A new clonal strain of rat pituitary tumour cells: a model for non-regulated secretion of prolactin

Abstract. A new clonal strain of Prl-secreting cells derived from the transplantable rat pituitary tumour. 7315a, has been established in culture. The cells of this strain, designed 235-1, have a highly developed Golgi complex, an extensive rough endoplasmic reticulum, and a few small but no large dense-core granules. When inoculated into athymic mice and rats of the Buffalo strain, the 235-1 cells produce tumours, and the host animals have hypertrophied mammary glands that produce milk, indicating that Prl secreted by these cells has mammotrophic activity. In monolayer culture, the doubling time of 235-1 cells is 31 ± 1 h (mean ± se). The cells secrete Prl, a trace quantity of GH, but no LH, FSH, TSH, ACTH, or α-MSH. Prl is released at a rate of 257 ± 12 fg per h per cell. The cellular content of Prl is 424 ± 23 fg per cell. Prl secretion by 235-1 cells is not affected by dopaminergic agonists and antagonists, TRH, or oestradiol-17β but is inhibited in the presence of EGTA or monensin, an ionophore that is believed to act at the level of the Golgi complex. The subcellular distribution of Prl in 235-1 cells is different from that in rat pituitary cells. In 235-1 cells, Prl is associated not with a single set of dense particles as it is in pituitary cells but with 2 sets of subcellular particles, of which co-et co-sedimented with particles having lysosomal enzyme activity. These findings suggest that Prl secretion by 235-1 cells involves secretory pathways that are different from those seen in normal lactotrophs.

Download Full-text

GROWTH IN MONOLAYER CULTURE OF RAT PITUITARY CELLS WHICH SYNTHETIZE AND RELEASE ACTH

Acta Endocrinologica ◽

10.1530/acta.0.0790421 ◽

1975 ◽

Vol 79 (3) ◽

pp. 421-430 ◽

Cited By ~ 2

Author(s):

R. E. Lang ◽

I. Hilwig ◽

K. H. Voigt ◽

H. L. Fehm ◽

E. F. Pfeiffer

Keyword(s):

Pituitary Gland ◽

Monolayer Culture ◽

Pituitary Cells ◽

Dependent Manner ◽

Antibody Technique ◽

Gland Cells ◽

Rat Pituitary ◽

Rat Pituitary Cells ◽

Dose Dependent ◽

Acth Release

ABSTRACT Cultures of rat pituitary gland cells were developed to study biosynthesis and release of ACTH. ACTH measurement was accomplished by radioimmunoassay. ACTH release was observed following stimulation with theophylline and cAMP in a dose-dependent manner. Biosynthesis was demonstrated by incorporation of 3H-phenylalanine into the hormone, employing a double antibody technique.

Download Full-text

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.

Download Full-text

Vitamin D-enhanced thyrotrophin release from rat pituitary cells: effects of Ca2+, dihydropyridines and ionomycin

Journal of Endocrinology ◽

10.1677/joe.0.1210441 ◽

1989 ◽

Vol 121 (3) ◽

pp. 441-450 ◽

Cited By ~ 6

Author(s):

M. C. d'Emden ◽

J. D. Wark

Keyword(s):

Vitamin D ◽

Pituitary Tumour ◽

Prolactin Secretion ◽

Pituitary Cells ◽

Dihydroxyvitamin D ◽

Normal Pituitary Gland ◽

Rat Pituitary ◽

Rat Pituitary Cells

ABSTRACT Vitamin D may regulate pituitary function, as there are selective effects of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) on gene expression in clonal pituitary tumour cells, and on TRH-induced TSH release in normal rat pituitary cells in vitro. The role of Ca2+ in 1,25-(OH)2D3-enhanced TSH release from primary rat pituitary cell cultures was investigated. Pretreatment with 10 nmol 1,25-(OH)2D3/l for 24 h augmented KCl (3–60 mmol/l)-induced TSH release over 1 h at all KCl concentrations greater than 7·5 mmol/l (P< 0·001), with a 76% enhancement of TSH release induced by 30 mmol KCl/l (P<0·001). The Ca2+ channel antagonist nifedipine (10 nmol/l–10 μmol/l) caused a concentration-dependent inhibition of KCl (60 mmol/l)-induced TSH secretion. Pretreatment with 1,25-(OH)2D3 enhanced KCl-induced release at all concentrations of nifedipine (P<0·001). The Ca2+ selective divalent cation ionophore ionomycin (1 nmol/l–1 μmol/l), and the Ca2+ channel agonist BAY K 8644 (10 nmol/l–1 μmol/l) increased prolactin secretion but did not increase TSH release, and 1,25-(OH)2D3 had no effect. At an extracellular Ca2+ concentration of less than 500 nmol/l, TRH-induced TSH release was observed only after treatment with 1,25-(OH)2D3 (P<0·01). As the extracellular Ca2+ concentration was increased, greater increments of TRH-induced TSH release were observed following pretreatment with 1,25-(OH)2D3 (P<0·01). However, the effect of 1,25-(OH)2D3 in the thyrotroph was independent of the pretreatment extracellular Ca2+ concentration. We have shown that 1,25-(OH)2D3 acts selectively on the thyrotroph to enhance in-vitro responsiveness to TRH and KCl. These data suggest that the action of 1,25-(OH)2D3 in the thyrotroph is to enhance intracellular signal transduction. They further support a permissive or regulatory role of vitamin D in the normal pituitary gland. Journal of Endocrinology (1989) 121, 441–450

