scholarly journals The role of thyroid hormones in maturation of the adrenaline-sensitive lung liquid reabsorptive mechanism in fetal sheep.

1990 ◽  
Vol 424 (1) ◽  
pp. 473-485 ◽  
Author(s):  
P M Barker ◽  
L B Strang ◽  
D V Walters
Keyword(s):  
Thyroid Hormones ◽  
Fetal Sheep ◽  
Lung Liquid

Nitric oxide decreases lung liquid production via guanosine 3′,5′-cyclic monophosphate

2001 ◽  
Vol 280 (5) ◽  
pp. L923-L929 ◽  
Author(s):  
James J. Cummings ◽  
Huamei Wang
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Epithelium ◽  
Fetal Sheep ◽  
Cgmp Analog ◽  
Pulmonary Arterial ◽  
Series Of Experiments ◽  
Lung Liquid ◽  
Tracer Dilution ◽  
Induced Changes

We studied the role of cGMP in nitric oxide (NO)-induced changes in lung liquid production ( J v ) in chronically instrumented fetal sheep. Forty-five studies were done in which J v was measured by a tracer dilution technique. Left pulmonary arterial flow (Qlpa) was measured by a Doppler flow probe. There were two series of experiments. In the first, we gave 8-bromo-cGMP, a cGMP analog, by either the pulmonary vascular or intraluminal route; in the second, we used agents to inhibit or enhance endogenous cGMP activity. When infused directly into the pulmonary circulation, 8-bromo-cGMP significantly increased Qlpa but had no effect on J v. Conversely, when instilled into the lung liquid, 8-bromo-cGMP had no effect on Qlpa but significantly reduced J v. Inhibition of guanylate cyclase activity with methylene blue totally blocked, whereas phosphodiesterase inhibition with Zaprinast significantly enhanced, the effect of instilled NO on J v. Thus the reduction in lung liquid caused by NO appears to be mediated by cGMP, perhaps through a direct effect on the pulmonary epithelium.

scholarly journals Effects of thyroid hormones on pulmonary and renal angiotensin-converting enzyme concentrations in fetal sheep near term

2002 ◽  
Vol 173 (1) ◽  
pp. 143-150 ◽  
Author(s):  
AJ Forhead ◽  
AL Fowden
Keyword(s):  
Angiotensin Converting Enzyme ◽  
Thyroid Hormones ◽  
Plasma Cortisol ◽  
Experimental Manipulation ◽  
Late Gestation ◽  
Converting Enzyme ◽  
Fetal Sheep ◽  
Near Term ◽  
Sheep Fetus

In the sheep fetus, pulmonary and renal concentrations of angiotensin-converting enzyme (ACE) increase towards term in parallel with the prepartum surges in plasma cortisol and tri-iodothyronine (T(3)). The ontogenic change in pulmonary ACE has been shown to be induced, at least in part, by cortisol but the role of the thyroid hormones is unknown. Therefore, this study investigated the effects of thyroid hormones on tissue ACE concentration in fetal sheep during late gestation. Pulmonary and renal ACE concentrations were measured in sheep fetuses after experimental manipulation of thyroid hormone status by fetal thyroidectomy and exogenous hormone infusion. In intact fetuses, pulmonary and renal ACE concentrations increased between 127-132 and 142-145 days of gestation (term 145 +/- 2 days), coincident with the prepartum rises in plasma cortisol and T(3). The ontogenic increment in pulmonary ACE concentration was abolished when the prepartum surge in T(3), but not cortisol, was prevented by fetal thyroidectomy. At 143-145 days, ACE concentration in the lungs and kidneys of the thyroidectomised fetuses were both lower than those in the intact fetuses. In intact fetuses at 127-132 days, pulmonary ACE was upregulated by intravenous infusions of either cortisol (2-3 mg/kg per day) or T(3) (8-12 microg/kg per day) for 5 days. Renal ACE was unaffected by cortisol or T(3) infusion. Therefore, thyroid hormones have an important role in the developmental control of pulmonary and renal ACE concentration in the sheep fetus towards term. In addition, the prepartum rise in plasma T(3) appears to mediate, in part, the maturational effect of cortisol on pulmonary ACE concentration.

