scholarly journals The hormonal status modulates the effect of neurokinin A on prolactin secretion in female rats

1998 ◽  
Vol 159 (3) ◽  
pp. 389-395 ◽  
Author(s):  
D Pisera ◽  
S Theas ◽  
A De Laurentiis ◽  
M Lasaga ◽  
B Duvilanski ◽  
...  
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
In Vitro Release ◽  
Anterior Pituitary Gland ◽  
Female Rats ◽  
Male Rats ◽  
Neurokinin A ◽  
Pituitary Cells ◽  
Anterior Pituitary Cells ◽  
Ovx Rats

We have previously reported that neurokinin A (NKA), a tachykinin closely related to substance P, increases the release of prolactin (PRL) from the anterior pituitary gland of male rats, but not from pituitaries of ovariectomized (OVX) female rats. In this study, we evaluated the influence of estrogens in the action of NKA on PRL secretion in female rats. NKA stimulated the in vitro release of PRL from pituitary glands of OVX-chronically estrogenized rats, and of proestrus and estrus rats, but had no effect in anterior pituitaries of diestrus rats. In addition, we observed that cultured anterior pituitary cells of OVX rats responded to NKA only when they were incubated for 3 days in the presence of estradiol 10(-9) M. This effect was blocked by L-659,877, an NK-2 receptor antagonist. We also studied the action of NKA on PRL release during lactation. The response of anterior pituitary cells to NKA was variable over this period. The maximal sensitivity to NKA was observed at day 10 of lactation. Furthermore, the blockade of endogenous NKA by the administration of an anti-NKA serum to lactating rats reduced the PRL surge induced by the suckling stimulus. These results show that the responsiveness of the anterior pituitary gland of female rats to NKA is modulated by the endocrine environment, and suggest that NKA may participate in the control of PRL secretion during the estrus cycle and lactation.

scholarly journals Intermedin/Adrenomedullin-2 Inhibits Growth Hormone Release from Cultured, Primary Anterior Pituitary Cells

Endocrinology ◽  
2006 ◽  
Vol 147 (2) ◽  
pp. 859-864 ◽  
Author(s):  
Meghan M. Taylor ◽  
Sara L. Bagley ◽  
Willis K. Samson
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Hormone Secretion ◽  
Prolactin Secretion ◽  
Anterior Pituitary Gland ◽  
Male Rats ◽  
Pituitary Cells ◽  
Anterior Pituitary Cells ◽  
Peptide Family

Intermedin (IMD), a novel member of the adrenomedullin (AM), calcitonin gene-related peptide (CGRP), amylin (AMY) peptide family, has been reported to act promiscuously at all the known receptors for these peptides. Like AM and CGRP, IMD acts in the circulation to decrease blood pressure and in the brain to inhibit food intake, effects that could be explained by activation of the known CGRP, AM, or AMY receptors. Because AM, CGRP, and AMY have been reported to affect hormone secretion from the anterior pituitary gland, we examined the effects of IMD on GH, ACTH, and prolactin secretion from dispersed anterior pituitary cells harvested from adult male rats. IMD, in log molar concentrations ranging from 1.0 pm to 100 nm, failed to significantly alter basal release of the three hormones. Similarly, IMD failed to significantly alter CRH-stimulated ACTH or TRH-stimulated prolactin secretion in vitro. However, IMD concentration-dependently inhibited GHRH-stimulated GH release from these cell cultures. The effects of IMD, although requiring higher concentrations, were as efficacious as those of somatostatin and, like somatostatin, may be mediated, at least in part, by decreasing cAMP accumulation. These actions of IMD were not shared by other members of the AM-CGRP-AMY family of peptides, suggesting the presence of a novel, unique IMD receptor in the anterior pituitary gland and a potential neuroendocrine action of IMD to interact with the hypothalamic mechanisms controlling growth and metabolism.

