scholarly journals The Regulation of Pituitary Prolactin Secretion: Hypothalamic, Intrapituitary and Intracellular Factors and Signaling Mechanisms

Prolactin ◽  
10.5772/55571 ◽  
2013 ◽  
Author(s):  
Viktoria Reinhoffer ◽  
Mark Olah ◽  
Miklos Vecsernyes ◽  
Bela E. ◽  
Gyorgy M.
Keyword(s):  
Prolactin Secretion ◽  
Signaling Mechanisms ◽  
Pituitary Prolactin

REDUCTIVE PATHWAYS OF PROGESTERONE METABOLISM IN THE RAT OVARY

1972 ◽  
Vol 69 (1) ◽  
pp. 141-152 ◽  
Author(s):  
A. Zmigrod ◽  
H. R. Lindner ◽  
S. A. Lamprecht
Keyword(s):  
Hydroxysteroid Dehydrogenase ◽  
Prolactin Secretion ◽  
Ovariectomized Rats ◽  
Corpora Lutea ◽  
Microsomal Preparation ◽  
Progesterone Metabolism ◽  
Rat Ovary ◽  
Reducing Activity ◽  
Pituitary Prolactin

ABSTRACT Progesterone underwent extensive reductive metabolism when incubated with a microsomal preparation from rat ovaries in the presence of NADPH. The major products formed were 3β-hydroxy-5α-pregnan-20-one, 5α-pregnane-3,20-dione and 5α-pregnane-3β,20α-diol. Newly formed corpora lutea of pregnancy were almost devoid of any microsomal A-ring reducing activity (5α-reductase and a 3β-hydroxysteroid dehydrogenase) and of soluble 20α-hydroxysteroid dehydrogenase. The behaviour of the A-ring reducing enzymes paralleled that of 20α-ol dehydrogenase in that their activity (i) was high during the oestrous cycle; (ii) declined between the third and seventh day of pregnancy; and (iii) increased sharply in corpora lutea of pregnancy when ergocornine – a drug blocking pituitary prolactin secretion – was given to the rats, yet remained low when prolactin and ergocornine were administered concurrently. However, the A-ring reducing activity did not show the sharp pre-partum rise exhibited by 20α-ol dehydrogenase, thus deviating from a pattern compatible with a co-ordinate control of the three enzymes involved in the metabolic inactivation of progesterone. Contrary to a report in the literature, 5α-pregnane-3,20-dione (20 mg/rat/day) was found to be ineffective when tested for pregnancy or deciduoma supporting activity in ovariectomized rats. The microsomal reductases, if indeed operative in vivo, may restrict the availability of progesterone as an oestrogen precursor.

MAMMARY GROWTH AND FUNCTION AND PITUITARY PROLACTIN SECRETION IN FEMALE NUDE MICE

1977 ◽  
Vol 86 (4) ◽  
pp. 794-802 ◽  
Author(s):  
Hiroshi Nagasawa ◽  
Reiko Yanai
Keyword(s):  
Nude Mice ◽  
Plasma Levels ◽  
Growth Stimulation ◽  
Prolactin Secretion ◽  
The Other ◽  
Dna And Rna ◽  
Female Nude ◽  
Structural Growth ◽  
And Function ◽  
Pituitary Prolactin

ABSTRACT Mammary structural growth in the wholemount preparation, content and synthesis of mammary DNA and RNA estimated by the incorporation of [3H]thymidine and [14C]uridine, pituitary and plasma levels of prolactin and weights and histological structures of some organs of female nude mice (nu/nu) were compared to those of the control (nu/+) with the same genetical background (BALB/c). Both at 3 months of age and on day 1 of lactation, the weights per 100 g body weight of adrenals, spleen and liver of nu/nu mice were significantly higher than those of nu/+ mice. Mammary growth stimulation by pituitary graft was much more marked in nu/nu mice than in nu/+ mice. Slight differences between groups were found in the pituitary and plasma levels of prolactin, in the histological structures of ovaries as well as of the adrenals and thyroids and in the pattern of oestrous cycles. On the other hand, the content and synthesis of mammary DNA at 3 months of age and content and synthesis of both DNA and RNA and RNA/DNA ratio on day 1 of lactation were significantly higher in nu/+ mice than in nu/nu mice. All findings suggest that thymus deficient immunosuppression has deleterious effects on mammary growth and function without its alteration in the secretion of prolactin and oestrogen and probably through its decrease in mammary responsiveness to mammotrophins.

