scholarly journals Fasting-Induced Changes in Hepatic Thyroid Hormone Metabolism in Male Rats Are Independent of Autonomic Nervous Input to the Liver

Endocrinology ◽  
2014 ◽  
Vol 155 (12) ◽  
pp. 5033-5041 ◽  
Author(s):  
E.M. de Vries ◽  
L. Eggels ◽  
H.C van Beeren ◽  
M.T. Ackermans ◽  
A. Kalsbeek ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Male Rats ◽  
Melanocortin System ◽  
Humoral Factors ◽  
Autonomic Nervous ◽  
Pituitary Thyroid Axis ◽  
Serum T3 ◽  
Thyroid Axis ◽  
Induced Changes ◽  
Expression And Activity

During fasting, profound changes in the regulation of the hypothalamus-pituitary-thyroid axis occur in order to save energy and limit catabolism. In this setting, serum T3 and T4 are decreased without an appropriate TSH and TRH response reflecting central down-regulation of the hypothalamus-pituitary-thyroid axis. Hepatic thyroid hormone (TH) metabolism is also affected by fasting, because type 3 deiodinase (D3) is increased, which is mediated by serum leptin concentrations. A recent study showed that fasting-induced changes in liver TH sulfotransferases (Sults) and uridine 5′-diphospho-glucuronosyltransferase (Ugts) depend on a functional melanocortin system in the hypothalamus. However, the pathways connecting the hypothalamus and the liver that induce these changes are currently unknown. In the present study, we investigated in rats whether the fasting-induced changes in hepatic TH metabolism are regulated by the autonomic nervous system. We selectively cut either the sympathetic or the parasympathetic input to the liver. Serum and liver TH concentrations, deiodinase expression, and activity and Sult and Ugt expression were measured in rats that had been fasted for 36 hours or were fed ad libitum. Fasting decreased serum T3 and T4 concentrations, whereas intrahepatic TH concentrations remained unchanged. D3 expression and activity increased, as was the expression of constitutive androstane receptor, Sult1b1, and Ugt1a1, whereas liver D1 was unaffected. Neither sympathetic nor parasympathetic denervation affected the fasting-induced alterations. We conclude that fasting-induced changes in liver TH metabolism are not regulated via the hepatic autonomic input in a major way and more likely reflect a direct effect of humoral factors on the hepatocyte.

scholarly journals Interleukin-18, a proinflammatory cytokine, contributes to the pathogenesis of non-thyroidal illness mainly via the central part of the hypothalamus-pituitary-thyroid axis

2004 ◽  
pp. 497-502 ◽  
Author(s):  
A Boelen ◽  
J Kwakkel ◽  
M Platvoet-ter Schiphorst ◽  
B Mentrup ◽  
A Baur ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Mrna Expression ◽  
Proinflammatory Cytokine ◽  
Biological Properties ◽  
Thyroid Hormone Metabolism ◽  
Pituitary Thyroid Axis ◽  
Serum T3 ◽  
Thyroid Axis ◽  
Hpt Axis

OBJECTIVE: Proinflammatory cytokines are involved in the pathogenesis of non-thyroidal illness (NTI), as shown by studies with IL-6-/- and IL-12-/- mice. Interleukin (IL)-6 changes peripheral thyroid hormone metabolism, and IL-12 seems to be involved in the regulation of the central part of the hypothalamic-pituitary-thyroid (HPT) axis during illness. IL-18 is a proinflammatory cytokine which shares important biological properties with IL-12, such as interferon (IFN)-gamma-inducing activity. DESIGN: By studying the changes in the HPT-axis during bacterial lipopolysaccharide (LPS)-induced illness in IL-18-/-, IFNgammaR-/- and wild-type (WT) mice, we wanted to unravel the putative role of IL-18 and IFNgamma in the pathogenesis of NTI. RESULTS: LPS induced a decrease in pituitary type 1 deiodinase (D1) activity (P<0.05, ANOVA) in WT mice, but not in IL-18-/- mice, while the decrease in D2 activity was similar in both strains. LPS decreased serum thyroid hormone levels and liver D1 mRNA within 24 h similarly in IL-18-/-, and WT mice. The expression of IL-1, IL-6 and IFNgamma mRNA expression was significantly lower in IL-18-/- mice than in WT, while IL-12 mRNA expression was similar. IFNgammaR-/- mice had higher basal D1 activity in the pituitary than WT mice (P<0.05); LPS induced a decrease of D2, but not of D1, activity in the pituitary which was similar in both strains. In the liver, the LPS-induced increase in cytokine expression was not different between IFNgammaR-/- mice and WT mice, and the decrease in serum T3 and T4 levels and hepatic D1 mRNA was also similar. CONCLUSIONS: The relative decrease in serum T3 and T4 and liver D1 mRNA in response to LPS is similar in IL-18-/-, IFNgammaR-/- and WT mice despite significant changes in hepatic cytokine induction. However, the LPS-induced decrease in D1 activity in the pituitary of WT mice is absent in IL-18-/- mice; in contrast, LPS did not decrease pituitary D1 activity in the IFNgammaR-/- mice or their WT, which might be due to the genetic background of the mice. Our results suggest that IL-18 is also involved in the regulation of the central part of the HPT axis during illness.

