Home About us Contact
|
Home About us Contact | ||
|
|
||
Sensitized Animals (sensitized + animals)
Selected AbstractsContext-dependent behavioural and neuronal sensitization in striatum to MDMA (ecstasy) administration in ratsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2006Kevin T. Ball Abstract To investigate the neuronal mechanisms underlying the behavioural alterations that accompany repeated exposure to MDMA (ecstasy), we recorded the activity of >,200 striatal units in response to multiple, intermittent, locomotor-activating doses (5.0 mg/kg) of MDMA. Rats were treated with once-daily injections of either saline or MDMA for 5 days when housed in their home cage, followed by a challenge injection 3,5 days later when housed in a recording chamber. Because contextual drug associations might be particularly important to the expression of behavioural sensitization to chronic MDMA, a separate group of rats received repeated injections of MDMA alternately in the recording chamber or home cage, according to the above timeline. A sensitized locomotor response was observed only in rats that had previously experienced MDMA in the context of the recording chamber, and only on the challenge day. These sensitized animals also showed a decreased basal firing rate in neurons that were subsequently excited by MDMA when compared with the same category of neurons earlier in the treatment regimen. This resulted in a greater percentage increase from the baseline firing rate on the challenge day compared with the first and fifth days of treatment, even though this trend was not evident with an analysis of absolute firing rate. These results strongly support a role for context in the expression of MDMA-induced locomotor sensitization, and implicate striatal involvement in the neurobehavioural changes associated with the repeated use of MDMA. [source] Interferon-,-dependent inhibition of late allergic airway responses and eosinophilia by CD8+,, T cellsIMMUNOLOGY, Issue 2 2007Susumu Isogai Summary We have previously shown that CD8+,, T cells decrease late allergic airway responses, airway eosinophilia, T helper 2 cytokine expression and increase interferon-, (IFN-,) expression. We hypothesized that the effects of CD8+,, T cells were IFN-, mediated. Brown Norway rats were sensitized to ovalbumin on day 1. Cervical lymph node CD8+,, T cells from sensitized animals were treated with antisense oligodeoxynucleotide (5 µmol/l) to inhibit IFN-, synthesis or control oligodeoxynucleotide and 3·5 × 104 CD8+,, T cells were injected intraperitoneally into sensitized recipients on day 13. Rats were challenged with aerosolized ovalbumin on day 15 and lung resistance was monitored over an 8 hr period, after which bronchoalveolar lavage was performed. Control oligodeoxynucleotide treated ,, T cells decreased late airway responses and eosinophilia in bronchoalveolar lavage. There was a complete recovery of late airway responses and a partial recovery of airway eosinophilia in recipients of antisense oligodeoxynucleotide treated cells. Macrophage ingestion of eosinophils was frequent in rats administered ,,T cells but reduced in recipients of antisense oligodeoxynucleotide treated cells. These results indicate that CD8+,, T cells inhibit late airway responses and airway eosinophilia through the secretion of IFN-,. Defective or altered ,, T-cell function may account for some forms of allergic asthma. [source] Oral tolerance induction to Dermatophagoides pteronyssinus and Blomia tropicalis in sensitized mice: occurrence of natural autoantibodies to immunoglobulin ECLINICAL & EXPERIMENTAL ALLERGY, Issue 11 2002M. N. Sato Summary Background The dust mites Dermatophagoides pteronyssinus (Dp) and Blomia tropicalis (Bt) are important sources of indoor allergens in tropical and subtropical countries. Murine models allow the analysis of the immune response and regulation of IgE production to Dp and Bt allergens. Oral tolerance induces unresponsiveness in naive animals, but its application in sensitized animals can provide useful information to improve allergy therapy. Objective To study the profile of IgE and IgG subclasses antibody upon oral administration with Bt and Dp extract in previously sensitized mice. Further, the occurrence of autoantibodies IgG anti-IgE in the immunization and in the oral tolerance was investigated. Methods A/Sn mice were immunized with Bt or Dp extract in alum, orally administrated with 0.25 mg of Bt or Dp extract or PBS at the 6th, 7th and 8th days after immunization and boosted twice with their respective allergens. To analyse the mice groups, specific IgE antibodies were measured by passive anaphylaxis reaction and specific IgG subclasses and anti-IgE IgG autoantibody by ELISA assay. Results IgE levels were markedly increased in Bt-immunized mice compared with Dp-immunized mice. A distinct profile of