ONSET OF OESTROGEN-INDUCED PROLACTIN SECRETION AND DNA SYNTHESIS BY THE RAT PITUITARY GLAND

1977 ◽  
Vol 72 (1) ◽  
pp. 35-39 ◽  
Author(s):  
JOAN JACOBI ◽  
H. M. LLOYD ◽  
J. D. MEARES
Keyword(s):  
Dna Synthesis ◽  
Pituitary Gland ◽  
Prolactin Secretion ◽  
Male Rat ◽  
Serum Prolactin ◽  
Rat Pituitary ◽  
The Times ◽  
Pituitary Prolactin

SUMMARY The times of onset of oestrogen-induced prolactin secretion and DNA synthesis were studied in the pituitary gland of the male rat. At intervals from 3 to 96 h after injection of 10 mg diethylstilboestrol dipropionate, serum and pituitary prolactin concentrations were measured by radioimmunoassay and pituitary DNA synthesis by incorporation of [3H]thymidine in vitro. Serum prolactin was raised significantly from 6 h onwards and DNA synthesis was increased from 30 h onwards. Pituitary prolactin concentration began to increase at 30 h. Significant correlations were obtained between serum prolactin and DNA synthesis from 24 to 72 h but not during the period of prolactin secretion from 6 to 24 h.

2-HYDROXYOESTRADIOL INHIBITS PROLACTIN RELEASE FROM THE SUPERFUSED RAT PITUITARY GLAND

1981 ◽  
Vol 90 (3) ◽  
pp. 315-322 ◽  
Author(s):  
ELIZABETH A. LINTON ◽  
NICKI WHITE ◽  
OFELIA LIRA DE TINEO ◽  
S. L. JEFFCOATE
Keyword(s):  
Pituitary Gland ◽  
Prolactin Secretion ◽  
Male Rat ◽  
Prolactin Release ◽  
Rat Pituitary ◽  
Lh Release

The effects of 2-hydroxyoestradiol (2OH-OE2), dopamine, oestradiol-17β and 2OH-OE2 plus dopamine on prolactin and LH release from the male rat pituitary gland were examined in vitro. 2-Hydroxyoestradiol reduced prolactin secretion by 51% at 10−10 mol/l and by 34% at 10−7 mol/l, while oestradiol-17β had no effect at these doses. Dopamine alone (5 × 10−7 mol/l) decreased prolactin released by 58%, 2OH-OE2 plus dopamine produced a similar inhibition of 60%. No significant effect on LH release was observed throughout.

DNA SYNTHESIS AND DEPLETION OF PROLACTIN IN THE PITUITARY GLAND OF THE MALE RAT

1978 ◽  
Vol 77 (1) ◽  
pp. 129-136 ◽  
Author(s):  
H. M. LLOYD ◽  
J. M. JACOBI ◽  
J. D. MEARES
Keyword(s):  
Growth Hormone ◽  
Dna Synthesis ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Prolactin Secretion ◽  
Male Rats ◽  
Male Rat ◽  
Serum Prolactin ◽  
Inhibitory Effects ◽  
Pituitary Prolactin

Haloperidol, bromocriptine and diethylstilboestrol dipropionate were given in various régimes to male rats to determine their effects on pituitary DNA synthesis, prolactin secretion and growth hormone secretion. Haloperidol increased serum prolactin but did not stimulate pituitary DNA synthesis or reduce pituitary prolactin concentrations. Haloperidol potentiated the effects of oestrogen on serum prolactin and on pituitary DNA synthesis; pituitary prolactin concentrations were greatly reduced, and growth hormone secretion was slightly inhibited. The inhibitory effects of bromocriptine in oestrogen-stimulated rats were demonstrated by smaller pituitary weights and decreased DNA synthesis; serum prolactin levels were lowered and pituitary prolactin concentrations were increased. Haloperidol, given to rats treated with oestrogen and bromocriptine, reversed the inhibitory effects of bromocriptine on DNA synthesis and serum prolactin; pituitary prolactin concentrations fell to well below normal. The results suggest that the haloperidol potentiation of oestrogeninduced pituitary DNA synthesis may depend upon stimulation of prolactin secretion together with reduction of intracellular prolactin levels.