scholarly journals Type 3 Deiodinase Role on Central Thyroid Hormone Action Affects the Leptin-Melanocortin System and Circadian Activity

Endocrinology ◽  
2016 ◽  
Vol 158 (2) ◽  
pp. 419-430 ◽  
Author(s):  
Zhaofei Wu ◽  
M. Elena Martinez ◽  
Donald L. St. Germain ◽  
Arturo Hernandez
Keyword(s):  
Energy Balance ◽  
Elevated Serum ◽  
Serum Levels ◽  
Leptin Resistance ◽  
Melanocortin System ◽  
White Adipocyte ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis ◽  
The Central Nervous System ◽  
Type 3

Abstract The role of thyroid hormones (THs) in the central regulation of energy balance is increasingly appreciated. Mice lacking the type 3 deiodinase (DIO3), which inactivates TH, have decreased circulating TH levels relative to control mice as a result of defects in the hypothalamic-pituitary-thyroid axis. However, we have shown that the TH status of the adult Dio3−/− brain is opposite that of the serum, exhibiting enhanced levels of TH action. Because the brain, particularly the hypothalamus, harbors important circuitries that regulate metabolism, we aimed to examine the energy balance phenotype of Dio3−/− mice and determine whether it is associated with hypothalamic abnormalities. Here we show that Dio3−/− mice of both sexes exhibit decreased adiposity, reduced brown and white adipocyte size, and enhanced fat loss in response to triiodothyronine (T3) treatment. They also exhibit increased TH action in the hypothalamus, with abnormal expression and T3 sensitivity of genes integral to the leptin-melanocortin system, including Agrp, Npy, Pomc, and Mc4r. The normal to elevated serum levels of leptin, and elevated and repressed expression of Agrp and Pomc, respectively, suggest a profile of leptin resistance. Interestingly, Dio3−/− mice also display elevated locomotor activity and increased energy expenditure. This occurs in association with expanded nighttime activity periods, suggesting a disrupted circadian rhythm. We conclude that DIO3-mediated regulation of TH action in the central nervous system influences multiple critical determinants of energy balance. Those influences may partially compensate each other, with the result likely contributing to the decreased adiposity observed in Dio3−/− mice.

scholarly journals Neuropeptide Y1 and Y5 Receptors Mediate the Effects of Neuropeptide Y on the Hypothalamic-Pituitary-Thyroid Axis

Endocrinology ◽  
2002 ◽  
Vol 143 (12) ◽  
pp. 4513-4519 ◽  
Author(s):  
Csaba Fekete ◽  
Sumit Sarkar ◽  
William M. Rand ◽  
John W. Harney ◽  
Charles H. Emerson ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Food Intake ◽  
Neuropeptide Y ◽  
Paraventricular Nucleus ◽  
Receptor Agonist ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis ◽  
Ad Libitum ◽  
Thyroid Hormone Levels ◽  
Hpt Axis

