Ontogeny of pituitary thyrotrophs and regulation by endogenous thyroid hormone feedback in the chick embryo

Increased thyroid hormone production is essential for hatching of the chick and for the increased metabolism necessary for posthatch endothermic life. However, little is known about the ontogeny and distribution of pituitary thyrotrophs during this period or whether pituitary thyroid-stimulating hormone (TSH) production is regulated by endogenous thyroid hormones during chick embryonic development. This study assessed the abundance and location of pituitary thyrotrophs and the regulation of TSHβ peptide and mRNA levels by endogenous thyroid hormones prior to hatching. TSHβ-containing cells were first detected on embryonic day (e) 11, and the thyrotroph population increased to maximum levels on e17 and e19 and then decreased prior to hatching (d1). Thyrotroph distribution within the cephalic lobe of the anterior pituitary was determined on e19 by whole-mount immunocytochemistry for TSHβ peptide and by whole-mount in situ hybridization for TSHβ mRNA. Thyrotroph distribution within the cephalic lobe was heterogeneous among embryos, but most commonly extended from the ventral medial region to the dorsal lateral regions, along the boundary of the cephalic and caudal lobes. Inhibition of endogenous thyroid hormone production with methi-mazole (MMI) decreased plasma thyroxine (T4) levels and increased pituitary TSHβ mRNA levels on e19 and d1. However, control pituitaries contained significantly more TSHβ peptide than MMI-treated pituitaries on e17 and e19, suggesting higher TSH secretion into the blood in MMI-treated groups. We conclude that thyrotroph abundance and TSH production increase prior to hatching, that thyrotrophs are localized heterogenenously within the cephalic lobe of the anterior pituitary at that time, and that TSH gene expression and secretion are under negative feedback regulation from thyroid hormones during this critical period of development.

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Establishment of Early Pregnancy Related Thyroid Hormone Models and Reference Intervals for Pregnant Women in China Based on Real World Data

Hormone and Metabolic Research ◽

10.1055/a-1402-0290 ◽

2021 ◽

Vol 53 (04) ◽

pp. 272-279

Author(s):

Chaochao Ma ◽

Xiaoqi Li ◽

Lixin Liu ◽

Xinqi Cheng ◽

Fang Xue ◽

...

Keyword(s):

Thyroid Hormone ◽

Thyroid Hormones ◽

Pregnant Women ◽

Early Pregnancy ◽

Gestational Age ◽

Dynamic Change ◽

Reference Intervals ◽

Thyroid Stimulating Hormone ◽

Free Thyroxine ◽

Stimulating Hormone

AbstractThyroid hormone reference intervals are crucial for diagnosing and monitoring thyroid dysfunction during early pregnancy, and the dynamic change trend of thyroid hormones during pregnancy can assist clinicians to assess the thyroid function of pregnant women. This study aims to establish early pregnancy related thyroid hormones models and reference intervals for pregnant women. We established two derived databases: derived database* and derived database#. Reference individuals in database* were used to establish gestational age-specific reference intervals for thyroid hormones and early pregnancy related thyroid hormones models for pregnant women. Individuals in database# were apparently healthy non-pregnant women. The thyroid hormones levels of individuals in database# were compared with that of individuals in database* using nonparametric methods and the comparative confidence interval method. The differences in thyroid stimulating hormone and free thyroxine between early pregnant and non-pregnant women were statistically significant (p<0.0001). The reference intervals of thyroid stimulating hormone, free thyroxine and free triiodothyronine for early pregnant women were 0.052–3.393 μIU/ml, 1.01–1.54 ng/dl, and 2.51–3.66 pg/ml, respectively. Results concerning thyroid stimulating hormone and free thyroxine reference intervals of early pregnancy are comparable with those from other studies using the same detection platform. Early pregnancy related thyroid hormones models showed various change patterns with gestational age for thyroid hormones. Early pregnancy related thyroid hormones models and reference intervals for pregnant women were established, so as to provide accurate and reliable reference basis for the diagnosing and monitoring of maternal thyroid disfunction in early pregnancy.

