Effects of domperidone on the secretion of prolactin from rat anterior pituitary glands

1982 ◽  
Vol 94 (3) ◽  
pp. 317-326 ◽  
Author(s):  
A. M. Bentley ◽  
M. Wallis
Keyword(s):  
Anterior Pituitary ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Prolactin Secretion ◽  
Female Rats ◽  
Constant Rate ◽  
Pituitary Glands ◽  
Prolactin Content ◽  
Tissue Incorporation ◽  
Perifusion System

The effects of domperidone on prolactin secretion from the anterior pituitary glands of female rats were studied. A perifusion system and radioimmunoassay were used to study secretion; static incubations and incorporation of [3H]leucine were used to measure biosynthesis. During perifusion, intact anterior lobes showed a constant rate of prolactin secretion for up to 5 h (after a 90-min preincubation to stabilize the tissue). Incorporation studies revealed an increase in protein synthesis in perifused hemipituitary glands. When glands were treated with 10 nm-domperidone, prolactin secretion began to decline after the first hour, reaching a maximum of 40–50% inhibition after a further 90 min. Growth hormone secretion showed no such decline. Inhibition of prolactin secretion continued for up to 2 h after withdrawal of the drug. Treatment with 100 nm-dopamine resulted in a more rapid inhibition of secretion, but the effect was reversed on withdrawal of the catecholamine. The prolactin content of perifused hemipituitary glands was measured after treatment with domperidone; the contents of control and treated glands did not differ, but were depleted compared with hemipituitary glands which had not been perifused.

Cell-density dependence of the rate of prolactin secretion from perifused rat anterior pituitary cells

1983 ◽  
Vol 97 (2) ◽  
pp. 221-228 ◽  
Author(s):  
A. M. Bentley ◽  
M. Wallis
Keyword(s):  
Density Dependence ◽  
Cell Density ◽  
Anterior Pituitary ◽  
Prolactin Secretion ◽  
Female Rats ◽  
Pituitary Cells ◽  
The Third ◽  
Pituitary Glands ◽  
Prolactin Content ◽  
Perifusion System

Anterior pituitary glands from female rats were dispersed enzymically in the absence of dopamine. Dispersed cells (106–107) were layered onto columns containing Bio-Gel P-2 and were then perifused for 3 h with Dulbecco's Modified Eagle's Medium. The prolactin content of the perifusate and cell homogenates was determined by radioimmunoassay. Prolactin secretion during the third hour of perifusion increased as the loading of cells increased. However, the increase was not linear, and when secretion rate per 106 cells was calculated it was found that increased loading decreased the rate, which fell to a plateau of 1·3 ± 0·1 (s.e.m.) ng/min per 106 cells at a loading of about 8 × 106 cells from 3·8 ± 0·1 ng/min per 106 cells for a loading of 106 cells. This cell-density dependence of the rate of prolactin secretion in the perifusion system may be due to intercellular contact since the isolation of the tissue removes the influence of hypothalamic factors, while localized build up of prolactin (potentially causing direct autoregulation on the lactotroph) seems unlikely because of the continuous flow of medium.

Prolactin and growth hormone secretion in chickens: stimulation by histamine and inhibition by gamma-aminobutyric acid

1984 ◽  
Vol 107 (1) ◽  
pp. 36-41 ◽  
Author(s):  
T. R. Hall ◽  
S. Harvey ◽  
A. Chadwick
Keyword(s):  
Growth Hormone ◽  
Direct Effect ◽  
Anterior Pituitary ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Aminobutyric Acid ◽  
Gamma Aminobutyric Acid ◽  
Gh Secretion ◽  
Pituitary Glands ◽  
Stimulation By Histamine

Abstract. Anterior pituitary glands from chickens (Gallus domesticus) were incubated with or without single, mediobasal chicken hypothalami in medium containing histamine, alone or together with the antagonist diphenhydramine or in medium containing gamma-aminobutyric acid (GABA), alone or together with the antagonists bicuculline or picrotoxin. The release of prolactin (Prl) and growth hormone (GH) was measured by homologous radioimmunoassay. Histamine had no direct effect on the release of either hormone but stimulated Prl (in a dose-related way) and GH release when anterior pituitary glands were co-incubated with hypothalami. Diphenhydramine also had no direct effect on Prl or GH secretion but blocked the stimulatory effect of histamine on hypothalamusinduced Prl and GH release. When anterior pituitary glands were incubated without hypothalami, GABA, bicuculline and picrotoxin had no effect on the release of Prl or GH. However, GABA inhibited the release of both hormones in a concentration-related manner, when anterior pituitary glands were co-incubated with hypothalami. This inhibition was blocked by both bicuculline and picrotoxin. These results suggest that histamine and GABA may be involved in controlling the secretion of Prl and GH from the avian pituitary gland, possibly by modifying the secretion of hypothalamic releasing and/or release-inhibiting hormones.

A procedure for the purification of somatotrophs isolated from rat anterior pituitary glands using Percoll density gradients

1982 ◽  
Vol 94 (2) ◽  
pp. 257-NP ◽  
Author(s):  
Marianne Hall ◽  
S. L. Howell ◽  
D. Schulster ◽  
M. Wallis
Keyword(s):  
Growth Hormone ◽  
Anterior Pituitary ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Cell Types ◽  
Male Rats ◽  
Prostaglandin E ◽  
Density Gradients ◽  
Pituitary Glands ◽  
Cyclic Amp Derivatives

We have used fractionation on density gradients of Percoll to separate the cell types in the rat anterior pituitary gland and to produce a purified preparation of somatotrophs. The method differs from those described previously which used, for example, albumin or Ficoll gradients, in being more rapid and avoiding low temperatures, and therefore gives cells with improved viability. Anterior pituitary glands from male rats were dispersed with trypsin to produce 1·5 × 106–2·0 × 106 cells/gland. These were fractionated on hyperbolic density gradients of Percoll. Two bands of cells containing somatotrophs were detected, one of which (band A; density 1·075–1·082 g/cm3) contained approximately 90% somatotrophs, whereas the other (band B; density 1·055–1·068 g/cm3) contained about 70% somatotrophs mixed with other cells, especially lactotrophs. Cells in band A appeared more responsive to secretagogues than those in band B; growth hormone secretion was stimulated markedly by cyclic AMP derivatives and prostaglandin E2, and inhibited by somatostatin. Such purified somatotrophs are well suited to biochemical studies on the mechanism of the control of growth hormone secretion.

