Thyroids

Wentworth, B. C.; Ringer, Robert K.

doi:10.1007/978-1-4612-4862-0_20

Cited by 17 publications

(17 citation statements)

References 116 publications

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“…The plasma T 3 pattern is the opposite to that of T 4 (review: Wentworth and Ringer, 1986;Cogburn and Freeman, 1987). These patterns for T 4 and T 3 are consistent with the idea that the release of thyroid hormones (almost entirely T 4 ) from the thyroid gland is highest during the dark period and extrathyroidal T 4 to T 3 conversion is highest during the light period.…”

Section: Diurnal Patternssupporting

confidence: 85%

“…Many aspects of the early techniques used for avian TSR measurements are now in question because they may seriously over-or underestimate TSR, so this historical work is difficult to evaluate. These studies did show that TSR is dynamic; for example, adult chickens maintained in cold temperatures had approximately double the TSR of birds maintained at warm temperatures, iodine-deficient diets lowered the TSR, and by 13 weeks of age the TSR had decreased to 0.6 μg T 4 /100 g body weight (Wentworth and Ringer, 1986). There do not appear to be any more recent investigations of TSR in birds.…”

Section: Thyroid Hormone Secretionmentioning

confidence: 95%

“…Birds lack a specific T 4 -binding protein such as the thyroxine-binding globulin (TBG) found in large mammals (review: Wentworth and Ringer, 1986). In Japanese quail and chicken plasma, in vitro studies with labeled T 4 show the relative proportions of T 4 bound by these proteins are 17-32% to TTR, 66-75% bound to albumin, and the remaining few percent bound to other plasma proteins (Davison et al, 1978;Tanabe et al, 1969;McNabb and Hughes, 1983).…”

Section: Transport Proteinsmentioning

confidence: 98%

“…Prior to the development of RIAs for measuring thyroid hormones, a number of studies measured the daily thyroid hormone secretion rate (TSR) of T 4 by several indirect methods (reviews: Astier, 1980;Wentworth and Ringer, 1986). Several of these methods indicated highly variable TSRs from different studies and different techniques but the values (range from 1.2 to 2.3 μg T 4 /100 g body weight in four studies of chickens <9 weeks of age) were generally in the range of the TSR in rats measured by the same techniques (∼2 μg T 4 /100 g body weight) and in humans (∼1.3 μg/100 g body weight; Chopra and Sabatino, 2000).…”

Section: Thyroid Hormone Secretionmentioning

confidence: 99%

See 3 more Smart Citations

The Hypothalamic-Pituitary-Thyroid (HPT) Axis in Birds and Its Role in Bird Development and Reproduction

McNabb

2007

Critical Reviews in Toxicology

189

163

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This article reviews thyroid function and its hypothalamic-pituitary-thyroid (HPT) axis control in birds with emphasis on the similarities and differences in thyroid function compared to mammals and other vertebrate classes. Thyroid hormones are important in metabolism and the thermogenesis required for homeothermy in birds, as in mammals, the other homeothermic class of vertebrates. Thyroid hormones play important roles in development and growth in birds, as is the case for all vertebrate classes. The developmental effects of thyroid hormones in birds are presented in the context of differences in precocial and altricial patterns of development and growth with emphasis on oviparous development. The sections on thyroid hormone actions include discussion of effects on the development of a number of tissue types as well as on seasonal organismal processes and interactions of the thyroid axis with reproduction. The current picture of how environmental chemicals may disrupt avian thyroid function is relatively limited and is presented in the context of the assessment endpoints that have been used to date. These endpoints are categorized as thyroid and HPT axis endpoints versus target organ endpoints. The final section discusses two recommended assay protocols, the avian two-generation toxicity assay and the avian one-generation assay, and whether these protocols can evaluate thyroid disruption in birds.

