Interaction between insulin and thyroid hormone in rat pituitary tumour cells: insulin attenuates tri-iodothyronine-induced growth hormone mRNA levels

ABSTRACT Insulin has previously been shown to inhibit basal and stimulated rat GH (rGH) secretion as well as basal GH transcription in rat pituitary cells. The effect of physiological doses of insulin on tri-iodothyronine (T3)-stimulated GH mRNA levels in rat pituitary tumour cells was therefore examined. Insulin (7 nmol/l) suppressed T3-stimulated GH mRNA levels in GC and GH3 rat pituitary tumour cells by 58%. This inhibitory effect of insulin on T3-stimulated GH mRNA levels was already present after 24 h of treatment, and persisted for at least 48 h after insulin treatment was withdrawn. The effect of insulin on GH mRNA was selective, as rat prolactin mRNA was stimulated by insulin and T3 in the same cells. Treatment of cells with cycloheximide (10 μmol/l) did not alter the attenuation of GH mRNA levels by insulin, indicating that the insulin effect is independent of new protein synthesis. When de-novo mRNA synthesis was blocked with actinomycin D (4 μg/ml) for up to 7 h, an additional decrease in the relative amount of GH mRNA levels was observed after 24, 48 and 72 h of insulin treatment, indicating that an effect of insulin on GH mRNA stability is likely. The results show that physiological doses of insulin selectively attenuate the stimulatory effect of T3 on GH mRNA levels. This suppressive effect of insulin occurs independently of protein synthesis and is presumably mediated both at a transcriptional and post-transcriptional level. Journal of Endocrinology (1993) 137, 107–114

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Studies on the glucocorticoid-receptor blocking action of RU 38486 in cultured ACTH-secreting human pituitary tumour cells and normal rat pituitary cells

Acta Endocrinologica ◽

10.1530/acta.0.1090064 ◽

1985 ◽

Vol 109 (1) ◽

pp. 64-69 ◽

Cited By ~ 19

Author(s):

S. W. J. Lamberts ◽

E. G. Bons ◽

P. Uitterlinden

Keyword(s):

Pituitary Tumour ◽

Tumour Cells ◽

Pituitary Cells ◽

Human Pituitary ◽

Inhibiting Effect ◽

Rat Pituitary ◽

Normal Rat ◽

Rat Pituitary Cells ◽

Acth Secreting ◽

Acth Release

Abstract. The glucocorticoid-receptor blocking actions of RU 38486, a new compound with anti-progesterone activity, have been investigated in cultured human ACTH-secreting pituitary tumour cells and normal rat pituitary cells. Pre-incubation of human pituitary tumour cells for 24 h with RU 38486 (1 μm) did not influence basal or CRF-stimulated ACTH release. RU 38486 (100 nm–1 μm) significantly overcame or prevented the dexamethasone (100 nm–1 μm)-induced inhibition of CRF-stimulated ACTH release by the cultured tumour cells prepared from 2 patients with Cushing's disease. The tumour cells of a third patient were insensitive to CRF. Pre-incubation for 24 h with 1 μm RU 38486 facilitated CRF-stimulated ACTH release significantly. Studies with cultured normal rat pituitary cells showed that the inhibiting effect of 24 h pre-incubation with 10 and 50 nm dexamethasone on CRF-stimulated ACTH release could be acutely (measured over 4 h) overruled in a dose-dependent way by RU 38486 (100 nm, 1 and 10 μ), while pre-incubation for 24 h of these cells with RU 38486 (100 nm and 1 μm) significantly attenuated the acute inhibiting effect of 1 μm dexamethasone on CRF-stimulated ACTH-release. The results of these in vitro experiments are discussed against the background of the possible therapeutic use RU 38486 in patients with Cushing's syndrome in order to block the deleterious effects of high circulating cortisol concentrations.

