Effect of short-term ozone exposure on exogenous thyroxine levels in thyroidectomized and hypophysectomized rats
Short-term ozone exposure (1 ppm X 24 hr) of male rats results in a significant reduction of circulating thyroid hormones and thyroid stimulating hormone (TSH). The reduction of thyroid hormone levels after ozone exposure has been hypothesized as a possible adaptive mechanism to enhance survival of rats during ozone exposure. In this study, the authors investigated the effect of ozone on thyroid hormone (T4) levels in thyroidectomized and hypophysectomized rats which received exogenous T4 in the drinking water. Groups of normal, intact rats, thyroidectomized rats maintained on T4 at doses ranging from 75 to 1000 micrograms/liter, and hypophysectomized rats maintained on 300 micrograms T4/liter were exposed to ozone (1 ppm X 24 hr), Plasma T4 concentrations were significantly reduced after ozone exposure, and the results indicated that the higher the circulating T4 levels before exposure the more they were reduced after ozone exposure. This reduction in T4 levels cannot be accounted for in these animals by reduced pituitary TSH levels or the effects of fasting, but is likely to be due to peripheral changes in plasma thyroid binding proteins initiated by ozone exposure.
- Research Organization:
- Lawrence Berkeley Lab., CA
- OSTI ID:
- 6346588
- Journal Information:
- Toxicol. Appl. Pharmacol.; (United States), Vol. 74:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
HYPOPHYSECTOMY
BIOLOGICAL EFFECTS
OZONE
THYROIDECTOMY
THYROXINE
BLOOD CHEMISTRY
DRINKING WATER
PITUITARY GLAND
RATS
TSH
AMINO ACIDS
ANIMALS
BODY
CARBOXYLIC ACIDS
ENDOCRINE GLANDS
GLANDS
HORMONES
HYDROGEN COMPOUNDS
MAMMALS
MEDICINE
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
ORGANS
OXYGEN COMPOUNDS
PEPTIDE HORMONES
PITUITARY HORMONES
RODENTS
SURGERY
THYROID HORMONES
VERTEBRATES
WATER
560305* - Chemicals Metabolism & Toxicology- Vertebrates- (-1987)