Effects of elevated fetal cortisol concentrations on the volume, secretion, and reabsorption of lung liquid

1995 ◽  
Vol 269 (4) ◽  
pp. R881-R887 ◽  
Author(s):  
M. J. Wallace ◽  
S. B. Hooper ◽  
R. Harding
Keyword(s):  
Plasma Cortisol ◽  
Fetal Lung ◽  
Liquid Volume ◽  
Fetal Sheep ◽  
Fetal Plasma ◽  
Age Related ◽  
Lung Liquid ◽  
Secretion Rates ◽  
Related Increase

We have examined the role of cortisol in the gestational age-related increase in the ability of epinephrine to inhibit the secretion and induce the reabsorption of fetal lung liquid. Chronically catheterized fetal sheep were infused with either saline (n = 6) or increasing doses of cortisol (1.5-3.5 mg/day; n = 6) between 120 and 130 days of gestation (term approximately 145 days). Lung liquid volumes and secretion rates were measured at 120 days (before infusion) and at 125 days, and then at 130 days we tested the ability of epinephrine to inhibit lung liquid secretion and induce liquid reabsorption. Cortisol infusions increased fetal plasma cortisol and 3,5,3'-triiodothyronine (T3) concentrations to levels observed just before labor and significantly increased the age-related increase in fetal lung liquid volume and secretion rate. At 130 days, epinephrine caused a significantly greater rate of lung liquid reabsorption in cortisol-infused fetuses (10.3 +/- 2.3 ml/h) than in saline-infused fetuses (1.5 +/- 1.6 ml/h). We conclude that a premature elevation in circulating fetal cortisol concentrations, probably in conjunction with elevated T3 concentrations, prematurely increases the epinephrine-induced reabsorption of fetal lung liquid. It is likely, therefore, that the preparturient increase of fetal cortisol concentrations plays an important role in the clearance of lung liquid at birth.

scholarly journals Role of thyroid hormones in the developmental control of tissue glycogen in fetal sheep near term

2009 ◽  
Vol 94 (10) ◽  
pp. 1079-1087 ◽  
Author(s):  
Alison J. Forhead ◽  
Samantha Cutts ◽  
Phillippa A. Matthews ◽  
Abigail L. Fowden
Keyword(s):  
Thyroid Hormones ◽  
Fetal Sheep ◽  
Developmental Control ◽  
Near Term

Role of the adrenal glands in the maturation of lung liquid secretory mechanisms in fetal sheep

1996 ◽  
Vol 270 (1) ◽  
pp. R33-R40 ◽  
Author(s):  
M. J. Wallace ◽  
S. B. Hooper ◽  
R. Harding
Keyword(s):  
Gestational Age ◽  
Adrenal Glands ◽  
Fetal Lung ◽  
Fetal Sheep ◽  
Fetal Plasma ◽  
Age Related ◽  
Lung Liquid ◽  
Secretion Rates ◽  
Related Increase

Our aim was to determine the role of the fetal adrenal glands in the gestational age-related increase in the ability of epinephrine to induce the reabsorption of lung liquid. Fetal lung liquid volumes and secretion rates were measured in five chronically catheterized control and six bilaterally adrenalectomized (ADX) fetal sheep at approximately 5-day intervals from 120 to 144 days of gestation (term approximately 146 days). The ability of epinephrine to induce the reabsorption of fetal lung liquid was then determined on day 144. Fetal adrenalectomy prevented the preparturient increase in fetal plasma cortisol and 3,5,3'-triiodothyronine (T3) concentration and significantly reduced the gestational age-related increase in fetal lung liquid volumes and secretion rates. Close to term (144 days), epinephrine infusions caused a significantly greater rate of lung liquid reabsorption in control (32.2 +/- 4.8 ml/h) compared with ADX (3.7 +/- 0.7 ml/h) fetuses. We conclude that the presence of the fetal adrenal glands is necessary for the age-related increase in 1) the lung liquid secretion rate and 2) the ability of the fetal lung to reabsorb liquid late in gestation. It is likely that cortisol is the active adrenal hormone involved, supporting the theory that cortisol plays a crucial role in the clearance of lung liquid at birth.

The Role of Zinc in Thyroid Hormones Metabolism

2019 ◽  
Vol 89 (1-2) ◽  
pp. 80-88 ◽  
Author(s):  
Juliana Soares Severo ◽  
Jennifer Beatriz Silva Morais ◽  
Taynáh Emannuelle Coelho de Freitas ◽  
Ana Letícia Pereira Andrade ◽  
Mayara Monte Feitosa ◽  
...  
Keyword(s):  
Thyroid Hormones ◽  
Scientific Evidence ◽  
Thyroid Stimulating Hormone ◽  
Zinc Transporters ◽  
Serum Concentrations ◽  
Metabolic Adaptations ◽  
Serum T3 ◽  
Regulatory Effects ◽  
Shed Light

Abstract. Thyroid hormones play an important role in body homeostasis by facilitating metabolism of lipids and glucose, regulating metabolic adaptations, responding to changes in energy intake, and controlling thermogenesis. Proper metabolism and action of these hormones requires the participation of various nutrients. Among them is zinc, whose interaction with thyroid hormones is complex. It is known to regulate both the synthesis and mechanism of action of these hormones. In the present review, we aim to shed light on the regulatory effects of zinc on thyroid hormones. Scientific evidence shows that zinc plays a key role in the metabolism of thyroid hormones, specifically by regulating deiodinases enzymes activity, thyrotropin releasing hormone (TRH) and thyroid stimulating hormone (TSH) synthesis, as well as by modulating the structures of essential transcription factors involved in the synthesis of thyroid hormones. Serum concentrations of zinc also appear to influence the levels of serum T3, T4 and TSH. In addition, studies have shown that Zinc transporters (ZnTs) are present in the hypothalamus, pituitary and thyroid, but their functions remain unknown. Therefore, it is important to further investigate the roles of zinc in regulation of thyroid hormones metabolism, and their importance in the treatment of several diseases associated with thyroid gland dysfunction.

