Luteinizing hormone-releasing hormone and neuropeptide Y influence deoxyribonucleic acid replication in three anterior pituitary cell types. Evidence for mediation by growth factors released from gonadotrophs.

Tilemans, Diane; Andries, Maria; Denef, Carl

doi:10.1210/endo.130.2.1310281

Cited by 25 publications

(21 citation statements)

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“…Gonadotrophs also appear to release paracrine growth factors. This release is stimulated by LHRH as well as by neuropeptide Y (NPY) (Tilemans et al 1992), a peptide which is synthesized within the anterior pituitary (Jones et al 1989) and can influence gonadotroph function (Crowley et al 1987;Shangold & Miller, 1990). These paracrine growth factors from gonadotrophs enhance the number of DNA-replicating lacto¬ trophs and corticotrophs and lower the number of DNA-replicating somatotrophs (Tilemans et al 1992).…”

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confidence: 99%

In vitro evidence that LHRH stimulates the recruitment of prolactin mRNA-expressing cells during the postnatal period in the rat

Bael

Huygen²,

Himpens³

et al. 1994

Journal of Molecular Endocrinology

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We have studied the effect of LHRH and neuropeptide Y (NPY) on prolactin (PRL) mRNA levels in pituitary reaggregate cell cultures from 14-day-old female rats, by means of in situ hybridization and Northern blot analysis. As estimated by computer-image analysis, addition of LHRH on day 5 in culture for 40 h resulted in a 37% increase in the total cytoplasmic areas of cells containing PRL mRNA, visualized using a digoxigenin-labelled PRL cRNA. The size of individual PRL-expressing cells was not influenced, nor was the content of PRL mRNA per cell. A similar effect of LHRH was found by dot blot hybridization of extracted RNA. PRL mRNA levels were not affected by NPY. LHRH induced a 29% increase in the number of PRL mRNA-expressing cells processing through the S phase of the cell cycle, visualized by the incorporation of [3H]thymidine ([3H]T) into DNA over 16 h. The fraction of [3H]T-labelled cells was 10-12% of the total cell population. NPY did not influence the number of [3H]T-positive cells expressing PRL mRNA, but completely blocked the effect of LHRH on the latter population. The present data suggest that LHRH, probably via a paracrine action of gonadotrophs, stimulates the recruitment of new lactotrophs, an action which is negatively modulated by NPY. Since the magnitude of this effect was the same in the total pituitary cell population as in cells processing through the S phase of the cell cycle and presumably mitosis, recruitment of lactotrophs seems to be based on differentiation of progenitor or immature cells into PRL-expressing cells, rather than on a mitogenic action on pre-existing lactotrophs alone.

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mentioning

confidence: 99%

In vitro evidence that LHRH stimulates the recruitment of prolactin mRNA-expressing cells during the postnatal period in the rat

Bael

Huygen²,

Himpens³

et al. 1994

Journal of Molecular Endocrinology

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“…Very interestingly, the same population of progenitor cells that develops after adrenalectomy also proliferates after gonadectomy (578). We also found enhanced cell mitosis in pituitary aggregate cell cultures during the first week of culture (116) and this mitotic activity was for a large part in nonhormonal cells (393). Other investigators found a three-fold increase in pituitary AVP secretion after a 3-day culture period (570).…”

Section: Corticotrophs As Autocrine/paracrine Cells and Targetsmentioning

confidence: 63%

“…By means of cell separation and recombination experiments, we again showed that the developmental actions of GnRH depend on the presence of gonadotrophs (116). Mediation by paracrine factor(s) was indicated by the finding that medium conditioned by a highly enriched population of gonadotrophs cultured in the presence of GnRH, mimicked the effects of GnRH (120, 121).…”

Section: Gonadotrophs Signal To Lactotrophs Somatotrophs and Corticomentioning

confidence: 77%

“…As far as tested in the 14-day-old rat pituitary aggregate cell culture system, treatment with GnRH for 40 h was found to enhance cell cycle entrance of lactotrophs and to lower that of somatotrophs (116). GnRH also inhibited the mitogenic effect of GH-releasing hormone (GHRH) on somatotrophs (117).…”