Further studies on the regulation, localization and function of the TRH-like peptide pyroglutamyl-glutamyl-prolineamide in the rat anterior pituitary gland

1995 ◽  
Vol 146 (2) ◽  
pp. 293-300 ◽  
Author(s):  
J M M Rondeel ◽  
W Klootwijk ◽  
E Linkels ◽  
P H M Jeucken, W ◽  
L J Hofland ◽  
...  
Keyword(s):  
Body Weight ◽  
Luteinizing Hormone ◽  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Anterior Pituitary Gland ◽  
Female Rats ◽  
Pituitary Cells ◽  
Anterior Pituitary Cells ◽  
Lhrh Antagonist

Abstract Recent evidence shows that thyrotrophin-releasing hormone (TRH) immunoreactivity in the rat anterior pituitary gland is accounted for by the TRH-like tripeptide prolineamide-glutamyl-prolineamide (pGlu-Glu-ProNH2, <EEP-NH2). The present study was undertaken to investigate further the regulation, localization and possible intrapituitary function of <EEP-NH2. Anterior pituitary levels of <EEP-NH2 were determined between days 5 and 35 of life, during the oestrous cycle and after treatment with the luteinizing hormone-releasing hormone (LHRH) antagonist Org 30276. Treatment of adult males with the LHRH antagonist either for 1 day (500 μg/100 g body weight) or for 5 days (50 μg/100 g body weight) reduced anterior pituitary <EEP-NH2 levels by 25–30% (P<0·05 versus saline-treated controls). Anterior pituitary <EEP-NH2 increased between days 5 and 35 of life. In females, these levels were 2- to 3-fold higher (P<0·05) than in males between days 15 and 25 after birth; these changes corresponded with the higher plasma follicle-stimulating hormone (FSH) levels in the female rats. After day 25, <EEP-NH2 levels in female rats decreased in parallel with a decrease in plasma FSH. Injections with the LHRH antagonist (500 μg/100 g body weight), starting on day 22 of life, led to reduced contents of <EEP-NH2 in the anterior pituitary gland of female rats on days 26 and 30 (55 and 35% decrease respectively). Levels of <EEP-NH2 in the anterior pituitary gland did not change significantly during the oestrous cycle. Fractionation of anterior pituitary cells by unit gravity sedimentation was found to be compatible with the localization of <EEP-NH2 in gonadotrophs. In vitro, <EEP-NH2 dose-dependently inhibited TRH-stimulated growth hormone (GH) release from anterior pituitary cells obtained from neonatal rats, but no consistent effects were seen on the in vitro release of luteinizing hormone (LH), FSH, prolactin (PRL) or thyroid-stimulating hormone (TSH) under basal or TRH/LHRH-stimulated conditions. Furthermore, <EEP-NH2 did not affect the in vitro hormone release by anterior pituitary cells obtained from adult rats. In vivo, <EEP-NH2 (0·3–1·0 μg intravenously) did not affect plasma PRL, TSH, LH, FSH and GH in adult male rats. We conclude that <EEP-NH2 in the anterior pituitary gland is regulated by LHRH, is probably localized in gonadotrophs and may play a (paracrine) role in neonatal GH release. Journal of Endocrinology (1995) 146, 293–300

Bradykinin stimulates phosphoinositide metabolism and prolactin secretion in rat anterior pituitary cells

1989 ◽  
Vol 2 (1) ◽  
pp. 47-53 ◽  
Author(s):  
T.H. Jones ◽  
B. L. Brown ◽  
P. R. M. Dobson
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Inositol Phosphate ◽  
Prolactin Secretion ◽  
Male Rats ◽  
Pituitary Cells ◽  
Phosphoinositide Metabolism ◽  
Phosphate Accumulation ◽  
Anterior Pituitary Cells ◽  
Inositol Phosphate Accumulation

