Role of capsaicin-sensitive afferents and sensory neuropeptides in endotoxin-induced airway inflammation and consequent bronchial hyperreactivity in the mouse

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32 Citations (Scopus)

Abstract

Substance P (SP) and calcitonin gene-related peptide (CGRP) released from capsaicin-sensitive afferents induce neurogenic inflammation via NK1, NK2 and CGRP1 receptor activation. This study examines the role of capsaicin-sensitive fibres and sensory neuropeptides in endotoxin-induced airway inflammation and consequent bronchial hyperreactivity with functional, morphological and biochemical techniques in mice. Carbachol-induced bronchoconstriction was measured with whole body plethysmography 24 h after intranasal lipopolysaccharide administration. SP and CGRP were determined with radioimmunoassay, myeloperoxidase activity with spectrophotometry, interleukin-1β with ELISA and histopathological changes with semiquantitative scoring from lung samples. Treatments with resiniferatoxin for selective destruction of capsaicin-sensitive afferents, NK1 antagonist SR 140333, NK2 antagonist SR 48968, their combination, or CGRP1 receptor antagonist CGRP(8-37) were performed. Lipopolysaccharide significantly increased lung SP and CGRP concentrations, which was prevented by resiniferatoxin pretreatment. Resiniferatoxin-desensitization markedly enhanced inflammation, but decreased bronchoconstriction. CGRP(8-37) or combination of SR 140333 and SR 48968 diminished neutrophil accumulation, MPO levels and IL-1β production, airway hyperresponsiveness was inhibited only by SR 48968. This is the first evidence that capsaicin-sensitive afferents exert a protective role in endotoxin-induced airway inflammation, but contribute to increased bronchoconstriction. Activation of CGRP1 receptors or NK1 + NK2 receptors participate in granulocyte accumulation, but NK2 receptors play predominant role in enhanced airway resistance.

Original languageEnglish
Pages (from-to)44-54
Number of pages11
JournalRegulatory Peptides
Volume141
Issue number1-3
DOIs
Publication statusPublished - Jun 7 2007

Keywords

  • CGRP1 receptor
  • Interleukin-1β
  • Myeloperoxidase activity
  • NK receptor
  • NK receptor
  • Somatostatin
  • Whole body plethysmography

ASJC Scopus subject areas

  • Biochemistry
  • Physiology
  • Endocrinology
  • Clinical Biochemistry
  • Cellular and Molecular Neuroscience

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