scholarly journals LOCALIZATION OF PHOSPHATASE ACTIVITIES IN THE RAT ANTERIOR PITUITARY GLAND

1972 ◽  
Vol 20 (1) ◽  
pp. 1-12 ◽  
Author(s):  
GEORGES PELLETIER ◽  
ALEX B. NOVIKOFF
Keyword(s):  
Golgi Apparatus ◽  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Secretory Cell ◽  
Cell Types ◽  
Anterior Pituitary Gland ◽  
Pituitary Cells ◽  
Blood Capillaries ◽  
Phosphatase Activities ◽  
Thiamine Pyrophosphatase

All five known secretory cell types of the rat anterior pituitary gland display nucleoside diphosphatase (NDPase) activity throughout the endoplasmic reticulum (ER), including the nuclear envelope but not the specialized region of ER at the inner aspect of the Golgi apparatus known as GERL. The functions of the ER diphosphatase are currently unknown. However, speculations concerning its association with glucuronyl transferase may focus on the metabolic roles of the ER in pituitary cells other than those directly related to secretory protein transport. The gonadotrophs have been studied for thiamine pyrophosphatase and acid phosphatase activities as well as NDPase activity. The results suggest that the secretory granules of gonadotrophs arise from GERL and not from the inner element of the Golgi apparatus. The innermost Golgi element of this cell type shows NDPase and thiamine pyrophosphatase activities and appears to be composed, in part at least, of anastomosing tubules. Nucleoside phosphatase activity is also present at the surfaces of all five secretory cell types and between the cells and adjacent blood capillaries.

scholarly journals In Vivo and In Vitro Arsenic Exposition Induces Oxidative Stress in Anterior Pituitary Gland

2016 ◽  
Vol 35 (4) ◽  
pp. 463-475 ◽  
Author(s):  
Sonia A. Ronchetti ◽  
María S. Bianchi ◽  
Beatriz H. Duvilanski ◽  
Jimena P. Cabilla
Keyword(s):  
Oxidative Stress ◽  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Inorganic Arsenic ◽  
Anterior Pituitary Gland ◽  
Pituitary Cells ◽  
Prolactin Release ◽  
Stress Responsive Genes

Inorganic arsenic (iAs) is at the top of toxic metalloids. Inorganic arsenic-contaminated water consumption is one of the greatest environmental health threats worldwide. Human iAs exposure has been associated with cancers of several organs, neurological disorders, and reproductive problems. Nevertheless, there are no reports describing how iAs affects the anterior pituitary gland. The aim of this study was to investigate the mechanisms involved in iAs-mediated anterior pituitary toxicity both in vivo and in vitro. We showed that iAs administration (from 5 to 100 ppm) to male rats through drinking water increased messenger RNA expression of several oxidative stress-responsive genes in the anterior pituitary gland. Serum prolactin levels diminished, whereas luteinizing hormone (LH) levels were only affected at the higher dose tested. In anterior pituitary cells in culture, 25 µmol/L iAs significantly decreased prolactin release in a time-dependent fashion, whereas LH levels remained unaltered. Cell viability was significantly reduced mainly by apoptosis evidenced by morphological and phosphatidylserine externalization studies. This process is characterized by early depolarization of mitochondrial membrane potential and increased levels of reactive oxygen species. Expression of some key oxidative stress-responsive genes, such as heme oxygenase-1 and metallothionein-1, was also stimulated by iAs exposure. The antioxidant N-acetyl cysteine prevented iAs-induced effects on the expression of oxidative stress markers, prolactin release, and apoptosis. In summary, the present work demonstrates for the first time that iAs reduces prolactin release both in vivo and in vitro and induces apoptosis in anterior pituitary cells, possibly resulting from imbalanced cellular redox status.

Three-dimensional architecture of Golgi apparatus in the hormone secretory cell

1991 ◽  
Vol 49 ◽  
pp. 252-253
Author(s):  
S. Tai ◽  
R.M. Albrecht
Keyword(s):  
Golgi Apparatus ◽  
Golgi Complex ◽  
Secretory Cell ◽  
Secretory Granules ◽  
Three Dimensional ◽  
Cell Types ◽  
Pituitary Cells ◽  
Golgi Stack ◽  
Secretory Products ◽  
Cell Fractions