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Section: Diurnal Patternssupporting

confidence: 85%

Section: Thyroid Hormone Secretionmentioning

confidence: 95%

Section: Transport Proteinsmentioning

confidence: 98%

Section: Thyroid Hormone Secretionmentioning

confidence: 99%

See 2 more Smart Citations

The Hypothalamic-Pituitary-Thyroid (HPT) Axis in Birds and Its Role in Bird Development and Reproduction

McNabb

2007

Critical Reviews in Toxicology

189

163

View full text Add to dashboard Cite

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“…Body weights and T4 concentrations in the control group G1 were significantly higher than in the OTAtreated groups. Wentworth & Ringer (1986) reported that T3 and T4 had a significant effect on growth and feed efficiency of broiler chickens and that treatment with T3 lowered feed consumption. On the other hand, Prior et al .…”

Section: Discussionmentioning

confidence: 99%

Experimental ochratoxicosis in broiler chickens

et al. 2006

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This study describes the toxicity signs that developed when the diet of male broiler chickens was artificially contaminated with different levels of the mycotoxin ochratoxin A (OTA). Chicks were assigned randomly to three groups of 80 chicks that were fed a diet containing 0 parts per billion (ppb) (control, group 1), 400 ppb (group 2) or 800 ppb (group 3) OTA from day 1 to 5 weeks of age. Signs of ochratoxicosis were assessed on the basis of changes in the following criteria: body weight, relative weights of two representative internal organs (gizzard and thymus), feed consumption, feed conversion ratio, mortality, thyroid activity, blood profile, humoral and cell mediated immunity. Feeding OTA at levels of 400 and 800 ppb (groups 2 and 3) significantly decreased the body weight, thymus weight, feed consumption, feed conversion ratio and thyroxine concentration (P B/0.05). The OTA groups developed anaemia manifested by a significant decrease in the red blood cell count, packed cell volume percentage and haemoglobin concentration (P B/0.05). By the end of the experiment both groups that received OTA showed a 37% reduction in red blood cell count compared with the control group. Furthermore, a significant decrease in the white blood cell count, humoral immune response and cell-mediated immunity was found in both groups fed ochratoxin compared with the control group (P B/0.05). The reduction in the above parameters was more noticeable with time and was proportional to the level of OTA exposure. A significant increase in relative gizzard weight, cumulative mortality and triiodothyronine concentration was found in OTA-fed chicks (P B/0.05). These data provide a description of ochratoxicosis in broilers that should be useful in diagnosis and in improved understanding of the practical implications on broiler performance and health, a problem that can threaten the poultry industry.

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Mercury exposure may influence fluctuating asymmetry in waterbirds

Herring

Eagles‐Smith

Ackerman

2016

Environmental Toxicology and Chemistry

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Variation in avian bilateral symmetry can be an indicator of developmental instability in response to a variety of stressors, including environmental contaminants. The authors used composite measures of fluctuating asymmetry to examine the influence of mercury concentrations in 2 tissues on fluctuating asymmetry within 4 waterbird species. Fluctuating asymmetry increased with mercury concentrations in whole blood and breast feathers of Forster's terns (Sterna forsteri), a species with elevated mercury concentrations. Specifically, fluctuating asymmetry in rectrix feather 1 was the most strongly correlated structural variable of those tested (wing chord, tarsus, primary feather 10, rectrix feather 6) with mercury concentrations in Forster's terns. However, for American avocets (Recurvirostra americana), black-necked stilts (Himantopus mexicanus), and Caspian terns (Hydroprogne caspia), the authors found no relationship between fluctuating asymmetry and either whole-blood or breast feather mercury concentrations, even though these species had moderate to elevated mercury exposure. The results indicate that mercury contamination may act as an environmental stressor during development and feather growth and contribute to fluctuating asymmetry of some species of highly contaminated waterbirds. Environ Toxicol Chem 2017;36:1599-1605. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

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Thyroids

Cited by 17 publications

References 116 publications

The Hypothalamic-Pituitary-Thyroid (HPT) Axis in Birds and Its Role in Bird Development and Reproduction

The Hypothalamic-Pituitary-Thyroid (HPT) Axis in Birds and Its Role in Bird Development and Reproduction

Experimental ochratoxicosis in broiler chickens

Mercury exposure may influence fluctuating asymmetry in waterbirds

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