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Age-dependent effects of ozone on substance P-innervation in airways of postnatal rats.

Authors
Mulvey-T; Satterfield-BE; Frazer-DG; Fedan-JS; Dey-RD
Source
FASEB J 2000 Mar; 14(4):A781
NIOSHTIC No.
20021021
Abstract
Exposure to airway irritants during early postnatal periods may contribute to asthma during childhood especially if the initial exposure occurs at critical periods of growth and development. Asthma in children is exacerbated by air pollution that may be partly attributed to neural mechanisms. This study examines the effects of ozone on SP nerve fiber density in neonatal through adolescent rat airways. Rats were exposed to 2 ppm ozone or filtered air for 1 hr at the following postnatal days (PD) of age: PD 0-3 days, PD 4-6, PD 7-9, PD 10-12, PD 13-15, PD 21-22, and PD 28-29(n=5-6 per group). After 24 hr, lungs were removed, fixed and prepared for immunocytochemical demonstration of SP. Extrapulmonary (EP, main stem bronchi) and intrapulmonary (IP, 3-5 generations) airway were dissected and nerve fiber density (NFD) was determined for epithelium (E) and smooth muscle (SM). SP NFD in the EP-E increased threefold from about 1% to 4% from PD 0-3 through PD 13-15 and was then maintained. NFD for EP-SM, IP-SM, and IP-E was constant through the age range at about 1.0%, 0.6% and 0.05% respectively. After ozone, NFD increased twofold to about 2% in EP-SM through PD13-15 and to 1.2% in IP-SM through PD 13-15 while EP-E and IP-E were minimally affected. The findings suggest that nerve fiber responses to ozone are moot pronounced in SM through PD 15 possibly identifying a critical developmental phase of neural sensitivity during which irritant exposure may be a predisposing factor to the pathogenic mechanisms leading to asthma.
Keywords
Age-factors; Laboratory-animals; Animals; Animal-studies; Airway-resistance; Airway-obstruction; Bronchial-asthma; Exposure-levels; Air-contamination; Pollution; Pollutants; Lung-irritants; Pulmonary-system-disorders; Respiratory-system-disorders
CODEN
FAJOEC
Publication Date
20000315
Document Type
Abstract; Conference/Symposia Proceedings
Fiscal Year
2000
NTIS Accession No.
NTIS Price
Issue of Publication
4
ISSN
0892-6638
NIOSH Division
HELD
Source Name
The FASEB Journal
State
WV; CA
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