Size heterogeneity of prolactin secreted from and stored in the rat anterior pituitary gland in vitro

1984 ◽  
Vol 4 (2) ◽  
pp. 129-137 ◽  
Author(s):  
Andrew M. Bentley ◽  
Teresa K. Surowy ◽  
Michael Wallis
Keyword(s):  
Anterior Pituitary ◽  
Relative Proportion ◽  
Gel Filtration ◽  
Prolactin Secretion ◽  
Female Rats ◽  
Pituitary Glands ◽  
Dimeric Form ◽  
Size Heterogeneity ◽  
Pituitary Prolactin

The size heterogeneity of rat pituitary prolactin was investigated using anterior pituitary glands from female rats incubated in vitro and gel filtration on Sephadex G-100. Monomeric prolactin was preferentially secreted compared with dimeric and ‘trimeric” material. When glands were incubated with dopamine, prolactin secretion was inhibited and the relative proportion of dimer in the gland (but not the medium) was decreased. Morphine sulphate reversed the effect of dopamine on prolactin secretion and on the proportion of prolactin in the gland that was in the dimeric form. The results suggest that monomeric prolactin is more readily secreted than dimer, and that dopamine decreases the production or stability of the dimer.

ACETYLCHOLINE STIMULATES GROWTH HORMONE SECRETION, PHOSPHATIDYL INOSITOL LABELLING, 45Ca2+ EFFLUX AND CYCLIC GMP ACCUMULATION IN BOVINE ANTERIOR PITUITARY GLANDS

1979 ◽  
Vol 80 (2) ◽  
pp. 203-213 ◽  
Author(s):  
P. W. YOUNG ◽  
R. J. BICKNELL ◽  
J. G. SCHOFIELD
Keyword(s):  
Growth Hormone ◽  
Cyclic Gmp ◽  
Anterior Pituitary ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Phosphatidyl Inositol ◽  
Maximal Response ◽  
Tissue Responses ◽  
Pituitary Glands ◽  
Esterase Inhibitor

Acetylcholine (25 μmol/l) in the presence of the choline esterase inhibitor physostigmine (67 μmol/l) increased the release of growth hormone and efflux of 45Ca2+ from perifused bovine pituitary slices; the time taken for the maximal response to occur was the same. In batch incubations, acetylcholine (1 μmol/l–1 mmol/l) increased pituitary cyclic GMP concentrations in the pituitary gland within 2 min, and increased incorporation of [3H]inositol and [32P]phosphate into pituitary phosphatidyl inositol within 15 min. Cyclic AMP concentrations were not significantly changed 2 or 5 min after acetylcholine addition. All the tissue responses were inhibited by prior exposure of the tissue to atropine (1 μmol/l) but not by tubocurarine (10 μmol/l–1 mmol/l), indicating that the responses were mediated by receptors of the muscarinic type. The similarities between these responses and those to known hypothalamic hypophysiotrophic hormones are discussed.

Bioregulatory role of the kallikrein-kinin system in the normal pituitary gland and its tumours

1992 ◽  
Vol 127 (6) ◽  
pp. 481-484 ◽  
Author(s):  
TH Jones ◽  
CD Figueroa ◽  
KD Bhoola
Keyword(s):  
Pituitary Gland ◽  
Pituitary Adenomas ◽  
Anterior Pituitary ◽  
Secretory Granules ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Female Rats ◽  
Tissue Kallikrein ◽  
Kinin System ◽  
Kallikrein Kinin System

Tissue kallikrein, a serine protease, is present in the prolactin-secreting cells of the normal anterior pituitary gland and pituitary adenomas. It is mainly located in the Golgi apparatus, but is also present in secretory granules. There is a distinct sexual dimorphism, with amount of tissue kallikrein being greater in anterior pituitary tissue from female rats. The intracellular levels of tissue kallikrein are increased by estradiol and in pituitary tumours, and decreased by ovariectomy, dopamine and its agonists. There is preliminary in vitro evidence that tissue kallikrein may be involved in the intracellular processing of the prolactin molecule before secretion. Tissue kallikrein synthesizes kinins which are present in the anterior pituitary and are capable of stimulating prolactin and growth hormone secretion by activating the phosphoinositide second messenger system. Prolactin physiology is uniquely linked to the kallikrein-kinin system in the normal pituitary and its tumours. Tissue kallikrein may have an important role in the pathophysiology of prolactin-secreting pituitary adenomas.

Direct Suppressive Effect of Prostaglandin D2 on Growth Hormone Secretion from Rat Anterior Pituitary

2010 ◽  
Vol 10 (4) ◽  
pp. 541-545
Author(s):  
Masayoshi Arisawa ◽  
Tsunehisa Makino ◽  
Nobuhiro Uchida ◽  
Takashi Nagai ◽  
Shun-ichiro Izumi ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Anterior Pituitary ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Suppressive Effect ◽  
Prostaglandin D2
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