ABSTRACT Bradykinin stimulated prolactin secretion from monolayer cultures of rat anterior pituitary cells, the stimulation being greater from the cells of male rats. This stimulated secretion was accompanied by a rise in total inositol phosphate accumulation, suggesting that the action of bradykinin is mediated by phosphoinositide hydrolysis. The increase in inositol phosphate accumulation was biphasic; a further sharp rise occurred when the concentration of bradykinin exceeded 1 μmol/l. This may indicate that bradykinin acts on other cell types in the pituitary gland. Bradykinin had no effect on growth hormone secretion from cells of normal pituitary glands, or on prolactin secretion and phosphoinositide metabolism in GH3 rat pituitary tumour cells. Bradykinin receptor antagonists (both B1 and B2) had no effect on either bradykinin-stimulated inositol phosphate accumulation or prolactin secretion. Kallikreins, the enzymes responsible for the generation of kinins, are known to be present in the adenohypophysis. Therefore, the results presented here would suggest that kinins may have a role as paracrine agents in the pituitary gland.

Estrogens sensitize anterior pituitary gland to apoptosis

2004 ◽  
Vol 287 (4) ◽  
pp. E767-E771 ◽  
Author(s):  
D. Pisera ◽  
M. Candolfi ◽  
S. Navarra ◽  
J. Ferraris ◽  
V. Zaldivar ◽  
...  
Keyword(s):  
Pituitary Gland ◽  
Estrous Cycle ◽  
Anterior Pituitary ◽  
Anterior Pituitary Gland ◽  
Female Rats ◽  
Cell Renewal ◽  
Apoptotic Response ◽  
Ovx Rats ◽  
17Β Estradiol ◽  
Induced Apoptosis

Tissue homeostasis results from a balance between cell proliferation and cell death by apoptosis. Estradiol affects proliferation as well as apoptosis in hormone-dependent tissues. In the present study, we investigated the apoptotic response of the anterior pituitary gland to lipopolysaccharide (LPS) in cycling female rats, and the influence of estradiol in this response in ovariectomized (OVX) rats. The OVX rats were chronically estrogenized with implanted Silastic capsules containing 1 mg of 17β-estradiol (E2). Cycling or OVX and E2-treated rats were injected with LPS (250 μg/rat ip). Apoptosis was determined by the terminal deoxynucleotidyl-mediated dUTP nick-end labeling (TUNEL) method in sections of the anterior pituitary gland and spleen. Chronic estrogenization induced apoptosis in the anterior pituitary gland. Acute endotoxemia triggered apoptosis of cells in the anterior pituitary gland of E2-treated rats but not of OVX rats. No differences were observed in the apoptotic response to LPS in spleen between OVX and E2-treated rats. The apoptotic response of the anterior pituitary to LPS was variable along the estrous cycle, being higher at proestrus than at estrus or diestrus I. Approximately 75% of the apoptotic cells were identified as lactotropes by immunofluorescence. In conclusion, our results indicate that estradiol induces apoptosis and enables the proapoptotic action of LPS in the anterior pituitary gland. Also, our study suggests that estrogens may be involved in anterior pituitary cell renewal during the estrous cycle, sensitizing lactotropes to proapoptotic stimuli.

Regulation of the TRH-like peptide pyroglutamyl-glutamyl-prolineamide in the rat anterior pituitary gland

1995 ◽  
Vol 145 (1) ◽  
pp. 43-49 ◽  
Author(s):  
J M M Rondeel ◽  
W Klootwijk ◽  
E Linkels ◽  
G A C van Haasteren ◽  
W J de Greef ◽  
...  
Keyword(s):  
Pituitary Gland ◽  
Sex Difference ◽  
Anterior Pituitary ◽  
Biological Significance ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Anterior Pituitary Gland ◽  
Female Rats ◽  
Male Rats ◽  
Rat Pituitary