Abstract Neuropeptide Y (NPY) is one of the most important hypothalamic-derived neuropeptides mediating the effects of leptin on energy homeostasis. Central administration of NPY not only markedly stimulates food intake, but simultaneously inhibits the hypothalamic-pituitary-thyroid axis (HPT axis), replicating the central hypothyroid state associated with fasting. To identify the specific NPY receptor subtypes involved in the action of NPY on the HPT axis, we studied the effects of the highly selective Y1 ([Phe7,Pro34]pNPY) and Y5 ([chicken pancreatic polypeptide1–7, NPY19–23, Ala31, Aib32 (aminoisobutyric acid), Q34]human pancreatic polypeptide) receptor agonists on circulating thyroid hormone levels and proTRH mRNA in hypophysiotropic neurons of the hypothalamic paraventricular nucleus. The peptides were administered continuously by osmotic minipump into the cerebrospinal fluid (CSF) over 3 d in ad libitum-fed animals and animals pair-fed to artificial CSF (aCSF)-infused controls. Both Y1 and Y5 receptor agonists nearly doubled food intake compared with that of control animals receiving aCSF, similar to the effect observed for NPY. NPY, Y1, and Y5 receptor agonist administration suppressed circulating levels of thyroid hormones (T3 and T4) and resulted in inappropriately normal or low TSH levels. These alterations were also associated with significant suppression of proTRH mRNA in the paraventricular nucleus, particularly in the Y1 receptor agonist-infused group [aCSF, NPY, Y1, and Y5 (density units ± sem), 97.2 ± 8.6, 39.6 ± 8.4, 19.9 ± 1.9, and 44.6 ± 8.4]. No significant differences in thyroid hormone levels, TSH, or proTRH mRNA were observed between the agonist-infused FSanimals eating ad libitum and the agonist-infused animals pair-fed with vehicle-treated controls. These data confirm the importance of both Y1 and Y5 receptors in the NPY-mediated increase in food consumption and demonstrate that both Y1 and Y5 receptors can mediate the inhibitory effects of NPY on the HPT axis.

scholarly journals Distinct Roles of Deiodinases on the Phenotype of Mct8 Defect: A Comparison of Eight Different Mouse Genotypes

Endocrinology ◽  
2011 ◽  
Vol 152 (3) ◽  
pp. 1180-1191 ◽  
Author(s):  
Xiao-Hui Liao ◽  
Caterina Di Cosmo ◽  
Alexandra M. Dumitrescu ◽  
Arturo Hernandez ◽  
Jacqueline Van Sande ◽  
...  
Keyword(s):  
Growth Response ◽  
Pituitary Thyroid Axis ◽  
Severe Impairment ◽  
Serum T3 ◽  
Serum T4 ◽  
Thyroid Axis ◽  
Mct8 Deficiency ◽  
The Brain ◽  
Insight Into ◽  
Serum Tsh

Mice deficient in the thyroid hormone (TH) transporter Mct8 (Mct8KO) have increased 5′-deiodination and impaired TH secretion and excretion. These and other unknown mechanisms result in the low-serum T4, high T3, and low rT3 levels characteristic of Mct8 defects. We investigated to what extent each of the 5′-deiodinases (D1, D2) contributes to the serum TH abnormalities of the Mct8KO by generating mice with all combinations of Mct8 and D1 and/or D2 deficiencies and comparing the resulting eight genotypes. Adding D1 deficiency to that of Mct8 corrected the serum TH abnormalities of Mct8KO mice, normalized brain T3 content, and reduced the impaired expression of TH-responsive genes. In contrast, Mct8D2KO mice maintained the serum TH abnormalities of Mct8KO mice. However, the serum TSH level increased 27-fold, suggesting a severely impaired hypothalamo-pituitary-thyroid axis. The brain of Mct8D2KO manifested a pattern of more severe impairment of TH action than Mct8KO alone. In triple Mct8D1D2KO mice, the markedly increased serum TH levels produced milder brain defect than that of Mct8D2KO at the expense of more severe liver thyrotoxicosis. Additionally, we observed that mice deficient in D2 had an unexplained marked reduction in the thyroid growth response to TSH. Our studies on these eight genotypes provide a unique insight into the complex interplay of the deiodinases in the Mct8 defect and suggest that D1 contributes to the increased serum T3 in Mct8 deficiency, whereas D2 mainly functions locally, converting T4 to T3 to compensate for distinct cellular TH depletion in Mct8KO mice.

Evaluation of hypothalamus-pituitary-thyroid axis function by chronic perchlorate exposure in male rats

2017 ◽  
Vol 33 (2) ◽  
pp. 209-219 ◽  
Author(s):  
Caroline Serrano-Nascimento ◽  
Jamile Calil-Silveira ◽  
Rafael Dalbosco ◽  
Telma Tenorio Zorn ◽  
Maria Tereza Nunes
Keyword(s):  
Male Rats ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis

scholarly journals The TRH Gene Is Regulated by Thyroid Hormone at the Level of Transcription in Vivo

2010 ◽  
Vol 31 (1) ◽  
pp. 136-136
Author(s):  
Michelle L. Sugrue ◽  
Kristen R. Vella ◽  
Crystal Morales ◽  
Marisol E. Lopez ◽  
Anthony N. Hollenberg
Keyword(s):  
Thyroid Hormone ◽  
Genomic Region ◽  
Model System ◽  
Model Systems ◽  
In Vivo Model ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis ◽  
Normal Production

