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

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 crys...

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Bibliographic Details
Published in:Toxicology (Amsterdam) 2006-08, Vol.225 (2), p.119-127
Main Authors: Huffman, L.J., Beighley, C.M., Frazer, D.G., McKinney, W.G., Porter, D.W.
Format: Article
Language:English
Subjects:
Albumins - analysis
Animals
Biological and medical sciences
Bronchoalveolar Lavage Fluid - chemistry
Bronchoalveolar Lavage Fluid - cytology
Disease Models, Animal
Disease Susceptibility
Dose-Response Relationship, Drug
Hyperthyroidism - chemically induced
Hyperthyroidism - complications
Intubation, Intratracheal
Leukocyte Count
Lung - drug effects
Lung Diseases - chemically induced
Macrophages, Alveolar - drug effects
Macrophages, Alveolar - metabolism
Macrophages, Alveolar - pathology
Male
Medical sciences
Neutrophils - pathology
Oxidants - toxicity
Oxidative Stress - drug effects
Ozone
Ozone - toxicity
Rat
Rats
Rats, Sprague-Dawley
Silica
Silicon Dioxide - toxicity
Thyroid hormone
Thyroxine - administration & dosage
Thyroxine - blood
Toxicology
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Summary: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 (0.1 mg/100 g BW or 1.0 mg/100 g 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 (1 ppm, 4 h 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.
ISSN:0300-483X
1879-3185
DOI:10.1016/j.tox.2006.05.008