Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of bacterial endotoxin (lipopolysaccharide; LPS) on the cerebral blood flow (CBF), amino acid levels and brain histology were studied in young rabbits. The CBF was slightly decreased in the cerebral cortex and markedly decreased in the cerebral white matter at 60 and 120 min after LPS administration. Histological examination revealed only slightly pyknotic neurons around small vessels at 24 hours, and multifocal necrosis in the deep cerebral cortex and white matter at 72 hours. Some amino acids were increased in the plasma and brain regions at 24 hours after LPS administration, most of which were essential amino acids. GABA in the cerebral white matter was decreased at 24 hours. At 72 hours, most non-essential and glucogenic amino acids were decreased. These results suggest that the brain histological changes are related mainly to hypoperfusion and vascular damage in the brain. The amino acid changes may also be related to inappropriate amino acid metabolism associated with brain cell damage.
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PMID:Endotoxin, cerebral blood flow, amino acids and brain damage in young rabbits. 306 28

Alterations in the immune system are often accompanied by reproductive disorders. The bacterial endotoxin lipopolysaccharide (LPS) has central inflammatory effects, and activates the release of cytokines (immune system mediatory factors) in the hypothalamus, where the LHRH neurons are located. Therefore, these studies were designed to investigate a possible effect of the LPS and LHRH secretion and the possible interaction with excitatory and inhibitory amino acids. Animals were decapitated at 09.00 h, and the preoptic mediobasal hypothalamic area (PO/MBH) dissected and superfused. Superfusate fractions were collected at 15-min intervals. After a stabilization superfusion period of 60 min four fractions were collected; LPS (100 ng/ml) was then added to the superfusion medium for the duration of 1 h. This was followed by a washout period of 60 min. The PO/MBH fragments were then subjected to a 56 mM K+ stimulus. Control PO/MBH fragments were continuously superfused with Earle's balanced salt solution. LHRH release was significantly (p < 0.05) reduced during and following exposure to LPS. At this time GABA and taurine concentrations increased in the superfusion medium, while glutamate decreased significantly compared with the control group. These observations indicate that LPS inhibits LHRH and glutamate release, but stimulates taurine and GABA secretion. These effects may be explained by the stimulation of cytokines of neuronal and/or glial source which may interact with the excitatory and inhibitory amino acids.
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PMID:Effects of endotoxin on in vitro release of LHRH and amino acid neurotransmitters by preoptic mediobasal hypothalamic fragments. 894 21

We previously reported that neurosteroids, including dehydroepiandrosterone sulfate (DHEAS), inhibit the production of TNF in vitro and in vivo. In this paper we evaluated the effect of DHEAS on TNF production by cultured rat astrocytes and murine glial cell clones, and compared it with the effect on monocytic THP-1 cells. We found that DHEAS at a concentration of 10(-4)-10(-7) M inhibits TNF production induced by lipopolysaccharide (LPS, 1 microgram/ml) in these cells. Since the inhibitory effect of DHEAS is not mediated by the glucocorticoid (GC) receptor and DHEAS is an allosteric antagonist of the GABAA receptor, we investigated the possible role of GABAA receptors in this effect. The results showed that the inhibitory effect of DHEAS (10(-6) M) on TNF production by THP-1 cells was completely reversed by addition of 10(-6) M GABA. However, a GABAA receptor antagonist (bicuculline) did not mimic the action of DHEAS. In conclusion, DHEAS can inhibit TNF production in astrocytic and microglial cells suggesting it could be an endogenous regulator of TNF production in the brain.
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PMID:DHEAS inhibits TNF production in monocytes, astrocytes and microglial cells. 921 49

In the hypothalamic paraventricular nucleus (PVN), the proenkephalin gene may be upregulated by lipopolysaccharide (LPS) and downregulated by the GABA-A agonist muscimol. Candidate transcription factors regulating the proenkephalin gene in opposite directions are cAMP-response-element-binding protein (CREB) (when phosphorylated, a positive regulator) and cAMP-responsive modulatory inducible cAMP early repressor (CREM/ICER) (a negative regulator). Our results demonstrate that CREM alpha,beta,gamma transcripts and ICER are induced in the PVN by LPS and remain elevated for periods of up to 12 h. PhosphoCREB is elevated after LPS administration, peaking at 8 h, but remaining elevated over control levels at 12 h. Phospho-CREB induction by LPS is also seen in primary hypothalamic cultures. Cotransfection of ICER with ENK-CAT12 into primary hypothalamic cultures produced a decrease in chloramphenicol acetyl transferase (CAT) levels following cAMP or LPS stimulation. PhosphoCREB is downregulated and CREM/ICER is upregulated in the PVN by muscimol, suggesting that the regulation of these transcription factors may underlie the inhibitory effect of muscimol on target genes in the PVN.
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PMID:PhosphoCREB and CREM/ICER: positive and negative regulation of proenkephalin gene expression in the paraventricular nucleus of the hypothalamus. 1063 69

