17β-Estradiol modulates the prolactin secretion induced by TRH through membrane estrogen receptors via PI3K/Akt in female rat anterior pituitary cell culture

2012 ◽  
Vol 302 (10) ◽  
pp. E1189-E1197 ◽  
Author(s):  
Liliana d. V. Sosa ◽  
Silvina Gutiérrez ◽  
Juan P. Petiti ◽  
Claudia M. Palmeri ◽  
Iván D. Mascanfroni ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Anterior Pituitary ◽  
Pituitary Cell ◽  
Female Rats ◽  
Akt Pathway ◽  
Pituitary Cells ◽  
Female Rat ◽  
Anterior Pituitary Cell ◽  
Pathway Activation ◽  
17Β Estradiol

Considering that estradiol is a major modulator of prolactin (PRL) secretion, the aim of the present study was to analyze the role of membrane estradiol receptor-α (mERα) in the regulatory effect of this hormone on the PRL secretion induced by thyrotropin-releasing hormone (TRH) by focusing on the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway activation. Anterior pituitary cell cultures from female rats were treated with 17β-estradiol (E2, 10 nM) and its membrane-impermeable conjugated estradiol (E2-BSA, 10 nM) alone or coincubated with TRH (10 nM) for 30 min, with PRL levels being determined by RIA. Although E2, E2-BSA, TRH, and E2/TRH differentially increased the PRL secretion, the highest levels were achieved with E2-BSA/TRH. ICI-182,780 did not modify the TRH-induced PRL release but significantly inhibited the PRL secretion promoted by E2 or E2-BSA alone or in coincubation with TRH. The PI3K inhibitors LY-294002 and wortmannin partially inhibited the PRL release induced by E2-BSA, TRH, and E2/TRH and totally inhibited the PRL levels stimulated by E2-BSA/TRH, suggesting that the mER mediated the cooperative effect of E2 on TRH-induced PRL release through the PI3K pathway. Also, the involvement of this kinase was supported by the translocation of its regulatory subunit p85α from the cytoplasm to the plasma membrane in the lactotroph cells treated with E2-BSA and TRH alone or in coincubation. A significant increase of phosphorylated Akt was induced by E2-BSA/TRH. Finally, the changes of ERα expression in the plasmalemma of pituitary cells were examined by confocal microscopy and flow cytometry, which revealed that the mobilization of intracellular ERα to the plasma membrane of lactotroph cells was only induced by E2. These finding showed that E2 may act as a modulator of the secretory response of lactotrophs induced by TRH through mER, with the contribution by PI3K/Akt pathway activation providing a new insight into the mechanisms underlying the nongenomic action of E2 in the pituitary.

scholarly journals Leptin and Leptin Receptor Expression in Normal and Neoplastic Human Pituitary: Evidence of a Regulatory Role for Leptin on Pituitary Cell Proliferation1

1999 ◽  
Vol 84 (8) ◽  
pp. 2903-2911 ◽  
Author(s):  
Long Jin ◽  
Bartolome G. Burguera ◽  
Marta E. Couce ◽  
Bernd W. Scheithauer ◽  
Jesse Lamsan ◽  
...  
Keyword(s):  
Anterior Pituitary ◽  
Leptin Receptor ◽  
Pituitary Cell ◽  
Receptor Expression ◽  
Receptor Protein ◽  
Pituitary Cells ◽  
Double Labeling ◽  
Messenger Ribonucleic Acid ◽  
Anterior Pituitary Cell ◽  
Anterior Pituitary Cells