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THYROID HORMONE REGULATES VASOACTIVE INTESTINAL PEPTIDE (VIP) mRNA LEVELS IN THE RAT ANTERIOR PITUITARY GLAND

Endocrinology ◽

10.1210/endo-125-4-2221 ◽

1989 ◽

Vol 125 (4) ◽

pp. 2221-2223 ◽

Cited By ~ 39

Author(s):

THOMAS P. SEGERSON ◽

KAREN S.L. LAM ◽

LUCINDA CACICEDO ◽

NAOTO MINAMITANI ◽

J. STEPHEN FINK ◽

...

Keyword(s):

Thyroid Hormone ◽

Pituitary Gland ◽

Vasoactive Intestinal Peptide ◽

Anterior Pituitary ◽

Anterior Pituitary Gland ◽

Mrna Levels

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Iodide Metabolism and Effects

Diagnosing and Managing Hashimoto’s Disease - Advances in Medical Diagnosis, Treatment, and Care ◽

10.4018/978-1-5225-9655-4.ch004 ◽

2020 ◽

pp. 25-33

Keyword(s):

Thyroid Hormone ◽

Thyroid Gland ◽

Thyroid Hormones ◽

Dietary Supplement ◽

Thyroid Function ◽

Thyroid Stimulating Hormone ◽

Hormone Synthesis ◽

Serum Tsh ◽

Tsh Stimulation ◽

Sensitive Marker

Iodine (I2) is essential in the synthesis of thyroid hormones T4 and T3 and functioning of the thyroid gland. Both T3 and T4 are metabolically active, but T3 is four times more potent than T4. Our body contains 20-30 mg of I2, which is mainly stored in the thyroid gland. Iodine is naturally present in some foods, added to others, and available as a dietary supplement. Serum thyroid stimulating hormone (TSH) level is a sensitive marker of thyroid function. Serum TSH is increased in hypothyroidism as in Hashimoto's thyroiditis. In addition to regulation of thyroid function, TSH promotes thyroid growth. If thyroid hormone synthesis is chronically impaired, TSH stimulation eventually may lead to the development of a goiter. This chapter explores the iodide metabolism and effects of Hashimoto's disease.

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Galanin gene expression in radiothyroidectomy-induced thyrotroph adenomas

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1996.271.1.e24 ◽

1996 ◽

Vol 271 (1) ◽

pp. E24-E30

Author(s):

J. F. Hyde ◽

J. P. Moore ◽

K. W. Drake ◽

D. G. Morrison

Keyword(s):

Gene Expression ◽

Thyroid Hormones ◽

Anterior Pituitary ◽

Human Growth ◽

Mrna Levels ◽

Male Mice ◽

Pituitary Glands ◽

Positive Regulators ◽

Hypothalamic Pituitary Axis ◽

Iodine 131

Galanin gene expression is markedly increased in the anterior pituitary glands of estrogen-treated rats (lactotroph hyperplasia) as well as human growth hormone-releasing hormone transgenic mice (somatotroph hyperplasia). The objective of this study was to examine galanin in a mouse model of thyrotroph adenoma formation. Male mice were radiothyroidectomized by use of iodine-131 (131I), and galanin peptide levels were assessed in the hypothalamic-pituitary axis. Immunoreactive galanin concentrations in the anterior pituitaries of 131I-treated mice were decreased 80% at 3, 6, 9, and 12 mo after radiothyroidectomy. Galanin peptide levels in the hypothalamus were decreased 20-25% at these times. Treatment with either estradiol or 3,3',5-triiodo-L-thyronine increased galanin peptide concentrations in the anterior pituitaries of 131I-treated mice, but neither treatment restored galanin concentrations. Galanin mRNA levels were decreased > 80% 1 yr after radiothyroidectomy. We conclude that, unlike animal models of lactotroph and somatotroph hyperplasia, galanin gene expression is suppressed throughout the development of thyrotroph adenomas, suggesting that galanin does not have a stimulatory role in the proliferation of thyrotrophs. Moreover, these data show that thyroid hormones are important positive regulators of galanin gene expression in the mouse and that estrogen may stimulate galanin gene expression in the absence of thyroid hormones.

