Extrapituitary βTSH and GH in early chick embryos

Murphy, Amy E.; Harvey, S.

doi:10.1016/s0303-7207(01)00615-3

Cited by 32 publications

(36 citation statements)

References 52 publications

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“…Thyrostimulin might therefore be produced in extrapituitary tissues as has been shown for TSH, which is expressed in lymphocytes (Harbour et al 1989, Peele et al 1993, thymus, and various tissues in chick embryo (Murphy & Harvey 2001). Indeed, a cross-talk between the immune and neuroendocrine systems (hypothalamiclymphoid-thyroid regulatory axis) has been postulated, since TRH increase GPBtsh expression in lymphocyte (Wang et al 1997).…”

mentioning

confidence: 97%

Differential expression of the thyrostimulin subunits, glycoprotein 2 and 5 in the rat pituitary

Nagasaki

Wang

Jackson

et al. 2006

Journal of Molecular Endocrinology

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Two glycoprotein hormone subunits, (glycoprotein hormone a2-subunit GPA2) and (glycoprotein hormone b5-subunit GPB5) have been recently discovered which, when expressed in vitro, heterodimerize to form a new hormone called thyrostimulin. Thyrostimulin activates the thyroid-stimulating hormone receptor (TSHR) and has thyrotropic activity. Immunological studies have indicated that both subunits co-localize in pituitary cells. To explore the function of thyrostimulin in the rat, we have cloned rat GPA2 and GPB5, reconstituted the heterodimers in vitro, and confirmed that rat thyrostimulin activates TSHR with an affinity similar to that of TSH. In situ hybridization of the pituitary showed that while GPA2 is expressed in the anterior lobe, GPB5 is not detected in any of the lobes. A quantitative analysis showed that the co-localization of GPA2 and GPB5 is restricted in the rat to the eye and the testis. We found that GPB5 can be detected in the pituitary by quantitative-PCR, but at extremely low levels, 2000-fold lower than TSH b-subunit (GPBtsh). Furthermore, the levels of GPB5 remain constant during the estrus cycle, while those of GPA2 vary. Finally, we found that none of the thyrostimulin subunits was induced by TRH in pituitary cell culture. These data point at the thyrostimulin system as being functionally different to the TSH system.

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confidence: 97%

Differential expression of the thyrostimulin subunits, glycoprotein 2 and 5 in the rat pituitary

Nagasaki

Wang

Jackson

et al. 2006

Journal of Molecular Endocrinology

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“…Early reports indicate that thyroid-stimulating activity and immunoreactive TSH are found in the cephalic lobe of the anterior pituitary gland in birds (Brasch & Betz 1971, Radke & Chiasson 1974, 1977, Sharp et al 1979, Thommes et al 1983, Murphy & Harvey 2001. More recently, cells containing the -subunit but not the -subunits for LH and FSH were found in the cephalic lobe in sagittal histological sections (Berghman et al 1993).…”

Section: Distribution Of Thyrotrophs Within the Cephalic Lobementioning

confidence: 97%

“…Thommes et al (1983) reported that the thyrotrophs were first detectable on embryonic day (e) 6·5 and dramatically increased on e11·5, the time in embryonic development when the HPT axis is thought to become functionally mature in chickens (Thommes et al 1983). However, Murphy & Harvey (2001 found no immunoreactive TSH in the pituitary on e7, and Nakamura et al (2004) first detected TSH-containing cells on e10. The -subunit mRNA is expressed as early as e3·5 (Kameda et al 2000), while TSH mRNA levels are present from e9 and increase at the end of embryonic development (Gregory et al 1998, Nakamura et al 2004.…”

Section: Introductionmentioning

confidence: 94%

“…Thyrotrophs have been localized in the cephalic lobe of the anterior pituitary by ICC on histology sections and by assessment of biological activity in tissue extracts (Brasch & Betz 1971, Radke & Chiasson 1974, 1977, Sharp et al 1979, Thommes et al 1983, Berghman et al 1993, Murphy & Harvey 2001, Iwasawa et al 2002, Nakamura et al 2004. However, the three-dimensional distribution of thyrotrophs within the cephalic lobe of the anterior pituitary has not been determined.…”

Section: Figurementioning

confidence: 99%

“…In addition to TRH, corticotropin-releasing hormone (CRH) has been shown to induce TSH release in chickens, and somatostatin can diminish the CRH-and TRH-induced TSH response through the type 2 and type 5 somatostatin receptors (Geris et al 1996, 2003a,b, DeGroef et al 2003. Thyroid-stimulating activity has been localized to the cephalic lobe of the anterior pituitary (Brasch & Betz 1971, Radke & Chiasson 1974, 1977, and cells containing immunoreactive TSH have been localized to the cephalic lobe in histological sections stained with antisera against mammalian TSH (Sharp et al 1979, Thommes et al 1983, Mikami 1986, Murphy & Harvey 2001, Sasaki et al 2003 or with an antiserum raised against a peptide based on the chicken TSH sequence (Iwasawa et al 2002, Nakamura et al 2004. Similarly, pituitary cells that stained with monoclonal antibodies against the chicken -subunit and that did not also stain with anti-chicken luteinizing hormone (LH) and follicle-stimulating hormone (FSH) monoclonal antibodies were localized to the cephalic lobe (Berghman et al 1993).…”

Section: Introductionmentioning

confidence: 99%

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

Muchow¹,

Bossis²,

Porter³

2005

Journal of Endocrinology

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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 TSH peptide and mRNA levels by endogenous thyroid hormones prior to hatching. TSH -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 TSH peptide and by wholemount in situ hybridization for TSH 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 methimazole (MMI) decreased plasma thyroxine (T 4 ) levels and increased pituitary TSH mRNA levels on e19 and d1. However, control pituitaries contained significantly more TSH 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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Peptide hormones as developmental growth and differentiation factors

Sanders

Harvey

2008

Developmental Dynamics

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Peptide hormones, usually considered to be endocrine factors responsible for communication between tissues remotely located from each other, are increasingly being found to be synthesized in developing tissues, where they act locally. Several hormones are now known to be produced in developing tissues that are unrelated to the endocrine gland of origin in the adult. These hormones are synthesized locally, and are active as differentiation and survival factors, before the developing adult endocrine tissue becomes functional. There is increasing evidence for paracrine and/or autocrine actions for these factors during development, thus, placing them among the conventional growth and differentiation factors. We review the evidence for the view that thyroid hormones, growth hormone, prolactin, insulin, and parathyroid hormone-related protein are developmental growth and differentiation factors. Developmental Dynamics 237:1537-1552, 2008.

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Extrapituitary βTSH and GH in early chick embryos

Cited by 32 publications

References 52 publications

Differential expression of the thyrostimulin subunits, glycoprotein 2 and 5 in the rat pituitary

Differential expression of the thyrostimulin subunits, glycoprotein 2 and 5 in the rat pituitary

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

Peptide hormones as developmental growth and differentiation factors

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