Catecholamines and pituitary function. IV. Effects of low-dose dopamine infusion and long-term bromocriptine treatment on the abnormal thyrotroph (TSH) dynamics in patients with pathological hyperprolactinaemia

1986 ◽  
Vol 111 (2) ◽  
pp. 154-161 ◽  
Author(s):  
Ildo Nicoletti ◽  
Paolo Filipponi ◽  
Leone Fedeli ◽  
Franca Ambrosi ◽  
Camillo Giammartino ◽  
...  
Keyword(s):  
Anterior Pituitary ◽  
Low Dose ◽  
Physiological Role ◽  
Serum Concentrations ◽  
Trh Test ◽  
Synthesis Inhibitor ◽  
Tsh Secretion ◽  
Insight Into

Abstract. In order to gain further insight into the role of dopamine (DA) in the control of TSH release and to investigate whether an increased or defective DA inhibition on pituitary thyrotrophs may be considered responsible for the abnormal TSH dynamics in pathological hyperprolactinaemia, we examined the effect of low-dose DA infusion on TRH stimulated TSH secretion in normally cycling women and in patients with pathological hyperprolactinaemia. The effect of long-term bromocriptine therapy on TSH dynamics was also evaluated in a selected group of hyperprolactinaemic women. Fifty-two hyperprolactinaemic patients with no other signs of pituitary or thyroid dysfunction had significantly higher mean TSH serum concentrations and mean TSH peak values after TRH administration than 75 healthy controls. Furthermore, the TSH rises induced by the DA-synthesis inhibitor α-methyl-p-tyrosine (AMPT, 500 mg orally) were enhanced in both prolactinoma and 'idiopathic hyperprolactinaemia' patients as compared with controls. There was a positive correlation between the TRH- and AMPT-induced TSH rises in the hyperprolactinaemic group. Low-dose DA infusion (0.1 μg/kg min) reduced TSH response to TRH in both regularly cycling women and patients with hyperprolactinaemic amenorrhoea. Long-term bromocriptine therapy (2.5 mg tid over 60– 150 days) not only normalized serum Prl levels, but also reduced the TSH response to TRH in 7 hyperprolactinaemic women who had presented exaggerated TSH responses to the basal TRH test. These findings confirm that DA plays a physiological role in the inhibition of TSH release, probably at the level of the anterior pituitary. The fact that both low-dose DA infusion and long-term bromocriptine treatment effectively reduced TSH release in hyperprolactinaemic patients seems to indicate that endogenous DA inhibition of pituitary thyrotrophs is reduced rather than enhanced in pathological hyperprolactinaemia.

Effect of hypothalamic neuropeptides on corticotrophin release from quarters of rat anterior pituitary gland in vitro

1984 ◽  
Vol 100 (2) ◽  
pp. 219-226 ◽  
Author(s):  
S. A. Nicholson ◽  
T. E. Adrian ◽  
B. Gillham ◽  
M. T. Jones ◽  
S. R. Bloom
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Low Dose ◽  
Physiological Role ◽  
Anterior Pituitary Gland ◽  
High Concentration ◽  
Response Curves ◽  
Corticotrophin Releasing Factor ◽  
Basal Release

ABSTRACT The effect of six hypothalamic peptides on the basal release of ACTH and that induced by arginine vasopressin (AVP) or by ovine corticotrophin releasing factor (oCRF) from fragments of the rat anterior pituitary gland incubated in vitro was investigated. Dose–response curves to AVP and to oCRF were obtained, and the response to a low dose of oCRF was potentiated by a low dose of AVP. Basal release of ACTH was not affected by any of the peptides in concentrations in the range 10−12 to 10−6 mol/l, and only substance P (SP) and somatostatin (SRIF) inhibited significantly the response to oCRF in a dose-related manner. The responses to a range of doses of oCRF or AVP were reduced by 10−8 and 10 − 6 mol SP or SRIF/1, and to a greater extent by the higher dose. Except in the case of 10−6 mol SRIF/1 on the response to AVP, the response was not further diminished by preincubation of the tissue with the peptide before the stimulating agent was added. The inhibition of the responses to AVP or oCRF by 10−9 mol SP/1 was not potentiated by its combination with either 5 × 10−10 or 10−8 mol SRIF/1; the inhibitory effects were merely additive. The results suggest that although SRIF and SP are able to modulate the release of ACTH from the anterior pituitary gland, they do so only at a high concentration. In the case of SRIF these concentrations are several orders of magnitude higher than those reported to be present in the hypophysial portal blood and therefore a physiological role for this peptide in the control of ACTH secretion is unlikely. J. Endocr. (1984) 100, 219–226

