Thyroid-Stimulating Hormone: Biosynthesis, Cell Biology, and Bioactivity

Magner, James A.

doi:10.1210/edrv-11-2-354

Cited by 160 publications

(83 citation statements)

References 141 publications

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“…The cumbersome immunopurification and concentration of plasma TSH are widely used to exclude the action of unknown factors, activating or inhibiting cAMP response (7,15). However, this procedure needs large quantities of blood (excluding the use of children's plasma) and has the main drawback that antibodies used in the immunopurification may recognize only particular glycosylation variants of TSH through which the intracellular signal transduction system may be activated to different degrees (16).…”

Section: Discussionmentioning

confidence: 99%

Plasma thyrotropin bioactivity in Down's syndrome children with subclinical hypothyroidism

Trotsenburg²,

Ris‐Stalpers³

et al. 2001

European Journal of Endocrinology

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Objective: Subclinical hypothyroidism occurs in a number of children with Down's syndrome (DS). The reason for the mildly elevated plasma thyrotropin (TSH) concentrations is not known. The present study investigated whether decreased TSH bioactivity plays a role in this phenomenon. Design: A retrospective study of plasma specimens from DS children with mildly elevated plasma TSH concentrations and thyroid hormone levels within the reference range, using a TSH receptor± adenylate cyclase mediated bioassay. Methods: Strain JP26 Chinese hamster ovary (CHO) cells, stable transfected with the human TSH receptor, were incubated with unfractionated plasma (1/10 diluted in hypotonic incubation medium) of 10 DS children with subclinical hypothyroidism and nine euthyroid children with insulindependent diabetes mellitus as controls. cAMP released in the incubation medium was measured by RIA. Mock-transfected CHO cells were used to correct for non-specific CHO response. WHO Second International Reference Preparation of human TSH was dissolved and diluted in pooled normal human plasma and simultaneously bioassayed to match patient and control results. Results: Plasma TSH levels were slightly increased in DS (mean^s.d., 6X5^1X3 mUalY reference range 0.4±4.0 mU/l). Plasma TSH levels for controls 1X3^0X4 mUal were within the reference range. Plasma thyroid hormone levels in patients and controls were normal, plasma TSH binding inhibitory immunoglobulin and thyroid peroxidase antibodies were negative. cAMP levels (corrected for non-specific CHO response) in DS patients 18X4^3X9 pmolawell and in controls 14X31 X3 pmolawell did not significantly differ from cAMP levels generated by patient-TSH equivalent TSH standards 16X3^0X9 pmolawellX Conclusions: The present results demonstrate normal TSH bioactivity in plasma of DS children, indicating that subclinical hypothyroidism in these patients is of primary (thyroidal) origin.

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Section: Discussionmentioning

confidence: 99%

Plasma thyrotropin bioactivity in Down's syndrome children with subclinical hypothyroidism

Trotsenburg²,

Ris‐Stalpers³

et al. 2001

European Journal of Endocrinology

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“…Thyrotrophin (TSH) is the major regulator of thyroid hormone synthesis and secretion (Magner 1990). Despite the fact that the primary site of action of TSH is the thyroid gland, there is accumulating evidence that there is also extrathyroidal TSH receptor (TSH-R) expression.…”

Section: Introductionmentioning

confidence: 99%

Thyrotrophin receptor protein expression in normal and adenomatous human pituitary

Theodoropoulou¹,

Arzberger²,

Gruebler³

et al. 2000

Journal of Endocrinology

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Thyrotrophin (TSH) synthesis and secretion is under the positive control of thyrotrophin releasing hormone and under the negative control of the thyroid hormones. However, it is hypothesised that TSH has a direct effect on the regulation of its own synthesis through an intrapituitary loop mediated by pituitary TSH receptors (TSH-R). The aim of this investigation was to study the expression of TSH-R in normal human pituitary at mRNA and protein levels, and to compare the pattern of protein expression between different pituitary adenomas. Using RT-PCR we were able to detect TSH-R mRNA in the normal pituitary, and immunohistochemical studies showed TSH-R protein expression in distinct areas of the anterior pituitary. Double immunostaining with antibodies against each of the intrapituitary hormones and S100 revealed that TSH-R protein is present in thyrotrophs and folliculostellate cells. Examination of 58 pituitary adenomas, including two clinically active and two clinically inactive thyrotroph adenomas, revealed TSH-R immunopositivity in only the two clinically inactive thyrotroph adenomas.This study shows, for the first time, the presence of TSH-R protein in the normal anterior pituitary and in a subset of thyrotroph adenomas. The expression of TSH-R in the thyrotroph and folliculostellate cell subpopulations provides preliminary evidence of a role for TSH in autocrine and paracrine regulatory pathways within the anterior pituitary gland.

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“…Of note, a previous study showed that T 3 crystalline implants in the hypothalamus did not influence TSH secretion in hypothyroid rats, although IR-pro-TRH was remarkably inhibited (Dyess et al 1988). The production and secretion of TSH by the pituitary gland are positively stimulated by TRH, while TRH also modulates the glycosylation of TSH, which affects TSH bioactivity (Magner 1990). Part of the explanation for unaltered plasma TSH in the presence of decreased pituitary Tshb mRNA as observed in this study may be a discrepancy between the biological activity and the immunological detectability of TSH (Persani & Bonomi 2014).…”

Section: Discussionmentioning

confidence: 94%

A model for chronic, intrahypothalamic thyroid hormone administration in rats

Zhi

Bisschop

Foppen

et al. 2016

Journal of Endocrinology

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In addition to the direct effects of thyroid hormone (TH) on peripheral organs, recent work showed metabolic effects of TH on the liver and brown adipose tissue via neural pathways originating in the hypothalamic paraventricular and ventromedial nucleus (PVN and VMH). So far, these experiments focused on short-term administration of TH. The aim of this study is to develop a technique for chronic and nucleus-specific intrahypothalamic administration of the biologically active TH tri-iodothyronine (T 3 ). We used beeswax pellets loaded with an amount of T 3 based on in vitro experiments showing stable T 3 release (~5 nmol l −1 ) for 32 days. Upon stereotactic bilateral implantation, T 3 concentrations were increased 90-fold in the PVN region and 50-fold in the VMH region after placing T 3 -containing pellets in the rat PVN or VMH for 28 days respectively. Increased local T 3 concentrations were reflected by selectively increased mRNA expression of the T 3 -responsive genes Dio3 and Hr in the PVN or in the VMH. After placement of T 3 -containing pellets in the PVN, Tshb mRNA was significantly decreased in the pituitary, without altered Trh mRNA in the PVN region. Plasma T 3 and T 4 concentrations decreased without altered plasma TSH. We observed no changes in pituitary Tshb mRNA, plasma TSH, or plasma TH in rats after placement of T 3 -containing pellets in the VMH. We developed a method to selectively and chronically deliver T 3 to specific hypothalamic nuclei. This will enable future studies on the chronic effects of intrahypothalamic T 3 on energy metabolism via the PVN or VMH.

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Thyroid-Stimulating Hormone: Biosynthesis, Cell Biology, and Bioactivity

Cited by 160 publications

References 141 publications

Plasma thyrotropin bioactivity in Down's syndrome children with subclinical hypothyroidism

Plasma thyrotropin bioactivity in Down's syndrome children with subclinical hypothyroidism

Thyrotrophin receptor protein expression in normal and adenomatous human pituitary

A model for chronic, intrahypothalamic thyroid hormone administration in rats

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