Abstract TRH-like peptides share the N- and C-terminal amino acids with TRH (pGlu-His-Pro-NH2) but differ in the middle amino acid residue. One of them, pGlu-Glu-Pro-NH2 (<EEP-NH2; EEP) is present in the rat pituitary gland, but its biological significance is unknown. We investigated the localization and regulation of this tripeptide in the rat pituitary gland. To distinguish between TRH and EEP two antisera were used for RIA: specificity of antiserum 4319 for the TRH-like peptides pGlu-Phe-Pro-NH2 and EEP was equal to or greater than that for TRH, whereas antiserum 8880 is TRH-specific. Our RIA data showed the presence of a TRH-like peptide in the anterior pituitary gland (AP) and of TRH in the posterior pituitary gland (PP). The TRH-like peptide in the AP was identified on anion-exchange chromatography and subsequent HPLC as EEP. Pathophysiological conditions such as altered thyroid and adrenal status and suckling did not affect pituitary gland levels of EEP. In general, however, there is a clear sex difference: levels of EEP are higher in male than in female rats. In both sexes gonadectomy leads to a substantial two- to threefold rise in EEP levels, abolishing the sex difference. Testosterone administration to gonadectomized male rats normalizes levels of EEP again. Disulfiram, an inhibitor of the enzyme peptidylglycine α-amidating monooxygenase, reduced levels of EEP in the AP by approximately 50%. In conclusion: 1) the TRH-like peptide EEP is present in the AP, whereas TRH is confined to the PP, 2) levels of EEP in the AP are regulated by sex steroids, 3) EEP is actively amidated in the AP and thus seems to be produced from a glycine-extended progenitor sequence. Journal of Endocrinology (1995) 145, 43–49

scholarly journals Living-cell imaging of transgenic rat anterior pituitary cells in primary culture reveals novel characteristics of folliculo-stellate cells

2009 ◽  
Vol 204 (2) ◽  
pp. 115-123 ◽  
Author(s):  
Kotaro Horiguchi ◽  
Motoshi Kikuchi ◽  
Kenji Kusumoto ◽  
Ken Fujiwara ◽  
Tom Kouki ◽  
...  
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Fluorescent Protein ◽  
Anterior Pituitary Gland ◽  
Pcr Analysis ◽  
Transgenic Rat ◽  
Pituitary Cells ◽  
Surface Receptors ◽  
Reverse Transcription Pcr ◽  
Anterior Pituitary Cells

Folliculo-stellate (FS) cells in the anterior pituitary gland appear to possess multifunctional properties. Recently, the development of transgenic rats (S100b–green fluorescent protein (GFP) rats) that express GFP specifically in FS cells in the anterior pituitary gland has allowed us to distinguish and observe living FS cells in other kinds of pituitary cells. We used S100b–GFP rats to investigate the topographic affinity of FS cells for other pituitary cells. We observed living FS cells in enzymatically dispersed anterior pituitary cells of S100b–GFP rats under a fluorescent microscope, and noted that FS cells markedly extended and contracted cytoplasmic processes and formed interconnections with neighboring FS cells. In addition, FS cells adhered to small clusters of GFP-negative cells, which were primarily hormone-producing cells, and these clusters further aggregated during the course of cytoplasmic contraction. In the presence of laminin, fibronectin, and varying types of collagen, FS cells showed marked changes in shape and specific proliferative activity; however, GFP-negative cells did not. On reverse transcription-PCR analysis and immunohistochemistry, FS cells were shown to express integrin subunits, which are the cell surface receptors for extracellular matrix (ECM). In the anterior pituitary gland, FS cells and the various types of hormone-producing cells generate a unique topography in the presence of basement membrane components and interstitial collagens. The novel characteristics of FS cells observed in the present study suggest that in the anterior pituitary gland, FS cells play important roles in determining and/or maintaining local cellular arrangement in the presence of ECM components.

scholarly journals Ghrelin Receptor Expression and Colocalization with Anterior Pituitary Hormones Using a GHSR-GFP Mouse Line

Endocrinology ◽  
2012 ◽  
Vol 153 (11) ◽  
pp. 5452-5466 ◽  
Author(s):  
Alex Reichenbach ◽  
Frederik J. Steyn ◽  
Mark W. Sleeman ◽  
Zane B. Andrews
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Pituitary Hormones ◽  
Anterior Pituitary Gland ◽  
Receptor Expression ◽  
Egfp Expression ◽  
Pituitary Cells ◽  
Anterior Pituitary Hormones ◽  
Anterior Pituitary Cells ◽  
Males And Females

