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Increased susceptibility of the lungs of hyperthyroid rats to oxidant injury: specificity of effects.

Authors
Huffman-LJ; Beighley-CM; Frazer-DG; McKinney-WG; Porter-DW
Source
Toxicology 2006 Aug; 225(2-3):119-127
NIOSHTIC No.
20030884
Abstract
Results from previous studies indicate that hyperthyroidism increases the risk of ozone-induced lung toxicity. This observation raised the possibility that pulmonary damage from other oxidant substances might be greater in a hyperthyroid state. To address this hypothesis, pulmonary responses to crystalline silica, a particulate with oxidant properties, were evaluated in normal or hyperthyroid adult male rats. To induce a hyperthyroid condition, time-release pellets containing thyroxine were implanted subcutaneously; control rats received placebo pellets. After 7 days, the animals were exposed to saline or silica (0.1mg/100g BW or 1.0mg/100g BW) by intratracheal instillation. Following silica treatment, there was a dose-related increase in bronchoalveolar lavage (BAL) albumin levels and neutrophil numbers. However, the effects of silica were similar in both normal and hyperthyroid rats. These findings were confirmed and contrasted with those regarding ozone (1ppm, 4h inhalation) in a subsequent experiment. The results indicated that, although exposure to either ozone or silica resulted in increases in BAL albumin levels and neutrophil numbers, only responses to ozone were enhanced in hyperthyroid rats. These findings suggest that specificity exists in regards to the modulation of oxidant-induced lung damage and inflammation by thyroid hormones.
Keywords
Laboratory-animals; Animals; Animal-studies; Injuries; Risk-factors; Risk-analysis; Lung-disorders; Silica-dusts; Silicates; Pulmonary-system-disorders; Respiratory-system-disorders
Contact
Health Effects Laboratory Division, National Institute for Occupational Safety and Health, M/S 2015, 1095 Willowdale Road, Morgantown, WV 26505, USA
CODEN
TXCYAC
Publication Date
20060815
Document Type
Journal Article
Email Address
DPorter@cdc.gov
Fiscal Year
2006
NTIS Accession No.
NTIS Price
Issue of Publication
2-3
ISSN
0300-483X
NIOSH Division
HELD
Source Name
Toxicology
State
WV
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