the specific isotypes was verified in Bt-immunized mice with a preferential production of IgG3 and IgA antibodies, whereas Dp-immunized mice developed high titres of anti-Dp IgG1, IgG2a and IgG2b antibodies. The antigen feeding inhibited IgE response in both fed-mice groups but only Dp-fed mice presented decreased levels of IgG antibodies. Free anti-IgE IgG autoantibodies were detected mainly in the Dp-immunization and they correlated with the antibody isotypes found against the allergen. Conclusions This is the first time that the murine-type I hypersensitivity is employed to study Bt-immunization, showing a marked IgE production, associated with IgG response, which is at least in part driven by T-independent antigens. The oral tolerance protocol in previously sensitized animals was able to down-modulate IgE response and points out this route as a strategy for allergy therapy. [source] Airway inflammation in a murine model of chronic asthma: evidence for a local humoral immune responseCLINICAL & EXPERIMENTAL ALLERGY, Issue 10 2000R. K. Kumar Background Asthma is an acute-on-chronic inflammatory disease of the airways characterized by recruitment of eosinophils into the epithelial layer, chronic inflammation in the lamina propria, as well as variable accumulation of mast cells in the airway wall. The role of local production of allergen-specific immunoglobulins in triggering mast cell-mediated asthmatic inflammation is unknown. Methods We used a chronic inhalational exposure model of asthma in ovalbumin-sensitized BALB/c mice to examine the phenotype of immunoglobulin-secreting cells and mast cells in the airway wall. In parallel, we assayed ovalbumin-specific IgG and total IgE in the plasma of these animals. Results In sensitized mice exposed to aerosolized ovalbumin for 6 weeks, aggregates of chronic inflammatory cells consisted of a majority of plasmacytoid cells, including numerous IgG-synthesizing cells, which were significantly increased in sensitized animals compared to controls. IgA-synthesizing cells were also present, but were not increased in the sensitized exposed mice. Immunoglobulins in the cytoplasm of the plasma cells were demonstrated to be antigen-specific. No IgM-or IgE-synthesizing cells were observed, although levels of total IgE in the plasma were significantly increased. There was no recruitment of mast cells of either the mucosal or the connective tissue phenotype into the lamina propria or the epithelium. Conclusion In this experimental model of chronic asthma, the pattern of inflammation in the airway wall is consistent with development of a local IgG-mediated humoral immune response. However, there is no evidence of local production of IgE or recruitment of mast cells. [source] Inhibitory effect of 1,8-cineole on guinea-pig airway challenged with ovalbumin involves a preferential action on electromechanical couplingCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 11 2009Vasco PD Bastos Summary 11,8-Cineole is a terpenoid constituent of essential oils with anti-inflammatory properties. It reduces the neural excitability, functions as an antinociceptive agent and has myorelaxant actions in guinea-pig airways. The aim of the present study was to investigate the mechanism underlying the myorelaxant effects of 1,8-cineole in guinea-pig isolated trachea from either naïve guinea-pigs or ovalbumin (OVA)-sensitized animals subjected to antigenic challenge. 2Isometric recordings were made of the tone of isolated tracheal rings. Rings with an intact epithelium relaxed beyond basal tone in the presence of 1,8-cineole (6.5 × 10,6 to 2 × 10,2 mol/L) in a concentration-dependent manner (P < 0.001, anova) with a pD2 value of 2.23 (95% confidence interval 2.10,2.37). Removal of the epithelium or pretreatment of intact tissue for 15 min with 50 µmol/L NG -nitro- l -arginine methyl ester, 5 mmol/L tetraethylammonium, 0.5 µmol/L tetrodotoxin or 5 µmol/L propranolol did not alter the potency (pD2) or the maximal myorelaxant effect (Emax) of 1,8-cineole. 31,8-Cineole also significantly decreased the Schultz-Dale contraction induced by OVA, mainly in preparations from OVA-sensitized animals submitted to antigen challenge. 1,8-Cineole decreased tracheal hyperresponsiveness to KCl and carbachol caused by antigen challenge and almost abolished the concentration,response curves to KCl, whereas it had little effect on the concentration,response curves to carbachol. Under Ca2+ -free conditions and in the presence of 10,4 mol/L acetylcholine, neither 1,8-cineole (6.5 × 10,3 mol/L) nor verapamil (1 × 10,5 mol/L) affected Ca2+ -induced contractions, but they almost abolished Ba2+ -induced contractions. 4In conclusion, the findings of the present study show that 1,8-cineole is a tracheal myorelaxant that acts preferentially on contractile responses elicited electromechanically. [source] | ||||||||||