PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “PROLACTIN”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23Linked to original sources
PubMed1991

Growth hormone and prolactin secretion in hypophysial stalk-transected pigs as affected by growth hormone and prolactin-releasing and inhibiting factors.

Control of growth hormone (GH) and prolactin (PRL) release was investigated in hypophysial stalk-transected (HST) and stalk-intact pigs by determining the effects of analogs of GH-releasing factors (GHRF), somatostatin (SRIF), arginine, thyrotropin-releasing hormone, alpha-methyl-rho-tyrosine, and haloperidol. HST and control gilts were challenged with intravenous injections of human pancreatic GHRF(1-40)OH, thyrotropin-releasing hormone, and analogs of rat hypothalamic GHRF. HST animals remained acutely responsive to GHRF by releasing 2-fold greater quantities of GH than seen in controls. This occurred in spite of a 38% reduction in pituitary gland weight and a 32 and 55% decrease in GH concentration and total content. During SRIF infusion, GH remained at similar basal concentrations in HST and control gilts, but increased immediately after stopping SRIF infusion only in the controls. Releasable pituitary GH appears to accumulate during SRIF infusion. GHRF given during SRIF infusion caused a 2-fold greater release of GH than seen in animals receiving only GHRF. Arginine increased (P less than 0.05) GH release in controls, but not in HST gilts, which suggests that it acts through the central nervous system. Basal PRL concentrations were greater (P less than 0.05) in HST gilts than in control gilts. TRH acutely elevated circulating PRL (P less than 0.001) in HST gilts, suggesting that it acts directly on the pituitary gland. Haloperidol, a dopamine receptor antagonist, increased circulating PRL in controls but not in HST animals. alpha-Methyl-rho-tyrosine did not consistently increase circulating PRL, however, suggesting that it did not sufficiently alter turnover rate of the tyrosine hydroxylase pool. The results indicate that the isolated pituitary after HST remains acutely responsive to hypothalamic releasing and inhibiting factors for both GH and PRL release in the pig.

Adrenal Glands↗
PubMed1992

Synthesis of a prolactin-like peptide by natural killer cells: positive regulation by CD16 and exogenous prolactin.

We have previously shown that Prolactin (PRL) activates the native and the in vitro acquired cytotoxicity and the DNA synthetic activity of Natural Killer (NK) cells. Here we show that the supernatant and the cell lysate of NK cells express a 35S-labelled 50 kDa peptide specifically immunostained by two different PRL-antisera. The supernatant of NK cells was biologically active in a Nb2 assay and the activity could be adsorbed by an anti-PRL antiserum. The production of the PRL-like peptide only occurred when NK cells were isolated through binding to immobilized immunocomplexes, the biological ligand for CD16, and was positively modulated by exogenous PRL. These results indicate that PRL, produced by NK cells following stimulation, may act in an autocrine fashion to maintain and/or activate the NK cell function.

Antigen-Antibody Complex↗
PubMed1991

[Secretory activity of ovarian granulosa cells in cows in relation to production of prolactin or prolactin-like substances in vitro].

Ovarian functions are regulated by a wide variety of substances of hypothalamic, pituitary and intraovarian origin. In particular, prolactin (PRL) plays an important role in the control of ovaries. The aim of our in-vitro experiments was to prove a possibility of PRL production by bovine granulosa cells and to search into the endocrine regulators of this process. In the course of experiment 1 it was observed that the marked time-dependent accumulation of immunoreactive PRL took place during long-time cultivation of granulosa cells both in serum-free and in serum-dependent medium. After 12-24 hours of cultivation this level was reduced, but after 120 hours of cell culture the medium PRL-immunoreactivity gradually rose to exceed the starting level 2.1-2.4 times. FSH additions (10-10,000 ng/ml) led to a dramatical rise of PRL-immunoreactivity in a dose-dependent manner. A greater increase in FSH doses (1000 or 10,000 ng/ml) activated this process 14.0-18.0 times. In the other experiments the effects of LH, LH-RH and various nonapeptide hormones on the PRL-like substance production were investigated. LH stimulated PRL-like substance production at a great dose only (10 IU/ml). The lower doses did not have any significant influence on the process. Low doses of oxytocin (1 or 10 IU/ml) blocked, and higher doses (100-1000 IU/ml) stimulated the granulosa PRL-like production. Arginine-8-vasopressin (AVP) (1-1000 ng/ml), arginine-8-vasotocin (AVT) (10-1000 ng/ml), or LH-RH (10-10,000 ng/ml) failed to influence the immunoreative PRL accumulation in the culture medium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Primary structure of chicken pituitary prolactin deduced from the cDNA sequence. Conserved and specific amino acid residues in the domains of the prolactins.