Download Full-text

The Effect of Age on Somatostatin Suppression of Basal, Growth Hormone (GH)-Releasing Factor-Stimulated, and Dibutyryl Adenosine 3′,5′-Monophospate-Stimulated GH Release from Rat Pituitary Cells in Monolayer Culture*

Endocrinology ◽

10.1210/endo-119-1-152 ◽

1986 ◽

Vol 119 (1) ◽

pp. 152-158 ◽

Cited By ~ 19

Author(s):

LEONA CUTTLER ◽

JOHN B. WELSH ◽

MARTA SZABO

Keyword(s):

Growth Hormone ◽

Monolayer Culture ◽

Pituitary Cells ◽

Rat Pituitary ◽

Rat Pituitary Cells ◽

Effect Of Age

Download Full-text

CONTROL OF GROWTH HORMONE PRODUCTION BY A CLONAL STRAIN OF RAT PITUITARY CELLS

The Journal of Cell Biology ◽

10.1083/jcb.43.3.432 ◽

1969 ◽

Vol 43 (3) ◽

pp. 432-441 ◽

Cited By ~ 92

Author(s):

Frank C. Bancroft ◽

Lawrence Levine ◽

Armen H. Tashjian

Keyword(s):

Growth Hormone ◽

Doubling Time ◽

Population Doubling ◽

Cell Protein ◽

Pituitary Cells ◽

Hormone Production ◽

Clonal Strain ◽

Rat Pituitary ◽

Rat Pituitary Cells ◽

And Control

Addition of hydrocortisone to the medium of a clonal strain of rat pituitary cells (GH3) stimulated the rate of production of growth hormone. The stimulation had a lag period of about 24 hr, reached a maximum at 70–100 hr, and was observed at a hydrocortisone concentration as low as 5 x 10-8 M. Cells maximally stimulated with 3 x 10-6 M hydrocortisone produced 50–160 µg growth hormone/mg cell protein/24 hr. These rates were four to eight times those observed in control cells. At maximum stimulation, intracellular levels of growth hormone in both stimulated and control cells were equal to the amount secreted into the medium in about 15 min. Removal of hydrocortisone from the medium of GH3 cells caused a return of the rate of growth hormone production to that in control cells. Addition of hydrocortisone to the medium of cells growing exponentially with a population-doubling time of 60 hr caused both an increase in the doubling time to 90 hr and a stimulation of growth hormone production. Cycloheximide (3.6 x 10-5 M) and puromycin (3.7 x 10-4 M) suppressed incorporation of labeled amino acids into protein by 93 and 98%, respectively, and suppressed growth hormone production by stimulated and control cells by at least 94%.

Download Full-text

EFFECTS OF SEX STEROIDS ON GROWTH HORMONE PRODUCTION IN CULTURED RAT PITUITARY CELLS

Acta Endocrinologica ◽

10.1530/acta.0.0870040 ◽

1978 ◽

Vol 87 (1) ◽

pp. 40-54 ◽

Cited By ~ 15

Author(s):

E. Haug ◽

K. M. Gautvik

Keyword(s):

Growth Hormone ◽

Sex Steroids ◽

Pituitary Tumour ◽

Maximum Effect ◽

Pituitary Cells ◽

Hormone Production ◽

Thyrotrophin Releasing Hormone ◽

Rat Pituitary ◽

Rat Pituitary Cells ◽

Dose Dependent

ABSTRACT Monolayer cultures of rat pituitary tumour cells (GH3) were used to study the effects of different sex steroids on growth hormone (GH) production expressed as the amount of extracellular hormone which accumulated during 24 h. The hormone was measured with a sensitive and specific radioimmunoassay. Oestradiol-17β (10−12 mol/l—10−6 mol/l) caused a dose-dependent decrease in GH production with the maximum effect (30 % of controls) at 10−10 mol/l. After the cessation of treatment with oestradiol-17β (10−8 mol/l for 7 days), control levels of GH were obtained within 11 days, after a transient augmentation of production. Progesterone (10−11–10−6 mol/l) caused a dose-dependent stimulation of GH production, and the maximum effect (160 % of controls) was observed at 10−6 mol/l. Testosterone (10−6 mol/l) decreased the production of GH to 70 % of control values, whereas 5α-dihydrotestosterone (DHT) had no effect. Cell growth was not affected by any of the sex steroids. Corticosterone (10−6 mol/l) increased GH production to about 400 % of control values, and this effect was inhibited by oestradiol-17β (10−6 mol/l). The hypothalamic peptides, thyrotrophin releasing hormone (TRH) and somatostatin, that both depressed GH production did not significantly inhibit the stimulatory effect of corticosterone. When used in combination, the effects of oestradiol-17β (10−6 mol/l) and TRH (3 × 10−7 mol/l) were additive which was not the case for the combination oestradiol-17β (10−6 mol/l) and testosterone (10−6 mol/l). These results suggest different mechanisms of action of peptide and steroid hormones on GH production in the GH3 cells. If the properties of the GH3 cells reflect those of normal somatotrophs the sex steroids may alter GH production at the pituitary level, an influence that may be further modulated by corticoids, TRH and somatostatin.

Download Full-text