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Transcriptional regulation of hepatic sterol 27-hydroxylase by bile acids

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1996.270.4.g646 ◽

1996 ◽

Vol 270 (4) ◽

pp. G646-G652 ◽

Cited By ~ 4

Author(s):

Z. R. Vlahcevic ◽

S. K. Jairath ◽

D. M. Heuman ◽

R. T. Stravitz ◽

P. B. Hylemon ◽

...

Keyword(s):

Bile Acid ◽

Bile Acids ◽

Specific Activity ◽

Feedback Regulation ◽

Initial Step ◽

Mrna Levels ◽

Acid Biosynthesis ◽

Negative Feedback Regulation ◽

Study Objective ◽

Specific Activities

The study objective was to determine whether and to what extent sterol 27-hydroxylase, the initial step in the "acidic" pathway of bile acid biosynthesis, is regulated by bile acids. Rats were fed diets supplemented with cholestyramine (CT, 5%), cholate (CA, 1%), chenodeoxycholate (CDCA, 1%), or deoxycholate (DCA, 0.25%). When compared with paired controls, sterol 27-hydroxylase and cholesterol 7 alpha-hydroxylase specific activities increased after CT administration by 188 +/- 20% (P < 0.05) and 415 +/- 36% (P < 0.01), respectively. Similarly, mRNA levels increased by 159 +/- 14% (P < 0.05) and 311 +/- 106% (P < 0.05), respectively. Feeding CA, CDCA, or DCA decreased sterol 27-hydroxylase specific activity to 57 +/- 6, 61 +/- 8, and 74 +/- 8% of controls, respectively (P < 0.05). By comparison, the specific activity of cholesterol 7 alpha-hydroxylase decreased to 46 +/- 7 , 32 +/- 10, and 26 +/- 8% (P = 0.001). mRNA levels and transcriptional activities for sterol 27-hydroxylase and cholesterol 7 alpha-hydroxylase transcriptional activity were changed to the same extent as the specific activities after CT or bile acid feeding. We conclude that sterol 27-hydroxylase and cholesterol 7 alpha-hydroxylase are subject to negative feedback regulation by hydrophobic bile acids at the level of transcription. However, the responses of sterol 27-hydroxylase to manipulation of the bile acid pool are less prominent than those of cholesterol 7 alpha-hydroxylase. During the diurnal cycle the specific activities of sterol 27-hydroxylase and cholesterol 7 alpha-hydroxylase changed in tandem, suggesting that both may be under control of glucocorticoids.

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Development of gonadal feedback regulation of gonadotropin gene expression and secretion in female rats

Acta Endocrinologica ◽

10.1530/acta.0.1270454 ◽

1992 ◽

Vol 127 (5) ◽

pp. 454-458 ◽

Cited By ~ 6

Author(s):

Pirjo A Pakarinen ◽

Ilpo T Huhtaniemi

Keyword(s):

Negative Feedback ◽

Feedback Regulation ◽

Female Rats ◽

Mrna Levels ◽

Neonatal Rats ◽

Adult Rats ◽

Gonadotropin Secretion ◽

Negative Feedback Regulation ◽

Pituitary Gonadotropin ◽

Old Adult

The postnatal development of the gonadal negative feedback control of gonadotropins was studied in female rats. Neonatal (5-day-old) and randomly cycling young (60-day-old) and more mature (180-day-old) adult rats were ovariectomized, and half of them received Silastic implants containing the synthetic estrogen, diethylstilbestrol. The neonatal rats were killed 5, 10 or 15 days, and the adult rats 7 days after the operation. Age-matched and sham-operated animals served as controls. There were no statistically significant responses of serum LH or FSH concentrations or of the pituitary gonadotropin subunit mRNA levels to ovariectomy at any of the neonatal ages. A marked increase (p<0.01) after ovariectomy was seen in serum gonadotropins and in the cognate mRNA levels at both adult ages. In spite of the weak feedback response of the neonatal rats to ovariectomy, diethylstilbestrol suppressed the basal pituitary gonadotropin concentrations and the specific LH and FSH β-chain mRNAs (p<0.01–0.05). These results demonstrate that the gonadal negative feedback regulation of gonadotropin synthesis and secretion is not fully developed in neonatal and prepubertal female rats before 20 days of age. This is probably due to the steroidogenic quiescence of the ovaries in early life. However, the capability of the pituitary to respond to negative estrogen feedback has developed in the neonatal female, as demonstrated by the suppressive effects of diethylstilbestrol treatment on gonadotropin secretion.

