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.

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.

Factors affecting ACTH release from perifused equine anterior pituitary cells

1993 ◽  
Vol 137 (3) ◽  
pp. 391-401 ◽  
Author(s):  
M. J. Evans ◽  
A. G. Marshall ◽  
N. E. Kitson ◽  
K. Summers ◽  
R. A. Donald
Keyword(s):  
Dose Response ◽  
Anterior Pituitary ◽  
Response Curve ◽  
Effective Concentration ◽  
Dose Response Curve ◽  
Pituitary Cells ◽  
Acth Secretion ◽  
Minimum Effective Concentration ◽  
Perifusion System

ABSTRACT The multifactorial control of ACTH is well established. We wished to establish and characterize an in-vitro perifusion system, using equine anterior pituitary cells and physiological concentrations of secretagogues, to investigate factors which affect the dynamics of ACTH secretion. Anterior pituitary tissue was divided for dispersion into cells with collagenase, trypsin or dispase, or by mechanical dispersion. After dispersal followed by 18-h incubation, cells were perifused and the ACTH response to 10-min pulses of arginine vasopressin (AVP; 100 nmol/l), corticotrophin-releasing hormone (CRH; 0·01 nmol/l), and AVP (100 nmol/l) plus CRH (0·01 nmol/l) determined. ACTH responses to these secretagogues were lower (P <0·05) in cells prepared using the enzymes dispase and trypsin than with the enzyme collagenase. Cells prepared by mechanical methods were not responsive. Collagenase-prepared cells were used in subsequent experiments. In dose-response studies (10-min pulse length), a steep CRH–ACTH dose-response curve was obtained with the minimum effective concentration of CRH between 0·001 and 0·01 nmol/l, and a maximum effective concentration of 1·0 nmol/l. A less steep AVP–ACTH dose-response curve was obtained with a minimum effective concentration of AVP between 0·5 and 5 nmol/l, and no plateau in response up to 5000 nmol AVP/l. Increasing the incubation time between cell preparation and stimulation with AVP from 18 h to 90 h significantly (P <0·01) increased the ACTH response. Repeated stimulation by AVP (100 nmol/l) or CRH (0·01 nmol/l) (5-min pulses every 30 min for 23 pulses) produced ACTH responses which decreased in an approximately exponential curve with time. When AVP and CRH were given at physiological concentrations, pulse lengths and pulse frequency, the ACTH response to repeated 1-min pulses of AVP, measured as height above basal secretion, was potentiated by the addition of CRH (1, 2·5, 5, 10 and 20 pmol/l) as a constant perifusion at all AVP concentrations tested (1 nmol AVP/l, P < 0·02; 10 nmol AVP/l, P <0·0005; 25 nmol AVP/l, P <0·0005). During the 1-min AVP pulse, the AVP concentration at the level of the cells was 30% of the expected concentration. Potentiation was increased both by increasing AVP concentration (P <0·00005) and by increasing CRH concentration (P <0·00005) up to 5 pmol CRH/l. The ACTH height response to repeated AVP stimulation significantly (P = 0·0034) decreased with time, independent of CRH and AVP concentration. There was a significant (P = 0·014) decrease in ACTH response to CRH infusion with time, independent of CRH concentration. We conclude that the responsiveness of pituitary cells is markedly influenced by the preparative techniques. The collagenase-dispersed cells, in the in-vitro perifusion system developed, responded to secretagogues which were given at physiological concentrations, pulse lengths and periods. The system thus fulfills our requirements of in-vitro responses reflecting those observed in vivo, and can therefore be used to investigate the multifactorial control of ACTH secretion further. Journal of Endocrinology (1993) 137, 391–401

scholarly journals Assessment of the labeling index of cohorts of the anterior pituitary cell population in phenobarbital-treated male rats by a double immunohistochemical technique for bromodeoxyuridine and pituitary hormones.