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Signal transduction alterations in GH12C1 rat pituitary tumour cells following treatment with 5-azacytidine

Journal of Molecular Endocrinology ◽

10.1677/jme.0.0060257 ◽

1991 ◽

Vol 6 (3) ◽

pp. 257-268

Author(s):

V. C. Parrow ◽

J. O. Gordeladze ◽

E. J. Paulssen ◽

P. Aleström ◽

K. M. Gautvik

Keyword(s):

Drug Treatment ◽

Adenylyl Cyclase ◽

Cholera Toxin ◽

Pertussis Toxin ◽

Pituitary Tumour ◽

Tumour Cells ◽

Temporary Increase ◽

Pituitary Cells ◽

Intact Cells ◽

Rat Pituitary

ABSTRACT In GH12C1 rat pituitary cells treated with 5-azacytidine, the stimulatory effects exerted by vasoactive intestinal peptide (VIP), the GTP analogue guanyl-5′-yl imidodiphosphate (Gpp(NH)p), 12-O-tetradecanoyl phorbol 13-acetate, cholera toxin and pertussis toxin on the membrane-bound adenylyl cyclase were almost completely abolished. The corresponding inhibitory effect of somatostatin was increased. Alterations in adenylyl cyclase responsiveness began at the end of the drug treatment, and were most pronounced on day 5 after removal of 5-azacytidine. The cells subsequently and completely recovered after 10 days in the absence of the drug. Measurements of cholera toxin- and VIP-enhanced cyclic AMP levels in intact cells confirmed these results, and VIP appeared to have no stimulatory effect on GH secretion after 5-azacytidine treatment. Down-regulation of Gαs RNA also occurred on day 5 after cessation of drug treatment. ADP-ribosylation subsequent to stimulation with pertussis toxin was markedly increased, indicating an enhancement of Gαi and/or GGαo. Furthermore, both basal and Gpp(NH)p-stimulated phospholipase C activities were augmented by pre-exposure to 5-azacytidine. Treatment of GH12C1 rat pituitary tumour cells with 5-azacytidine therefore causes a marked but temporary increase in the ratio of Gαi/Gαs protein levels.

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THE PRESENCE OF BIOSYNTHETIC PRECURSORS AND HETEROGENEOUS MESSENGER RNAs FOR PROLACTIN IN CULTURED RAT PITUITARY TUMOUR CELLS

Acta Endocrinologica ◽

10.1530/acta.0.103s066 ◽

1983 ◽

Vol 104 (2_Supplb) ◽

pp. S66-S69

Author(s):

P. Aleström ◽

E.J. Paulssen ◽

V. Gautvik ◽

M. Kriz ◽

E. Haug ◽

...

Keyword(s):

Pituitary Tumour ◽

Tumour Cells ◽

Messenger Rnas ◽

Rat Pituitary

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Growth hormone decreases muscle glutamine production and stimulates protein synthesis in hypercatabolic patients

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.2000.279.2.e323 ◽

2000 ◽

Vol 279 (2) ◽

pp. E323-E332 ◽

Cited By ~ 34

Author(s):

Gianni Biolo ◽

Fulvio Iscra ◽

Alessandra Bosutti ◽

Gabriele Toigo ◽

Beniamino Ciocchi ◽

...

Keyword(s):

Growth Hormone ◽

Protein Synthesis ◽

Amino Acid ◽

De Novo ◽

Muscle Protein ◽

Recombinant Human Growth Hormone ◽

Glutamine Metabolism ◽

Trauma Patients ◽

Mrna Levels ◽

Glutamine Production

We determined the effects of 24-h recombinant human growth hormone (rhGH) infusion into a femoral artery on leg muscle protein kinetics, amino acid transport, and glutamine metabolism in eight adult hypercatabolic trauma patients. Metabolic pathways were assessed by leg arteriovenous catheterization and muscle biopsies with the use of stable amino acid isotopes. Muscle mRNA levels of selected enzymes were determined by competitive PCR. rhGH infusion significantly accelerated the inward transport rates of phenylalanine and leucine and protein synthesis, whereas the muscle protein degradation rate and cathepsin B and UbB polyubiquitin mRNA levels were not significantly modified by rhGH. rhGH infusion decreased the rate of glutamine de novo synthesis and glutamine precursor availability, total branched-chain amino acid catabolism, and nonprotein glutamate utilization. Thus net glutamine release from muscle into circulation significantly decreased after rhGH administration (∼50%), whereas glutamine synthetase mRNA levels increased after rhGH infusion, possibly to compensate for reduced glutamine precursor availability. We conclude that, after trauma, the anticatabolic action of rhGH is associated with a potentially harmful decrease in muscle glutamine production.