The Golgi apparatus plays an important role in the process of packaging and sorting of secretory granules in endocrine and exocrine cells. The intra Golgi site for concentrating secretory materials, packaging, and sorting the secretory granules has been widely studied using cytochemical, immunocytochemical and biochemical methods on cells and cell fractions. It is generally accepted that the secretory products fo How the cis to trans pathway across the Golgi stack. Within the Golgi complex, secretory products appear to be concentrated in the dilated rims of the trans-most cisternae which are associated with the formation of secretory granules. In pituitary cells the organization of the Golgi apparatus is not as regular as that described for many other cell types. The cisternae of different Golgi stacks are irregular in size and shape. The cis-trans arrangement is not in a definitive orientation.

scholarly journals Intermedin/Adrenomedullin-2 Inhibits Growth Hormone Release from Cultured, Primary Anterior Pituitary Cells

Endocrinology ◽  
2006 ◽  
Vol 147 (2) ◽  
pp. 859-864 ◽  
Author(s):  
Meghan M. Taylor ◽  
Sara L. Bagley ◽  
Willis K. Samson
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Hormone Secretion ◽  
Prolactin Secretion ◽  
Anterior Pituitary Gland ◽  
Male Rats ◽  
Pituitary Cells ◽  
Anterior Pituitary Cells ◽  
Peptide Family

Intermedin (IMD), a novel member of the adrenomedullin (AM), calcitonin gene-related peptide (CGRP), amylin (AMY) peptide family, has been reported to act promiscuously at all the known receptors for these peptides. Like AM and CGRP, IMD acts in the circulation to decrease blood pressure and in the brain to inhibit food intake, effects that could be explained by activation of the known CGRP, AM, or AMY receptors. Because AM, CGRP, and AMY have been reported to affect hormone secretion from the anterior pituitary gland, we examined the effects of IMD on GH, ACTH, and prolactin secretion from dispersed anterior pituitary cells harvested from adult male rats. IMD, in log molar concentrations ranging from 1.0 pm to 100 nm, failed to significantly alter basal release of the three hormones. Similarly, IMD failed to significantly alter CRH-stimulated ACTH or TRH-stimulated prolactin secretion in vitro. However, IMD concentration-dependently inhibited GHRH-stimulated GH release from these cell cultures. The effects of IMD, although requiring higher concentrations, were as efficacious as those of somatostatin and, like somatostatin, may be mediated, at least in part, by decreasing cAMP accumulation. These actions of IMD were not shared by other members of the AM-CGRP-AMY family of peptides, suggesting the presence of a novel, unique IMD receptor in the anterior pituitary gland and a potential neuroendocrine action of IMD to interact with the hypothalamic mechanisms controlling growth and metabolism.

Functional ATP receptors in rat anterior pituitary cells

1997 ◽  
Vol 273 (6) ◽  
pp. C1963-C1971 ◽  
Author(s):  
Carlos Villalobos ◽  
Sara R. Alonso-Torre ◽  
Lucía Núñez ◽  
Javier García-Sancho
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Neural Tissue ◽  
Cell Types ◽  
P2x Receptors ◽  
Large Percentage ◽  
The Other ◽  
Pituitary Cells ◽  
Atp Receptors ◽  
Anterior Pituitary Cells

The effects of ATP and other nucleotides on the cytosolic Ca2+ concentration ([Ca2+]i) of single immunocytochemically typed anterior pituitary (AP) cells have been studied. ATP increased [Ca2+]iin a large percentage (60–88%) of all five AP cell types: lactotropes, somatotropes, corticotropes, gonadotropes, and thyrotropes. Additivity experiments suggest the presence of at least two different receptors, one accepting both ATP and UTP (U receptor), producing Ca2+ release from the intracellular stores, and the other preferring ATP (A receptor), producing Ca2+ (and Mn2+) entry. The characteristics of the U and A receptors were consistent with those of P2Y2 and P2X2, respectively, and their distribution in the different AP cell types was not homogeneous. The presence of other ATP receptors such P2Y1 or P2X2/P2X3heteropolymers in a small fraction of the cells cannot be excluded. Thus functional ionophoric P2X receptors, which are typical of neural tissue, are also present in the pituitary gland and could contribute to regulation of the gland’s function.

scholarly journals Glial-Derived Neurotropic Factor and RET Gene Expression in Normal Human Anterior Pituitary Cell Types and in Pituitary Tumors

2002 ◽  
Vol 87 (4) ◽  
pp. 1879-1884 ◽  
Author(s):  
Miguel A. Japón ◽  
Angel G. Urbano ◽  
Carmen Sáez ◽  
Dolores I. Segura ◽  
Alfonso Leal Cerro ◽  
...  
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Pituitary Tumors ◽  
Cell Types ◽  
Anterior Pituitary Gland ◽  
Tyrosine Kinase Receptor ◽  
Positive Immunostaining ◽  
Normal Human ◽  
Human Anterior Pituitary ◽  
Neurotropic Factor

