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LPS Effects (lp + effects)
Selected AbstractsSickness and Aggressive Behavior in Dominant and Subordinate Mice,ETHOLOGY, Issue 2 2009Daniel W. H. Cohn Sick animals show a set of organized behavioral changes (sickness behavior), which is the result of a motivational re-organization of the behavior as a whole. Sickness behavior display can be influenced by the social context. In this work, we sought to investigate the regulation of sickness behavior within a pair of mice in the presence of an intruder mouse. Dominant and subordinate mice were treated with the bacterial endotoxin lipopolysaccharide (LPS) and were challenged with the presence of an intruder mouse. LPS effects depended on ranking and social context. Even though dominant mice displayed more agonistic interaction towards the intruder, subordinate mice displayed agonistic behavior towards the intruder when their dominant companion was treated with LPS. The results show that, not only sickness behavior is differentially expressed among different social ranks, but also that sickness behavior is related to different reactions among surrounding animals. These data are relevant for a biological approach to the relation between sickness behavior and social behavior. [source] Inter-relationship of cytokine production and NOS2 expression in microgliaJOURNAL OF NEUROCHEMISTRY, Issue 2002C. Dello Russo Under normal conditions, glial cells provide neurotrophic support, but can contribute to damage during neurodegenerative disorders such as multiple sclerosis and Alzheimer's disease. Once activated, glia produce and release inflammatory mediators and potentially neurotoxic substances (including cytokines, NO, and prostanoids) whose interactions could lead to sustained inflammation. We investigated the relationship between cytokine production and NO release using enriched cultures of rat microglia. Preliminary data suggest that low concentrations of endotoxin LPS (1,10 ng/mL) activated microglia by a complex mechanism involving NF,B activation, cAMP increase and PKA activation, and IL-1, production and release. We characterized this system using pharmacological activators and inhibitors of NF,B and PKA, and IL-1r, to reduce IL-1, effects. Norepinephrine (NE) dose-dependently inhibited LPS-induced NOS2 expression and NO generation, via activation of ,-2 adrenergic receptors (,2-ARs) and elevation of cAMP. Similarly, NE dose-dependently blocked LPS-dependent IL-1, production. The addition of PKA inhibitors did not reverse the suppressive effects of NE on NO production, but did reverse its effects on IL-1,. Addition of IL-1r, also reduced NO production, and exogenous IL-1, reversed the inhibitory effects of NE. These data suggest that effects of NE on LPS-dependent NO release is, at least in part, mediated by blocking of IL-1, secretion. At the same time, results with inhibitors suggest that PKA activation is necessary for LPS effects. Together, these results point to the existence of autocrine and paracrine regulatory mechanisms of microglia activation. The relationship between cytokines and NO could be an important mechanism of sustained and disruptive microglia activation. [source] Inhibition of Caspases In Vivo Protects the Rat Liver Against Alcohol-Induced Sensitization to Bacterial LipopolysaccharideALCOHOLISM, Issue 6 2001Ion V. Deaciuc Background: The mechanisms of liver sensitization by alcohol to Gram-negative bacterial lipopolysaccharide (LPS) remain elusive. The purpose of this study was two-fold: (1) to test the hypothesis that alcohol-enhanced liver apoptosis may be a sensitizing mechanism for LPS and (2) to further characterize the liver apoptotic response to alcohol. Methods: Rats were fed a high-fat, alcohol-containing liquid diet for 14 weeks, treated with LPS (1.0 mg/kg of body weight, intravenously) or saline, followed by injection of a pan-caspase inhibitor {IDN1965;N -[(1,3-dimethylindole-2-carbonyl)-valinyl]-3-amino-4-oxo-5-fluoropentanoic acid; 10 mg/kg of body weight, intraperitoneally} or vehicle, and killed. The following parameters were assessed: plasma aspartate: 2-oxoglutarate aminotransferase activity (AST); liver histology and terminal deoxyribonucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) response; caspase-3, ,8, and ,9 activity; and mRNA and protein expression for two apoptosis-signaling molecules: Fas receptor and Fas ligand; and three apoptosis adaptors: Bax, Bcl-XL, and Bcl-2. Results: Alcohol-feeding-induced liver steatosis, slightly increased caspases' activity, the number of TUNEL-positive nuclei, and facilitated the LPS necrotic effect without affecting mRNA expression of apoptosis signals and adaptors. LPS induced a significant increase in AST and the number of TUNEL-positive nuclei, both effects being more pronounced in alcohol-treated rats. LPS produced hepatic necrosis only in alcohol-treated rats. LPS effects were associated with up-regulation of mRNA expression for both apoptosis adaptors and signaling molecules. IDN1965 administration 3 hr after LPS injection strongly inhibited caspases' activity, particularly that of caspase-3. IDN1965 also abolished the increase in TUNEL-positive nuclei, reversed the effect of LPS on plasma AST in alcohol-treated rats, and prevented LPS-induced necrosis. Conclusions: (1) Alcohol-enhanced liver apoptosis may not involve regulatory steps at the transcriptional level. LPS-induced liver apoptosis seems to involve transcriptional regulation of several apoptosis adaptors. Therefore, alcohol and LPS may enhance liver apoptosis through different mechanisms. (2) Alcohol-enhanced liver apoptosis precedes and may facilitate the hepatic effects of LPS. LPS superimposed on alcohol further elevates the rate of apoptosis in the liver. This may exceed the phagocytosing capacity of the liver so that all the apoptotic cells are not phagocytosed, but rather die of necrosis. [source] Effects of sepsis on mast cells in rat dura mater: influence of L -NAME and VIPBRITISH JOURNAL OF PHARMACOLOGY, Issue 7 2001F Tore The influence of lipopolysaccharide (LPS)-induced sepsis on the various mast cell phenotypes of rat dura mater were examined both by immunohistochemical and biochemical methods. Three different populations of mast cells were identified in control rats: connective tissue type mast cells (CTMC) which contain rat mast cell protease1 (RMCP1), histamine, serotonin and heparin, mucosal type mast cells (MMC) which contain RMCP2, histamine and serotonin, and intermediate type which contains both RMCP1 and RMCP2 and probably various proportions of amines and heparin. LPS (25 mg kg,1 i.p.) caused changes in the proportions of the various types of mast cells. The number of MMC and intermediate type mast cells significantly increased and the number of mast cells immunopositive for both heparin and serotonin significantly decreased. Biochemical analysis showed that the histamine concentration of dura increased while its serotonin concentration decreased. While vasoactive intestinal peptide (VIP) (25 ng kg,1 i.p.) appears to potentiate LPS effects on dura mater mast cells, non-selective inhibition of nitric oxide (NO) synthase by Ng -nitro- L -arginine methyl ester (L -NAME) (30 mg kg,1 i.p.) did not influence sepsis-induced mast cell changes. These findings suggest that mast cells of dura mater may play a role in brain protection during sepsis. British Journal of Pharmacology (2001) 134, 1367,1374; doi:10.1038/sj.bjp.0704412 [source] | |||||||||||||