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Vitamin D-induction of secretory responses in rat pituitary tumour (GH4C1) cells

Journal of Endocrinology ◽

10.1677/joe.0.1170293 ◽

1988 ◽

Vol 117 (2) ◽

pp. 293-298 ◽

Cited By ~ 9

Author(s):

J. D. Wark ◽

V. Gurtler

Keyword(s):

Vitamin D ◽

Time Course ◽

Cell Model ◽

Hormone Secretion ◽

Pituitary Tumour ◽

Prolactin Secretion ◽

Tumour Cells ◽

Bay K 8644 ◽

Similar Time ◽

Rat Pituitary

ABSTRACT 1,25-Dihydroxyvitamin D3(1,25-(OH)2D3) selectively enhances prolactin gene expression in GH4C1 clonal rat pituitary tumour cells. Because this effect requires extracellular Ca2+, we studied the effect of 1,25-(OH)2D3 on another Ca2+-dependent process, agonist-induced hormone secretion. Pretreatment with 1,25-(OH)2D3 (1 nmol/l) caused at least 25-fold sensitization of GH4C1 cells to the voltage-sensitive Ca2+ channel agonist BAY K 8644 (methyl-1,4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluoromethylphenyl)-pyridine-5-carboxylate) as a prolactin secretagogue. This inductive effect of 1,25-(OH)2D3 followed a similar time-course to the enhancement of prolactin production. 1,25-(OH)2D3 had no effect on basal or BAY K 8644-induced 45Ca2+ uptake. The Ca2+-selective divalent cation ionophore 11,19,21-trihydroxy-4,6,8,12,14,18,20-heptamethyl-9-oxo-22-(tetrahydro-5 methyl-5-tetra hydro-5-(1-hydroxyethyl)-5-methyl-2-furanyl)-10,16-docosadienoic acid (ionomycin; 12 nmol/l–1·2 μmol/l) caused no significant increase in prolactin secretion in the absence of 1,25-(OH)2D3, but in cells treated with 1,25-(OH)2D3-(1 nmol/l), it increased prolactin secretion by 73% at 12 nmol/l and by a maximum of 98% at 0·12 μmol/l. These data demonstrate that vitamin D markedly enhances the responsiveness of GH4C1 functional pituitary tumour cells to two secretagogues which acts primarily through Ca2+-dependent mechanisms. They support the proposal that 1,25-(OH)2D3 acts in this cultured cell model either by effecting a redistribution of intracellular Ca2+ or by increasing the response of a Ca2+ -sensitive effector system, but not by enhancing agonist-induced Ca2+ uptake. J. Endocr. (1988) 117, 293–298

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Activation of protein kinase C inhibits calcium-activated potassium channels in rat pituitary tumour cells.

The Journal of Physiology ◽

10.1113/jphysiol.1996.sp021413 ◽

1996 ◽

Vol 493 (3) ◽

pp. 665-672 ◽

Cited By ~ 57

Author(s):

M J Shipston ◽

D L Armstrong

Keyword(s):

Protein Kinase C ◽

Protein Kinase ◽

Potassium Channels ◽

Pituitary Tumour ◽

Tumour Cells ◽

Kinase C ◽

Rat Pituitary ◽

Calcium Activated Potassium Channels

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Progesterone together with estradiol promotes luteinizing hormone β-subunit mRNA stability in rat pituitary cells cultured in vitro

Acta Endocrinologica ◽

10.1530/eje.0.1340236 ◽

1996 ◽

Vol 134 (2) ◽

pp. 236-242 ◽

Cited By ~ 11

Author(s):

Deokbae Park ◽

Minseok cheon ◽

Changmee Kim ◽

Kyungjin Kim ◽

Kyungza Ryu

Keyword(s):

