Expression of the ?-subunit of glycoprotein hormones in the pars tuberalis-specific glandular cells in rat, mouse and guinea-pig

Me, Stoeckel; Hindelang, C.; Mj, Klein; Poissonnier, M; Jm, Felix

doi:10.1007/bf00331382

Cited by 22 publications

(21 citation statements)

References 28 publications

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“…Since PRL secretion by the PT is negligible , a strong hypothesis is that the PT produces unidentified molecules, so called 'tuberalins' (Stoeckel et al 1994, that modulate PRL release through mechanisms unknown.…”

Section: Structure and Function In The Ptmentioning

confidence: 99%

What is the role of melatonin within the anterior pituitary?

Hazlerigg

2001

Journal of Endocrinology

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The pineal hormone, melatonin, is uniquely defined by its role as hormonal time, but the processes whereby cells extract temporal information from the melatonin signal are not understood. Melatonin receptors are expressed in the pars tuberalis (PT) and, during fetal and perinatal life, in the pars distalis (PD). Functional studies suggest that the PT mediates the seasonal effects of melatonin on prolactin secretion, whilst the PD may be involved in photoperiodic programming of the developing gonadotrophic axis. To understand these effects at the cellular level we need to know the phenotype of melatonin-responsive cells. This review summarises current understanding in this area, and highlights present shortcomings. A case is presented for exploring the hypothesis that there is a functional association between melatonin receptor expression and cell differentiation in the anterior pituitary.

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Section: Structure and Function In The Ptmentioning

confidence: 99%

What is the role of melatonin within the anterior pituitary?

Hazlerigg

2001

Journal of Endocrinology

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“…However, the specific subunit of these hormones was missing from these cells (Böckers et al 1994, Wittkowski et al 1999. This has led to the suggestion that in the PT-specific cells the subunit is associated with subunit(s) which has not yet been identified (Stoeckel et al 1994, cf. Wittkowski et al 1999.…”

Section: Discussionmentioning

confidence: 99%

“…The evidence indicates that the PT-specific cells may synthesise one or more novel glycoprotein hormone(s), that have tentatively been called 'tuberalin(s)' (Stoeckel et al 1994, Morgan et al 1996, Wittkowski et al 1999. Isolation and identification of tuberalin (s) have not yet been reported.…”

Section: Discussionmentioning

confidence: 99%

“…There is also evidence that a PT factor regulates the secretory activity of a second non-lactotropic cell type of the PD (Morgan et al 1996). Although the PT-specific secretory product(s) has not been identified, the evidence supporting its existence is strong enough to have led Stoeckel et al (1994) and Morgan et al (1996) to designate this factor as 'tuberalin'. We shall follow this nomenclature.…”

Section: Introductionmentioning

confidence: 99%

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Identification, cellular and subcellular distribution of 21 and 72 kDa proteins (tuberalins?) secreted by specific cells of the pars tuberalis

