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DEX
Terms modified by DEX Selected AbstractsEffects of excessive glucocorticoid receptor stimulation during early gestation on psychomotor and social behavior in the rat ,DEVELOPMENTAL PSYCHOBIOLOGY, Issue 2 2010Karine Kleinhaus Abstract Severe psychological stress in the first trimester of pregnancy increases the risk of schizophrenia in the offspring. To begin to investigate the role of glucocorticoid receptors in this association, we determined the effects of the glucocorticoid dexamethasone (2,mg/kg), administered to pregnant rats on gestation days 6,8, on maternal behaviors and schizophrenia-relevant behaviors in the offspring. Dams receiving dexamethasone exhibited increased milk ejection bouts during nursing. Offspring of dexamethasone-treated dams (DEX) showed decreased juvenile social play and a blunted acoustic startle reflex in adolescence and adulthood, effects that were predicted by frequency of milk ejections in the dams. DEX offspring also showed increased prepulse inhibition of startle and reduced amphetamine-induced motor activity, effects not correlated with maternal behavior. It is postulated that over-stimulation of receptors targeted by glucocorticoids in the placenta or other maternal tissues during early gestation can lead to psychomotor and social behavioral deficits in the offspring. Moreover, some of these deficits may be mediated by alterations in postnatal maternal behavior and physiology produced by early gestational exposure to excess glucocorticoids. © 2010 Wiley Periodicals, Inc. Dev Psychobiol 52:121,132, 2010 [source] Free fatty acids as mediators of adaptive compensatory responses to insulin resistance in dexamethasone-treated ratsDIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 2 2008Michela Novelli Abstract Background Chronic low-dose dexamethasone (DEX) treatment in rats is associated to insulin resistance with compensatory hyperinsulinaemia and reduction in food intake. We tested the hypothesis that the elevation in circulating free fatty acids (FFAs) induced by DEX is the common mediator of both insulin resistance and insulin hyperproduction. Methods For this purpose, an anti-lipolytic agent was administered during DEX treatment to lower lipacidaemia for several hours prior to glucose and insulin tolerance tests. Leptin expression in adipose tissue (by Northern blot) and plasma leptin levels (by radioimmunoassay) were also investigated to verify whether a rise in circulating leptin could be responsible for the anorectic effect of DEX. Results Our data show that a transient pharmacological reduction of elevated plasma FFA levels abates the post-loading hyperinsulinaemia and counteracts the insulin resistance induced by DEX, supporting the hypothesis that the chronic elevation in FFAs is the common mediator of DEX-induced changes. Despite enhanced leptin expression in white adipose tissue, DEX-treated rats show no significant increase in plasma leptin levels. This suggests that the anorectic effect of DEX should be mediated, at least partially, by other factors, possibly related to the influence of concomitantly elevated plasma FFA and insulin levels on the hypothalamic centers regulating feeding. Conclusions Our results sustain the idea that a prolonged increase in plasma FFA levels plays an important role in the adaptive regulation of glucose and energy homeostasis, not only by potentiating insulin secretion but also by providing a signal of ,nutrient abundance' capable of restraining food intake. Copyright © 2007 John Wiley & Sons, Ltd. [source] Clenbuterol antagonizes glucocorticoid-induced atrophy and fibre type transformation in miceEXPERIMENTAL PHYSIOLOGY, Issue 1 2004Maria Antonietta Pellegrino Beta-agonists and glucocorticoids are frequently coprescribed for chronic asthma treatment. In this study the effects of 4 week treatment with beta-agonist clenbuterol (CL) and glucocorticoid dexamethasone (DEX) on respiratory (diaphragm and parasternal) and limb (soleus and tibialis) muscles of the mouse were studied. Myosin heavy chain (MHC) distribution, fibres cross sectional area (CSA), glycolytic (phosphofructokinase, PFK; lactate dehydrogenase, LDH) and oxidative enzyme (citrate synthase, CS; cytochrome oxidase, COX) activities were determined. Muscle samples were obtained from four groups of adult C57/B16 mice: (1) Control (2) Mice receiving CL (CL, 1.5 mg kg,1 day,1 in drinking water) (3) Mice receiving DEX (DEX, 5.7 mg kg,1 day,1s.c.) (4) Mice receiving both treatments (DEX + CL). As a general rule, CL and DEX showed opposite effects on CSA, MHC distribution, glycolytic and mitochondrial enzyme activities: CL alone stimulated a slow-to-fast transition of MHCs, an increase of PFK and LDH and an increase of muscle weight and fibre CSA; DEX produced an opposite (fast-to-slow transition) change of MHC distribution, a decrease of muscle weight and fibre CSA and in some case an increase of CS. The response varied from muscle to muscle with mixed muscles, as soleus and diaphragm, being more responsive than fast muscles, as tibialis and parasternal. In combined treatments (DEX + CL), the changes induced by DEX or CL alone were generally minimized: in soleus, however, the effects of CL predominated over those of DEX, whereas in diaphragm DEX prevailed over CL. Taken together the results suggest that CL might counteract the unwanted effects on skeletal muscles of chronic treatment with glucocorticoids. [source] Cell proliferation and apoptosis: dual-signal hypothesis tested in tuberculous pleuritis using mycobacterial antigensFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 1 2004Sulochana D. Das Abstract Antigens and mitogens have the innate ability to trigger cell proliferation and apoptosis thus exhibiting a dual-signal phenomenon. This dual-signal hypothesis was tested with mycobacterial antigens (PPD and heat killed Mycobacterium tuberculosis, MTB) in tuberculous pleuritis patients where the immune response is protective and compartmentalized. We compared and correlated the cell-cycle analysis and antigen-induced apoptosis in normal and patients' peripheral blood mononuclear cells (PBMCs) and patients' pleural fluid mononuclear cells (PFMCs). In cell-cycle analysis, PFMCs showed good mitotic response with PPD and MTB antigens where 10% and 7% of resting cells entered the S and G2/M phases of cell cycle, respectively. This antigen-induced proliferation of PFMCs correlated well with the lymphocyte transformation test (LTT) results. On the other hand, PFMCs also showed 21% of spontaneous apoptosis, which further increased to 43%, by induction with known apoptotic agent like Dexamethasone (DEX) and the mycobacterial antigens PPD and MTB. Further we demonstrated by anti-CD3 induction experiments that prior activation of cells is prerequisite for them to