Effect of ascorbic acid on pituitary prolactin secretion in the non-ascorbate synthesizing osteogenic disorder shionogi (ODS) rat

Life Sciences ◽  
1993 ◽  
Vol 52 (11) ◽  
pp. 975-979 ◽  
Author(s):  
Masanobu Kawaguchi ◽  
Fuminori Hayakawa ◽  
Yoshinobu Kamiya ◽  
Toru Fujii ◽  
Junko Ito ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Prolactin Secretion ◽  
Pituitary Prolactin

Potentiation of sulpiride-induced prolactin secretion by sodium deprivation in man

1980 ◽  
Vol 94 (1) ◽  
pp. 25-29 ◽  
Author(s):  
Masatomo Mori ◽  
Isao Kobayashi ◽  
Kihachi Ohshima ◽  
Sakae Maruta ◽  
Yohnosuke Shimomura ◽  
...  
Keyword(s):  
Control Diet ◽  
Normal Subjects ◽  
Sodium Content ◽  
Prolactin Secretion ◽  
Serum Prolactin ◽  
Aldosterone Secretion ◽  
Low Sodium Diet ◽  
Specific Radioimmunoassay ◽  
Prolactin Response ◽  
Pituitary Prolactin

Abstract. Previous studies suggest that prolactin is not an important osmoregulatory hormone in man, while aldosterone is well known to be important in osmoregulation. The present investigation was undertaken to ascertain whether serum osmotic changes affect pituitary prolactin secretion following sulpiride administration. Five normal subjects were placed on a constant isocaloric diet with different sodium content. Serum prolactin and aldosterone level were measured by specific radioimmunoassay. The basal serum level of prolactin was unaffected by changes in sodium content of the diet, in contrast to the basal level of aldosterone. On the other hand, the maximum levels of serum prolactin in response to sulpiride (50 mg, im) were significantly higher on a low sodium diet (3 g of salt/day) than on a control diet (12– 15 g of salt/day). When the content of diet changed from low salt to high salt (25 g of salt/day), sulpiride-induced prolactin response decreased, though it was not significantly lower than that on a control diet. However, sulpiride administration could not stimulate aldosterone secretion under any of the various sodium contents of the diet. The present study provides evidence that lowering of serum osmolarity stimulates serum prolactin response to sulpiride administration in man and this response is not modulated by aldosterone secretion.

The posterior pituitary: regulation of anterior pituitary prolactin secretion

Science ◽  
1981 ◽  
Vol 213 (4508) ◽  
pp. 659-661 ◽  
Author(s):  
L. Peters ◽  
M. Hoefer ◽  
N Ben-Jonathan
Keyword(s):  
Anterior Pituitary ◽  
Prolactin Secretion ◽  
Posterior Pituitary ◽  
Pituitary Prolactin

Increased dopaminergic inhibition of prolactin in the hypoprolactinaemic IPL nude rat

1985 ◽  
Vol 107 (3) ◽  
pp. 325-329 ◽  
Author(s):  
H. Cohen ◽  
I. Sabbagh ◽  
P. Guillaumot ◽  
J. Bertrand
Keyword(s):  
Adult Male ◽  
Physiological Saline ◽  
Prolactin Secretion ◽  
Male Rats ◽  
Saline Control ◽  
Plasma Prolactin ◽  
Synthesis Inhibitor ◽  
Nude Rat ◽  
Prolactin Content ◽  
Pituitary Prolactin

ABSTRACT In this study, aimed at investigating whether dopaminergic regulation of prolactin could be implicated in the hypoprolactinaemia observed in the IPL nude rat, dopaminergic inhibition of prolactin was suppressed using a catecholamine synthesis inhibitor α-methyltyrosine (MT) and a dopaminergic antagonist sulpiride. Adult male rats (IPL nude and normal) were injected through implanted atrial cannulae with either MT (250 mg/kg) or physiological saline (control). Rats were decapitated 2 h after the injection. Plasma prolactin levels, compared with basal values, increased by 15·6 ± 1·9 (s.e.m.)- and 5·89 ± 0·6-fold in IPL nude and normal rats respectively. This difference was highly significant. The pituitary prolactin content was decreased in both groups. In a second experiment, adult male IPL nude or normal rats were injected with either sulpiride (1 mg/kg) or saline and decapitated 2, 4, 8, 12, 14 and 24 h later. Plasma prolactin levels, compared with basal values, were increased in rats injected with sulpiride by 9·2 ± 1·8 and 3·4 ± 0·7-fold in IPL nude and normal rats respectively. The pituitary prolactin content was reduced more in IPL nude than in normal sulpiride-injected rats. These data suggest that prolactin secretion, as well as synthesis, is under an increased dopaminergic inhibition in the male IPL nude rat. J. Endocr. (1985) 107, 325–329

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