Asphalt exposure enhances Substance P (SP) levels in sensory neurons projecting to nasal epithelium.
Sikora-ER; Stone-S; Tomblyn-S; Frazer-DG; Castranova-V; Dey-RD
Am J Respir Crit Care Med 2001 Apr; 163(5)(2)(Suppl):A160
Asphalt fumes have been reported to cause nasal irritation in road crew workers. Since inhaled irritants may increase SP production in the airways, the effects of asphalt fumes on sensory neurons innervating the rat nasal epithelium were investigated. Cell bodies of trigeminal ganglia (TG) providing sensory innervation to nasal epithelia were identified by instillation of 8 micro-l of rhodamine-labeled latex microspheres to all rats ten days prior to sacrifice. Two separate asphalt exposure studies were conducted. In the first (n- 8 per group), Fischer 344 rats were exposed to an asphalt fume concentration of 10.4 mg/m3, five consecutive days, 3 hr/day. In the second (n=7/group), Sprague/Dawley rats were exposed to a fume concentration of 16.0 mg/m3, 5 consecutive days, 3.5 hr/day. The nasal cavities were lavaged and the TG removed and processed for SP immunoreactivity (IR) in both studies and CGRP-IR in the second study. The percentage of SP-IR neurons projecting to the nasal epithelium in the first study was 71.6 in asphalt-exposed rats and 49.1 in controls. In the second study, the percentage of SP-IR neurons was 83.7 following asphalt and 58.5 in controls. The percentage of CGRP-lR in the second study increased from 49.7 in control to 65.3 following asphalt. Therefore, exposure to asphalt fumes results in an increase in SP and CGRP in TO neurons projecting to the nasal epithelium. Enhanced sensory neuropeptide release from nerve terminals in the nasal cavity may mediate neurogenic inflammation associated with nasal irritation following exposure to asphalt fumes.
Respiratory-irritants; Respiratory-system-disorders; Nasal-cavity; Construction-workers; Construction-industry; Road-construction; Road-surfacing; Asphalt-industry; Asphalt-fumes; Fumes; Animal-studies; Laboratory-animals
American Journal of Respiratory and Critical Care Medicine. Abstracts of the American Thoracic Society 2001 International Conference, May 18-23, 2001, San Francisco, California