undergo apoptosis. Our results showed that PPD and MTB antigens induced both cell proliferation and apoptosis in PFMCs, which were pre-sensitized to mycobacterial antigens in vivo. Thus the dual-signal phenomenon was operative against these antigens in tuberculous pleuritis. We also demonstrated that the activated cells are more predisposed to apoptosis. [source] Fabrication of Microbeads with a Controllable Hollow Interior and Porous Wall Using a Capillary Fluidic DeviceADVANCED FUNCTIONAL MATERIALS, Issue 18 2009Sung-Wook Choi Abstract Poly(D,L -lactide-co-glycolide) (PLGA) microbeads with a hollow interior and porous wall are prepared using a simple fluidic device fabricated with PVC tubes, glass capillaries, and a needle. Using the fluidic device with three flow channels, uniform water-in-oil-in-water (W-O-W) emulsions with a single inner water droplet can be achieved with controllable dimensions by varying the flow rate of each phase. The resultant W-O-W emulsions evolve into PLGA microbeads with a hollow interior and porous wall after the organic solvent in the middle oil phase evaporates. Two approaches are employed for developing a porous structure in the wall: emulsion templating and fast solvent evaporation. For emulsion templating, a homogenized, water-in-oil (W/O) emulsion is introduced as the middle phase instead of the pure oil phase. Low-molecular-weight fluorescein isothiocyanate (FITC) and high-molecular-weight fluorescein isothiocyanate,dextran conjugate (FITC,DEX) is added to the inner water phase to elucidate both the pore size and their interconnectivity in the wall of the microbeads. From optical fluorescence microscopy and scanning electron microscopy images, it is confirmed that the emulsion-templated microbeads (W-W/O-W) have larger and better interconnected pores than the W-O-W microbeads. These microstructured microbeads can potentially be employed for cell encapsulation and tissue engineering, as well as protection of active agents. [source] Reliability and validity of the Japanese version of the Dysexecutive Questionnaire (DEX) in Alzheimer's disease: validation of a behavioral rating scale to assess dysexecutive symptoms in Japanese patients with Alzheimer's diseaseINTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 10 2007Yoshihiro Shinagawa Abstract Background Both executive cognitive dysfunction and behavioral problems contribute to dysexecutive symptoms in daily life. The aim of the present study was to develop a behavior rating scale for assessing dysexecutive symptoms in Japanese patients with AD. Method The Dysexecutive Questionnaire (DEX), devised by Burgess et al. (1998), was used to evaluate 122 Japanese patients with AD. The factor structure, internal consistency, test-retest reliability, and construct validity of the Japanese version of the DEX were then examined. Results The Japanese version of the DEX demonstrated a good internal reliability and a good test,retest reliability. Factor analysis revealed three factors that were named ,apathy', ,hyperactivity' and ,planning and monitoring process of the purposive action'. The ,apathy' factor of the DEX was significantly correlated with the ,apathy' score of the Neuropsychiatric Inventory (NPI), while ,planning and monitoring process' factor of the DEX was significantly correlated with the total score of the Frontal Assessment Battery (FAB) and the ,hyperactivity' factor of the DEX was significantly correlated with the ,aggression', ,euphoria' and ,disinhibition' scores of the NPI. Conclusions The Japanese DEX is a reliable and valid instrument for assessing executive dysfunction conveniently in real life situations of AD patients. While two factors, ,apathy' and ,hyperactivity', were associated with emotional and behavioral changes, the ,planning and monitoring process' was associated with the cognitive executive function in the patients with AD. These findings suggest that both a neuropsychiatric syndrome and cognitive function contribute to the dysexecutive symptoms experienced by AD patients in daily life. Copyright © 2007 John Wiley & Sons, Ltd. [source] Direct Inhibitory Effect of Glucocorticoids on Corticotrophin-Releasing Hormone Gene Expression in Neurones of the Paraventricular Nucleus in Rat Hypothalamic Organotypic CulturesJOURNAL OF NEUROENDOCRINOLOGY, Issue 9 2008B. Bali Corticotrophin-releasing hormone (CRH) in the parvocellular neurosecretory neurones of hypothalamic paraventricular nucleus governs neuroendocrine stress cascade and is the major target of the negative feedback effect of corticosteroids. To assess whether glucocorticoids exert their inhibitory effect on CRH expression directly on parvocellular neurones or indirectly through a complex neuronal circuit, we examined the effect of corticosterone (CORT) and dexamethasone (DEX) on CRH mRNA levels in slice explant cultures of the rat hypothalamus. Organotypic slice cultures were prepared from 6 days old rat pups and maintained in vitro for 14 days. CRH mRNA expression was measured by in situ hybridisation histochemistry. Under basal conditions, CRH mRNA expressing cells were exclusively revealed in the paraventricular region along the third ventricle. Inhibition of action potential spike activity by tetrodotoxin (TTX, 1 ,m) reduced CRH mRNA signal in the organotypic cultures. CORT (500 nm) or DEX (50 nm) treatment for 24 h significantly inhibited CRH expression in the parvocellular neurones and this effect of corticosteroids was not affected following blockade of voltage dependent sodium channels by TTX. Forskolin-stimulated CRH mRNA levels in the paraventricular nucleus were also inhibited by CORT or DEX in the presence and in the absence of TTX. These studies identify paraventricular CRH neurones as direct target of corticosteroid feedback. Type II corticosteroid receptor agonists act directly on paraventricular neurones to inhibit basal and forskolin-induced CRH mRNA expression in explant cultures of the rat hypothalamus. [source] Chronic Prenatal Ethanol Exposure Increases Glucocorticoid-Induced Glutamate Release in the Hippocampus of the Near-Term Foetal Guinea PigJOURNAL OF NEUROENDOCRINOLOGY, Issue 11 2006U. Iqbal Exposure to high cortisol concentration can injure the developing brain, possibly via an excitotoxic mechanism involving glutamate (Glu). The present study tested the hypothesis that chronic prenatal ethanol exposure (CPEE) activates the foetal hypothalamic-pituitary-adrenal axis to produce high cortisol exposure in the foetal compartment and alters sensitivity to glucocorticoid-induced Glu release in the foetal hippocampus. Pregnant guinea pigs received daily oral administration of ethanol (4 g/kg maternal body weight/day) or isocaloric-sucrose/pair-feeding from gestational day (GD) 2 until GD 63 (term, approximately GD 68) at which time they were euthanised, 1 h after their