DNA SYNTHESIS AND THE SECRETION OF PROLACTIN AND GROWTH HORMONE BY THE PITUITARY GLAND OF THE MALE RAT: EFFECTS OF DIETHYLSTILBOESTROL AND 2-BROMO-α-ERGOCRYPTINE METHANESULPHONATE

1974 ◽  
Vol 61 (3) ◽  
pp. 411-417 ◽  
Author(s):  
CAROL DAVIES ◽  
JOAN JACOBI ◽  
H. M. LLOYD ◽  
J. D. MEARES
Keyword(s):  
Growth Hormone ◽  
Single Dose ◽  
Dna Synthesis ◽  
Pituitary Gland ◽  
Growth Hormone Response ◽  
Male Rat ◽  
Serum Prolactin ◽  
Hormone Response ◽  
Pituitary Prolactin

SUMMARY The effects of 2-bromo-α-ergocryptine methanesulphonate on the response of the pituitary gland of the male rat to diethylstilboestrol dipropionate were studied by radioimmunoassay of prolactin and growth hormone and measurements of DNA synthesis. Given before diethylstilboestrol, 2-bromo-α-ergocryptine prevented the oestrogen-induced rise in serum prolactin and partly inhibited pituitary DNA synthesis. Given on days 4–6 of a 6-day period after a single dose of diethylstilboestrol, 2-bromo-α-ergocryptine rapidly increased pituitary prolactin concentration, diminished serum prolactin, reduced pituitary DNA synthesis and did not affect the growth hormone response to oestrogen.

ESTIMATION OF PROLACTIN AND GROWTH HORMONE LEVELS BY POLYACRYLAMIDE DISC ELECTROPHORESIS

1969 ◽  
Vol 45 (2) ◽  
pp. 183-NP ◽  
Author(s):  
C. S. NICOLL ◽  
J. A. PARSONS ◽  
R. P. FIORINDO ◽  
C. W. NICHOLS
Keyword(s):  
Growth Hormone ◽  
Adult Male ◽  
Prolactin Secretion ◽  
Disc Electrophoresis ◽  
Male Rat ◽  
Rat Pituitary ◽  
Hypothalamic Tissue ◽  
Prolactin Content ◽  
High Degree

SUMMARY A procedure for estimating rat prolactin and growth hormone (somatotrophin, STH), by measuring the optical density of the electrophoretically isolated and stained hormone bands in polyacrylamide gel columns, is described and evaluated. A simple and inexpensive densitometer is also described. Prolactin levels in adenohypophyses and in medium from pituitary incubates were measured by electrophoresis-densitometry (ED) and by the pigeon crop-sac assay. The two methods showed a high degree of correlation. The validity of the ED method for estimating prolactin levels in adenohypophysial tissue and in incubation medium was demonstrated by comparing the prolactin content of adult male and female and of oestrogen-treated male glands and by experiments in vitro. The female pituitary contained about three times more prolactin than the male and the glands of oestrogen-treated males had levels about the same as those of females. It was also shown that the ED method could be used to demonstrate the inhibitory effects of extract of rat hypothalamic tissue on prolactin secretion in vitro by the rat pituitary. Levels of STH in adult male glands, as measured by this method, were comparable to results obtained by others using immunoassays. Propylthiouracil-induced hypothyroidism depressed the STH and prolactin levels in male rat pituitaries, in agreement with the observations of others. The stainability of the prolactin band in rat adenohypophyses was observed to decrease with time when the glands were stored on dry ice. No such change occurred in the staining characteristics of the STH band. Other aspects of the ED method are discussed, including its precision, efficiency, sensitivity, economy and utility.

Effect of tamoxifen on growth and prolactin secretion of rat pituitary tumours

1983 ◽  
Vol 97 (2) ◽  
pp. 261-266 ◽  
Author(s):  
R. A. Prysor-Jones ◽  
J. J. Silverlight ◽  
J. S. Jenkins
Keyword(s):  
Dna Synthesis ◽  
Dopamine Agonist ◽  
Pituitary Adenomas ◽  
Tumour Growth ◽  
Prolactin Secretion ◽  
Moderate Increase ◽  
Plasma Prolactin ◽  
Pituitary Tumours ◽  
Rat Pituitary

The antioestrogenic drug tamoxifen was administered to rats bearing transplanted prolactin-secreting tumours derived from spontaneously occurring pituitary adenomas in Wistar–Furth rats. Some inhibition of tumour growth was observed but this was accompanied by an increase in plasma prolactin concentrations. Bromocriptine, however, consistently inhibited both growth and prolactin secretion of these tumours. The addition of tamoxifen to bromocriptine treatment produced no increased response to the dopamine agonist. Tamoxifen increased prolactin secretion by tumour cells in vitro but did not affect DNA synthesis. Normal rats responded to tamoxifen with a moderate increase in plasma prolactin concentrations and there was no change in pituitary DNA synthesis.

