Peripheral Metabolism of Thyroid Hormones in Vitamin A-Deficient Rats

1982 ◽  
Vol 26 (3) ◽  
pp. 191-200 ◽  
Author(s):  
Paul Higueret ◽  
Henri Garcin
Keyword(s):  
Vitamin A ◽  
Thyroid Hormones ◽  
Peripheral Metabolism

Effects of vitamin A and other retinoids on the differentiation and morphogenesis of the integument and limbs of vertebrates

1991 ◽  
Vol 69 (2) ◽  
pp. 263-273 ◽  
Author(s):  
Keith J. Johnson ◽  
Steven R. Scadding
Keyword(s):  
Cell Differentiation ◽  
Vitamin A ◽  
Thyroid Hormones ◽  
Mechanism Of Action ◽  
Limb Development ◽  
Common Mechanism ◽  
Complex Processes ◽  
Normal Differentiation ◽  
Pattern Regulation ◽  
Related Compounds

Exogenous vitamin A is a well-known teratogen and modifies the course of cell differentiation, embryonic development, and morphogenesis. Recent evidence has shown that vitamin A and related compounds (the "retinoids") are likely natural morphogens, carrying out important roles in such processes as limb development and epithelial differentiation. Retinoids can modify the differentiation of individual cells and can induce specific modifications of morphogenesis in such structures as epithelial appendages, developing limbs, and regenerating limbs. Evidence is accumulating that there may be a common mechanism of action underlying these diverse phenomena. Retinoids may enter cells and induce changes in gene transcription in a manner similar to that reported for steroid and thyroid hormones and their receptors. Retinoids are particularly useful probes in the study of cell differentiation and morphogenesis because an understanding of their action can provide clues to the mechanisms involved in the complex processes of normal differentiation, morphogenesis, and pattern regulation.

The peripheral metabolism of thyroid hormones and regulation of thyroidal status in poikilotherms

1985 ◽  
Vol 63 (6) ◽  
pp. 1217-1231 ◽  
Author(s):  
J. G. Eales
Keyword(s):  
Thyroid Hormone ◽  
Body Temperature ◽  
Thyroid Hormones ◽  
Secondary Effects ◽  
Larval Amphibians ◽  
Factors Influencing ◽  
Receptor Sites ◽  
Plausible Model ◽  
Thyroidal Status ◽  
Peripheral Metabolism

Available data from poikilotherms (primarily salmonid teleosts and larval amphibians) indicate that, as in the intensively researched mammals, peripheral regulation of thyroidal status takes place. An extreme but physiologically plausible model is that the thyroidally secreted thyroxine (T4) is an inactive prohormone; the hypothalamic–hypophyseal–thyroidal axis may merely ensure that adequate T4 is secreted to serve as a substrate for conversion, by extrathyroidal 5′-monodeiodinase activity in various tissues, to the active thyroid hormone (TH), 3,5,3′-triiodo-L-thyronine (T3). Regulation of thyroidal status may be achieved at several peripheral levels by altering (i) TH transport from plasma into tissues, (ii) tissue T4 5′-monodeiodinase activity, and (iii) the capacities and possibly affinities of putative nuclear T3 receptor sites. Blind assumption in poikilotherms of the superficially similar mammalian model can be highly misleading since major differences exist between poikilotherms and mammals in (i) plasma protein – TH interactions, with secondary effects on plasma TH levels and kinetics, and (ii) pathways of T4 deiodination, possibly related to differences in iodide economy. In contrast, the nuclear TH receptor properties are phylogenetically conservative. However, the factors influencing their properties have been scarcely studied. In this regard variable body temperature, the distinguishing feature between poikilotherms and homeotherms, remains largely unexplored.

scholarly journals Tissue iodoprotein formation during the peripheral metabolism of the thyroid hormones

1969 ◽  
Vol 48 (11) ◽  
pp. 2168-2175 ◽  
Author(s):  
Martin I. Surks ◽  
Harold L. Schwartz ◽  
Jack H. Oppenheimer
Keyword(s):  
Thyroid Hormones ◽  
Peripheral Metabolism

The Differential Growth Response of Embryonic Chick Limb-bone Rudiments to Triiodothyronine in vitro

Development ◽  
1961 ◽  
Vol 9 (1) ◽  
pp. 42-51
Author(s):  
Kirstie Lawson
Keyword(s):  
Vitamin A ◽  
Thyroid Hormones ◽  
Growth Response ◽  
Nutritional Deficiencies ◽  
Embryonic Chick ◽  
Differential Growth ◽  
Relative Growth ◽  
Limb Bone ◽  
Leg Bones

The proportionate development of the embryonic chick skeleton can be influenced experimentally by a variety of factors such as nutritional deficiencies (Byerly, Titus, Ellis, & Landauer, 1935; Landauer, 1936; Romanoff & Bauernfeind, 1942; Couch, Cravens, Elvehjem, & Halpin, 1948), teratogens (Ancel & Lallemand, 1942; Zwilling & de Bell, 1950; Landauer, 1952, 1953a, 1954) and excess hormones (Willier, 1924; Landauer & Bliss, 1946; Duraiswami, 1950). The leg bones are generally more severely affected than the wing bones, but a comparison of the action of several teratogens on the character of the malformations and on the relative growth of the leg bones indicated that the response of individual bones varies with the different agents (Landauer & Rhodes, 1952; Landauer, 1953 a, b, 1954). Cartilaginous limb-bone rudiments also respond differentially when they are isolated from the embryo and exposed in culture to various compounds, such as insulin (Chen, 1954), vitamin A, and the thyroid hormones (Fell & Mellanby, 1955, 1956).

scholarly journals Bexarotene-Induced Hypothyroidism: Bexarotene Stimulates the Peripheral Metabolism of Thyroid Hormones

2007 ◽  
Vol 92 (7) ◽  
pp. 2496-2499 ◽  
Author(s):  
Johannes W. A. Smit ◽  
Marcel P. M. Stokkel ◽  
Alberto M. Pereira ◽  
Johannes A. Romijn ◽  
Theo J. Visser
Keyword(s):  
Thyroid Hormones ◽  
Peripheral Metabolism

Body-composition, bone density, peripheral metabolism and thyroid hormones in anorexia nervosa

1996 ◽  
Vol 6 (S1) ◽  
pp. 177-177
Author(s):  
P. Schneider ◽  
J. Rendl ◽  
M. Luster ◽  
M. Geling ◽  
Chr Reiners
Keyword(s):  
Body Composition ◽  
Anorexia Nervosa ◽  
Bone Density ◽  
Thyroid Hormones ◽  
Peripheral Metabolism
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