final treatment. Adrenocorticotrophic hormone (ACTH) and cortisol concentrations were determined in foetal plasma. Basal and electrically stimulated Glu and ,-aminobutyric acid (GABA) efflux in the presence or absence of dexamethasone (DEX), a selective glucocorticoid-receptor agonist, were determined ex vivo in foetal hippocampal slices. Glucocorticoid receptor (GR), mineralocorticoid receptor (MR) and N -methyl- d -aspartate (NMDA) receptor NR1 subunit mRNA expression were determined in situ in the hippocampus and dentate gyrus. In the near-term foetus, CPEE increased foetal plasma ACTH and cortisol concentrations. Electrically stimulated glutamate, but not GABA, release was increased in CPEE foetal hippocampal slices. Low DEX concentration (0.3 µM) decreased stimulated glutamate, but not GABA, release in both CPEE and control foetal hippocampal slices. High DEX concentration (3.0 µM) increased basal release of Glu, but not GABA, in CPEE foetal hippocampal slices. GR, but not MR, mRNA expression was elevated in the hippocampus and dentate gyrus, whereas NR1 mRNA expression was increased in the CA1 and CA3 fields of the foetal hippocampus. These data demonstrate that CPEE increases high glucocorticoid concentration-induced Glu release in the foetal hippocampus, presumably as a consequence of increased GR expression. These effects of CPEE, coupled with increased glutamate release and increased NMDA receptor expression, may predispose the near-term foetal hippocampus to GR and Glu-NMDA receptor-mediated neurodevelopmental toxicity. [source] Effect of dexmedetomidine on the characteristics of bupivacaine in a caudal block in pediatricsACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 2 2009I. SAADAWY Background: Dexmedetomidine (DEX) is a highly selective ,2 -adrenoceptor agonist that has been used increasingly in children. However, the effect of caudal DEX has not been evaluated before in children. This prospective randomized double-blinded study was designed to evaluate the analgesic efficacy of caudal DEX with bupivacaine in providing pain relief over a 24-h period. Methods: Sixty children (ASA status I) aged 1,6 years undergoing unilateral inguinal hernia repair/orchidopexy were allocated randomly to two groups (n=30 each). Group B received a caudal injection of bupivacaine 2.5 mg/ml, 1 ml/kg; Group BD received the same dose of bupivacaine mixed with DEX 1 ,g/kg during sevoflurane anesthesia. Processed electroencephalogram (bispectral index score), heart rate, blood pressure, pulse oximetry and end-tidal sevoflurane were recorded every 5 min. The characteristics of emergence, objective pain score, sedation score and quality of sleep were recorded post-operatively. Duration of analgesia and requirement for additional analgesics were noted. Results: The end-tidal sevoflurane concentration and the incidence of agitation were significantly lower in the BD group (P<0.05). The duration of analgesia was significantly longer (P<0.001) and the total consumption of rescue analgesic was significantly lower in Group BD compared with Group B (P<0.01). There was no statistically significant difference in hemodynamics between both groups. However, group BD had better quality of sleep and a prolonged duration of sedation (P<0.05). Conclusion: Caudal DEX seems to be a promising adjunct to provide excellent analgesia without side effects over a 24-h period. It has the advantage of keeping the patients calm for a prolonged time. Implications statement: Caudally administered DEX (1 ,g/kg), combined with bupivacaine, was associated with an extended duration of post-operative pain relief. [source] Correlation between serum concentrations following continuous intravenous infusion of dexmedetomidine or medetomidine in cats and their sedative and analgesic effectsJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 1 2000Ansah Dexmedetomidine (DEX) may have some therapeutic advantages over the racemate medetomidine (MED). Here we have examined how serum concentrations of DEX correlate with some of its anaesthetic effects. Cats (n = 6) were administered with a continuous stepwise intravenous (i.v.) infusion of DEX or MED on different occasions in a cross-over design. Maintenance infusion rates (mg/kg/min) used were: DEX = 0.25 (MED = 0.50); DEX = 1 (MED = 2) and DEX = 4 (MED = 8) for infusion steps 1, 2 and 3, respectively. Each maintenance infusion lasted at least 50 min and was preceded with a loading dose. There was no significant difference between serum DEX and 0.5 serum MED concentrations at any dose level nor was there a significant difference between serum DEX and the (entire) serum MED concentrations. There was no significant difference between DEX and MED for sedation, analgesia, muscular relaxation and heart and respiratory rates. For both DEX and MED, serum drug concentration and analgesia were dose-dependent and sedation increased until the end of infusion step 2 (dose level 2) and decreased at the end of step 3 (dose level 3). Muscular relaxation was not dose-dependent. We conclude that increasing the blood concentration of DEX or MED beyond a certain level decreases the level of sedation instead of increasing it even though analgesia increases. The rate at which DEX and MED are metabolized in cats may not be the same. [source] Interaction Between Polymer Chains Covalently Fixed to Single-Walled Carbon NanotubesMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 9 2006Hiromi Kitano Abstract Summary: A single-walled carbon nanotube (SWNT), which had been oxidized with a mixture of nitric acid and sulfuric acid to afford polar groups at its ends, was incubated with an azo-type macroinitiator carrying dextran (DEX), poly(ethylene glycol) (PEG) or poly(N -vinylpyrrolidone) (PVPy) chains at 70,°C. Similarly, the oxidized SWNT was incubated with 2,2,-azoisobutyronitrile and acrylic acid (HAA) or N -vinylpyrrolidone at 70,°C. Due to the large radical trapping ability of SWNT, the polymer chains corresponding to the cloven macroinitiator (PEG, DEX or PVPy) and the propagating polymer chains (poly(acrylic acid) (HPAA) or PVPy) were covalently fixed to the surface of the SWNTs. The hydrophilic polymer-modified SWNTs could be stably dispersed in water. Furthermore, the SWNTs modified with PEG and DEX sedimented in the presence of free DEX and PEG, respectively, whereas there was no precipitation of the PEG- and DEX-modified SWNTs in the presence of the same kind of free polymer. This seemed to be related to the phase separation phenomena in water soluble DEX and PEG systems induced by the repulsive interaction between PEG and DEX molecules. However, the mixture of two kinds of polymer-modified SWNTs (PEG-SWNT and DEX-SWNT) did not show noticeable phase separation, probably due to steric hindrance for the efficient repulsive polymer-polymer interaction by fixation