Melatonin stimulates thyroid-stimulating hormone accumulation in the thyrotropes of the rat pars tuberalis

2000 ◽  
Vol 114 (3) ◽  
pp. 213-218 ◽  
Author(s):  
Shinya Sakamoto ◽  
Kazuaki Nakamura ◽  
Kinji Inoue ◽  
Takafumi Sakai
Keyword(s):  
Thyroid Stimulating Hormone ◽  
Pars Tuberalis ◽  
Stimulating Hormone

scholarly journals OR16-05 Single-Cell Sequencing Identifies Novel Regulators of Thyrotrope Populations and POU1F1-Independent Thyroid-Stimulating Hormone Expression

2020 ◽  
Vol 4 (Supplement_1) ◽  
Author(s):  
Leonard Cheung ◽  
Alexandre Daly ◽  
Michelle Brinkmeier ◽  
Sally Ann Camper
Keyword(s):  
Transcription Factor ◽  
Single Cell ◽  
Molecular Mechanisms ◽  
Thyroid Stimulating Hormone ◽  
Pars Tuberalis ◽  
Pituitary Cells ◽  
Pars Distalis ◽  
Mouse Development ◽  
Single Cell Sequencing ◽  
Stimulating Hormone

Abstract We implemented single-cell RNA sequencing (scRNAseq) technology as a discovery tool to identify factors enriched in differentiated thyrotropes. Thyroid-stimulating hormone (TSH) is produced in the pars distalis of the anterior pituitary (AP) and primarily acts on the thyroid gland to regulate metabolism through T3/T4. However, TSH is also produced by cells in the pars tuberalis (PT), which is comprised of a thin layer of cells that extends rostrally from the pars distalis along the pituitary stalk to the median eminence in the hypothalamus. TSH produced by PT thyrotropes acts on hypothalamic tanycytes to regulate seasonal reproduction. PT thyrotropes likely descend from rostral tip thyrotropes that arise at e12.5 of mouse development, which transcribe the TSH beta subunit (Tshb) without detectable expression of the transcription factor POU1F1. POU1F1 is required for Tshb transcription in thyrotropes of the adenohypophysis, and it acts synergistically with GATA2 to drive cell fate. The molecular mechanisms driving Tshb expression independently of Pou1f1 in PT thyrotropes are unclear. Thyrotropes are the least abundant endocrine cell-type in the pituitary gland. We used genetic labeling and fluorescence-activated cell sorting (FACS) to enrich for thyrotropes for single-cell sequencing. We performed scRNAseq on 7-day-old GFP-positive pituitary cells from Tshb-Cre; R26-LSL-eYFP and intact whole pituitaries, recovering more than 15,000 cells altogether. We observe two distinct populations of cells expressing Tshb. The larger thyrotrope population has approximately twenty fold higher levels of Tshb and five fold higher Cga transcripts than the smaller population, and they are also distinguished by expression of Pou1f1, TSH-releasing hormone receptor (Trhr), and deiodinase 2 (Dio2), consistent with expectations for AP thyrotropes. The smaller thyrotrope population does not express Pou1f1, but those cells are characterized by expression of TSH receptor (Tshr) and melatonin receptor 1A (Mtnr1a), consistent with expectations for PT thyrotropes. They express mildly increased levels of Eya3 and Six1, although these genes are expressed in other cell-types including AP thyrotropes, stem cells, and gonadotropes. They have two-fold higher levels of Gata2 transcripts and uniquely express the transcription factor Sox14. SOX14 is a SoxB2 family transcription factor that counteracts the transcriptional activity of SoxB1 family members, such as Sox2. In conclusion, our scRNAseq has identified novel markers of PT thyrotropes and unveils novel insights into the similarities and differences in the development and function of pituitary thyrotrope subpopulations.

scholarly journals Molecular economy of nature with two thyrotropins from different parts of the pituitary: pars tuberalis thyroid-stimulating hormone and pars distalis thyroid-stimulating hormone