Recent evidence suggests that stress-activated protein kinases expressed in glial cells have very important roles during cerebral ischemia. The neuroprotective agent chlomethiazole, which is known to enhance the conductance at the GABA(A) receptor complex, is presently in clinical trials for the treatment of severe stroke. Here the authors suggested that chlormethiazole has anti-inflammatory properties because it potently and selectively inhibited p38 mitogen-activated protein (MAP) kinase in primary cortical glial cultures. The inhibition of p38 MAP kinase resulted in the attenuation of the induction of c-fos and c-jun mRNA and AP-1 DNA binding by lipopolysaccharide (LPS). In addition, chlomethiazole inhibited the activation of an AP-1-dependent luciferase reporter plasmid in SK-N-MC human neuroblastoma cells in response to glutamate. Chlomethiazole inhibited the p38 MAP kinase activity as revealed by the decrease in the LPS-induced phosphorylation of the substrates ATF-2 and hsp27, whereas the phosphorylation status of the p38 MAP kinase itself was unaffected. Interestingly, chlomethiazole exhibited an IC(50) of approximately 2 micromol/L for inhibition of c-fos mRNA expression, indicating 25 to 75 times higher potency than reported EC(50) values for enhancing GABA(A) chloride currents. The results indicated a novel mechanism of action of chlomethiazole, and provided support for a distinctive role of p38 MAP kinase in cerebral ischemia.
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PMID:Neuroprotective agent chlomethiazole attenuates c-fos, c-jun, and AP-1 activation through inhibition of p38 MAP kinase. 1090 41

Pregabalin [S-(+)-3-isobutylgaba] is a novel compound under development for its analgesic, anxiolytic, and anticonvulsant properties, and its interaction with the alpha(2)delta-subunit of voltage-dependent Ca(2+) channels. In this study, we investigate the antinociceptive activity of pregabalin in a rat model of delayed visceral hyperalgesia induced by i.p. lipopolysaccharide (LPS) administration. LPS (Escherichia coli, serotype O111:B4) leads to a delayed lowering threshold (9-12 h) of abdominal contractions in response to rectal distension (RD) in awake rats surgically prepared for electromyography of abdominal muscles. This allodynic effect of LPS was blocked by morphine (0.3 mg/kg s.c.), and the action of morphine was antagonized by naloxone (2.5 mg/kg s.c.). A single i.p. (10, 30 mg/kg) and oral (1, 3, 10 and 30 mg/kg) treatment of pregabalin dose dependently suppressed LPS-induced rectal hypersensitivity. When administered 2 h before RD (but preceded 12 h by LPS injection), the oral dose of 10 mg/kg was effective both in the allodynic response induced by LPS and in the intensity of the nociceptive response related to RD. Pretreatment by either naloxone or bicuculline (a GABA(A) antagonist, 0.5 mg/kg i.p.) did not affect the antiallodynic effect of pregabalin. We conclude that pregabalin is a therapeutic candidate in the treatment of gut hypersensitivity not acting through GABA(A) and opiate receptors.
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PMID:Antinociceptive effect of pregabalin in septic shock-induced rectal hypersensitivity in rats. 1099 74

In young (two months) and aged (18 months) male rats injected s.c. with Freund's adjuvant or adjuvant's vehicle 18 days earlier, 24-h variations in mitogenic responses, lymphocyte subsets and monoamine and amino acid content were examined in submaxillary lymph nodes. Mitogenic responses to concanavalin A (Con A) and lipopolysaccharide (LPS) were higher during the light phase of daily photoperiod. Old rats exhibited a suppressed or impaired mitogenic response to Con A but not to LPS. Acrophases of 24-h rhythm in lymphocyte subset populations in submaxillary lymph nodes were: 18:37-19:44h (B cells), 09:00-10:08h (T and CD4(+) cells) and 12:19-15:58h (CD8(+) cells). Aging augmented B cells and decreased T, CD4(+) and CD8(+) cells. Significant correlations were found between Con A activity and T cells, between lymph node 5HT content and B, T and CD8(+) lymphocytes, and between lymph node 5HT and taurine and GABA content. Aging increased lymph node 5HT content but did not modify NE content. Lymph node concentration of aspartate, glutamate and taurine was higher at night while that of GABA attained peak values at late afternoon. Old rats injected with Freund's adjuvant showed a higher mean value (glutamate) and smaller amplitude (glutamate, taurine) than their respective young controls. The results further document the effects of aging on the chronobiology of the immune system.
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PMID:Aging-induced changes in 24-h rhythms of mitogenic responses, lymphocyte subset populations and neurotransmitter and amino acid content in rat submaxillary lymph nodes during Freund's adjuvant arthritis. 1122 42

