Somatostatin inhibits prolactin release from the lactotroph primed with oestrogen and cyproterone acetate in man

Gooren, L. J. G.; Harmsen‐Louman, W.; Kessel, H. Van

doi:10.1677/joe.0.1030333

Cited by 17 publications

(7 citation statements)

References 9 publications

(15 reference statements)

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“…Despite the inability of SRIF to inhibit PRL secretion in male rat primary lactotroph cultures, E 2 treatment similarly sensitizes these cells to SRIF (Goth et al 1996, Lee & Shin 1996. In addition, SRIF inhibits PRL induction by estrogen in male-to-female transsexuals, even more so upon co-treatment with cyproterone acetate, a compound with anti-androgen characteristics (Gooren et al 1984). Taken together, the regulation of PRL secretion through SRIF-dependent pathways appears to be receptor subtype specific, BMP dependent, and sensitive to the presence of estrogen.…”

Section: Prl Secretionmentioning

confidence: 88%

Somatostatin system: molecular mechanisms regulating anterior pituitary hormones

Eigler¹,

Ben-Shlomo²

2014

Journal of Molecular Endocrinology

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The somatostatin (SRIF) system, which includes the SRIF ligand and receptors, regulates anterior pituitary gland function, mainly inhibiting hormone secretion and to some extent pituitary tumor cell growth. SRIF-14 via its cognate G-protein-coupled receptors (subtypes 1-5) activates multiple cellular signaling pathways including adenylate cyclase/cAMP, MAPK, ion channel-dependent pathways, and others. In addition, recent data have suggested SRIF-independent constitutive SRIF receptor activity responsible for GH and ACTH inhibition in vitro. This review summarizes current knowledge on ligand-dependent and independent SRIF receptor molecular and functional effects on hormone-secreting cells in the anterior pituitary gland.

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Section: Prl Secretionmentioning

confidence: 88%

Somatostatin system: molecular mechanisms regulating anterior pituitary hormones

Eigler¹,

Ben-Shlomo²

2014

Journal of Molecular Endocrinology

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“…This might be achieved by treatment with PRL-suppressing agents (28) that can drastically lower the levels of circulating PRL. A future approach to suppress PRL secretion might consist of the use of somatostatin analogs (33,34) or hypothalamic PRL release-inhibiting factor, which is possibly related to gonadotropin-releasing hormone-associated peptide (35). Treatments with these polypeptides could be combined with long-term treatment of LH-releasing hormone (LH-RH) agonists (36) that were found to be effective in estrogendependent human breast cancer when given either alone (37)(38)(39) or in combination with other regimens (40).…”

Section: Discussionmentioning

confidence: 99%

Micromethod for the determination of free and total prolactin receptors: measurement of receptor levels in normal and malignant mammary and prostate tissues.

Ben-David¹,

Kádár²

1986

Proc. Natl. Acad. Sci. U.S.A.

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A sensitive micromethod for the determination of free and total prolactin receptors in normal or malignant tissues has been developed. Positive and negative quality controls are incorporated in the procedure. Either whole tissue or the pellet fraction remaining from tissue that had undergone processing for estrogen receptors can be used. Crude microsomal and plasma membrane fractions obtained by homogenization and differential centrifugation are incubated with labeled prolactin in the presence or absence of increasing amounts of unlabeled hormone. The labeled ligand is prepared by a stoichiometric iodination procedure in which one atom of iodine-125 is incorporated into one molecule of the hormone, resulting in an intact labeled prolactin with a high specific activity of 170-186 muCi/micrograms (1 Ci = 37 GBq). Human prolactin labeled by this procedure has much greater specific binding capacity to various rat tissues than does iodinated rat prolactin. This technique permits an accurate measurement of prolactin receptors in as little as 50 micrograms of membrane protein. Highest levels of free and total prolactin receptors were found in the liver of 60-day-old female rats that served as a positive control. Liver of immature 21-day-old male rats, devoid of prolactin receptors, was used as a negative control. The amount of detectable free receptors was dependent on the level of circulating plasma prolactin. In 3-day postpartum lactating rats with high prolactin levels in plasma, all prolactin receptors in the mammary glands were found to be occupied, and no free receptors could be detected. When these receptors were desaturated from the endogenous prolactin by exposure to 3 M MgCl2, one class of receptors in a high quantity (1.75 nmol/mg of protein) and with a moderate affinity (Kd = 6.41 X 10(-9) M) was detected. A similar type of receptor was found in the mammary glands of rats at midpregnancy and of cycling adult female rats. In malignant rat mammary tissue, however, fewer receptors (27 pmol/mg of protein) but with a very high affinity (Kd = 6.8 X 10(-14) M) were detected. Normal ventral and dorsolateral rat prostate contained two classes of prolactin receptors (Kd = 3.46 X 10(-10) M and 1.93 X 10(-8) M). In the cancerous rat prostate, however, only one of these two classes of receptors was detected, and the number was smaller.