Guerra

Rodríguez

2001

Journal of Endocrinology

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The cell types of the pars tuberalis (PT) are the follicular cells, the pars distalis cells and the so-called PT-specific cells. The latter are distinct endocrine cells displaying melatonin receptors. Although the nature of the secretory product(s) of the PT-specific cells has not yet been clarified, the function of these cells has started to be unfolded. For practical reasons, previous authors have designated the, as yet, unidentified PT hormone(s) as tuberalin(s). PT-specific cells synthesise the common subunit of the pars distalis glycoprotein hormones, and it has been suggested that tuberalin would correspond to the chain of a specific glycoprotein secreted by these cells. The aims of the present investigation were to identify the compounds secreted by the specific cells of bovine PT, and to establish their cellular and subcellular distribution. For this purpose, proteins secreted into the culture medium of PT explants were separated by electrophoresis and used to raise antibodies. Two of these proteins, with an apparent molecular mass of 21 and 72, generated antibodies (Ab-21 and Ab-72) that differentially immunoreacted with PT-specific cells. These two antibodies were used for immunoblotting of conditioned medium and of PT explants, and for light and electron microscopy immunocytochemistry. In immunoblots, Ab-21 reacted with compounds of 21, 22, 47 and 52 kDa, whereas Ab-72 revealed a compound of 72 kDa only. Ab-72 immunoreactive material corresponded to a protein, here designated as tuberalin I, secreted by a small population of PT-specific cells (type 2 cells), and stored in 140 nm secretory granules. Immunoreactive tuberalin I was missing from bovine pars distalis and from rat PT. The predominant population of PT-specific cells (type 3 cells) secreted and stored, within 280 nm secretory granules, an Ab-21 immunoreactive protein, here designated as tuberalin II. All cells of rat PT immunoreacted with Ab-21. In the cells of bovine and rat PT, immunoreactive tuberalin II was mostly confined to a paranuclear spot; this spot also bound wheat germ agglutinin and reacted with an antibody against the chain of glycoprotein pars distalis hormones.It is suggested that tuberalin II would correspond to the chain of a specific glycoprotein secreted by type 3 PT-specific cells. In bovine PT, the cells displaying immunoreactive tuberalins I and II did not react with any of the antibodies against pars distalis hormones.

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“…However, expression of further necessary genes does not follow (Lanctot et al, 1999). These cells do not react with a specific antibody against the ␤-subunit of LH (Böckers et al, 1996;Stoeckel et al, 1994). The folliculostellate cells of the PT differ from those described in the PD (Kameda, 1996a(Kameda, , 1996b.…”

mentioning

confidence: 89%

Ultrastructural and immunocytochemical studies of the viscacha (Lagostomus maximus maximus) pituitary pars tuberalis

et al. 2005

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The hypophyseal pars tuberalis (PT) has been the focus of numerous studies attempting to understand its physiological role in the reproductive regulation and modulation by the neuroendocrine system. Ultrastructural studies of the PT in a number of species have shown that it consists of a well-developed hypophyseal area with important secretory activity, demonstrated by the abundance of secretory granules in the cytoplasm and the marked blood irrigation. This article describes ultrastructural and immunocytochemical aspects of the PT in viscachas captured in their habitat. The cell types identified were PT-specific cells, agranulated cells, and Folliculostellate cells. PT-specific cells are divided into type I and II. Type I cells have cytoplasms with secretory granules of 150-500 nm diameter. The secretory granules of type II PT-specific cells are 65-200 nm in diameter. Both cellular types exhibit numerous nerve endings on the plasmatic membranes. Agranulated cells exhibit nuclei with lax chromatin, mitochondria, phagosomes, scarce Golgi complex, and rough endoplasmic reticulum. Folliculostellate cells exhibit an irregularly shaped and moderately condensed nucleus. All the described cellular types exhibit deposits of cytoplasmic glycogen. The immunocytochemical study revealed the presence of cells immunostained for LH-␤ and FSH-␤ in the PT caudal zone. ACTH was only detected in the zona tuberalis. No staining was observed with antiprolactin, anti-TSH-␤, and anti-GH sera. Folliculostellate cells exhibited staining with anti-S-100. The results demonstrate that the viscacha PT is a hypophyseal zone with specific cellular types, which exhibits evident secretory activity. The presence of nerve endings suggests neural control of the function of PT cells.

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Expression of the ?-subunit of glycoprotein hormones in the pars tuberalis-specific glandular cells in rat, mouse and guinea-pig

Cited by 22 publications

References 28 publications

What is the role of melatonin within the anterior pituitary?

What is the role of melatonin within the anterior pituitary?

Identification, cellular and subcellular distribution of 21 and 72 kDa proteins (tuberalins?) secreted by specific cells of the pars tuberalis

Ultrastructural and immunocytochemical studies of the viscacha (Lagostomus maximus maximus) pituitary pars tuberalis

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