Pituicytes, the glial cells of the neurohypophysis, secrete interleukin-6 upon stimulation with various inflammatory mediators, i.e. lipopolysaccharide. Previous studies have identified several receptors on pituicytes. This study investigates the effect of GABA(B) receptor activation on interleukin-6 release from pituicytes. Cultured murine pituicytes were stimulated for 24 h with lipopolysaccharide (0.5 ng/ml) to give a significant interleukin-6 release compared to control. The interleukin-6 release was significantly potentiated by the GABA(B) receptor agonist (R)-4-amino-3-(4-chlorophenyl) butanoic acid (R-baclofen; 10, 100 or 500 microM). However, R-baclofen itself (10, 100 or 500 microM) did not stimulate the interleukin-6 secretion. Furthermore, the potent GABA(B) receptor antagonists 3-[[(3,4-Dichlorophenyl)methyl]amino]propyl]diethoxymethyl) phosphinic acid (CGP52432; 30 or 300 microM) and (RS)-3-Amino-2-(4-chlorophenyl)-2-hydroxypropyl-sulphonic acid (2-OH-saclofen; 10 or 100 microM) did not remove the effect of R-baclofen (100 microM). Gamma-amino butyric acid (GABA; 30 or 300 microM) did not alter the lipopolysaccharide-mediated interleukin-6 response. After 30 min, intracellular cyclic AMP (cAMP) was higher in cells stimulated with lipopolysaccharide compared to control, and R-baclofen significantly inhibited this increase in cAMP. Nevertheless, neither lipopolysaccharide nor R-baclofen had any effect on intracellular cAMP after 24 h of stimulation. The results suggest that the effect of R-baclofen on lipopolysaccharide-stimulated interleukin-6 secretion is independent of GABA(B) receptors.
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PMID:Baclofen influences lipopolysaccharide-mediated interleukin-6 release from murine pituicytes. 1223 93

gamma-Aminobutyric acid (GABA) can act as a neuroprotective agent besides its well-established role as the main inhibitory neurotransmitter in the CNS. Here we report that microglial cells express GABA(B) receptors indicating that these prominent immunocompetent cells in the brain are a target for GABA. Agonists of GABA(B) receptors triggered the induction of K(+) conductance in microglial cells from acute brain slices and in culture. Both subunits of GABA(B) receptors were identified in cultured microglia by Western blot analysis and immunocytochemistry, and were detected on a subpopulation of microglia in situ by immunohistochemistry. In response to facial nerve axotomy, we observed an increase in GABA(B) receptor expressing microglial cells in the facial nucleus. We activated microglial cells in culture with lipopolysaccharide (LPS) to induce the release of interleukin-6 and interleukin-12p40. This release activity was attenuated by simultaneous activation of the GABA(B) receptors indicating that GABA can modulate the microglial immune response.
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PMID:Microglia express GABA(B) receptors to modulate interleukin release. 1501 47

Sutherlandia frutescens is a South African herb used traditionally by the natives to treat cancer, and more recently to improve the overall health in HIV/AIDS patients. Gas chromatography/mass spectrometer profiling and liquid chromatographic/mass spectral investigation confirmed and quantified the presence of canavanine, GABA and arginine in the herbal preparation used in this study. In vitro study demonstrated a concentration dependent effect of Sutherlandia on several tumor cell lines, with 50% inhibition (IC50) of proliferation of MCF7, MDA-MB-468, Jurkat and HL60 cells at 1/250, 1/200, 1/150 and 1/200 dilutions, respectively. Sutherlandia treatment did not induce HL60 differentiation along the macrophage/monocyte or granulocyte lineage. It demonstrated antioxidant activity in reducing free radical cations with an estimated activity of 0.5 microl of Sutherlandia extract equivalent to that of 10 microM of Trolox. However, it did not significantly suppress lipopolysaccharide stimulated nitric oxide production by murine macrophage/monocyte RAW 264.7 cells, nor did it significantly inhibit IL-1beta and TNF-alpha mRNA expression in RAW 264.7 cells. In conclusion, Sutherlandia ethanolic extract showed a concentration dependent antiproliferative effect on several human tumor cell lines but did not show significant antioxidant effects. Further studies are needed to explore the activities of this multipurpose South African herbal preparation.
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PMID:In vitro culture studies of Sutherlandia frutescens on human tumor cell lines. 1518 98


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