Mrna Stability ◽

Actinomycin D ◽

Pituitary Cells ◽

Mrna Levels ◽

Ovarian Steroids ◽

Subunit Mrna ◽

Rat Pituitary ◽

Lh Release ◽

Rat Pituitary Cells

Park D, Cheon M, Kim C, Kim K, Ryu K. Progesterone together with estradiol promotes luteinizing hormoneβ-subunit mRNA stability in rat pituitary cells in vitro. Eur J Endocrinol 1996;134:236–42. ISSN 0804–4643 The present study examined the role of ovarian steroids, estradiol and/or progesterone in the regulation of luteinizing hormone β-subunit (LH-β) mRNA levels and LH release in the rat anterior pituitary cells cultured in vitro. When estradiol (10 nmol/l and/or progesterone (100 nmol/l) were added to the cultures, neither estradiol or progesterone nor both together altered the basal LH-β mRNA levels or LH release. Continuous exposure to gonadotropin-releasing hormone (GnRH, 0.2 nmol/l) for 24 h markedly induced LH-β mRNA accumulation, and in this experimental condition, progesterone alone and progesterone + estradiol further augmented GnRH-induced LH-β mRNA levels and LH release. Then we explored further the possibility that ovarian steroids are involved in modulating LH-β mRNA stability in cultured rat pituitary cells where transcription was inhibited by actinomycin D. Anterior pituitary cells were preincubated with GnRH (0.2 nmol/l) for 16 h and, after removing GnRH from culture medium, the cells were incubated further in the presence of actinomycin D (5 μmol/l) for 24 h. The LH-β mRNA levels gradually declined to about 30% of the control values (zero time point after GnRH removal) in a time-dependent manner. During this period, either progesterone alone or progesterone + estradiol clearly blocked the degradation of LH-β mRNA species. These results indicate that ovarian steroids promote LH-β mRNA stability, thereby contributing to the maintenance of GnRH-stimulated LH-β mRNA levels. Kyungza Ryu, Department of Pharmacology, College of Medicine, Yonsei University, 120-749, Seoul, Korea

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Human chorionic somatomammotropin and growth hormone gene expression in rat pituitary tumour cells is dependent on proximal promoter sequences

Nucleic Acids Research ◽

10.1093/nar/17.11.4327 ◽

1989 ◽

Vol 17 (11) ◽

pp. 4327-4337 ◽

Cited By ~ 25

Author(s):

Mark W. Nachtigal ◽

Barbara E. Nickel ◽

Margaret E. Klassen ◽

Wengang Zhang ◽

Norman L. Eberhardt ◽

...

Keyword(s):

Gene Expression ◽

Growth Hormone ◽

Pituitary Tumour ◽

Tumour Cells ◽

Proximal Promoter ◽

Growth Hormone Gene ◽

Promoter Sequences ◽

Rat Pituitary ◽

Chorionic Somatomammotropin

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Effects of glucocorticosteroids on prolactin and growth hormone production and characterization of the intracellular hormone receptors in rat pituitary tumour cells

Acta Endocrinologica ◽

10.1530/acta.0.0950319 ◽

1980 ◽

Vol 95 (3) ◽

pp. 319-327 ◽

Cited By ~ 16

Author(s):

Oddvar Naess ◽

Egil Haug ◽

Kaare Gautvik

Keyword(s):

Growth Hormone ◽

Hormone Receptors ◽

Pituitary Tumour ◽

Tumour Cells ◽

Scatchard Analysis ◽

Hormone Production ◽

Single Class ◽

High Affinity ◽

Rat Pituitary

Abstract. The effect of corticosterone and dexamethasone on the production of growth hormone and prolactin was studied in rat pituitary tumour cells (GH3-cells) in culture. Corticosterone and dexamethasone caused a dose-dependent stimulation of growth hormone synthesis, and the highest concentration (10−6 mol/l) increased growth hormone levels to 250% of controls. This concentration, however, decreased prolactin synthesis to 25% of the control values. The cytosol fractions from monolayer cultures as well as from tumours of GH3-cells were found to possess receptor molecules for glucocorticoid hormones, having a sedimentation constant close to 8 S in a salt-free buffer and 4 S in the presence of 0.5 mol/l KCL. Isoelectric point of the receptor was 5.8. Scatchard analysis showed one single class of binding sites with high affinity (Kd 2.1 ± 0.4 (sd × 10−9 mol/l). Studies on the steroid specificity revealed that dexamethasone had the highest affinity for the receptor. Corticosterone, cortisol and progesterone had also high affinity, whereas testosterone and oestradiol-17β had no significant affinity for the receptors. After in vivo administration of [3H]dexamethasone to GH3 tumour-bearing rats, radioactivity could be extracted from purified nuclei bound to 4 S macromolecules. The presence of receptors for glucocorticosteroid hormones in the GH3-cells, suggests that these hormones may alter growth hormone and prolactin production at the anterior pituitary level.

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