The perform of chicken prolactin (PRL) deduced from the cDNA sequence contains a signal peptide of 30 amino acid residues followed by a mature PRL of 199 residues. Chicken PRL shows 77, 68, 67, 58, and 31% identity of amino acid sequence with whale, human, ovine, rat, and salmon PRLs, respectively. Elucidation of the primary structure of avian PRL enabled extended analysis of the specific and conserved amino acid residues and domains of the PRL molecules. The mammalian, teleostean, and avian PRLs share 32 common residues, and these conserved residues are observed to cluster in four distinct domains (PD1 to PD4), corresponding to four of five conserved domains of the growth hormones. Of the 32 residues, 8 residues in the PD2 and PD4 domains, including 4 cysteines, are conserved by other members of the growth hormone family, which indicates that these 8 residues may be essential for common structural features of the gene family. On the other hand, 13 other residues distributed among all four domains are conserved almost exclusively in the PRLs, suggesting that these residues are indispensable for specific binding of the PRLs to their receptors.

Amino Acid Sequence↗
PubMed1987

Familial occurrence of big-big prolactin as the predominant immunoreactive human prolactin species in blood.

The occurrence of big-big prolactin (PRL) as the major form of circulating immunoactive PRL has been described in ovulatory hyperprolactinemia. In this study, we have analyzed the heterogeneity of circulating human PRL in 17 members of three families in which one member, bearing galactorrhea-hyperprolactinemic syndrome, was known to have serum big-big PRL as the predominant circulating species. Gel filtration patterns of serum samples of all subjects revealed the presence of significant proportions of big-big PRL in more than one member of the same family, thus suggesting the familial occurrence of big-big as the predominant immunoreactive PRL species in blood.

Adult↗
PubMed1987

Effects of thyroidectomy on the metabolic clearance rate of prolactin and prolactin release in the rat.

The effects of thyroidectomy on both the secretion of rat prolactin (PRL) in vivo and the release of PRL from rat anterior pituitary glands (Aps) in vitro in the absence of ovarian steroids were studied. Rats were ovariectomized (Ovx) 42 days after thyroidectomy or sham-thyroidectomy. On day 15 following ovariectomy the rats were either decapitated for examining the in vitro release of PRL from AP or anesthetized for measuring the metabolic clearance rate (MCR) of rat PRL. After decapitation, blood samples were collected and APs were incubated with or without the extract of rat medial basal hypothalamus (rHE) at 37 degrees C for 4 h. The MCR of iodinated rat PRL was determined by a single injection method. Blood samples were collected by heart puncture at frequent intervals. Serum PRL concentrations of decapitated thyroidectomized-ovariectomized (TX-Ovx) rats were 56% lower than those found in Ovx rats. Thyroidectomy in Ovx rats resulted in a significant reduction of the spontaneous release of PRL from AP. The rHE decreased PRL levels in the medium after incubation with APs from sham Tx rats, but not those from Tx rats. MCR of PRL was reduced in Ovx rats by thyroidectomy. These results indicate that thyroidectomy reduces the spontaneous release of rat PRL by AP and secretion rate of rat PRL in the absence of ovarian steroids.

Animals↗
PubMed1983

Circadian rhythms in plasma prolactin, luteinizing hormone and hypophyseal prolactin levels in lactating rats.

