Endocrine Regulation of Fetal Adipose Tissue Metabolism in the Pig: Ontogeny of Thyroxine Influence

Hausman, Dorothy B.; Hausman, Gary; Martin, Roy J.

doi:10.1159/000244347

Cited by 4 publications

(7 citation statements)

References 8 publications

(17 reference statements)

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“…Serum T4 concentrations were not increased in the hypophysectomized fetuses treated with T4 alone, compared with the untreated hypophysectomized fetuses. This finding is in contrast with those of our previous studies (3,6), where a consistent return of serum T 4 to intact values was observed in hypophysectomized fetuses treated for 3 to 14 days with T4 pellets. Serum triiodothyronine was not measured in this study because we had failed to detect measurable levels of this hormone after 20 days T4 treatment in a previous study (4).…”

Section: Resultscontrasting

confidence: 99%

“…Other notable alterations in the serum profile of preobese fetuses and in fetuses from diabetic dams include increases in thyroid hormones and glucocorticoids (21,22). Our recent studies indicate that treatment of hypophysectomized pig fetuses with either hormone results in specific stimulatory effects on adipose tissue development both in vivo and in vitro (3,4,6,16,18,(33)(34)(35). In addition, combined treatment with both hormones had an additive effect on lipogenesis, lipid accretion, and fat cell cluster development (36,37).…”

Section: Discussionmentioning

confidence: 99%

“…Treatment of hypox fetuses with thyroxine (T4) normalized hormone-stimulated lipolysis (3), fat cell number (4), and serum insulin-like growth factor (lGF)-I (5). In contrast, T4 treatment of hypox fetuses augmented hypox-induced elevations in LPL activity (4) and lipogenesis (3,6). These increases were not observed with T4 treatment in intact fetuses.…”

Section: Introductionmentioning

confidence: 99%

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Endocrine Regulation of Fetal Adipose Tissue Metabolism in the Pig: Interaction of Porcine Growth Hormone and Thyroxine

Hausman

Martin

1999

Obesity Research

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HAUSMAN, D.B., GJ. HAUSMAN, AND RJ. MARTIN. Endocrine regulation of fetal adipose tissue metabolism in the pig: interaction of porcine growth hormone and thyroxine. Obes Res. 1999;7:76-82. Objective: This study tested the hypothesis that combined treatment of thyroxine (T 4) and growth hormone (GH) could normalize cellular and metabolic aspects of adipose tissue development of hypophysectomized fetal pigs. Research Methods and Procedures:On day 70 of gestation, pig fetuses were hypophysectomized by microcauterization or remained intact. Hypophysectomized fetuses remained untreated or were treated from day 90 to day 105 of gestation with T 4, GH, or a combination of both hormones. Results: Body weights were unaffected by hypophysectomy or hormone treatment. De novo lipogenesis in subcutaneous adipose tissue was increased 10-fold by hypophysectomy, consistent with our previous results. This increase was abolished by GH treatment in the hypophysectomized fetuses. In contrast, T 4 treatment of the hypophysectomized fetuses resulted in a 12-fold further increase in adipose tissue lipogenesis, an effect that was negated by concomitant administration of GH. Lipolytic response to isoproterenol was decreased by hypophysectomy, unaffected by GH treatment, and restored to intact values by T4 or by T4+GH treatment in the hypophysectomized fetuses. Discussion: In contrast to T 4 , GH does not influence serum insulin-like growth factor-lor adipose tissue lipolysis, but decreases lipogenesis in the fetal pig. However, replacing both T 4 and GH normalized hypophysectomized fetuses to a greater extent than either GH or T 4 alone. Thus, any

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Section: Resultscontrasting

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Endocrine Regulation of Fetal Adipose Tissue Metabolism in the Pig: Interaction of Porcine Growth Hormone and Thyroxine

Hausman

Martin

1999

Obesity Research

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“…Conversely, the weight-specific rates of fetal O 2 consumption and oxidation of glucose carbon are reduced by 20-30% by thyroidectomy of fetal sheep and restored to normal values by T 4 replacement (Fowden & Silver 1995). Availability of T 4 has also been shown to regulate glucose oxidation in adipose tissue of fetal pigs (Hausman et al 1996). In addition, fetal hypothyroidism prevents the normal fall in fetal glucose oxidation observed in response to short-term fasting of pregnant ewes (Fowden et al 2001a).…”