to the gigantic SWNTs. Furthermore, upon mixing the dispersions of HPAA-SWNT and PEG-SWNT or PVPy-SWNT, the turbidity of the dispersions gradually increased, while no increase in turbidity of the dispersion mixture was observed in the presence of dimethyl sulfoxide, indicating hydrogen bonding between the HPAA and PEG or PVPy chains on the surface of the SWNTs. The modification methods examined in this work would be promising to give various functions to SWNT. Susceptible processes of radical trap on SWNT surface. [source] An In-Vivo Analysis of Capillary Stasis and Endothelial Apoptosis in a Model of HypertensionMICROCIRCULATION, Issue 8 2007Edward D. Tran ABSTRACT Objective: Recent evidence suggests endothelial apoptosis may be a mechanism for capillary rarefaction in hypertensives. The objective of this study was to examine the early phase of endothelial apoptosis and capillary blood flow in the spontaneously hypertensive rat (SHR) and the normotensive Wistar-Kyoto (WKY) rat. Methods: Since hypertension in SHR is dependent on glucocorticoids, the animals were treated with dexamethasone (DEX), by intraperitoneal injection and then by superfusion on exposed mesentery. Selected capillaries were continuously observed. Annexin V and propidium iodide were used to detect apoptosis. Results: Without central pressure reduction, permanent capillary stasis was initiated by the entrapment of leukocytes at the location of an endothelial cell that had platelets attached to it. Apoptosis of the endothelial cell was followed by apoptosis in other endothelial cells of the obstructed capillary. The incidence of stasis and total cell death in WKY+DEX were higher than WKY, whereas there were no differences between SHR+DEX and SHR. Blockade of the lectin domain of L-selectin or a platelet membrane adhesion molecule (glycoprotein IIb/IIIa) blocked the development of stasis. Conclusions: Glucocorticoid facilitates cell death and microvessel stasis. Immobilized platelets and leukocytes play a central role in capillary stasis, which leads to progression of endothelial apoptosis. [source] Effect of dexamethasone therapy on pulmonary function in chronic lung disease: A comparison of disease typesPEDIATRICS INTERNATIONAL, Issue 3 2001Masami Mizobuchi Abstract Background: In the present study, we investigated the effect of dexamethasone (DEX) therapy on extubation and pulmonary function in patients with chronic lung disease (CLD) who required long-term mechanical ventilation. In addition, we compared the effects of DEX therapy among CLD types. Methods: Twenty-two CLD patients who were ventilator dependent for 28 days or longer received DEX therapy for the purposes of extubation. A tapering dose of DEX, starting from 0.5 mg/kg per day, was administered for 7 days. Pulmonary function was measured at initiation of administration and 4 days after initiation. We evaluated static respiratory system compliance (Crs) and static respiratory system resistance (Rrs) adjusted by bodyweight. Chronic lung disease types were categorized according to the classification of the Ministry of Health and Welfare Research Project. We compared the effect of DEX therapy among CLD types. Results: Dexamethasone therapy was started at a mean (±SD) 45±11 days after birth and 32.1±1.3 weeks of postconceptional age in infants with a mean bodyweight of 939±153 g. After DEX therapy, extubation was successful in all 22 patients. Following DEX administration, Crs was significantly increased from 0.69±0.13 to 1.17±0.21 mL/cm H2O per kg. In contrast, Rrs did not show any clear changes. Comparing CLD types, no difference was observed for Crs and Rrs in each disease type. Conclusions: Dexamethasone was administered to CLD patients requiring long-term mechanical ventilation for the purposes of extubation and extubation was successful in all patients. It was found that Crs was increased in all patients following DEX, regardless of CLD type. The increase in Crs following DEX administration may have been related to successful extubation. [source] Hybrid Lethality in Interspecific F1 Hybrid Nicotiana gossei×N. tabacum Involves a MAP-Kinases Signalling CascadePLANT BIOLOGY, Issue 3 2007M. Mino Abstract: A cultured cell line, GTH4 (Nicotiana gossei Domin ×N. tabacum L.), which exhibits hybrid lethality, died at 26 °C, but not at 37 °C. Pharmacological experiments using inhibitors of protein phosphatases and protein kinases indicated the involvement of a protein kinase signalling pathway in the cell death process. Immunoblot analysis revealed that salicylic acid-induced protein kinase (SIPK) was phosphorylated soon after the shift in temperature from 37 °C to 26 °C. Cultured cells of the hybrid of N. gossei× transgenic N. tabacum harboring a steroid (dexamethasone; DEX)-inducible NtMEK2DD or NtMEK2KR, constitutively active and inactive forms of NtMEK2, respectively, were established. Induction of NtMEK2DD by DEX in the hybrid cells induced the activation of SIPK, the generation of hydrogen peroxide (H2O2), and cell death at 37 °C. The activation of SIPK, generation of H2O2, and cell death at 26 °C were compromised by DEX treatment in hybrid cells harbouring NtMEK2KR. This study provides evidence for the involvement of MAPK signalling in the regulation of cell death in hybrids. [source] Rapid mass spectrometric analysis of 15N-Leu incorporation fidelity during preparation of specifically labeled NMR samplesPROTEIN SCIENCE, Issue 9 2008Stephanie M.E. Truhlar Abstract Advances in NMR spectroscopy have enabled the study of larger proteins that typically have significant overlap in their spectra. Specific 15N-amino acid incorporation is a powerful tool for reducing spectral overlap and attaining reliable sequential assignments. However, scrambling of the label during protein expression is a common problem. We describe a rapid method to evaluate the fidelity of specific 15N-amino acid incorporation. The selectively labeled protein is proteolyzed, and the resulting peptides are analyzed using MALDI mass spectrometry. The 15N incorporation is determined by analyzing the isotopic abundance of the peptides in the mass spectra using the program DEX. This analysis determined that expression with a 10-fold excess of unlabeled amino acids relative to the 15N-amino acid prevents the scrambling of the 15N label that is observed when equimolar amounts are used. MALDI TOF-TOF MS/MS data provide additional information that shows where the "extra" 15N labels are incorporated, which can be useful in confirming ambiguous assignments. The described procedure provides a rapid technique to monitor the fidelity of selective labeling that does not require a lot of protein. These advantages make it an ideal way of determining optimal expression conditions for selectively labeled NMR samples. [source] Alterations in Syncytiotrophoblast Cytokine Expression