Leptin is a circulating hormone secreted by adipose and a few other tissues. The leptin receptor consists of a single transmembrane-spanning polypeptide that is present as a long physiologically important form as well as in several short isoforms. Recent studies have suggested that the anterior pituitary may have a role in the regulatory effects of leptin in animal models. To test this possibility in human pituitaries, we examined the expression of leptin and OB-R in normal and neoplastic pituitaries, and the possible functions of leptin in the pituitary were also analyzed. Leptin was present in 20–25% of anterior pituitary cells and was expressed in most normal anterior pituitary cells, including ACTH (70% of ACTH cells), GH (21%), FSH (33%), LH (29%), TSH (32%), and folliculo-stellate cells (64%), but was colocalized with very few PRL cells (3%), as detected by double labeling immunohistochemistry with two different antileptin antibodies. In addition, leptin expression was detected by RT-PCR in some pituitary tumors, including ACTH (three of four), GH (one of four), null cells (two of four), and gonadotroph (one of four) tumors as well as in normal pituitary. Immunohistochemical staining showed greater immunoreactivity for leptin in normal pituitaries compared to adenomas. Treatment of an immortalized cultured anterior pituitary cell line, HP75, with leptin stimulated pancreastatin secretion in vitro. Leptin also inhibited cell growth in the human HP75 and in the rat pituitary GH3 cell lines. Both long (OB-Rb) and common (OB-Ra) forms of the leptin receptor messenger ribonucleic acid and leptin receptor protein were expressed in normal and neoplastic anterior pituitary cells. These findings show for the first time that leptin is expressed by most human anterior pituitary cell types and that there is decreased leptin protein immunoreactivity in pituitary adenomas compared to that in normal pituitary tissues. We also show that OB-Rb is widely expressed by normal and neoplastic anterior pituitary cells, implicating an autocrine/paracrine loop in the production and regulation of leptin in the pituitary.

Purification of functional lactotrophs and somatotrophs from female rats using fluorescence-activated cell sorting

1990 ◽  
Vol 126 (2) ◽  
pp. 269-274 ◽  
Author(s):  
D. Wynick ◽  
R. Critchley ◽  
M. S. Venetikou ◽  
J. M. Burrin ◽  
S. R. Bloom
Keyword(s):  
Cell Surface ◽  
Cell Sorting ◽  
Anterior Pituitary ◽  
Cell Types ◽  
Female Rats ◽  
Normal Female ◽  
Pituitary Cells ◽  
Female Rat ◽  
Fluorescence Activated Cell Sorting ◽  
Surface Labelling

ABSTRACT As the secretory granules of anterior pituitary cells fuse with the cell surface, there would appear to be sufficient hormone present on the cell surface to be labelled by polyclonal hormone antibodies and thus analysed by flow cytometry. We have therefore applied fluorescence-activated cell sorting to these labelled pituitary cells. Percentage purity and depletion of other cell types was assessed by immunocytochemistry and the reverse haemolytic plaque assay (RHPA). Results demonstrate that fluorescence-activated cell sorting allows almost complete purification of functional lactotrophs and somatotrophs to 96·7 ±1·7 (s.e.m.)% and 98±1·0% respectively by immunocytochemistry, and to 95·8 ±1·1% and 97±0·8% respectively by RHPA. Depletion of other anterior pituitary cell types to less than 2% was demonstrated by both immunocytochemistry and RHPA. Fluorescence-activated cell sorting to this degree of purity was routinely possible with cell yields of 91 ±3·4%. To obtain such purity/depletion, it was necessary to use specific antisera of high titre, at concentrations which ensured maximal cell-surface labelling associated with maximal stimulation of hormonal secretion by the appropriate hypothalamic stimulatory factor. Separating cells on the basis of the intensity of prolactin cell-surface labelling demonstrated a low level of binding of the prolactin antibody to gonadotrophs (but not of sufficient fluorescence intensity to be sorted into the prolactin enriched population), raising the possibility of prolactin receptors on gonadotrophs. We were unable to demonstrate the presence of mammosomatotrophs in the normal female rat, since purified lactotrophs did not contain or secrete GH nor did purified somatotrophs contain or secrete prolactin. Journal of Endocrinology (1990) 126, 269–274

scholarly journals The Pulsatility of ACTH Secretion in the Rat Anterior Pituitary Cell Perifusion System