Investment opportunities for student housing in Europe

2018 ◽  
Vol 36 (6) ◽  
pp. 578-584 ◽  
Author(s):  
Nick French ◽  
Geetha Bhat ◽  
Gurpreet Matharu ◽  
Filipe Ortigão Guimarães ◽  
David Solomon
Keyword(s):  
Student Housing ◽  
European Countries ◽  
Content Type ◽  
Market Requirements ◽  
Investment Opportunities ◽  
Property Markets ◽  
Practical Implications ◽  
Insight Into

Purpose The purpose of this paper is to provide an insight into how the demographic of international and home students in the major university cities in three European countries (France, Spain and Germany) offers investors an opportunity to provide students housing. This paper looks at how a mobile and demanding student clientele now demands, well priced, good quality and purpose built accommodation during their studies at University. This offers a good property investment opportunity. Design/methodology/approach This practice briefing is an overview of the demand factors that are creating opportunities in France, Spain and Germany. Findings This paper analyses the link between the under provision of purpose built student housing and an opportunity to develop a long-term cash flow producing investment asset. Practical implications The role of the property developers and investors is to successfully identify trends and demands and provide the assets that meet the market requirements. This paper looks at the meeting point in three major European countries for this latent and, currently, poorly served demand. Originality/value This provides guidance on how investment opportunities develop in non-traditional property markets.

scholarly journals Etiology of differentiated carcinoma of the thyroid current apprehension

2003 ◽  
Vol 50 (3) ◽  
pp. 51-55
Author(s):  
Ruben Han
Keyword(s):  
Animal Experiments ◽  
Growth Control ◽  
Significant Risk ◽  
Ionising Radiation ◽  
Sodium Iodide Symporter ◽  
Chemical Agents ◽  
Tsh Secretion ◽  
Genetic And Environmental Factors

It is apparent that in the last decade carcinoma of the thyroid is becoming increasingly prevalent. The multistage complex theory of thyroid carcinogenesis is based on observations made on cohort patients studies and during animal experiments over a period of last fifty years. The process of thyroid oncogenesis is conceived to be a series of events induced by genetic and environmental factors which alter follicular cells division and growth control. These factors can be considered as initiators (chemical agents and ionising radiation) and promoters (some goitrogenes and drugs). The first class of factors induce incipient tumorigenesis while the second augments TSH secretion and radically increases tumour growth. Normally silent, intracellular proto-oncogenes (of which Ret/PTC series are the most conceived ones) can become activated by chromosomal translocations, deletions or mutations and can transform normal follicular cell into a condition of uncontrolled division and growth. The most significant known cause of thyroid carcinomas in men is exposure to external or internal ionising radiation. Beside that, long-term iodine deficiency, effects of certain chemical carcinogens, drugs and goitrogenes must be considered as significant risk factors. Possible role of sodium/iodide symporter is becoming an objective of the most recent investigations.

Insight into the physiological role of a compartmentalised ferritin like protein in Rhodospirillum rubrum

2014 ◽  
Vol 31 ◽  
pp. S43-S44
Author(s):  
Jon Marles-Wright ◽  
Didi He ◽  
Atanas Georgiev ◽  
David Clarke
Keyword(s):  
Rhodospirillum Rubrum ◽  
Physiological Role ◽  
Insight Into

scholarly journals History and perspectives of pituitary folliculo-stellate cell research

2005 ◽  
Vol 153 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Wilfried Allaerts ◽  
Hugo Vankelecom
Keyword(s):  
Cell Population ◽  
Anterior Pituitary ◽  
Hormone Secretion ◽  
Physiological Role ◽  
Pituitary Cell ◽  
Stem Cell Population ◽  
Cell Group ◽  
Pituitary Hormone ◽  
Topographical Distribution

Historically, the study of folliculo-stellate (FS) cells of the anterior pituitary dates back to the onset of electron microscopical observation of the pituitary gland. The morphological and electrophysiological characteristics, topographical distribution and contribution to intercellular junctions of these FS cells have been instrumental to the understanding of their putative function. Moreover, many studies have documented the role of FS cells as a source of newly discovered peptides, growth factors and cytokines. Quantitative immunohistochemical observation of FS cells in situ and functional in vitro studies, using either cultured FS cells or cells from an immortalized FS cell line, forwarded the notion of immunophenotypical and functional heterogeneity of the FS cell group. Double immunolabeling with a classical FS cell marker (S-100 protein) and with major histocompatibility complex class II markers characteristic for dendritic cells (DC) have shown a considerable overlap of FS cells with DC. The latter cells are immunocompetent cells belonging to the mononuclear phagocyte system. In this review, the FS cell heterogeneity is discussed with respect to the question of their embryological origin and developmental fate and with respect to the physiological relevance of functionally heterogeneous subpopulations. Recent findings of a myeloid origin of part of the interstitial cells of the anterior pituitary are confronted by other developmental paradigms of pituitary cell differentiation. The possibility that FS cells represent an adult stem cell population of the pituitary is critically examined. Also the physiological role of FS cells in the interferon-γ- and nitric oxide-mediated effects on pituitary hormone secretion is discussed. New approaches for the study of this enigmatic cell group using immortalized cell lines and new markers for an hitherto unrecognized pituitary cell population, the so-called ‘side population’, are evaluated.