Following Treatment with LipopolysaccharideAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 1 2006Yuehong Ma Problem, The placental syncytium is a differentiated cell type on the surface of the villus that has the potential to release cytokines directly to maternal blood. Responsiveness of this cell type to inflammatory compounds remains largely unelucidated. Method of study, Response to a pro-inflammatory (lipopolysaccharide, LPS) and an anti-inflammatory (dexamethasone, DEX) compound was studied in primary cultures of syncytiotrophoblasts (SCTs). Cells were incubated with and without LPS and DEX. Cytokine levels in conditioned media were determined by enzyme-linked immunosorbent assay and proteome arrays. Results, LPS treatment induced a fourfold increase in interleukin-8 (IL-8) levels in SCTs. LPS enhanced the expression of both pro- and anti-inflammatory cytokines in SCTs. DEX treatment reduced IL-8 levels in control and LPS-treated cultures by 70,90%. Conclusion, Cytokine expression in SCTs was enhanced by LPS treatment and this effect was suppressed by glucocorticoid treatment. This suggests that inflammatory compounds may alter cytokine expression in the syncytium throughout gestation. [source] Overexpression of CRK13, an Arabidopsis cysteine-rich receptor-like kinase, results in enhanced resistance to Pseudomonas syringaeTHE PLANT JOURNAL, Issue 3 2007Biswa R. Acharya Summary Protein kinases play important roles in relaying information from perception of a signal to the effector genes in all organisms. Cysteine-rich receptor-like kinases (CRKs) constitute a sub-family of plant receptor-like kinases (RLKs) with more than 40 members that contain the novel C-X8-C-X2-C motif (DUF26) in the extracellular domains. Here we report molecular characterization of one member of this gene family, CRK13. Expression of this gene is induced more quickly and strongly in response to the avirulent compared with the virulent strains of Pseudomonas syringae, and peaks within 4 h after pathogen infection. In response to dexamethasone (DEX) treatment, plants expressing the CRK13 gene from a DEX-inducible promoter exhibited all tested features of pathogen defense activation, including rapid tissue collapse, accumulation of high levels of several defense-related gene transcripts including PR1, PR5 and ICS1, and accumulation of salicylic acid (SA). In addition, these plants suppressed growth of virulent pathogens by about 20-fold compared with the wild-type Col-0. CRK13 -conferred pathogen resistance is salicylic acid-dependent. Gene expression analysis using custom cDNA microarrays revealed a remarkable overlap between the expression profiles of the plants overexpressing CRK13 and the plants treated with Pst DC3000 (avrRpm1). Our studies suggest that upregulation of CRK13 leads to hypersensitive response-associated cell death, and induces defense against pathogens by causing increased accumulation of salicylic acid. [source] Depletion of the neural precursor cell pool by glucocorticoidsANNALS OF NEUROLOGY, Issue 1 2010Shuang Yu MD Objective Glucocorticoids (GCs) are indicated for a number of conditions in obstetrics and perinatal medicine; however, the neurodevelopmental and long-term neurological consequences of early-life GC exposure are still largely unknown. Preclinical studies have demonstrated that GCs have a major influence on hippocampal cell turnover by inhibiting neurogenesis and stimulating apoptosis of mature neurons. Here we examined the fate of the limited pool of neural progenitor cells (NPCs) after GC administration during neonatal development; the impact of this treatment on hippocampal structure was also studied. Methods Phenotype-specific genetic and antigenic markers were used to identify cultured NPCs at various developmental stages; the survival of these cells was monitored after exposure to the synthetic glucocorticoid dexamethasone (DEX). In addition, the effects of neonatal DEX treatment on the neurogenic potential of the rat hippocampus were examined by monitoring the incorporation of bromodeoxyuridine and expression of Ki67 antigen at various postnatal ages. Results Multipotent nestin-expressing NPCs and T,1-tubulin,expressing immature neurons succumb to GC-induced apoptosis in primary hippocampal cultures. Neonatal GC treatment results in marked apoptosis among the proliferating population of cells in the dentate gyrus, depletes the NPC pool, and leads to significant and sustained reductions in the volume of the dentate gyrus. Interpretation Both NPCs and immature neurons in the hippocampus are sensitive to the proapoptotic actions of GCs. Depletion of the limited NPC pool during early life retards hippocampal growth, thus allowing predictions about the potential neurological and psychiatric consequences of neonatal GC exposure. ANN NEUROL 2010;67:21,30 [source] 1,25-dihydroxyvitamin D3 modulates Th17 polarization and interleukin-22 expression by memory T cells from patients with early rheumatoid arthritisARTHRITIS & RHEUMATISM, Issue 1 2010E. M. Colin Objective To examine the immunologic mechanism by which 1,25-dihydroxyvitamin D3 (1,25[OH]2D3) may prevent corticosteroid-induced osteoporosis in patients with early rheumatoid arthritis (RA), with a focus on T cell biology. Methods Peripheral blood mononuclear cells (PBMCs) and CD4+CD45RO+ (memory) and CD4+CD45RO, (non-memory) T cells separated by fluorescence-activated cell sorting (FACS) from treatment-naive patients with early RA were stimulated with anti-CD3/anti-CD28 in the absence or presence of various concentrations of 1,25(OH)2D3, dexamethasone (DEX), and 1,25(OH)2D3 and DEX combined. Levels of T cell cytokines were determined by enzyme-linked immunosorbent assay and flow cytometry. Results The presence of 1,25(OH)2D3 reduced interleukin-17A (IL-17A) and interferon-, levels and increased IL-4 levels in stimulated PBMCs from treatment-naive patients with early RA. In addition, 1,25(OH)2D3 had favorable effects on tumor necrosis factor , (TNF,):IL-4 and IL-17A:IL-4 ratios and prevented the unfavorable effects of DEX on these ratios. Enhanced percentages of IL-17A, and IL-22,expressing CD4+ T cells and IL-17A,expressing memory T cells were observed in PBMCs from treatment-naive patients with early RA as compared with healthy controls. Of note, we found no difference in the percentage of CD45RO+ and CD45RO, cells between these 2 groups. Interestingly, 1,25(OH)2D3, in contrast to DEX, directly modulated human Th17 polarization, accompanied by suppression of IL-17A, IL-17F, TNF,, and IL-22 production by memory T cells sorted by FACS from patients with early RA. Conclusion These data indicate that 1,25(OH)2D3 may contribute its bone-sparing effects in RA patients taking corticosteroids by the modulation of Th17 polarization, inhibition of Th17 cytokines, and stimulation of IL-4. [source] Differential