2017 ◽  
Vol 41 (1) ◽  
pp. 154-162
Author(s):  
Qiong Deng ◽  
Zeng Zhang ◽  
Yong Wu
Keyword(s):  
Anterior Pituitary ◽  
Physiological Mechanism ◽  
Fold Increase ◽  
Pituitary Cell ◽  
Male Rats ◽  
Pituitary Cells ◽  
Acth Secretion ◽  
Physiological Concentration ◽  
Anterior Pituitary Cell ◽  
Perifusion System

Aims: This study aimed to examine the physiological mechanism whereby the corticotropin-releasing hormone (CRH) and arginine vasopressin (AVP) exert their influence on adrenocorticotropic hormone (ACTH) secretion in pituitary cells. Methods: Anterior pituitary cells were harvested from male rats and placed in the perifusion system. Cells were perifused with serum-free medium for 6 hours before fraction collection. After 30-minute of baseline collection, perifusion media was changed to expose the cells to CRH with or without AVP. ACTH concentration in each fraction was measured using enzyme immunoassay chemiluminescent kit. Results: The lowest physiological concentration of CRH (10 pM) or AVP (10 pM) was not able to induce a marked increase in ACTH secretion. Higher concentration of CRH (30 pM) or AVP (100 pM) in the physiological range caused sustained elevation of ACTH secretion (P < 0.001), while the secretion remained at similar levels for up to 1 hour with continuous stimulation. Perifusion with 10 pM AVP and 10 pM or 30 pM CRH caused a 2.38-fold and 2.99-fold increase in pulsatile ACTH secretion in pituitary cells, respectively. The duration of pulsatility caused by perifusion with 10 pM AVP and 30 pM CRH was close to that observed under physiological condition. Conclusions: By using the rat anterior pituitary cell perifusion system, we found that CRH and AVP potentiate the effect of each other on ACTH secretion, but AVP was a less potent agonist than CRH. The data suggest that CRH and AVP are essential for the pulsatility of ACTH, and AVP acts like a switch of the pulsatility.

17β-Estradiol stimulates the translocation of endogenous estrogen receptor α at the plasma membrane of normal anterior pituitary cells

2012 ◽  
Vol 355 (1) ◽  
pp. 169-179 ◽  
Author(s):  
Silvina Gutiérrez ◽  
Liliana d V. Sosa ◽  
Juan P. Petiti ◽  
Jorge H. Mukdsi ◽  
Iván D. Mascanfroni ◽  
...  
Keyword(s):  
Estrogen Receptor ◽  
Plasma Membrane ◽  
Anterior Pituitary ◽  
Estrogen Receptor Α ◽  
Pituitary Cells ◽  
Anterior Pituitary Cells ◽  
Endogenous Estrogen ◽  
17Β Estradiol

JAK2/STAT5 Pathway Mediates Prolactin-Induced Apoptosis of Lactotropes

2018 ◽  
Vol 108 (2) ◽  
pp. 84-97 ◽  
Author(s):  
Nataly de Dios ◽  
Santiago Orrillo ◽  
Martín Irizarri ◽  
María Susana Theas ◽  
Florence Boutillon ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Signaling Pathways ◽  
Anterior Pituitary ◽  
Pituitary Cell ◽  
Gh3 Cells ◽  
Akt Pathway ◽  
Cell Turnover ◽  
Akt Phosphorylation ◽  
Anterior Pituitary Cell ◽  
Induced Apoptosis

