased pressor responsiveness to 100 and 300 ng kg-1 NA but not to 1 microgram kg-1 NA. 5. Infusion of sodium nitroprusside (30 micrograms kg-1 min-1) decreased responsiveness to NA even when the hypotension was corrected by co-infusion of vasopressin (50 ng kg-1 min-1). 6. These results demonstrate that the restoration of vascular responsiveness to NA in LPS-treated anaesthetized rats by inhibitors of the L-arginine/nitric oxide pathway is stereospecific and reversible. Furthermore, the experiments involving indomethacin suggest that although cyclo-oxygenase products of arachidonic acid may contribute to the development of LPS-induced hyporeactivity, the effect of L-NAME is unlikely to involve inhibition of the cyclo-oxygenase pathway. Comparison of NA responsiveness during vasopressin and L-NMMA/L-NAME-induced hypertension shows that increasing the blood pressure may modify LPS-induced hyporeactivity, but cannot account for the complete restoration of responses to NA by L-NMMA and L-NAME. These observations suggest that activation of nitric oxide formation from L-arginine makes a direct contribution to the production of vascular hyporeactivity by LPS in vivo.
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PMID:The effect of inhibitors of the L-arginine/nitric oxide pathway on endotoxin-induced loss of vascular responsiveness in anaesthetized rats. 190 34

Treatment of EMT 6 mammary adenocarcinoma cells with Interferon-gamma (IFN-gamma, 10 U.ml-1) plus endotoxin lipopolysaccharide (LPS, 100 ng.ml-1) induces concomitantly a growth arrest and production of citrulline and nitrite from L-arginine. A similar L-arginine-dependent metabolism is responsible for the vascular smooth muscle relaxing effect of stimulated endothelial cells. We therefore investigated the ability of EMT 6 cells to induce the relaxation of endothelium-denuded rat aortic rings precontracted with noradrenaline (1 microM). Pretreatment of EMT 6 cells with IFN-gamma + LPS increased their relaxing potency by 5-10 times. The relaxin effects of control and treated EMT 6 cells were entirely counteracted by NG-monomethyl-L-arginine (300 microM), a specific inhibitor of nitrite and citrulline production from L-arginine, and by methylene blue (10 microM) and LY 83583 (10 microM), two inhibitors of NOo-induced activation of guanylate cyclase. The effect of NG-monomethyl-L-arginine was reversed by L- but not D-arginine (1 mM). It is concluded that IFN-gamma + LPS increase the production of a relaxing factor in EMT 6 cells through the L-arginine-NOo-synthase pathway.
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PMID:Production of an arginine-derived relaxing factor induced by IFN-gamma plus endotoxin in murine adenocarcinoma EMT 6 cells. 212 6

Recent evidence indicates that stress can suppress immune responses and thus increase the severity of viral and neoplastic diseases. Although, the mechanisms for stress-induced modulation of immunologic competence are unclear, neuroendocrine hormones are thought to be involved. A direct suppressive effect could result from the action of neuroendocrine hormones on lymphokine and monokine release. The central role of interleukin-1 (IL-1) in regulating cellular immune responses to infection and neoplasms stimulated the present study evaluating the effects of neuroendocrine hormones on IL-1 production. Norepinephrine and epinephrine inhibited the capacity of gamma interferon and lipopolysaccharide to stimulate IL-1 production from mouse peritoneal macrophages. Moreover, when intracellular and extracellular levels of IL-1 were quantitated, the studies demonstrated a catecholamine-mediated block in IL-1 synthesis without effect on its release. We also observed that exogenous cyclic AMP (cAMP) administered to mouse macrophages suppressed IL-1 production. This, coupled with the capacity of norepinephrine and epinephrine to enhance intracellular cAMP levels in macrophages, strongly suggested that the catecholamine-induced suppression of IL-1 production may be mediated by elevated intracellular cAMP levels. These findings demonstrate that selected stress-related neuroendocrine hormones can modulate IL-1 production by macrophages and further support the hypothesis that alteration of macrophage function by neuropeptides and neurohormones is a significant feature of stress-induced enhancement of viral and neoplastic disease.
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PMID:Catecholamine-induced suppression of interleukin-1 production. 302 61


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