Section: Metabolic Effects Of the Thyroid Hormonesmentioning

confidence: 99%

Thyroid hormones in fetal growth and prepartum maturation

Forhead

Fowden

2014

Journal of Endocrinology

341

270

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The thyroid hormones, thyroxine (T 4 ) and triiodothyronine (T 3 ), are essential for normal growth and development of the fetus. Their bioavailability in utero depends on development of the fetal hypothalamic-pituitary-thyroid gland axis and the abundance of thyroid hormone transporters and deiodinases that influence tissue levels of bioactive hormone. Fetal T 4 and T 3 concentrations are also affected by gestational age, nutritional and endocrine conditions in utero, and placental permeability to maternal thyroid hormones, which varies among species with placental morphology. Thyroid hormones are required for the general accretion of fetal mass and to trigger discrete developmental events in the fetal brain and somatic tissues from early in gestation. They also promote terminal differentiation of fetal tissues closer to term and are important in mediating the prepartum maturational effects of the glucocorticoids that ensure neonatal viability. Thyroid hormones act directly through anabolic effects on fetal metabolism and the stimulation of fetal oxygen consumption. They also act indirectly by controlling the bioavailability and effectiveness of other hormones and growth factors that influence fetal development such as the catecholamines and insulin-like growth factors (IGFs). By regulating tissue accretion and differentiation near term, fetal thyroid hormones ensure activation of physiological processes essential for survival at birth such as pulmonary gas exchange, thermogenesis, hepatic glucogenesis, and cardiac adaptations. This review examines the developmental control of fetal T 4 and T 3 bioavailability and discusses the role of these hormones in fetal growth and development with particular emphasis on maturation of somatic tissues critical for survival immediately at birth.

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“…The reason for these differences is not clear, but could be due to differences in treatment prior to differentiation (Boone et al, 2000) or the degree of differentiation achieved with other components of the differentiation cocktail (Suryawan et al, 1997). Thyroxine treatment promote the development of porcine adipose tissue in vivo in hypophysectomized but not intact, foetal pigs (Hausman, 1992) and treatment with thyroxine increased adipose tissue lipogenesis in hypophysectomized foetal pigs but such effects could be indirect via other factors such as IGF-1 (Chen et al, 1996;Hausman et al, 1996). Thyroxine treatment had no effect on the accumulation of adipose tissue in intact neonatal lambs (Gate et al, 2000).…”

Section: Lipid Synthesismentioning

confidence: 99%

Differential control of lipogenesis and lipolysis during development of ovine preadipocytesin vitro

Soret¹,

Melrose²,

Finley

et al. 2006

Anim. Sci.

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The stromovascular fraction of adipose tissue from sheep, like that of other species, contains preadipocytes which can be induced to differentiate in culture, providing a potentially useful system for studying adipocyte development. Differentiation of ruminant preadipocytes has only been partly characterized previously so we have investigated the factors regulating the development of lipogenesis and lipolysis in sheep cells. Insulin, rosiglitazone (a peroxisome proliferation activated receptor-g agonist) and either dexamethasone or a lipid suplement are required during differentiation for maximum rates of lipogenesis, whereas all four components are required to achieve maximum rates of catecholamine-stimulated lipolysis. Tri-iodothyronine had no effect on the development of lipogenesis but resulted in a reduced rate of catecholamine-stimulated lipolysis. Lipogenesis and lipolysis also differed in that the rate of lipogenesis increased to a maximum at about 10 days of differentiation and then fell, whereas the rate of lipolysis reached a plateau at about 10 days. By contrast to catecholamine-stimulated lipolysis, there is little or no evidence for development of the adenosine-based antilipolytic system; this may be because response to adenosine develops very late during preadipocyte differentiation or additional, unidentified factors are required to induce this antilipolytic system. Lipogenesis in differentiated preadipocytes responded to both insulin and growth hormone. These studies show that the development of lipogenesis and lipolysis are under distinct control systems. Furthermore, while preadipocytes differentiated in vitro show many of the characteristics of adipocytes differentiated in vivo, there are still significant differences.

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Endocrine Regulation of Fetal Adipose Tissue Metabolism in the Pig: Ontogeny of Thyroxine Influence

Cited by 4 publications

References 8 publications

Endocrine Regulation of Fetal Adipose Tissue Metabolism in the Pig: Interaction of Porcine Growth Hormone and Thyroxine

Endocrine Regulation of Fetal Adipose Tissue Metabolism in the Pig: Interaction of Porcine Growth Hormone and Thyroxine

Thyroid hormones in fetal growth and prepartum maturation

Differential control of lipogenesis and lipolysis during development of ovine preadipocytesin vitro

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