Estradiol and its membrane-impermeable conjugate estradiol–BSA inhibit tamoxifen-stimulated prolactin secretion in incubated rat pituitaries

In the absence of estrogen (E), the selective E receptor modulator tamoxifen (TX) has two agonist effects in the rat pituitary: induction of progesterone receptor (PR)-dependent GnRH self-priming in the gonadotrope, and stimulation of prolactin (PRL) secretion in the lactotrope. TX-induced gonadotropin (GnRH) self-priming is absent when 10−8M estradiol-17β (E2) is added to the incubation medium of pituitaries from TX-treated rats. The present experiments investigated whether PR-independent PRL release into the incubation medium of pituitaries from TX-treated ovariectomized (OVX) rats was affected by E2, and the effect of different ER ligands (ICI182780, TX, estradiol-17α, E2–BSA) on TX-stimulated PRL secretion. Moreover, the effect of E2on TRH-stimulated PRL secretion in pituitaries collected from estradiol benzoate- and TX-treated OVX rats was studied. It was found that: i) incubation with E2supressed the PRL releasing effect of injected TX; ii) whereas coincubation with the pure anti-E type II ICI182780 antagonized the inhibitory effect of E2, coincubation with the anti-E type I TX did not; iii) estradiol-17α lacked inhibitory action, whereas a dose-dependent inhibitory effect of both E2and E2–BSA was noticed; and iv) TRH stimulatory effect on PRL release in pituitaries from TX-treated rats was blocked by addition of E2to the medium. Taken together, these data argue in favor of the presence of specific membrane recognition sites for E in the lactotrope involved in steroid-specific E2inhibition of TX-stimulated PRL secretion.

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Effects of a novel gonadotropin-releasing hormone antagonist (ORG 30850) on gonadotropin and prolactin secretion by rat pituitary cells in culture

Acta Endocrinologica ◽

10.1530/acta.0.1240098 ◽

1991 ◽

Vol 124 (1) ◽

pp. 98-106 ◽

Cited By ~ 2

Author(s):

Paul Franchimont ◽

Sabine M. Almer ◽

Chantal-J. Charlet-Renard ◽

Christine L. Daubresse ◽

Peter P. Kicovic

Keyword(s):

Culture Medium ◽

Gnrh Antagonist ◽

Inhibitory Effect ◽

Prolactin Secretion ◽

Male Rat ◽

Pituitary Cells ◽

Cell Content ◽

Rat Pituitary ◽

Rat Pituitary Cells ◽

Lh Secretion

Abstract. The effect of a new GnRH antagonist (ORG 30850 ANT) on FSH, LH, and PRL secretion was studied using male rat pituitary cells in monolayer cell culture. In the absence of GnRH, ORG 30850 ANT did not alter spontaneous FSH and LH secretion into culture medium or the cell content of these hormones. In the presence of GnRH (10−8 mol/l), ORG 30850 ANT significantly and dose-dependently inhibited FSH and LH secretion into culture medium while increasing their cell content. Conversely, in the presence of a single dose of ORG 30850 ANT, FSH and LH secretion rose significantly when subjected to increasing amounts of GnRH, whereas the hormonal cell content diminished. Furthermore, inhibition of GnRH-induced FSH and LH release by ORG 30850 ANT was not changed by pre-incubation with the GnRH antagonist regardless of the pre-incubation time. The inhibitory effect of the GnRH antagonist was observed early, with its peak occurring within 6 h of culture. These short-term studies indicate that ORG 30850 ANT specifically inhibits GnRH-induced gonadotropin release into culture medium, exerts no effect on the rate of gonadotropin production in the presence or absence of GnRH, competitively and reversibly inhibits the binding of natural GnRH to its receptors, and does not lead to any modifications in PRL secretion.

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Antiprogestins RU486 and ZK299 suppress basal and LHRH-stimulated FSH and LH secretion at pituitary level in the rat in an oestrous cycle stage-dependent manner

Journal of Endocrinology ◽

10.1677/joe.0.1630079 ◽

1999 ◽

Vol 163 (1) ◽

pp. 79-85 ◽

Cited By ~ 19

Author(s):

C Bellido ◽

D Gonzalez ◽

R Aguilar ◽

JE Sanchez-Criado

Keyword(s):