Short‐ and long‐term responsiveness to low dose growth hormone (GH) in adult GH deficiency: Role of GH receptor polymorphism

2019 ◽  
Vol 31 (4) ◽  
pp. e12692 ◽  
Author(s):  
Antonio Bianchi ◽  
Antonella Giampietro ◽  
Linda Tartaglione ◽  
Sabrina Chiloiro ◽  
Raffaella Gentilella ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Low Dose ◽  
Gh Deficiency ◽  
Gh Receptor ◽  
Adult Gh Deficiency ◽  
Short And Long Term ◽  
Receptor Polymorphism

Physiological role of galanin in the regulation of anterior pituitary function in humans

1994 ◽  
Vol 266 (1) ◽  
pp. E57-E61 ◽  
Author(s):  
A. Giustina ◽  
M. Licini ◽  
M. Schettino ◽  
M. Doga ◽  
G. Pizzocolo ◽  
...  
Keyword(s):  
Anterior Pituitary ◽  
Physiological Role ◽  
Thyroid Stimulating Hormone ◽  
Pituitary Function ◽  
Slight Reduction ◽  
Baseline Serum ◽  
Releasing Hormone ◽  
Anterior Pituitary Function ◽  
Stimulating Hormone

The aim of our study was to elucidate the physiological role of the neuropeptide galanin in the regulation of anterior pituitary function in human subjects. Six healthy men (age range 26-35 yr, body mass index range 20-24 kg/m2) underwent in random order 1) an intravenous bolus injection of growth hormone-releasing hormone (GHRH)-(1-29)-NH2 (100 micrograms) + thyrotropin-releasing hormone (TRH, 200 micrograms) + luteinizing hormone-releasing hormone (LHRH, 100 micrograms) + corticotropin-releasing hormone (CRH, 100 micrograms), and 2) intravenous saline (100 ml) at time 0 plus either human galanin (500 micrograms) in saline (100 ml) or saline (100 ml) from -15 to +30 min. Human galanin determined a significant increase in serum GH (GH peak: 11.3 +/- 2.2 micrograms/l) from both baseline and placebo levels. No significant differences were observed between GH values after galanin and those after GHRH alone (24.3 +/- 5.2 micrograms/l). Human galanin significantly enhanced the GH response to GHRH (peak 49.5 +/- 10 micrograms/l) with respect to either GHRH or galanin alone. Human galanin caused a slight decrease in baseline serum adrenocorticotropic hormone (ACTH; 16.3 +/- 2.4 pg/ml) and cortisol levels (8 +/- 1.5 micrograms/dl). Galanin also determined a slight reduction in both the ACTH (peak 27 +/- 8 pg/ml) and cortisol (peak 13.8 +/- 1.3 micrograms/dl) responses to CRH. Baseline and releasing hormone-stimulated secretions of prolactin, thyroid-stimulating hormone, LH, and follicle-stimulating hormone were not altered by galanin. Our data suggest a physiological role for the neuropeptide galanin in the regulation of GH secretion in humans.(ABSTRACT TRUNCATED AT 250 WORDS)

The utility of relationships in the creation and maintenance of an event portfolio

2018 ◽  
Vol 36 (2) ◽  
pp. 260-275 ◽  
Author(s):  
Donna M. Kelly ◽  
Sheranne Fairley
Keyword(s):  
Process Model ◽  
Structured Interviews ◽  
Content Type ◽  
Key Stakeholders ◽  
Strategic Goals ◽  
The Creation ◽  
Practical Implications ◽  
Insight Into

