J. Blain, P. Sirois
Jun 1, 2000
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Prostaglandins Leukotrienes and Essential Fatty Acids
Abstract
Abstract Cysteinyl leukotrienes are potent inflammatory molecules playing a major role in asthma. The involvement of these mediators in hypersensitivity in mice is not well known. This study aimed at elucidating their implication by using MK-571, a cysLT 1 receptor antagonist. Mice were sensitized with a suspension of ovalbumin (8 μg) adsorbed to alum (2 mg) and were challenged with an aerosolized ovalbumin solution (0.5%). Inflammatory cell infiltration in the bronchoalveolar lavage (mostly eosinophils) following antigen challenge was inhibited by dexamethasone (0.1, 1 and 5 mg kg −1 s.c.) and MK-571 (1, 10, 100 mg kg −1 i.v.) in a dose-dependent manner. Maximal inhibition was 95% with 5 mg kg −1 dexamethasone and 90% with 100 mg kg −1 MK-571. When injected together they showed an additive inhibitory effect on eosinophil infiltration. Bronchial hyperreactivity, measured by the increased pulmonary insufflation pressure to carbachol injections, was also inhibited dose-dependently by MK-571. The EC 50 values for carbachol were of 22.39±1.12 μg kg −1 in sensitized and challenged animals that did not receive MK-571 and increased to 43.65±1.10, 50.12±1.15 and 83.18±1.16 μg kg −1 in animals treated with 1, 10 and 100 mg kg −1 MK-571 respectively. Lung microvascular leakage (as measured by Evans blue extravasation) induced by antigen bronchoprovocation was reduced by 22% after treatment with 10 mg kg −1 MK-571. All these inhibitory effects of MK-571 suggest a role for leukotriene D 4 in this animal model of allergic asthma.