Glucose disposal and lipid metabolism in man: role of thyroid hormones

1988 ◽  
Vol 117 (4_Suppl) ◽  
pp. S130-S131
Author(s):  
M. J. MÜLLER ◽  
A. G. BURGER ◽  
E. JEQUIER ◽  
K.J. ACHESON
Keyword(s):  
Lipid Metabolism ◽  
Thyroid Hormones ◽  
Glucose Disposal

scholarly journals Role of Thyroid Hormones in Skeletal Development and Bone Maintenance

2016 ◽  
Vol 37 (2) ◽  
pp. 135-187 ◽  
Author(s):  
J. H. Duncan Bassett ◽  
Graham R. Williams
Keyword(s):  
Thyroid Hormones ◽  
Skeletal Development ◽  
Bone Maintenance

Ontogeny of neuronally released norepinephrine on renin secretion in sheep

1989 ◽  
Vol 257 (4) ◽  
pp. R765-R770 ◽  
Author(s):  
K. T. Nakamura ◽  
J. M. Klinkefus ◽  
F. G. Smith ◽  
T. Sato ◽  
J. E. Robillard
Keyword(s):  
Renin Secretion ◽  
Renal Nerves ◽  
Nerve Terminals ◽  
Norepinephrine Release ◽  
Fetal Sheep ◽  
Postnatal Maturation ◽  
Active Renin ◽  
Inactive Renin ◽  
Cortical Slices

The role of renal nerves and norepinephrine release on renin secretion during fetal and postnatal maturation has not been studied. Experiments were performed to determine the effect of veratridine, a substance known to promote norepinephrine release from nerve terminals, on active and inactive renin secretion from renal cortical slices of fetal (134-138 days gestation; term is 145 days), newborn (4-9 days of age), and adult nonpregnant sheep. Veratridine (10-300 microM) significantly increased active renin secretion and produced a small but nonsignificant rise in inactive renin secretion in all three groups of animals (P less than 0.05). The percent rise in active renin secretion during veratridine stimulation was similar among all groups. Veratridine-stimulated (300 microM) active renin secretion was antagonized by tetrodotoxin (0.5 and 5.0 microM) and DL-propranolol (1 microM) in fetal renal cortical slices. However, neither tetrodotoxin nor propranolol completely inhibited the stimulatory effect of veratridine on active renin secretion. These results suggest that 1) norepinephrine released from nerve terminals may regulate active renin secretion early during development; 2) the effect of veratridine on active renin secretion was similar in fetal, newborn, and adult sheep; 3) veratridine had no significant effect on inactive renin secretion; and 4) active renin secretion due to depolarization of nerve terminals in fetal sheep is dependent on activation of beta-adrenoceptors as it is in adults.

scholarly journals Inhibition of hepatic deiodination of thyroxine is caused by selenium deficiency in rats

1987 ◽  
Vol 248 (2) ◽  
pp. 443-447 ◽  
Author(s):  
G J Beckett ◽  
S E Beddows ◽  
P C Morrice ◽  
F Nicol ◽  
J R Arthur
Keyword(s):  
Thyroid Hormones ◽  
Production Rate ◽  
Selenium Deficiency ◽  
Enzyme Complex ◽  
Measurable Effect ◽  
Direct Role ◽  
Mechanism Of Inhibition ◽  
Se Deficiency

Selenium (Se) deficiency produced up to a 14-fold decrease in hepatic tri-iodothyronine (T3) production from thyroxine (T4) in vitro. The T3 production rate could not be restored by the addition of a variety of cofactors, nor by the addition of control homogenate. The impairment in hepatic T3 production observed in Se deficiency was reflected in the concentrations of thyroid hormones circulating in plasma, T4 being increased approx. 40% and T3 being decreased by 30%. However, the fall in plasma T3 concentrations was smaller than might be expected in view of the marked decreased in T3 production. Se deficiency had no measurable effect on plasma reverse-tri-iodothyronine concentrations. The data suggest that Se deficiency produces an inhibition of both 5- and 5′-deiodination, consistent with the widely held view that these reactions are catalysed by the same enzyme complex. The mechanism of inhibition appears not be mediated by changes in thiol levels, but a direct role of Se in the activity of the deiodinase complex cannot be excluded.

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