Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8537794 | Pulmonary Pharmacology & Therapeutics | 2018 | 7 Pages |
Abstract
Recurrent airway obstruction (RAO) is a main characteristic of horses with severe equine asthma syndrome. The presence of bacterial lipopolysaccharide (LPS) in the airways of horses is thought to play a crucial role in the clinical expression of this disorder. This study pharmacologically characterized the effect of LPS on the responsiveness of equine bronchial tissue. Equine isolated bronchi were incubated overnight with LPS (0.1-100â¯ng/ml) and then stimulated by electrical field stimulation (EFS). The role of capsaicin sensitive-sensory nerves (capsaicin desensitization treatment), neurokinin-2 (NK2) receptors (blocked by GR159897), transient receptor potential vanilloid type 1 receptors (TRPV1; blocked by SB366791), and neurokinin A (NKA) were investigated. Untreated bronchi were used as control tissues. LPS (1 ng/ml) significantly increased the EFS-evoked contractility of equine bronchi compared with control tissues (+742 ± 123 mg; P < 0.001). At higher concentrations LPS induced desensitization to airways hyperresponsiveness (AHR; EC50: 5.9â¯Â±â¯2.6â¯ng/ml). Capsaicin desensitization and GR159897 significantly prevented AHR induced by LPS at EFS1-50Hz (â197â¯Â±â¯25%; Pâ¯<â¯0.01). SB366791 inhibited AHR at very low EFS frequency (EFS1Hz â193â¯Â±â¯29%; Pâ¯<â¯0.01 vs. LPS-treated bronchi). LPS (1â¯ng/ml) significantly (Pâ¯<â¯0.01) increased 3.7â¯Â±â¯0.7 fold the release of NKA compared with control bronchi. LPS induces biphasic dysfunctional bronchial contractility due to the stimulation of capsaicin sensitive-sensory nerves, increased release of NKA, and activation of NK2 receptors, whereas TRPV1 receptors appear to play a marginal role in this response. The overnight challenge with low concentrations of LPS represents a suitable model to investigate pharmacological options that may be of value in the treatment of equine RAO.
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Authors
Luigino Calzetta, Paola Rogliani, Elena Pistocchini, Maurizio Mattei, Giuseppe Cito, Pietro Alfonsi, Clive Page, Maria Gabriella Matera,