mechanism of NF-,B inhibition by two glucocorticoid receptor modulators in rheumatoid arthritis synovial fibroblastsARTHRITIS & RHEUMATISM, Issue 11 2009Valerie Gossye Objective To investigate and compare the molecular mechanisms by which 2 glucocorticoid receptor (GR),activating compounds, dexamethasone (DEX) and Compound A (CpdA), interfere with the NF-,B activation pathway in rheumatoid arthritis (RA) synovial cells. Methods Quantitative polymerase chain reaction was performed to detect the tumor necrosis factor , (TNF,),induced cytokine gene expression of interleukin-1, (IL-1,) and to investigate the effects of DEX and CpdA in RA fibroblast-like synoviocytes (FLS) transfected with small interfering RNA (siRNA) against GR (siGR) compared with nontransfected cells. Immunofluorescence analysis was used to detect the subcellular distribution of NF-,B (p65) under the various treatment conditions, and active DNA-bound p65 was measured using a TransAM assay and by chromatin immunoprecipitation analysis of IL-1,. Signaling pathways were studied via Western blotting of siGR-transfected cells, compared with nontransfected and nontargeting siRNA,transfected control cells, to detect the regulation of phospho-IKK, I,B,, phospho-p38, phospho-ERK, and phospho-JNK. Results Both DEX and CpdA efficiently inhibited IL-1, gene expression in a GR-dependent manner. In addition, CpdA attenuated the TNF,-induced nuclear translocation and DNA binding of p65 in RA FLS, via the attenuation of IKK phosphorylation and subsequent I,B, degradation. CpdA also displayed profound effects on TNF,-induced MAPK activation. The effects of CpdA on TNF,-induced kinase activities occurred independently of the presence of GR. In sharp contrast, DEX did not affect TNF,-induced IKK phosphorylation, I,B, degradation, p65 nuclear translocation, or MAPK activation in RA FLS. Conclusion DEX and CpdA display a dissimilar molecular mechanism of interaction with the NF-,B activation pathway ex vivo. A dual pathway, partially dependent and partially independent of GR (nongenomic), may explain the gene-inhibitory effects of CpdA in RA FLS. [source] Interaction of dexloxiglumide, a cholecystokinin type-1 receptor antagonist, with human cytochromes P450BIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 4 2004Michael Hall Abstract Dexloxiglumide (DEX) is a cholecystokinin type-1 receptor antagonist under development for the treatment of constipation-predominant irritable bowel syndrome. Studies of the potential interaction of DEX with human cytochromes P450 (CYPs) were conducted in vitro. DEX (300µM), both with and without a 15-min pre-incubation, was incubated with pooled human liver microsomes and substrates selective for each of eight CYPs. This resulted in >30% inhibition of tolbutamide 4-methyl-hydroxylase (CYP2C9/10) and lauric acid 11-hydroxylase (CYP2E1) activities. Mean Ki (SD) for CYP2C9/10 and CYP2E1 were 69.0 (24.3) and 426 (60)µM, respectively. Incubations of [14C]DEX with pooled human liver microsomes produced one major phase I metabolic fraction, with Vmax=131 pmol/min/mg protein and Km=23.7µM. Further incubations with (i) liver microsomes from 16 individual donors (correlation analysis), (ii) SupersomesÔ and (iii) selective chemical inhibitors, implicated CYP3A4/5, CYP2B6 and CYP2C9 in the formation of this component. Thus, DEX interacts with CYP2C9 both as inhibitor (Ki=69.0µM) and as substrate in vitro. However, based on the maximum concentration (27µM) after repeated oral doses of 200mg t.i.d. and the unbound fraction (0.03) of DEX in human plasma, no clinically relevant metabolic interactions with other CYP substrates are predicted. Copyright © 2004 John Wiley & Sons, Ltd. [source] Sialylation enhancement of CTLA4-Ig fusion protein in Chinese hamster ovary cells by dexamethasoneBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2010Ying Jing Abstract The importance of glycoprotein sialic acid levels is well known, as increased levels have been shown to increase in vivo serum half-life profiles. Here we demonstrate for the first time that dexamethasone (DEX) was capable of improving the sialylation of a CTLA4-Ig fusion protein produced by Chinese hamster ovary (CHO) cells. DEX was shown to enhance the intracellular addition of sialic acid by sialyltransferases as well as reduce extracellular removal of sialic acid by sialidase cleavage. We illustrated that DEX addition resulted in increased expression of the glycosyltransferases ,2,3-sialyltransferase (,2,3-ST) and ,1,4-galactosyltransferase (,1,4-GT) in CHO cells. Based upon our previous results showing DEX addition increased culture cell viability, we confirmed here that cultures treated with DEX also resulted in decreased sialidase activity. Addition of the glucocorticoid receptor (GR) antagonist mifepristone (RU-486) was capable of blocking the increase in sialylation by DEX which further supports that DEX affected sialylation as well as provides evidence that the sialylation enhancement effects of DEX on recombinant CHO cells occurred through the GR. Finally, the effects of DEX on increasing sialylation were then confirmed in 5-L controlled bioreactors. Addition of 1,µM DEX to the bioreactors on day 2 resulted in harvests with average increases of 16.2% for total sialic acid content and 15.8% in the protein fraction with N-linked sialylation. DEX was found to be a simple and effective method for increasing sialylation of this CTLA4-Ig fusion protein expressed in CHO cells. Biotechnol. Bioeng. 2010;107: 488,496. © 2010 Wiley Periodicals, Inc. [source] E-cadherin synergistically induces hepatospecific phenotype and maturation of embryonic stem cells in conjunction with hepatotrophic factorsBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2005Anouska Dasgupta Abstract Since effective cell sourcing is a major challenge for the therapeutic management of liver disease and liver failure, embryonic stem (ES) cells are being widely investigated as a promising source of hepatic-like cells with their proliferative and pluripotent capacities. Cell,cell interactions are crucial in embryonic development modulating adhesive and signaling functions; specifically, the cell,cell adhesion ligand, cadherin is instrumental in gastrulation and hepatic morphogenesis. Inspired by the role of cadherins in development, we investigated the role of expression of E-cadherin in cultured murine ES cells on the induction of hepatospecific phenotype and maturation. The cadherin-expressing embryonic stem (CE-ES) cells intrinsically formed pronounced cell aggregates and cuboidal morphology whereas cadherin-deficient cadherin-expressing embryonic stem (CD-ES) cells remained more spread out and corded in morphology. Through controlled stimulation with single or combined forms of hepatotrophic growth factors; hepatocyte growth factor (HGF), dexamethasone (DEX) and oncostatin M (OSM), we investigated the progressive maturation of CE-ES cells, in relation to the control, CD-ES cells. Upon growth factor treatment, the CE-ES cells adopted a more compacted morphology, which exhibited a significant hepatocyte-like cuboidal appearance in the presence of DEX-OSM-HGF. In contrast, the CD-ES cells exhibited a mixed morphology and appeared to be more elongated in the presence of DEX-OSM-HGF. Reverse-transcriptase polymerase chain reaction was used to delineate the most differentiating condition in terms of early (alpha-fetoprotein (AFP)), mid (albumin), and late-hepatic (glucose-6-phosphatase) markers in relation to growth factor presentation for both CE-ES and CD-ES cells. We report that following the most differentiating condition of DEX-OSM-HGF stimulation, CE-ES cells expressed increased levels of albumin and glucose-6-phosphatase, whereas the CD-ES cells showed low levels of AFP and marginal levels of albumin and glucose-6-phosphatase. These trends suggest that the membrane expression of E-cadherin in ES cells can elicit a marked response to growth factor stimulation and lead to the induction of later stages of hepatocytic maturation. Thus, cadherin-engineered ES cells could be used to harness the cross-talk between the hepatotrophic and cadherin-based signaling pathways for controlled acceleration of ES hepatodifferentiation. © 2005 Wiley Periodicals, Inc. [source] Phase II study of the irinotecan (CPT-11), mitoxantrone and dexamethasone regimen in elderly patients with relapsed or refractory peripheral T-cell lymphomaCANCER SCIENCE, Issue 1 2007Nozomi Niitsu We treated elderly patients with relapsed or refractory peripheral T-cell lymphoma (PTCL) using a CMD (CPT-11, mitoxantrone [MIT], dexamethasone [DEX]) regimen and studied its safety and efficacy. The subjects were 70,79-year-old patients with relapsed or refractory PTCL. CPT-11 at 25 mg/m2 on days 1 and 2, MIT at 8 mg/m2 on day 3, and DEX at 40 mg/day on days 1,3 were administered once every 3 weeks, and this was performed for six cycles. Eleven (37%) of the 30 patients achieved complete remission and seven patients (23%) achieved partial remission. With a median follow-up period of 32 months, the 3-year survival rate was 28.2% and the 3-year progression-free survival rate was 17.5%. The main adverse drug reaction was hematological toxicity and there were no deaths related to the treatment. B-type natriuretic peptide and troponin T levels did not increase after the treatment and none of the patients showed electrocardiogram or echocardiogram abnormalities. Our results indicate that the CMD regimen is safe in elderly patients and no cardiotoxicities developed as a result of this regimen. In addition, it was effective in patients who had previously been treated with doxorubicin and good treatment results were obtained in elderly patients with relapsed PTCL. (Cancer Sci 2007; 98: 109,112) [source] Characterisation of ligand binding to the parathyroid hormone/parathyroid hormone-related peptide receptor in MCF7 breast cancer cells and SaOS-2 osteosarcoma cellsCELL BIOCHEMISTRY AND FUNCTION, Issue 2 2007Majed S. Alokail Abstract Parathyroid hormone-related peptide (PTHrP) and parathyroid hormone (PTH)/PTHrP-receptor, PTH/PTHrP-R, are frequently expressed in mammary carcinomas as well as in bone cells. In this study we compared the ligand binding characteristics of the PTH/PTHrP,R in SaOS-2 human osteosarcoma cells with those in MCF7 breast cancer cells. We used both Scatchard analysis of saturation kinetics for iodinated ligand and the level of expressed receptor protein by visualising the single radio-labelled receptor-ligand complex from isolated membrane preparations from the two cell lines. In MCF7 cells, ligand binding, (receptor number) was increased by prior exposure of the cultured cells to epidermal growth factor (EGF), estradiol (E2), or dexamethasone (DEX), and decreased following calcitriol (1,25 DHCC). In contrast in the SaOS-2 cells, PTH/PTHrP-R number was increased by exposure to E2 and 1,25DHCC and decreased by DEX while EGF had no effect. These data were confirmed when the PTH/PTHrP-R was cross linked with 125I-PTHrP-1-34Tyr, and extended by visualising the intensity of the isolated radiolabelled receptor complex by autoradiography following SDS-PAGE at several time points during the treatment. Copyright © 2005 John Wiley & Sons, Ltd. [source] 3412: Anti-VEGF and corticosteroids therapy in macular edema secondary to venous occlusionsACTA OPHTHALMOLOGICA, Issue 2010JAC POURNARAS Purpose To assess the evidence on interventions to improve visual acuity (VA) and to treat macular edema (ME) secondary to central (CRVO) and branch retinal vein occlusion (BRVO) Methods Recent randomized studies have evaluated the safety and efficacy of corticosteroids (triamcinolone, dexamethasone) and anti-VEGF therapies (ranibizumab). Score study evaluates preservative-free intravitreal triamcinolone with standard care in BRVO and CRVO. In Geneva study, dexamethasone (DEX) intravitreal implant is compared with sham in BRVO and CRVO. BRAVO and Cruise studies evaluate intraocular injections of ranibizumab in patients with ME following BRVO and CRVO, respectively. Results In SCORE study, there was no difference identified in visual acuity at 12 months for the standard care group compared with the triamcinolone groups in BRVO patients. Intravitreal triamcinolone is superior to observation for treating vision loss associated with ME secondary to CRVO. Improvements in BCVA with DEX implant were seen in patients with BRVO and CRVO, although the patterns of response differed. Intraocular injections of 0.3 mg or 0.5 mg ranibizumab provided rapid, effective treatment for ME following BRVO and CRVO Conclusion Grid photocoagulation remains the standard care for patients with vision loss associated with ME secondary to BRVO. Intravitreal triamcinolone is superior to observation for treating vision loss associated with ME secondary to CRVO. Dexamethasone intravitreal implant can both reduce the risk of vision loss and improve the speed and incidence of visual improvement in eyes with ME secondary to BRVO or CRVO. Anti-VEGF therapies represent new therapeutical option in the treatment of ME secondary to BRVO and CRVO. Further randomized studies are needed [source] The action of pro-inflammatory cytokines on retinal endothelial cell barrier permeability: protective effect of corticosteroidsACTA OPHTHALMOLOGICA, Issue 2008AF AMBROSIO Purpose The pro-inflammatory cytokines interleukin-1, (IL-1,) and tumor necrosis factor-alpha (TNF-,) were found to be increased in the vitreous of diabetic patients and in diabetic rat retinas, and increased cytokine levels were correlated with elevated retinal vascular permeability. In this work, we investigated the mechanisms underlying