Abstract Glial-derived neurotropic factor (GDNF) signaling is mediated through a 2-component system consisting of the so-called GDNF receptor-α (GFRα1), which binds to GDNF. This complex activates the tyrosine kinase receptor RET. In this paper we demonstrate GDNF, GFRα1, and RET mRNA and protein expression in the human anterior pituitary gland. Double immunohistochemistry of anterior pituitary sections showed GDNF immunoreactivity in more than 95% of somatotrophs and to a lesser extent in corticotrophs (20%); it was almost absent in the remaining cell types. Also, although more than 95% of somatotrophs were stained for RET, no positive immunostaining could be detected in other cell types. Furthermore, we have looked for GDNF and RET in human pituitary adenomas of various hormonal phenotypes. Strong positive immunostaining was found for c-RET in all of the GH-secreting adenomas screened as well as in 50% of ACTH-producing adenomas. Positive immunostaining for GDNF was found in all of the GH-secreting adenomas and in 10% of the corticotropinomas. Lastly, we found strong positive immunostaining for GFRα1 in 90% of the somatotropinomas and 50% of the corticotropinomas as well as in 1 of 8 prolactinomas and 1 of 13 nonfunctioning adenomas. All of the remaining pituitary tumors screened were negative for RET, GDNF, and GFRα1. This study indicates that GDNF may well be acting in the regulation of somatotroph cell growth and/or cell function in the normal human anterior pituitary gland. The expression of RET in all of the somatotropinomas and in 50% of the ACTH-producing tumors implies that GDNF and RET could be involved in the pathogenesis of pituitary tumors.

scholarly journals Ras-dva Is a Novel Pit-1- and Glucocorticoid-Regulated Gene in the Embryonic Anterior Pituitary Gland

Endocrinology ◽  
2013 ◽  
Vol 154 (1) ◽  
pp. 308-319 ◽  
Author(s):  
Laura E. Ellestad ◽  
Tom E. Porter
Keyword(s):  
Transcription Factor ◽  
Pituitary Gland ◽  
Binding Sites ◽  
Anterior Pituitary ◽  
Promoter Activity ◽  
Embryonic Stem ◽  
Anterior Pituitary Gland ◽  
Pituitary Cells ◽  
Mrna Levels ◽  
Flanking Region

Glucocorticoids play a role in functional differentiation of pituitary somatotrophs and lactotrophs during embryogenesis. Ras-dva was identified as a gene regulated by anterior neural fold protein-1/homeobox expressed in embryonic stem cells-1, a transcription factor known to be critical in pituitary development, and has an expression profile in the chicken embryonic pituitary gland that is consistent with in vivo regulation by glucocorticoids. The objective of this study was to characterize expression and regulation of ras-dva mRNA in the developing chicken anterior pituitary. Pituitary ras-dva mRNA levels increased during embryogenesis to a maximum on embryonic day (e) 18 and then decreased and remained low or undetectable after hatch. Ras-dva expression was highly enriched in the pituitary gland on e18 relative to other tissues examined. Glucocorticoid treatment of pituitary cells from mid- and late-stage embryos rapidly increased ras-dva mRNA, suggesting it may be a direct transcriptional target of glucocorticoids. A reporter construct driven by 4 kb of the chicken ras-dva 5′-flanking region, containing six putative pituitary-specific transcription factor-1 (Pit-1) binding sites and two potential glucocorticoid receptor (GR) binding sites, was highly activated in embryonic pituitary cells and up-regulated by corticosterone. Mutagenesis of the most proximal Pit-1 site decreased promoter activity in chicken e11 pituitary cells, indicating regulation of ras-dva by Pit-1. However, mutating putative GR binding sites did not substantially reduce induction of ras-dva promoter activity by corticosterone, suggesting additional DNA elements within the 5′-flanking region are responsible for glucocorticoid regulation. We have identified ras-dva as a glucocorticoid-regulated gene that is likely expressed in cells of the Pit-1 lineage within the developing anterior pituitary gland.

scholarly journals Living-cell imaging of transgenic rat anterior pituitary cells in primary culture reveals novel characteristics of folliculo-stellate cells