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SIGNIFICANCE OF TRIIODOTHYRONINE FOR THYROID HORMONE SUPPLY DURING STIMULATION

Acta Endocrinologica ◽

10.1530/acta.0.0530151 ◽

1966 ◽

Vol 53 (1) ◽

pp. 151-161 ◽

Cited By ~ 1

Author(s):

Dieter Emrich ◽

Peter Pfannenstiel ◽

Günter Hoffmann ◽

Walter Keiderling

Keyword(s):

Thyroid Hormone ◽

Thyroid Hormones ◽

Thyroid Function ◽

Hormone Production ◽

Partial Inhibition

ABSTRACT The metabolism of the two thyroid hormones thyroxine (T4) and triiodothyronine (T3) and particularly the T4/T3 ratio was studied by the 131I technique in rats and rabbits during stimulation. Both exogenous TSH and experimentally increased endogenous TSH (secondary to the partial inhibition of thyroid function by sodiumperchlorate) caused a change in the T4/T3 ratio in favour of T3. This response of thyroid hormone production (in rats) and secretion (in rabbits) was found at different times after the use of 131I. It depended on the intensity of the direct or indirect thyrotrophic stimulation. From this observation it is suggested that the synthesis and the secretion of the biologically more effective T3 is more markedly increased during stimulation than is T4 probably in order to compensate more successfully for deficiencies in the peripheral thyroid hormone supply.

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The association of thyroid hormones and blood pressure in euthyroid preadolescents

Journal of Pediatric Endocrinology and Metabolism ◽

10.1515/jpem-2015-0084 ◽

2016 ◽

Vol 29 (4) ◽

Author(s):

Bo Hyun Park ◽

Sun Jung Baik ◽

Hye Ah Lee ◽

Young Sun Hong ◽

Hae Soon Kim ◽

...

Keyword(s):

Blood Pressure ◽

Thyroid Hormone ◽

Thyroid Hormones ◽

Diastolic Blood Pressure ◽

Pressure Control ◽

Thyroid Stimulating Hormone ◽

University Hospital ◽

Hypertension Status ◽

Childhood Hypertension ◽

Serum Tsh

AbstractHypertension is the leading cause of cardiovascular disease worldwide, and both high and low blood pressures are associated with various chronic diseases. Thyroid hormones have profound effects on cardiovascular function, including on blood pressure. Recent studies have shown that childhood hypertension can lead to adult hypertension. Therefore, adequate blood pressure control is important from early life. Employing a life-course approach, we aimed to investigate the association between thyroid hormones and blood pressure in children.A total of 290 children from the Ewha Woman’s University Hospital birth cohort participated in a preadolescent check-up program. We assessed the levels of serum thyroid-stimulating hormone (TSH) and free thyroxine (FT4) and the blood pressure status in these children. Thyroid hormone concentrations were measured using an electro-chemiluminescence immunoassay (ECLIA), and hypertension was defined according to the guideline of the Korea Centers for Disease Control and Prevention.The sex-, age-, and height-adjusted prevalence of hypertension was 27.0% in the present study. On regression analysis, serum FT4 showed significantly negative association with diastolic blood pressure (DBP; β=–8.24, 95% CI: –14.19–2.28, p=0.007). However, these relationships were not significant after adjustment for sex, age, and current body mass index. The levels of serum TSH showed no relationship with mean systolic blood pressure (SBP) and diastolic blood pressure (DBP) after adjustment. No significant differences in serum TSH and FT4 levels according to hypertension status were found.These findings suggest that thyroid hormone is not independently associated with increased blood pressure in euthyroid preadolescents.