ABSTRACT The expression of the TRH gene in the paraventricular nucleus (PVH) of the hypothalamus is required for the normal production of thyroid hormone (TH) in rodents and humans. In addition, the regulation of TRH mRNA expression by TH, specifically in the PVH, ensures tight control of the set point of the hypothalamic-pituitary-thyroid axis. Although many studies have assumed that the regulation of TRH expression by TH is at the level of transcription, there is little data available to demonstrate this. We used two in vivo model systems to show this. In the first model system, we developed an in situ hybridization (ISH) assay directed against TRH heteronuclear RNA to measure TRH transcription directly in vivo. We show that in the euthyroid state, TRH transcription is present both in the PVH and anterior/lateral hypothalamus. In the hypothyroid state, transcription is activated in the PVH only and can be shut off within 5 h by TH. In the second model system, we employed transgenic mice that express the Cre recombinase under the control of the genomic region containing the TRH gene. Remarkably, TH regulates Cre expression in these mice in the PVH only. Taken together, these data affirm that TH regulates TRH at the level of transcription in the PVH only and that genomic elements surrounding the TRH gene mediate its regulation by T3. Thus, it should be possible to identify the elements within the TRH locus that mediate its regulation by T3 using in vivo approaches.

scholarly journals Minireview: The Neural Regulation of the Hypothalamic-Pituitary-Thyroid Axis

Endocrinology ◽  
2012 ◽  
Vol 153 (9) ◽  
pp. 4128-4135 ◽  
Author(s):  
Ricardo H. Costa-e-Sousa ◽  
Anthony N. Hollenberg
Keyword(s):  
Thyroid Hormone ◽  
Adult Life ◽  
Feedback System ◽  
Primary Hypothyroidism ◽  
Neural Regulation ◽  
Pituitary Thyroid Axis ◽  
Genes Encoding ◽  
Thyroid Axis ◽  
Hpt Axis

Thyroid hormone (TH) signaling plays an important role in development and adult life. Many organisms may have evolved under selective pressure of exogenous TH, suggesting that thyroid hormone signaling is phylogenetically older than the systems that regulate their synthesis. Therefore, the negative feedback system by TH itself was probably the first mechanism of regulation of circulating TH levels. In humans and other vertebrates, it is well known that TH negatively regulates its own production through central actions that modulate the hypothalamic-pituitary-thyroid (HPT) axis. Indeed, primary hypothyroidism leads to the up-regulation of the genes encoding many key players in the HPT axis, such as TRH, type 2 deiodinase (dio2), pyroglutamyl peptidase II (PPII), TRH receptor 1 (TRHR1), and the TSH α- and β-subunits. However, in many physiological circumstances, the activity of the HPT axis is not always a function of circulating TH concentrations. Indeed, circadian changes in the HPT axis activity are not a consequence of oscillation in circulating TH levels. Similarly, during reduced food availability, several components of the HPT axis are down-regulated even in the presence of lower circulating TH levels, suggesting the presence of a regulatory pathway hierarchically higher than the feedback system. This minireview discusses the neural regulation of the HPT axis, focusing on both TH-dependent and -independent pathways and their potential integration.

Effect of winter sleep on pituitary-thyroid axis in American black bear.

1979 ◽  
Vol 237 (3) ◽  
pp. E227 ◽  
Author(s):  
F Azizi ◽  
J E Mannix ◽  
D Howard ◽  
R A Nelson
Keyword(s):  
Black Bear ◽  
Delayed Response ◽  
American Black Bear ◽  
Pituitary Thyroid Axis ◽  
Serum T3 ◽  
Serum T4 ◽  
Thyroid Axis ◽  
American Black ◽  
Maximum Increment ◽  
Winter Sleep

During winter sleep the black bear has decreased levels of serum total and free thyroxine (T4) and triiodothyronine (T3) and a prolonged, delayed response of serum thyrotropin (TSH) (bioassay) to thyrotropin-releasing hormone (TRH). Four weeks after the end of winter sleep, levels of serum thyroid hormones increase, and TSH response to TRH is short and brisk. Serum T4 and T3 rise after TRH administration both during and after winter sleep; however, the maximum increment in serum T3 is greater during winter sleep when the TSH rise is also prolonged and exaggerated. These observations suggest that transient hypothyroidism of possible hypothalamic origin occurs in bears during winter sleep.

Sign in / Sign up

Export Citation Format

Share Document