ANTI-OESTROGENIC EFFECTS OF NAFOXIDINE ON THE SYNTHESIS OF DNA BY THE RAT PITUITARY GLAND

1978 ◽  
Vol 76 (3) ◽  
pp. 555-556 ◽  
Author(s):  
J. M. JACOBI ◽  
H. M. LLOYD
Keyword(s):  
Pituitary Gland ◽  
Male Rat ◽  
Serum Prolactin ◽  
Free Access ◽  
Sprague Dawley ◽  
Target Organs ◽  
Sprague Dawley Rats ◽  
Rat Pituitary ◽  
Pelleted Diet ◽  
Principal Actions

Department of Medicine, University of Queensland, Clinical Sciences Building, Royal Brisbane Hospital, Queensland 4029, Australia Received 25 October 1977 One of the principal actions of oestrogens on their target organs is stimulation of the synthesis of DNA and cell division. In the rat pituitary gland, anti-oestrogens inhibit the oestrogen-induced increase in weight (Schreiber, Přibyl & Roháčová, 1972) and prevent the rise in the level of serum prolactin induced by oestradiol-17β (Jordan, Koerner & Robinson, 1975). The effects of anti-oestrogens on the synthesis of DNA by the pituitary gland have not been described. The experiments reported here show that the anti-oestrogen nafoxidine completely inhibits the synthesis of DNA and affects the secretion of growth hormone (GH) and prolactin in the male rat. Male Sprague–Dawley rats, 100 days old, were allowed free access to a pelleted diet and water and were maintained in a controlled environment (12 h light, 12 h darkness).

Evidence for direct action of calcitonin in the rat pituitary gland

1989 ◽  
Vol 120 (5) ◽  
pp. 682-688 ◽  
Author(s):  
G. Morel ◽  
J.-G. Chabot ◽  
A. Enjalbert ◽  
M. Priam ◽  
P. M. Dubois
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Direct Action ◽  
Secretory Granules ◽  
In Vitro Study ◽  
Male Rat ◽  
Pituitary Cells ◽  
Cytoplasmic Matrix ◽  
Rat Pituitary

Abstract. Classic concepts of calcitonin (CT) function have focused on the effects of CT on calcium homeostasis. More recently CT actions on brain and pituitary have been investigated. In order to evaluate the effects of CT on the anterior pituitary gland we studied the action(s) of CT in vitro and visualized endogenous CT in adult male rat pituitary gland by immunocytochemistry on ultrathin sections obtained by cryoultramicomy. In vitro study using dispersed anterior pituitary cells indicated that CT stimulated the secretion of PRL, whereas the secretion of GH, TSH and LH was not affected. CT-like immunoreactivity was observed in lactotropes only. The other pituitary cell types were not immunoreactive. In lactotropes, immunostaining was observed in the cytoplasm and in the nucleus. In the cytoplasm, CT-like immunoreactivity was visuzalized in the cytoplasmic matrix and in the secretory granules. In the nucleus, immunostaining was distributed primarly in the euchromatin, in the vincinity of heterochromatin region. CT-like immunoreactivity was also observed at the plasma membrane but was only scarce. No reaction product was found when anti-CT serum pre-incubated with CT was used. In conclusion, these results bring evidence for a direct action of CT on lactotrope regulation in vitro as well as in intact animals.

scholarly journals Experimental modification of rat pituitary prolactin cell function during and after spaceflight

1996 ◽  
Vol 80 (3) ◽  
pp. 971-980 ◽  
Author(s):  
W. C. Hymer ◽  
T. Salada ◽  
L. Avery ◽  
R. E. Grindeland
Keyword(s):  
Posttranslational Modifications ◽  
Cell Function ◽  
Biological Activities ◽  
Male Rat ◽  
Molecular Weights ◽  
Significant Difference ◽  
Rat Pituitary ◽  
Cellular And Humoral Immunity ◽  
Pituitary Prolactin

This study was done to evaluate the effects of microgravity on prolactin (PRL) cells of the male rat pituitary gland. We used the identical passive closed-vial cell culture system that was described for the culture of growth hormone cells (W. C. Hymen, R. E. Grindeland, T. Salada, P. Nye, E. Grossman, and P. Lane. J. Appl. Physiol. 80:955-970, 1996). After an 8-day spaceflight, all flight media (containing released PRL), as well as extracts (containing intracellular PRL), contained significantly lower amounts of immunoreactive PRL than their corresponding ground control samples. On the other hand, these same samples, when assessed for their biological activities by two different in vitro lymphocyte assays, yielded disparate results that may reflect posttranslational modifications to the hormone molecule. Other data showed that 1) the apparent molecular weights of released PRL molecules were not altered by microgravity, but 2) the region from which the PRL cells came (dorsal or ventral) made a significant difference in the amount and activity of PRL released from the flight cells. Because there is much current interest in the role that PRL may play in the regulation of the immune system and because changes in both cellular and humoral immunity accompany spaceflight, this study could help define future microgravity research in this area.