2021 ◽  
Vol 17 (1) ◽  
pp. 189-195
Author(s):  
Sibel Ertek
Keyword(s):  
Pineal Gland ◽  
Light Stimulus ◽  
Peripheral Circulation ◽  
Thyroid Stimulating Hormone ◽  
Breeding Period ◽  
Pars Tuberalis ◽  
Pars Distalis ◽  
Subunit Expression ◽  
The Brain ◽  
Stimulating Hormone

Thyrotropin (TSH) is classically known to be regulated by negative feedback from thyroid hormones and stimulated by thyrotropin-releasing hormone (TRH) from the hypothalamus. At the end of the 1990s, studies showed that thyrotroph cells from the pars tuberalis (PT) did not have TRH receptors and their TSH regulation was independent from TRH stimulation. Instead, PT-thyrotroph cells were shown to have melatonin-1 (MT-1) receptors and melatonin secretion from the pineal gland stimulates TSH- subunit formation in PT. Electron microscopy examinations also revealed some important differences between PT and pars distalis (PD) thyrotrophs. PT-TSH also have low bioactivity in the peripheral circulation. Studies showed that they have different glycosylations and PT-TSH forms macro-TSH complexes in the periphery and has a longer half-life. Photoperiodism affects LH levels in animals via decreased melatonin causing increased TSH- subunit expression and induction of deiodinase-2 (DIO-2) in the brain. Mammals need a light stimulus carried into the suprachiasmatic nucleus (which is a circadian clock) and then transferred to the pineal gland to synthesize melatonin, but birds have deep brain receptors and they are stimulated directly by light stimuli to have increased PT-TSH, without the need for melatonin. Photoperiodic regulations via TSH and DIO 2/3 also have a role in appetite, seasonal immune regulation, food intake and nest-making behaviour in animals. Since humans have no clear seasonal breeding period, such studies as recent ‘’domestication locus’’ studies in poultry are interesting. PT-TSH that works like a neurotransmitter in the brain may become an important target for future studies about humans.

scholarly journals Molecular basis for regulating seasonal reproduction in vertebrates

2016 ◽  
Vol 229 (3) ◽  
pp. R117-R127 ◽  
Author(s):  
Taeko Nishiwaki-Ohkawa ◽  
Takashi Yoshimura
Keyword(s):  
Thyroid Hormone ◽  
Pituitary Gland ◽  
Environmental Changes ◽  
Thyroid Stimulating Hormone ◽  
Day Length ◽  
Adaptive Behaviors ◽  
Seasonal Reproduction ◽  
Pars Tuberalis ◽  
Light Detection ◽  
Stimulating Hormone

Animals that inhabit mid- to high-latitude regions exhibit various adaptive behaviors, such as migration, reproduction, molting and hibernation in response to seasonal cues. These adaptive behaviors are tightly regulated by seasonal changes in photoperiod, the relative day length vs night length. Recently, the regulatory pathway of seasonal reproduction has been elucidated using quail. In birds, deep brain photoreceptors receive and transmit light information to the pars tuberalis in the pituitary gland, which induces the secretion of thyroid-stimulating hormone. Thyroid-stimulating hormone locally activates thyroid hormone via induction of type 2 deiodinase in the mediobasal hypothalamus. Thyroid hormone then induces morphological changes in the terminals of neurons that express gonadotropin-releasing hormone and facilitates gonadotropin secretion from the pituitary gland. In mammals, light information is received by photoreceptors in the retina and neurally transmitted to the pineal gland, where it inhibits the synthesis and secretion of melatonin, which is crucial for seasonal reproduction. Importantly, the signaling pathway downstream of light detection and signaling is fully conserved between mammals and birds. In fish, the regulatory components of seasonal reproduction are integrated, from light detection to neuroendocrine output, in a fish-specific organ called the saccus vasculosus. Various physiological processes in humans are also influenced by seasonal environmental changes. The findings discussed herein may provide clues to addressing human diseases, such as seasonal affective disorder.

scholarly journals Glutamine and glutamic acid enhance thyroid-stimulating hormone β subunit mRNA expression in the rat pars tuberalis