Purpose Event portfolios promote synergies among events and stakeholders within a destination in order to maximise resources. The purpose of this paper is to examine the role of relationships in the creation and maintenance of an event portfolio using the four stages of Parvatiyar and Sheth’s (2000) process model of relationship marketing: formation, management and governance, performance evaluation, and evolution. Design/methodology/approach Nine semi-structured interviews were conducted with tourism and government stakeholders involved in the creation and maintenance of an event portfolio within a single destination. Findings The destination outlined clear strategic goals through an event strategy. An Events Board was established to bring together key stakeholders from tourism, events, and government to oversee the development of an event portfolio. The Events Board gave advice to relevant tourism and government stakeholders on which events they should provide funding. Developing relationships was not a stated objective, but the Events Board realised the importance of relationships to create and maintain the destination’s event portfolio. Long-term funding contracts were used as a mechanism to establish relationships and were an impetus for interaction. Relationships were also maintained through dedicated staff who managed the relationships between the destination stakeholders and the events. Practical implications Understanding factors that contribute to the successful creation and maintenance of event portfolios can inform destination stakeholders who are responsible for generating tourism through events. Originality/value Limited research has examined the creation and maintenance of event portfolios. This study provides insight into the central importance of relationships in creating and maintaining an event portfolio.

THE DETERMINATION OF CORTICOTROPHIN-RELEASING ACTIVITY IN STEROID-BLOCKED MICE

1964 ◽  
Vol 46 (1) ◽  
pp. 71-79 ◽  
Author(s):  
Claus Rerup
Keyword(s):  
Synthetic Peptides ◽  
Anterior Pituitary ◽  
Physiological Role ◽  
Weight Basis ◽  
Corticotrophin Releasing Factor ◽  
Lysine Vasopressin ◽  
Threshold Doses ◽  
Transmitter Substance

ABSTRACT The possibility of elaborating a sensitive test for the determination of CRF (Corticotrophin-releasing factor) was investigated in corticosteroid-blocked mice. Two synthetic peptides known to possess corticotrophin-releasing activity (CRA) in the rat, i. e. lysine-vasopressin and histidyl-seryl-lysine-vasopressin (CRA-41) were used as test substances. The results showed that it is possible to perform quantitative estimations of CR-activity and that both the peptides tested are true corticotrophin-releasing substances in mice. Lysine-vasopressin was more potent than its synthetic histidyl-seryl-analogue both on an absolute weight basis and in terms of pressor- or corticotrophin equivalents. Threshold doses for CR-activity of lysine-vasopressin in mice were calculated to be about 4 ng (nanograms). From the findings it appears that in mice, the main blocking action of the glucocorticoid dexamethasone is exerted at hypothalamic or higher centres, and not in the cells of the anterior pituitary gland. It is proposed to abandon arbitrary units for CR-activity and to use vasopressin or hypothalamic extracts as a standard for CRF-assay. The possibility of a physiological role of vasopressin as a transmitter substance for corticotrophin-release is briefly discussed.

scholarly journals Chronic Microcystin-LR Exposure Induces Hepatocarcinogenesis via Increased Gankyrin in Vitro and in Vivo

2018 ◽  
Vol 49 (4) ◽  
pp. 1420-1430 ◽  
Author(s):  
Lixiong He ◽  
Yujing Huang ◽  
Qiaonan Guo ◽  
Hui Zeng ◽  
Chuanfen Zheng ◽  
...  
Keyword(s):  
Low Dose ◽  
Soft Agar ◽  
Tumor Formation ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
L02 Cells ◽  
Insight Into

Background/Aims: Our recent study indicated that the serum microcystin-LR (MC-LR) level is positively linked to the risk of human hepatocellular carcinoma (HCC). Gankyrin is over-expressed in cancers and mediates oncogenesis; however, whether MC-LR induces tumor formation and the role of gankyrin in this process is unclear. Methods: We induced malignant transformation of L02 liver cells via 35 passages with exposure to 1, 10, or 100 nM MC-LR. Wound healing, plate and soft agar colony counts, and nude mice tumor formation were used to evaluate the tumorigenic phenotype of MC-LR-treated cells. Silencing gankyrin was used to confirm its function. We established a 35-week MC-LR exposure rat model by twice weekly intraperitoneal injection with 10 μg/kg body weight. In addition, 96 HCC patients were tested for tumor tissue gankyrin expression and serum MC-LR levels. Results: Chronic low-dose MC-LR exposure increased proliferation, mobility, clone and tumor formation abilities of L02 cells as a result of gankyrin activation, while silencing gankyrin inhibited the carcinogenic phenotype of MC-LR-treated cells. MC-LR also induced neoplastic liver lesions in Sprague-Dawley rats due to up-regulated gankyrin. Furthermore, a trend of increased gankyrin was observed in humans exposed to MC-LR. Conclusion: These results suggest that MC-LR induces hepatocarcinogenesis in vitro and in vivo by increasing gankyrin levels, providing new insight into MC-LR carcinogenicity studies.

Sign in / Sign up

Export Citation Format

Share Document