1994 ◽  
Vol 42 (4) ◽  
pp. 543-549 ◽  
Author(s):  
H B Jones ◽  
S J Harbottle ◽  
A L Bowdler
Keyword(s):  
Alkaline Phosphatase ◽  
Cell Population ◽  
Anterior Pituitary ◽  
Pituitary Hormones ◽  
Pituitary Cell ◽  
Functional Adaptation ◽  
Male Rats ◽  
Brdu Incorporation ◽  
Anterior Pituitary Cell ◽  
Significant Difference

A previous study demonstrated that administration of phenobarbital for up to 7 days to male AP Wistar rats caused alterations in labeling indices (LIs) of several different tissues as determined by immunohistochemical visualization of bromodeoxyuridine (BrdU) incorporation into S-phase nuclei. The pivotal role of the pituitary gland in the function of the endocrine system and changes in circulating hormone levels that result from administration of xenobiotics prompted our consideration of the possible changes in LIs of individual cohorts of the anterior pituitary cell population that may occur as a specific functional adaptation during phenobarbital administration. We evaluated the LIs of individual anterior pituitary cell cohorts by modifying a double immunohistochemical staining method for bromodeoxyuridine and pituitary hormones using a sequential peroxidase-anti-peroxidase (PAP)/alkaline phosphatase-anti-alkaline phosphatase (APAAP) method employing diaminobenzidine and New Fuchsin chromogens, respectively. The method was robust and reproducible. Differences were noted in individual anterior pituitary cohort LIs between control and phenobarbital-treated groups, although no statistically significant difference was evident. We conclude that no detectable effects on individual cohort LIs were induced by treatment with phenobarbital for up to 7 days and that any functional adaptation to treatment was associated with increased hormone release. We believe that the visualization, identification, and quantitation of replicating cells in specific hormone-positive cohorts of the anterior pituitary cell population provide opportunities for understanding the influence of xenobiotics and disease processes on pituitary function.

Ketoconazole inhibits cAMP generation and ACTH secretion in rat anterior pituitary cell culture

1987 ◽  
Vol 116 (3_Suppl) ◽  
pp. S32-S33 ◽  
Author(s):  
G. K. STALLA ◽  
J. STALLA ◽  
M. HUBER ◽  
O. A. MÜLLER
Keyword(s):  
Cell Culture ◽  
Anterior Pituitary ◽  
Pituitary Cell ◽  
Acth Secretion ◽  
Anterior Pituitary Cell ◽  
Camp Generation

scholarly journals Quantification of in Vivo 3H-Estrogen Uptake by Individual Anterior Pituitary Cell Types of Male Rat:

1981 ◽  
Vol 29 (1A_suppl) ◽  
pp. 167-174 ◽  
Author(s):  
Donald A. Keefer
Keyword(s):  
Anterior Pituitary ◽  
Cell Types ◽  
Pituitary Cell ◽  
Male Rats ◽  
Male Rat ◽  
Pituitary Cells ◽  
Cell Tissue ◽  
Reliable Quantification ◽  
Refined Version

A refined version of the combined dry-mount auto-radiographic-immunocytochemical technique (Keefer DA, Stumpf WE, Petrusz P: Cell Tissue Res 166:25, 1976) is described in detail. In vivo nuclear estrogen uptake is measured by silver grain counting in immunocytochemically stained gonadotropes (G), somatotropes (S), lactotropes (L), corticotropes (C), and thyrotropes (T) of male rats. In rats 1 day after orchidectomy and adrenalectomy, the order of nuclear estrogen uptake was S = L G = C T, with T concentrating less than half as much radioactivity as L or S. Fifteen percent of anterior pituitary cells neither concentrated estrogen nor stained immunocytochemically. Estrogen uptake was examined in gonadotropes 1, 14, and 50 days after orchidectomy and was found to be identical at all three times. Estrogen uptake in gonadotropes of rats 14 days following orchidectomy and treatment with progesterone was reduced significantly. Guidelines for reliable quantification of the autoradiographic data is discussed.

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 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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