Section: Gonadotrophs Signal To Lactotrophs Somatotrophs and Corticomentioning

confidence: 99%

“…In this respect, it should be realised that gonadotrophs may not necessarily use GnRH as their physiological agonist and that different agonists may elicit different paracrine contacts with lactotrophs. For example, neuropeptide Y (NPY) can mimic the action of GnRH on lactotroph mitosis in pituitary cell aggregates (116) but it inhibits the stimulation of PRL mRNA by GnRH (118). …”

Section: Gonadotrophs Signal To Lactotrophs Somatotrophs and Corticomentioning

confidence: 99%

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Endogenous Cannabinoids: Structure and Metabolism

Bisogno

2008

J Neuroendocrinology

144

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D9 -Tetrahydrocannabinol (THC), the main psychoactive compound extracted from Cannabis sativa, is the most representative component of the mixture of therapeutic substances that are communally referred to as cannabinoids (1). It acts as an agonist at specific G-protein-coupled receptors, cannabinoid receptor subtypes CB 1 and CB 2 (2). The discovery of cannabinoid receptors has driven the investigation of the existence of their natural ligands and, soon after, endocannabinoids were identified. N-arachidonoyl-ethanolamine (AEA, anandamide) and 2-arachidonoyl glycerol (2-AG) are the two most studied endocannabinoids. They are biosynthesised 'on demand' by cleavage of their membrane lipid precursors N-arachidonoyl-phosphatidylethanolamine (N-ArPE) and sn-1-acyl-2-arachidonoylglycerols (DAGs) respectively, and then inactivated by intracellular hydrolysing enzymes. Cannabinoid receptors, endocannabinoids and enzymes that biosynthesise [N-acyl-phosphatidylethanolamine-selective phospholipase D (NAPE-PLD) and diacylglycerol lipase (DAGL)] and degrade [fatty acid amide hydrolase (FAAH) and the monoacylglycerol lipases (MAGL)] AEA and 2-AG, respectively, are key components in the endocannabinoid system (3). Despite a large number of excellent studies having contributed to the current understanding of the endocannabinoid regulation and function, further efforts are necessary to fully comprehend this signalling system. Here, a review on the current knowledge on structure and metabolism of the best studied endogenous cannabinoids is presented. In particular, this review concentrates on the mechanisms responsible for the biosynthesis and inactivation of the endocannabinoids, as well as on the several inhibitors of their metabolism identified to date. Endocannabinoids and related N-acyl-ethanolaminesEndocannabinoids are defined as endogenous compounds capable of binding to and functionally activating cannabinoid receptors. At least five endocannabinoids have been identified to date (Fig. 1). Anandamide, the amide between arachidonic acid and ethanolamine, was the first endogenous ligand to be reported at the end of 1992 (4) and additional polyunsaturated ethanolamines that bind to cannabinoid receptors, homolinolenylethanolamide and docosatetraenylethanolamide, have been isolated in the brain. Other endocannabinoids, all derived from arachidonic acid, were identified. The identification of 2-AG, the ester of arachidonic acid with glycerol, isolated from canine gut and brain has also been reported (5, 6). Subsequently, the first endocannabinoid characterised by ether bond, 2-arachidonyl glyceryl ether or noladin ether, was isolated from porcine brain (7) and N-arachidonoyldopamine (NADA), a selective CB 1 agonist and a potent agonist of vanilloid receptors, was discovered (8, 9). O-arachidonoylethanolamine, the ester derivative of ethanolamine with arachidonic acid, with the same molecular weight as anandamide but with opposite orientation of the polar ethanolamine moiety, was named virodhamine from the Sanskrit word virodha, ...

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Corticotropin releasing factor inhibits proliferation ofAtT-20 cells

Melzig

1994

In Vitro Cell Dev Biol - Animal

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Luteinizing hormone-releasing hormone and neuropeptide Y influence deoxyribonucleic acid replication in three anterior pituitary cell types. Evidence for mediation by growth factors released from gonadotrophs.

Cited by 25 publications

References 4 publications

In vitro evidence that LHRH stimulates the recruitment of prolactin mRNA-expressing cells during the postnatal period in the rat

In vitro evidence that LHRH stimulates the recruitment of prolactin mRNA-expressing cells during the postnatal period in the rat

Endogenous Cannabinoids: Structure and Metabolism

Corticotropin releasing factor inhibits proliferation ofAtT-20 cells

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