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Ammonium perchlorate effects on thyroid function and growth in bobwhite quail chicks
Author(s) -
Mcnabb F. M. ANNE,
Larsen Calvert T.,
Pooler Penelope S.
Publication year - 2004
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1897/03-362
Subject(s) - ammonium perchlorate , thyroid , endocrinology , medicine , perchlorate , bobwhite quail , thyroid function , hormone , chemistry , quail , stimulation , biology , biochemistry , ion , organic chemistry , catalysis
Abstract Bobwhite quail chicks were used to investigate ammonium perchlorate (AP; NH 4 ClO 4 ) effects on thyroid function and growth. Beginning at 3 to 4 d posthatch, we evaluated organismal thyroid status (circulating hormones), activation of the hypo‐thalamic‐pituitary‐thyroid axis (thyroid wt) and thyroidal hormone content over a wide range of AP concentrations (50 μg/L — 4,000 mg/L) in drinking water, for relatively short (2‐week) and longer (8‐week) exposures. Thyroidal thyroxine (T 4 ) content, the most sensitive index of decreased thyroid function, decreased markedly in response to increasing perchlorate exposure. Thyroid weight and plasma T 4 were less sensitive indicators and similar in their ability to detect thyroid changes. Growth measurements (body wt and skeletal growth) were very insensitive indices. Because thyroids contain large hormone stores, with low exposures or short time periods, these stores can be used to maintain circulating hormones, at least temporarily. Most depletion of thyroidal T 4 occurred during the first two weeks of AP exposure. Subsequent decreases were at a slower rate presumably because thyrotropin stimulation of the thyroids at least partially compensated for some of the perchlorate effect. Additional studies of the interactions between AP concentration and exposure time are needed for understanding the complex nature of thyroid responses to perchlorate.