During a 24 h period lactating rats were decapitated at 2 h intervals and the trunk blood and pituitaries were collected. Suckling activity was registered at the time of sacrifice. Plasma prolactin (PRL), LH and hypophyseal (HYP) PRL levels were measured by RIA. The trough of the plasma PRL curve was at 09.30 h and was followed by about 4.5-fold elevation by 13.30 (the lights were on from 03.30 to 17.30). The plasma PRL levels showed 2.5-fold decrease by 19.30 h. The HYP PRL concentration exhibited 3.5-fold elevation from 01.30 to 05.30 h. After this peak concentration, the HYP PRL showed a 4-fold decrease at 11.30 h. A statistically non-significant rhythm was found in the plasma LH levels. Our data suggest that there are circadian rhythms in the plasma and HYP PRL levels of lactating rats in the early lactation period. The two rhythms are in an 8 h phase shift. Neither these rhythms nor the LH levels depended on the actual suckling activity of freely behaving lactating rats.

Animals↗
PubMed1980

Characterization of antisera against bovine prolactin for in vivo studies on prolactin function in the rat.

The IgG fraction of rabbit antisera to bovine prolactin (PRL), intended for in vivo studies on the role of PRL in the rat, was prepared and characterized in vitro and in vivo. The antibodies showed a strong reaction with bovine PRL in double diffusion, immunoelectrophoresis, radioimmunoassay and passive haemagglutination using bovine PRL-coated erythrocytes. In indirect immunofluorescence on paraffin sections of bovine pituitary glands the antibodies could be used for the detection of PRL-producing cells. Cross-reaction with rat PRL was observed in passive haemagglutination with rat PRL-coated erythrocytes and in indirect immunofluorescence on rat pituitary gland, but not in any of the other test systems. The ability of the antibodies to neutralize homologous, i.e. bovine, PRL was tested in lactating rats depleted of endogenous PRL by bromergocriptin treatment. The impaired lactation performance of such animals can be restored by substitution with bovine PRL. If the bovine PRL used for substitution was complexed with anti-bovine PRL-IgG, it lost its biological activity. On the other hand, injections of even high amounts of the antibodies into lactating rats failed to reveal any effect on lactation. It is concluded that either the antibodies do not cross-react with circulating rat PRL in contrast to pituitary PRL (preprolactin?) or that the cross-reacting antibody-populations(s) lack(s) the ability to neutralize the biological function of rat PRL.

Animals↗
PubMed1996

Dual Effect of Prolactin on Protein Kinase C Activity in CHO Cells Expressing Functional Prolactin Receptors.

We investigated the effects of prolactin (PRL) on the protein kinase C (PKC) activity in Chinese hamster ovary (CHO-E32) cells stably transfected with rabbit mammary gland PRL receptor cDNA. These cells express a functional long form of PRL-R. A 10-min to 2-hour treatment with 5 nM PRL resulted in the translocation of PKC activity from the cytosol to the membrane. Longer treatment (10-24 h) with the same concentration of PRL decreased the PKC activity in both particulate and cytoplasmic fractions. The PRL effect was dose dependent: maximal action was obtained with 1-10 nM. The PRL-induced activation of PKC was blocked by 20 nM staurosporine, a PKC inhibitor. Two inhibitors of tyrosine kinase, herbimycin A (1.75 &mgr;M) and genistein (100 &mgr;M), had no effect on PRL-induced activation of PKC. Copyright 1996 S. Karger AG, Basel

Journal Article↗
PubMed2002

Prolactin-producing pituitary adenoma associated with prolactin cell hyperplasia.