2009 ◽  
Vol 204 (2) ◽  
pp. 115-123 ◽  
Author(s):  
Kotaro Horiguchi ◽  
Motoshi Kikuchi ◽  
Kenji Kusumoto ◽  
Ken Fujiwara ◽  
Tom Kouki ◽  
...  
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Fluorescent Protein ◽  
Anterior Pituitary Gland ◽  
Pcr Analysis ◽  
Transgenic Rat ◽  
Pituitary Cells ◽  
Surface Receptors ◽  
Reverse Transcription Pcr ◽  
Anterior Pituitary Cells

Folliculo-stellate (FS) cells in the anterior pituitary gland appear to possess multifunctional properties. Recently, the development of transgenic rats (S100b–green fluorescent protein (GFP) rats) that express GFP specifically in FS cells in the anterior pituitary gland has allowed us to distinguish and observe living FS cells in other kinds of pituitary cells. We used S100b–GFP rats to investigate the topographic affinity of FS cells for other pituitary cells. We observed living FS cells in enzymatically dispersed anterior pituitary cells of S100b–GFP rats under a fluorescent microscope, and noted that FS cells markedly extended and contracted cytoplasmic processes and formed interconnections with neighboring FS cells. In addition, FS cells adhered to small clusters of GFP-negative cells, which were primarily hormone-producing cells, and these clusters further aggregated during the course of cytoplasmic contraction. In the presence of laminin, fibronectin, and varying types of collagen, FS cells showed marked changes in shape and specific proliferative activity; however, GFP-negative cells did not. On reverse transcription-PCR analysis and immunohistochemistry, FS cells were shown to express integrin subunits, which are the cell surface receptors for extracellular matrix (ECM). In the anterior pituitary gland, FS cells and the various types of hormone-producing cells generate a unique topography in the presence of basement membrane components and interstitial collagens. The novel characteristics of FS cells observed in the present study suggest that in the anterior pituitary gland, FS cells play important roles in determining and/or maintaining local cellular arrangement in the presence of ECM components.

scholarly journals The Thyrotrope-Restricted Isoform of the Retinoid-X Receptor-γ1 Mediates 9-cis-Retinoic Acid Suppression of Thyrotropin-β Promoter Activity

1997 ◽  
Vol 11 (4) ◽  
pp. 481-489 ◽  
Author(s):  
Bryan R. Haugen ◽  
Nicole S. Brown ◽  
William M. Wood ◽  
David F. Gordon ◽  
E. Chester Ridgway
Keyword(s):  
Gene Expression ◽  
Retinoic Acid ◽  
Pituitary Gland ◽  
Nuclear Receptors ◽  
Anterior Pituitary ◽  
Promoter Activity ◽  
Hormone Receptors ◽  
Cell Types ◽  
Anterior Pituitary Gland ◽  
Gh3 Cells

Abstract TSHβ is a subunit of TSH that is uniquely expressed and regulated in the thyrotrope cells of the anterior pituitary gland. Thyroid hormone receptors (TR) are known to mediate T3 suppression of TSHβ gene expression at the level of promoter activity. The role of other nuclear receptors in regulation of this gene is less clearly defined. Retinoid X receptors (RXR) are a family of nuclear transcription factors that function both as 9-cis-retinoic acid (RA) ligand-dependent receptors and heterodimeric partners with TR and other nuclear receptors. Recently, the RXR isoform, RXRγ, has been identified in the anterior pituitary gland and found to be restricted to thyrotrope cells within the pitutiary. In this report, we have further characterized the distribution of RXRγ1, the thyrotrope-restricted isoform of RXRγ, in murine tissues and different cell types. We have found that RXRγ1 mRNA and protein are expressed in the TtT-97 thyrotropic tumor, but not the thyrotrope-variant αTSH cells or somatotrope-derived GH3 cells. Furthermore, we have studied the effects of RXRγ1 on TSHβ promoter activity and hormone regulation in these pituitary-derived cell types. Both T3 and 9-cis-RA independently suppressed promoter activity in the TtT-97 thyrotropes. Interestingly, the combination of ligands suppressed promoter activity more than either alone, indicating that these hormones may act cooperatively to regulate TSHβ gene expression in thyrotropes. The RXRγ1 isoform was necessary for the 9-cis-RA-mediated suppression of TSHβ promoter activity in αTSH and GH3 cells, both of which lack this isoform. RXRβ, a more widely distributed isoform, did not mediate these effects. Finally, we showed that the murine TSHβ promoter region between −200 and −149 mediated a majority of the 9-cis-RA suppression of promoter activity in thyrotropes. This region is distinct from the T3-mediated response region near the transcription start site. These data suggest that retinoids can mediate TSHβ gene regulation in thyrotropes and the thyrotrope-restricted isoform, RXRγ1, is required for this effect.

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