Abstract Ghrelin is the endogenous ligand for the GH secretagogue receptor (GHSR) and robustly stimulates GH release from the anterior pituitary gland. Ghrelin also regulates the secretion of anterior pituitary hormones including TSH, LH, prolactin (PRL), and ACTH. However, the relative contribution of a direct action at the GHSR in the anterior pituitary gland vs. an indirect action at the GHSR in the hypothalamus remains undefined. We used a novel GHSR-enhanced green fluorescent protein (eGFP) reporter mouse to quantify GHSR coexpression with GH, TSH, LH, PRL, and ACTH anterior pituitary cells in males vs. females and in chow-fed or calorie-restricted (CR) mice. GHSR-eGFP-expressing cells were only observed in anterior pituitary. The number of GHSR-eGFP-expressing cells was higher in male compared with females, and CR did not affect the GHSR-eGFP cell number. Double staining revealed 77% of somatotrophs expressed GHSR-eGFP in both males and females. Nineteen percent and 12.6% of corticotrophs, 21% and 9% of lactotrophs, 18% and 19% of gonadotrophs, and 3% and 9% of males and females, respectively, expressed GHSR-eGFP. CR increased the number of TSH cells, but suppressed the number of lactotrophs and gonadotrophs, expressing GHSR-eGFP compared with controls. These studies support a robust stimulatory action of ghrelin via the GHSR on GH secretion and identify a previously unknown sexual dimorphism in the GHSR expression in the anterior pituitary. CR affects GHSR-eGFP expression on lactotrophs, gonadotrophs, and thyrotrophs, which may mediate reproductive function and energy metabolism during periods of negative energy balance. The low to moderate expression of GHSR-eGFP suggests that ghrelin plays a minor direct role on remaining anterior pituitary cells.

Pro-oestrous-specific role for polyamines in mediating the secretion of prolactin induced by thyrotrophin-releasing hormone in the rat

1993 ◽  
Vol 137 (1) ◽  
pp. 133-139 ◽  
Author(s):  
G. A. Wynne-Jones ◽  
A. M. Gurney
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Prolactin Secretion ◽  
Anterior Pituitary Gland ◽  
Oestrous Cycle ◽  
Male Rats ◽  
Pituitary Cells ◽  
Plasma Prolactin ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone

ABSTRACT The activity of ornithine decarboxylase (ODC) in the rat anterior pituitary gland varies during the oestrous cycle, with a rise in activity seen at pro-oestrus. This enzyme, which is rate-limiting for the synthesis of the polyamines, can be specifically and irreversibly blocked by α-difluoromethylornithine (DFMO). A previous study showed that when this drug was administered to rats in vivo on the afternoon of pro-oestrus, it suppressed the normal surge in plasma prolactin levels that occurred later that day. The effect of DFMO was associated with reduced levels of putrescine in the anterior pituitary gland, suggesting that ODC activity in the lactotroph might be involved in the prolactin surge. We have examined the effects of DFMO on the secretion of prolactin from anterior pituitary cells, isolated either from male rats or from females at different stages of the oestrous cycle. The drug was found to reduce prolactin secretion stimulated by thyrotrophin-releasing hormone (TRH), but only in cells isolated from pro-oestrous animals and only for 2 days after cell isolation. Basal secretion was unaffected by DFMO. The results imply that ODC is important for TRH-stimulated prolactin secretion at pro-oestrus, and it is specific for pro-oestrus. The prolactin surge could therefore be influenced by this ODC-dependent effect of TRH. The pro-oestrous-specific response to TRH may be a consequence of the increased ODC activity seen at this time. Alternatively, the increased ODC activity could be a consequence of coupling to TRH receptors, which are known to increase in number at pro-oestrus. Journal of Endocrinology (1993) 137, 133–139

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