Prolactinomas are increasingly viewed as a “problem of signal transduction.” Consequently, the identification of factors and signaling pathways that control lactotrope cell turnover is needed in order to encourage new therapeutic developments. We have previously shown that prolactin (PRL) acts as a proapoptotic and antiproliferative factor on lactotropes, maintaining anterior pituitary cell homeostasis, which contrasts with the classical antiapoptotic and/or proliferative actions exerted by PRL in most other target tissues. We aimed to investigate the PRLR-triggered signaling pathways mediating these nonclassical effects of PRL in the pituitary. Our results suggest that (i) the PRLR/Jak2/STAT5 pathway is constitutively active in GH3 cells and contributes to PRL-induced apoptosis by increasing the Bax/Bcl-2 ratio, (ii) PRL inhibits ERK1/2 and Akt phosphorylation, thereby contributing to its proapoptotic effect, and (iii) the PI3K/Akt pathway participates in the PRL-mediated control of lactotrope proliferation. We hypothesize that the alteration of PRL actions in lactotrope homeostasis due to the dysregulation of any of the mechanisms of actions described above may contribute to the pathogenesis of prolactinomas.

scholarly journals Binding of 2-hydroxyestradiol to rat anterior pituitary cell membranes.

1980 ◽  
Vol 255 (20) ◽  
pp. 9838-9843
Author(s):  
J.M. Schaeffer ◽  
S. Stevens ◽  
R.G. Smith ◽  
A.J. Hsueh
Keyword(s):  
Anterior Pituitary ◽  
Cell Membranes ◽  
Pituitary Cell ◽  
Anterior Pituitary Cell

Control of secretion in anterior pituitary cells--linking ion channels, messengers and exocytosis

1988 ◽  
Vol 139 (1) ◽  
pp. 287-316
Author(s):  
W. T. Mason ◽  
S. R. Rawlings ◽  
P. Cobbett ◽  
S. K. Sikdar ◽  
R. Zorec ◽  
...  
Keyword(s):  
Ion Channels ◽  
Intracellular Calcium ◽  
Anterior Pituitary ◽  
Hormone Secretion ◽  
Cell Types ◽  
Pituitary Cell ◽  
Pituitary Cells ◽  
Calcium Activity ◽  
Anterior Pituitary Cells ◽  
Voltage Dependent

Normal anterior pituitary cells, in their diversity and heterogeneity, provide a rich source of models for secretory function. However, until recently they have largely been neglected in favour of neoplastic, clonal tumour cell lines of pituitary origin, which have enabled a number of studies on supposedly homogeneous cell types. Because many of these lines appear to lack key peptide and neurotransmitter receptors, as well as being degranulated with accompanying abnormal levels of secretion, we have developed a range of normal primary anterior pituitary cell cultures using dispersion and enrichment techniques. By studying lactotrophs, somatotrophs and gonadotrophs we have revealed a number of possible transduction mechanisms by which receptors for hypothalamic peptides and neurotransmitters may control secretion. In particular, the transduction events controlling secretion from pituitary cells may differ fundamentally from those found in other cell types. Patch-clamp recordings in these various pituitary cell preparations have revealed substantial populations of voltage-dependent Na+, Ca2+ and K+ channels which may support action potentials in these cells. Although activation of these channels may gate Ca2+ entry to the cells under some conditions, our evidence taken with that of other laboratories suggests that peptide-receptor interactions leading to hormone secretion occur independently of significant membrane depolarization. Rather, secretion of hormone and rises in intracellular calcium measured with new probes for intracellular calcium activity, can occur in response to hypothalamic peptide activation in the absence of substantial changes in membrane potential. These changes in intracellular calcium activity almost certainly depend on both intracellular and extracellular calcium sources. In addition, strong evidence of a role for multiple intracellular receptors and modulators in the secretory event suggests we should consider the plasma membrane channels important for regulation of hormone secretion to be predominantly agonist-activated, rather than of the more conventional voltage-dependent type. Likewise, evidence from new methods for recording single ion channels suggests the existence of intracellular sites for channel modulation, implying they too may play an important role in secretory regulation. We shall consider new data and new technology which we hope will provide key answers to the many intriguing questions surrounding the control of pituitary hormone secretion. We shall highlight our work with recordings of single ion channels activated by peptides, and recent experiments using imaging of intracellular ionized free calcium.(ABSTRACT TRUNCATED AT 250 WORDS)

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