EFFECTS OF TWO SUBSTITUTED BENZAMIDES, TIAPRIDE AND SULTOPRIDE, ON GONADOTROPHINS AND PROLACTIN

1978 ◽  
Vol 89 (1) ◽  
pp. 29-37 ◽  
Author(s):  
M. L'Hermite ◽  
R. M. MacLeod ◽  
C. Robyn
Keyword(s):  
Pituitary Gland ◽  
Pituitary Tumour ◽  
Prolactin Secretion ◽  
High Serum ◽  
Serum Prolactin ◽  
Acute Effects ◽  
Substituted Benzamides ◽  
Normal Men

ABSTRACT The acute effects in the human of tiapride and sultopride, two new substituted benzamides related to sulpiride, were studied with respect to gonadotrophins (LH and FSH) and prolactin (PRL) secretion. Two different groups of 3 normal men and 3 normally cycling women received im injections of either 100 mg sultopride or 200 mg tiapride. Five min after the injection of either psychotropic drug, the serum PRL concentration increased significantly (P < 0.001 by variance analysis) and reached maximal values by 30 min and remained elevated for at least 6 h; women tended to release more prolactin than men. Although tiapride (500 nm) had no direct effect on the in vitro synthesis or secretion of prolactin, the drug blocked the inhibitory action of dopamine (500 nm) on the secretion of prolactin. Rats bearing a transplantable prolactin-secreting pituitary tumour MtTW15 have extremely high serum prolactin and through an autofeed mechanism the host's pituitary gland is suppressed. The in vitro synthesis and secretion of prolactin by these rats' pituitary gland is decreased. The in vivo administration of tiapride to these tumour-bearing rats restored the in vitro secretion of prolactin to control values. The in vitro data support the concept that tiapride increases prolactin secretion directly at the pituitary level by blocking the inhibitory activity of dopamine; an additional effect at a higher level can not, however, be ruled out. In vivo in the human, no significant modification of LH and FSH occurred after either drug, suggesting that the menstrual cycle disturbances observed during chronic treatment with tiapride might be related to hyperprolactinaemia or be the result of a mechanism similar to that inducing hyperprolactinaemia.

Autoregulation of rat pituitary prolactin secretion demonstrated by a new perfusion method

1982 ◽  
Vol 242 (4) ◽  
pp. E226-E233
Author(s):  
H. A. Zacur ◽  
W. E. Mitch ◽  
J. E. Tyson ◽  
P. T. Ostrow ◽  
G. V. Foster
Keyword(s):  
Prolactin Secretion ◽  
Renal Capsule ◽  
In Vitro Perfusion ◽  
Prolactin Release ◽  
Rat Pituitary ◽  
Inbred Rats ◽  
Pituitary Glands ◽  
Prolactin Content ◽  
Pituitary Prolactin

Regulation of prolactin secretion was investigated by perfusing rat pituitaries in vitro. Two pituitary glands from inbred rats were transplanted beneath the renal capsule of a third recipient rat. Three weeks later, the transplanted kidney was removed and perfused in vitro with a defined cell-free medium. Normal renal function was maintained during perfusion, and cell morphology of the transplants remained unchanged as assessed by electron microscopy. Pituitary prolactin content did not change after 120 min of perfusion despite release of approximately 10 micrograms of hormone. Thyrotropin-releasing hormone (10 ng/ml) did not stimulate prolactin release; dopamine (20 ng/ml) rapidly, but transiently inhibited prolactin release; bromocriptine (20 ng/ml) rapidly and persistently inhibited prolactin release; haloperidol (100 ng/ml) blocked the inhibition by dopamine or bromocriptine, but when given alone inhibited prolactin release. Finally, prolactin release was also inhibited by the presence of 100 and 200 ng/ml, but not 50 ng/ml of NIAMDD RP-1 rat prolactin. It is concluded that in vitro perfusion of transplanted rat pituitaries provides a new model for studying the direct effect of agents on the secretion of prolactin from the pituitary and that rat prolactin and/or its metabolites directly inhibit pituitary prolactin secretion.

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