IL-1,- and TNF-,-induced retinal endothelial cell permeability and evaluated the ability of a glucocorticoid, dexamethasone (DEX), to prevent changes in permeability. Methods Primary cultures of bovine retinal endothelial cells (BRECs) were grown on transwell filters and exposed to IL-1, and TNF-,. BRECs permeability to 70 kDa RITC-dextran was measured. The content and localization of tight junction proteins was assessed by Western blotting and immunocytochemistry. Results IL-1, and TNF-, increased retinal endothelial cell permeability in a concentration- and time-dependent manner, but TNF-, was more effective (increased permeability at a lower dose and shorter time-point). The increase in permeability was not due to changes in cell viability. IL-1, and TNF-, altered ZO-1 and claudin-5 content. TNF-, also decreased ZO-1 staining at the cell border. Pre-treatment with DEX prevented TNF-,-induced cell permeability, and the protective effect of DEX was partially abolished by the glucocorticoid receptor antagonist RU486. Conclusion These data demonstrate that TNF-, and IL-1, potently induce endothelial cell permeability through alterations in tight junctions. Also, the study supports the potential therapeutic use of glucocorticoids to reduce retinal vascular permeability. Support: FCT (Portugal), NIH, JDRF and Allergan [source] Zoledronate has an antitumor effect and induces actin rearrangement in dexamethasone-resistant myeloma cellsEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 5 2007Masayuki Koizumi Abstract New strategies are needed to overcome the resistance of multiple myeloma (MM) to dexamethasone (Dex). Several recent in vitro studies demonstrated the antitumor effect of nitrogen-containing amino-bisphosphonates (N-BPs) in various tumor cell lines. Inhibition of the prenylation of small G proteins is assumed to be one of the principal mechanisms by which N-BPs exert their effects. There have been few reports on N-BP treatment of MM cells that are resistant to Dex. Additionally, it is not known how small G proteins are altered in N-BP-treated MM cells. In this study, we evaluated the effect of the most potent N-BP, zoledronate (ZOL), on a Dex-resistant human MM cell subline (Dex-R) that we established from the well-documented RPMI8226 cell line. ZOL reduced the viability and induced apoptosis of Dex-R cells. Some of the ZOL-treated RPMI8226 cells and ZOL-treated Dex-R cells were elongated; however, elongated cells were not seen among the Dex-treated RPMI8226 cells. Furthermore, we found that portions of the small G proteins, Rho and Rap1A, were unprenylated in the ZOL-treated MM cells. Geranylgeraniol reduced the above-mentioned ZOL-induced effects. These findings suggest that ZOL may be beneficial for the treatment of Dex-resistant MM by suppressing the processing of RhoA and Rap1A. [source] Idiotype-specific CD4+CD25+ T suppressor cells prevent, by limiting antibody diversity, the occurrence of anti-dextran antibodies crossreacting with histone H3EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 5 2003Christoph Specht Abstract CD25+ suppressor T cells regulate the immune response against the type-2 "thymus independent" bacterial polysaccharide antigen ,(1,3)dextran (Dex) in BALB/c mice. These T cells, represented by the clone 178-4 Ts, restrict the Dex-specific IgG antibody repertoire such that the J558 idiotype dominates. Antibodies with other structures in the heavy-chain variable region (VH region), predominantly within the CDR3 domain, occur when the T cell control fails. This increase of antibody diversity caused by a lack of CD25+ Ts cells, e.g. in nude mice, does not result in the appearance of antibodies with enhanced affinity to the antigen Dex, but often leads to a crossreactivity with autologous proteins. Twenty-two out of sixty Dex-specific hybridomas from nude mice, but no hybridomas from euthymic mice, crossreact with a nuclear protein, as tested by ELISA. This nuclear protein was identified as histone H3. Ten of the sixty hybridomas from nude mice were sequenced and show VH sequences that deviate from the original J558 sequence. Three of these ten hybridomas crossreact with the histone H3. Adoptive transfer of CD25+ Ts cells to nude mice leads to a marked increase of antibodies carrying the original J558 idiotype within the IgG pool after immunization with Dex. Our data demonstrate a CD25+ Ts cell-mediated restriction of VH usage, which prevents the appearance of crossreactive autoantibodies. [source] Dexamethasone suppresses monocyte chemoattractant protein-1 production via mitogen activated protein kinase phosphatase-1 dependent inhibition of Jun N-terminal kinase and p38 mitogen-activated protein kinase in activated rat microgliaJOURNAL OF NEUROCHEMISTRY, Issue 3 2007Yan Zhou Abstract Microglial cells release monocyte chemoattractant protein-1 (MCP-1) which amplifies the inflammation process by promoting recruitment of macrophages and microglia to inflammatory sites in several neurological diseases. In the present study, dexamethasone (Dex), an anti-inflammatory and immunosuppressive drug has been shown to suppress the mRNA and protein expression of MCP-1 in activated microglia resulting in inhibition of microglial migration. This has been further confirmed by the chemotaxis assay which showed that Dex or MCP-1 neutralization with its antibody inhibits the microglial recruitment towards the conditioned medium of lipopolysaccharide (LPS)-treated microglial culture. This study also revealed that the down-regulation of the MCP-1 mRNA expression by Dex in activated microglial cells was mediated via mitogen-activated protein kinase (MAPK) pathways. It has been demonstrated that Dex inhibited the phosphorylation of Jun N-terminal kinase (JNK) and p38 MAP kinases as well as c-jun, the JNK substrate in microglia treated with LPS. The involvement of JNK and p38 MAPK pathways in induction of MCP-1 production in activated microglial cells was confirmed as there was an attenuation of MCP-1 protein release when microglial cells were treated with inhibitors of JNK and p38. In addition, Dex induced the expression of MAP kinase phosphatase-1 (MKP-1), the negative regulator of JNK and p38 MAP kinases in microglial cells exposed to LPS. Blockade of MKP-1 expression by triptolide enhanced the phosphorylation of JNK and p38 MAPK pathways and the mRNA expression of MCP-1 in activated microglial cells treated with Dex. In summary, Dex inhibits the MCP-1 production and subsequent microglial cells migration to the inflammatory site by regulating MKP-1 expression and the p38 and JNK MAPK pathways. This study reveals that the MKP-1 and MCP-1 as novel mediators of biological effects of Dex may help developing better therapeutic strategies for the treatment of patients with neuroinflammatory diseases. [source] | ||||||||||||||||||||||||||||||||||||||||