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“…Male rat lactotroph primary cultures do not exhibit SRIF-inhibition of PRL secretion, but in fact gain SRIF sensitivity after 17β estradiol treatment [109,110]. Moreover, SRIF inhibits estrogen-mediated PRL increase in men (male-to-female transsexuals), and to a greater degree in men treated with both estrogen and cyproterone acetate [111]. SRIF inhibition of basal PRL secretion becomes important in the presence of an estrogen surge in both men and women.…”

Section: Physiological Effects Of Srif Receptor Signalingmentioning

confidence: 99%

Pituitary somatostatin receptor signaling

Ben-Shlomo

Melmed

2010

Trends in Endocrinology & Metabolism

180

131

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Somatostatin (SRIF) is a major regulator of pituitary function, mostly inhibiting hormone secretion and to a lesser extent pituitary cell growth. Five SRIF receptor subtypes (SSTR1-5) are ubiquitously expressed G-protein coupled receptors. In the pituitary, SSTR1, SSTR2, SSTR3 and SSTR5 are expressed, with SSTR2 and SSTR5 predominating. As new SRIF-analogs have recently been introduced for treatment of pituitary disease, we evaluate the current knowledge of cell-specific pituitary SRIF receptor signaling and highlight areas of future research for comprehensive understanding of these mechanisms. Elucidating pituitary SRIF receptor signaling enables understanding of pituitary hormone secretion and cell growth, and also points to future therapeutic development for pituitary disorders. Keywords somatostatin receptors; pituitarySomatotropin-release inhibitory factors (SRIF) or somatostatins are cyclic peptides cleaved from a precursor pre-pro-somatostatin peptide to produce two bioactive products SRIF14 (14 amino acids) and SRIF28 which comprises an additional 14 N-terminal amino acids [1]. SRIFs are phylogenetically ancient, as SRIF-like immunoreactivity is found in protozoans, primitive intervertebrates and vertebrates [1,2]. SRIFs are produced from specialized cells in the brain, gastrointestinal tract (GIT), liver, pancreas, lungs, immune system, kidneys, adrenals and urogenital tracts [1]. SRIF exerts broad, mostly inhibitory effects on endocrine and exocrine secretions. Other than pituitary hormones discussed in this review, SRIF also inhibits secretion of gastro intestinal tract (GIT) hormones including insulin, glucagon, gastrin, cholecystokinin, vasoactive intestinal peptide and secretin. SRIF also inhibits exocrine gastric acid, pepsin, pancreatic enzymes, bile and intestinal fluids secretions [3]. SRIF inhibits gastric emptying, gallbladder contraction, and small intestine segmentation, but inducess migrating motor complex activity and splanchnic vasoconstriction [1]. Brain SRIF inhibits release of hypothalamic hormones including corticotropin releasing hormone (CRH), thyrotropin releasing hormone (TRH), and also dopamine and norepinephrine [1].Hypothalamic SRIF is a major regulator of pituitary gland hormone secretion and to a lesser extent, pituitary cell development and growth. The peptide is produced predominantly in the Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Released SRIF is rapidly inactivated by tissue and blood peptidases, and the very short halflife (~ 2 minutes) limits its therapeutic use. Octreotide and lanreotide are clinically approved ...

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Somatostatin inhibits prolactin release from the lactotroph primed with oestrogen and cyproterone acetate in man

Cited by 17 publications

References 9 publications

Somatostatin system: molecular mechanisms regulating anterior pituitary hormones

Somatostatin system: molecular mechanisms regulating anterior pituitary hormones

Micromethod for the determination of free and total prolactin receptors: measurement of receptor levels in normal and malignant mammary and prostate tissues.

Pituitary somatostatin receptor signaling

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