A 24-yr-old woman with amenorrhea, galactorrhea, hyperprolactinemia, and sellar mass underwent transsphenoidal surgery. Histologic, immunohistochemical, and electron microscopic investigation revealed a well-differentiated, sparsely granulated prolactin (PRL) cell adenoma of the pituitary showing conclusive PRL immunoreactivity. In the nontumorous adenohypophysis PRL cell hyperplasia was noted. Marked differences were evident between the neoplastic and hyperplastic areas. The tumor consisted of sparsely granulated PRL cells immunoreactive only for PRL. As demonstrated by immunoelectron microscopy, the hyperplastic area comprised monohormonal sparsely granulated PRL cells as well as bihormonal mammosomatotrophs immunoreactive for both PRL and growth hormone. The MIB-1 index was higher whereas microvessel density was lower in the adenoma as compared with the hyperplastic area. In addition, the nontumorous area showed lymphocytic infiltration whereas inflammatory reaction was not seen in the adenoma. This case represents a rare association of a PRL cell adenoma and PRL cell hyperplasia. The fact that these two lesions were contiguous in the surgically removed material raises the possibility that hyperplasia can precede and transform into adenoma.

Adult↗
PubMed1987

Binding of prolactin and monoclonal antibody to prolactin receptors immobilized on a nitrocellulose membrane filter.

Mammary prolaction (PRL) receptors in 3-[(3-cholamidopropyl)dimethylammonio]propanesulfonic acid (Chaps) extract were immobilized on a nitrocellulose (NC) filter, and a binding assay using the filter-bound receptors was carried out in the absence of detergent. PRL binding to the receptors was dependent on the quantity of the receptors and the PRL added to the filters. The filter-bound receptors retained the specificity of binding to peptide hormones. Scatchard analysis showed that the number of PRL receptors and the dissociation constant for PRL binding are essentially unchanged after immobilization on a NC filter, indicating that the PRL binding site does not participate in the binding to the NC filter and is equally available for PRL binding. The monoclonal antibody (MAb) against the PRL receptor was able to bind specifically to the Chaps-solubilized and filter-bound PRL receptors, as shown by curvilinear Scatchard plots. Immobilization on NC filters permits direct detection and characterization of the soluble PRL receptor using labeled PRL or MAb.

Animals↗
PubMed2003

Developmental ontogeny of prolactin and prolactin receptor in the sea bream (Sparus aurata).

The expression of PRL and its receptor (PRLR) were characterised during sea bream embryonic and larval development, by semi-quantitative and quantitative RT-PCR, respectively, until 46 days post-hatch (DPH). Immunocytochemistry with antisera specific for sea bream PRLR was carried out with larval sections from hatching up to 46 DPH. A single transcript of PRL (1.35 Kb) and PRLR (2.8 Kb) identical to the transcripts previously characterised in adult tissue, are present in sea bream embryos and larvae. PRL expression is first detectable at neurula and in all samples collected thereafter. The lowest levels of PRL mRNA are detected in sea bream embryos up until neurula when expression starts to increase. The maximal levels of PRL expression were detected at 24 DPH. PRLR transcripts first appear at 12h post-fertilisation (0.002 rho mol/microg total larvae RNA) (blastula) and increase significantly during gastrulation (0.245 rho mol/microg total larvae RNA) reaching a maximum at 2 DPH (0.281 rho mol/microg total larvae RNA). After hatching a significant reduction in PRLR expression is observed which reaches a minimum at 4 DPH (0.103 rho mol/microg total larvae RNA), gradually increasing thereafter. Immunocytochemistry revealed the presence of PRLR in early post-hatching stages of larvae in tissues derived from all three germ layers.

Aging↗
PubMed1982

Intracellular localization of prolactin receptor and prolactin in the rat ovary by immunocytochemistry.

The localization of the PRL receptor as well as of PRL has been studied by immunoperoxidase techniques in the ovaries of cycling, pregnant, and lactating rats. Specific antisera to the receptor and to the hormone were used. By light microscopy, immunostaining for the PRL receptor coincided with that for the hormone. Staining was found intracellularly in most components of the ovary, except the theca, and was most striking in the luteal cells. Both PRL and its receptor were concentrated heavily in the ovum. Beginning 24-36 h postpartum, there was a change in the pattern of luteal cell staining, with a shift in the intensity of staining products to the periphery of the luteal cell, giving a ring appearance to these cells. The results suggest roles for PRL in ovarian function involving both maintenance of the corpus luteum and maturation of the ovum. This study also demonstrates the intracellular localization of a polypeptide hormone in association with its specific receptor.

Animals↗