2012 ◽  
Vol 212 (3) ◽  
pp. 383-394 ◽  
Author(s):  
Sayaka Aizawa ◽  
Takafumi Sakai ◽  
Ichiro Sakata
Keyword(s):  
Glutamic Acid ◽  
Mrna Expression ◽  
Regulatory Mechanism ◽  
Thyroid Stimulating Hormone ◽  
Pars Tuberalis ◽  
Melatonin Receptor ◽  
Subunit Mrna ◽  
Glutamine Transporter ◽  
Stimulating Hormone

Thyroid-stimulating hormone (TSH)-producing cells of the pars tuberalis (PT) display distinct characteristics that differ from those of the pars distalis (PD). The mRNA expression ofTSHβandαGSUin PT has a circadian rhythm and is inhibited by melatonin via melatonin receptor type 1; however, the detailed regulatory mechanism forTSHβexpression in the PT remains unclear. To identify the factors that affect PT, a microarray analysis was performed on laser-captured PT tissue to screen for genes coding for receptors that are abundantly expressed in the PT. In the PT, we found high expression of theKA2, which is an ionotropic glutamic acid receptor (iGluR). In addition, the amino acid transporter A2 (ATA2), also known as the glutamine transporter, and glutaminase (GLS), as well asGLS2, were highly expressed in the PT compared to the PD. We examined the effects of glutamine and glutamic acid onTSHβexpression andαGSUexpression in PT slice cultures.l-Glutamine andl-glutamic acid significantly stimulatedTSHβexpression in PT slices after 2- and 4-h treatments, and the effect ofl-glutamic acid was stronger than that ofl-glutamine. In contrast, treatment with glutamine and glutamic acid did not affectαGSUexpression in the PT or the expression ofTSHβorαGSUin the PD. These results strongly suggest that glutamine is taken up by PT cells through ATA2 and that glutamic acid locally converted from glutamine by Gls inducesTSHβexpression via the KA2 in an autocrine and/or paracrine manner in the PT.

Diurnal Change of Thyroid-Stimulating Hormone mRNA Expression in the Rat Pars Tuberalis

2007 ◽  
Vol 19 (11) ◽  
pp. 839-846 ◽  
Author(s):  
S. Aizawa ◽  
S. Hoshino ◽  
I. Sakata ◽  
A. Adachi ◽  
S. Yashima ◽  
...  
Keyword(s):  
Mrna Expression ◽  
Thyroid Stimulating Hormone ◽  
Diurnal Change ◽  
Pars Tuberalis ◽  
Stimulating Hormone

The Pituitary Gland: Embryology, Physiology, and Pathophysiology

2000 ◽  
Vol 19 (2) ◽  
pp. 9-17 ◽  
Author(s):  
Angela Dorton
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Pituitary Hormones ◽  
Thyroid Stimulating Hormone ◽  
The Body ◽  
Pars Intermedia ◽  
Pituitary Hormone ◽  
Pars Tuberalis ◽  
Pars Distalis ◽  
Stimulating Hormone

The pituitary gland, the “master gland” of the body, is composed of endocrine cells, which secrete hormones essential for homeostasis. The gland consists of the adenohypophysis (anterior pituitary) and the neurohypophysis (posterior pituitary), two unique structures that differ anatomically and functionally.The neurohypophysis is innervated by nerve cells in the hypothalamus and forms the connection between it and the pituitary gland. The hypothalamus stimulates release and inhibition of pituitary hormones. The neurohypophysis secretes oxytocin and antidiuretic hormone.The adenohypophysis is composed of three structures: the pars distalis, the pars intermedia, and the pars tuberalis. The anterior pituitary (pars distalis) is responsible for the release of hormones that include growth hormone, prolactin, thyroid-stimulating hormone, follicle-stimulating hormone, luteinizing hormone, adrenocorticotropic hormone, and melanocyte-stimulating hormone.Disorders of the pituitary are predominately those of insufficient hormone release and may have profound effects on the neonate. The potential causes of and clinical symptomatology that may accompany pituitary hormone insufficiency in the neonatal period are explored.

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