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Short-Term Plasticity of Cyclic Adenosine 3′,5′-Monophosphate Signaling in Anterior Pituitary Corticotrope Cells: The Role of Adenylyl Cyclase Isotypes

Molecular Endocrinology ◽

10.1210/me.2002-0369 ◽

2003 ◽

Vol 17 (4) ◽

pp. 692-703 ◽

Cited By ~ 24

Author(s):

Ferenc A. Antoni ◽

Alexander A. Sosunov ◽

Anders Haunsø ◽

Janice M. Paterson ◽

James Simpson

Keyword(s):

Protein Kinase C ◽

Protein Kinase ◽

Anterior Pituitary ◽

Feedback Regulation ◽

Pituitary Cells ◽

Adenylyl Cyclases ◽

Physiological Control ◽

Negative Feedback Regulation ◽

Phorbol Dibutyrate ◽

Kinase C

Abstract Anterior pituitary corticotropes show a wide repertory of responses to hypothalamic neuropeptides and adrenal corticosteroids. The hypothesis that plasticity of the cAMP signaling system underlies this adaptive versatility was investigated. In dispersed rat anterior pituitary cells, depletion of intracellular Ca2+ stores with thapsigargin combined with ryanodine or caffeine enhanced the corticotropin releasing-factor (CRF)-evoked cAMP response by 4-fold, whereas reduction of Ca2+ entry alone had no effect. CRF-induced cAMP was amplified 15-fold by arginine-vasopressin (AVP) or phorbol-dibutyrate ester. In the presence of inhibitors of cyclic nucleotide phosphodiesterases and phorbol-dibutyrate ester, the depletion of Ca2+ stores had no further effect on CRF-induced cAMP accumulation. Adenohypophysial expression of mRNAs for the Ca2+-inhibited adenylyl cyclases (ACs) VI and IX, and the protein kinase C-stimulated ACs II and VII was demonstrated. ACIX was detected in corticotropes by immunocytochemistry, whereas ACII and ACVI were not present. The data show negative feedback regulation of CRF-induced cAMP levels by Ca2+ derived from ryanodine receptor-operated intracellular stores. Stimulation of protein kinase C by AVP enhances Ca2+-independent cAMP synthesis, thus changing the characteristics of intracellular Ca2+ feedback. It is proposed that the modulation of intracellular Ca2+ feedback in corticotropes by AVP is an important element of physiological control.

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Athyroid Pax8−/− Mice Cannot Be Rescued by the Inactivation of Thyroid Hormone Receptor α1

Endocrinology ◽

10.1210/en.2005-0114 ◽

2005 ◽

Vol 146 (7) ◽

pp. 3179-3184 ◽

Cited By ~ 22

Author(s):

Jens Mittag ◽

Sönke Friedrichsen ◽

Heike Heuer ◽

Silke Polsfuss ◽

Theo J. Visser ◽

...

Keyword(s):

Thyroid Hormone ◽

Thyroid Hormones ◽

Hormone Receptor ◽

Thyroid Hormone Receptor ◽

Postnatal Life ◽

Mrna Levels ◽

Negative Effects ◽

Double Knockout ◽

Short Life Span ◽

Knockout Animals

Abstract The Pax8−/− mouse provides an ideal animal model to study the consequences of congenital hypothyroidism, because its only known defect is the absence of thyroid follicular cells. Pax8−/− mice are, therefore, completely athyroid in postnatal life and die around weaning unless they are substituted with thyroid hormones. As reported recently, Pax8−/− mice can also be rescued and survive to adulthood by the additional elimination of the entire thyroid hormone receptor α (TRα) gene, yielding Pax8−/−TRαo/o double-knockout animals. This observation has led to the hypothesis that unliganded TRα1 might be responsible for the lethal phenotype observed in Pax8−/− animals. In this study we report the generation of Pax8−/−TRα1−/− double-knockout mice that still express the non-T3-binding TR isoforms α2 and Δα2. These animals closely resemble the phenotype of Pax8−/− mice, including growth retardation and a completely distorted appearance of the pituitary with thyrotroph hyperplasia and hypertrophy, extremely high TSH mRNA levels, reduced GH mRNA expression, and the almost complete absence of lactotrophs. Like Pax8−/− mice, Pax8−/−TRα1−/− compound mutants die around weaning unless they are substituted with thyroid hormones. These findings do not support the previous interpretation that the short life span of Pax8−/− mice is due to the negative effects of the TRα1 aporeceptor, but, rather, suggest a more complex mechanism involving TRα2 and an unliganded TR isoform.

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