Li P-C, Chen W-C, Chang L-C, Lin S-C. Substance P acts via the neurokinin receptor 1 to elicit bronchoconstriction, oxidative stress, and upregulated ICAM-1 expression after oil smoke exposure. Am J Physiol Lung Cell Mol Physiol 294: L912-L920, 2008. First published March 7, 2008 doi:10.1152/ajplung.00443.2007.-This study aimed to 1) assess whether substance P (SP) acts via neurokinin (NK)-1 and NK-2 receptors to stimulate neurogenic inflammation (indicated by formation of ICAM-1 expression and oxidative stress) following oil smoke exposure (OSE) in rats; and 2) determine if pretreatment with antioxidants ameliorates the deleterious effects of OSE. Rats were pretreated with NK-1 receptor antagonist CP-96345, NK-2 receptor antagonist SR-48968, vitamin C, or catechins. OSE was for 30 -120 min. Rats were killed 0 -8 h later. Total lung resistance (RL), airway smooth muscle activity (ASMA), lung ICAM-1 expression, neurogenic plasma extravasation (via India ink and Evans blue dye), bronchoalveolar lavage fluid SP concentrations, and reactive oxygen species formation [via lucigenin-and luminalamplified chemiluminescence (CL)] were assessed. Lung histology was performed. SP concentrations increased significantly in nonpretreated rats following OSE in a dose-dependent manner. RL and total ASMA increased over time after OSE. Vitamin C and catechin pretreatments were associated with significantly reduced lucigenin CL 2 and 4 h after OSE. Pretreatment with catechins significantly reduced luminal CL counts 4 and 8 h after OSE. Evans blue levels were significantly reduced following 60 and 120 min of OSE in catechinand CP-96345-pretreated rats. ICAM-1 protein expression was significantly decreased in all pretreatment groups after OSE. Thickening of the alveolar capillary membrane, focal hemorrhaging, interstitial pneumonitis, and peribronchiolar inflammation were apparent in OSE lungs. These findings suggest that SP acts via the NK-1 receptor to provoke neurogenic inflammation, oxidative stress, and ICAM-1 expression after OSE in rats.reactive oxygen species; intracellular adhesion molecule-1; acute lung injury ACTIVATION OF NONMYELINATED bronchopulmonary C-fiber endings by various stimuli [including cigarette smoke (9), airway surface osmolality changes (14), and fire smoke (22)] causes the release of tachykinins and calcitonin gene-related peptide neuropeptides stored in the peripheral nerve terminals, eliciting both central nervous system (CNS) and local axon reflex responses (4). The CNS reflex consists of bronchoconstriction, expiratory apnea, rapid shallow breathing, cough, hypotension, and bradycardia, whereas the axon reflex response initiates local inflammation, increased mucous secretion, and bronchoconstriction. Substance P (SP), a tachykinin neuropeptide, induces a range of neuroimmunogenic effects on target smooth muscle or parasympathetic ganglia cells expressing neurokinin (NK)-1 or NK-2 receptors (1, 2). These effects, collectively termed neurogenic airway inflammation, comprise bronchoconstriction, microvasc...