Suppressive Effect ◽

Inhibitory Effect ◽

Type I ◽

Dependent Manner ◽

Natural Ligand ◽

Ovx Rats ◽

20 Nm ◽

Lh Secretion

We have previously shown that administration of antiprogestin (AP) type II RU486 to ovariectomized (OVX) rats on the morning of pro-oestrus decreases the magnitude of preovulatory gonadotrophin surge. This suggests that the effect of RU486 on LHRH-dependent gonadotrophin release may be independent of its ability to block progesterone actions. The aim of the present research was to study the possible site of RU486 action and to determine whether the gonadotrophin suppressive effect of APs RU486 and ZK299 is dependent on the oestrogen background. Intact or OVX rats in the morning of pro-oestrus were injected s.c. with 4 mg of RU486 or ZK299 (AP type I) at 0900 h on pro-oestrus. At 1830 h, serum concentration of FSH and LH and median eminence (ME) content of LHRH were determined. In the second experiment, the effect of RU486 and ZK299 on pituitary responsiveness to LHRH (100 ng, i.p.) and ME content of LHRH at 1830 h pentobarbital-blocked intact or OVX rats was evaluated. In the last study, the anterior pituitary release of FSH and LH from pro-oestrus or metoestrus donors incubated with or without LHRH (1, 10 or 100 nM) in the presence or absence of APs (20 nM) was evaluated. Both APs reduced serum FSH and LH levels at 1830 h on pro-oestrus in intact and OVX rats. The suppressive effect on gonadotrophin release brought about by AP treatment was also evidenced in PB-blocked intact and OVX rats. This suggested that the inhibitory effect of APs occurred, at least in part, at pituitary level. Furthermore, in the absence of the natural ligand, APs significantly reduced basal and LHRH-stimulated FSH and LH release from pro-oestrous but not from metoestrus pituitaries. In conclusion, these experiments have shown, both 'in vivo' and 'in vitro', that APs RU486 and ZK299 have suppressive effects at pituitary level on basal and LHRH-stimulated FSH and LH secretion, regardless of their antiprogestagenic activity, in pro-oestrus but not in metoestrus.

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A paradoxical inhibitory effect of oestradiol-17β on GnRH self-priming in pituitaries from tamoxifen-treated rats

Journal of Endocrinology ◽

10.1677/joe.1.06162 ◽

2005 ◽

Vol 186 (1) ◽

pp. 43-49 ◽

Cited By ~ 2

Author(s):

José E Sánchez-Criado ◽

Carmina Bellido ◽

Rafaela Aguilar ◽

José C Garrido-Gracia

Keyword(s):

Oestrogen Receptor ◽

Inhibitory Effect ◽

Dependent Manner ◽

Receptor Modulator ◽

Selective Agonist ◽

Ovx Rats ◽

Incubation Experiments ◽

Oestradiol Benzoate ◽

Dose Dependent ◽

Selective Oestrogen Receptor Modulator

Two-week ovariectomized (OVX) rats were injected over three days with 25 μg oestradiol benzoate (EB), 3 mg tamoxifen (TX) and 0.2 ml oil and their pituitaries were harvested for incubation experiments. Pituitaries from EB-and TX-treated OVX rats exhibited GnRH self-priming when incubated with their corresponding ligand. However, incubation of pituitaries with different ligands yielded divergent results: when pituitaries from EB-treated rats were incubated with 10−7 M TX they displayed GnRH self-priming, whereas incubation of pituitaries from TX-treated rats with 10−8 M oestradiol-17β (E2) blocked GnRH self-priming. Further studies to analyse the latter finding revealed that: (a) E2 inhibited TX-induced GnRH self-priming in a dose-dependent manner while 10−8 M oestradiol-17α did not; (b) co-incubation of E2 with the pure anti-oestrogen ICI 182,780, but not with the selective oestrogen receptor modulator TX, reversed the E2 inhibitory effect; (c) the oestrogen receptor (ER)-α selective agonist propylpyrazole triol, but not the ERβ selective agonist diarylpropionitrile, mimicked the inhibitory effect of E2; (d) the analogue membrane-impermeable conjugated E2-BSA also inhibited TX-induced GnRH self-priming; and (e) a 15-min exposure of the pituitaries to E2 was sufficient to inhibit the GnRH self-priming elicited by TX. Although other explanations may exist, altogether these results suggested that E2, via an ER different from classical ER, inhibits the GnRH self-priming elicited by TX.

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Stimulation of prolactin secretion by oestradiol in the rat is associated with increased hypothalamic release of thyrotrophin-releasing hormone

Journal of Endocrinology ◽

10.1677/joe.0.1030257 ◽

1984 ◽

Vol 103 (2) ◽

pp. 257-261 ◽

Cited By ~ 9

Author(s):

S. Franks ◽

H. D. Mason ◽

K. I. J. Shennan ◽

M. C. Sheppard

Keyword(s):

Incubation Medium ◽

Prolactin Secretion ◽

Serum Prolactin ◽

Thyrotrophin Releasing Hormone ◽

Releasing Hormone ◽

Threefold Increase ◽

Rat Pituitary ◽

Pituitary Glands ◽

Pituitary Prolactin ◽

Stimulation Of

ABSTRACT We have studied the effect of oestradiol (OE2) on secretion of prolactin and TSH by rat pituitary glands and correlated this with changes in hypothalamic content and release of thyrotrophin-releasing hormone (TRH). Ovariectomized Wistar rats received s.c. silicone elastomer implants of OE2 at a dose known to give pro-oestrous OE2 levels. After 1 week rats were decapitated, blood was collected for assay of prolactin and TSH, blocks of hypothalamus were dissected out and pituitary glands were removed and bisected. Medium bathing hemipituitary glands was collected for measurement of prolactin and TSH after a 30-min incubation. Immunoreactive TRH was measured in medium removed from hypothalami and in extracts of homogenized hypothalami. Serum prolactin was higher in OE2-treated than in control animals (59·3 ± 19·5 (s.e.m.) vs 9·4 ± 1·5 μg/l; P<0·05) and this was associated with a threefold increase in pituitary prolactin in the medium. By contrast, TSH concentrations in serum and pituitary incubation medium were not significantly different in the two groups. There was no difference between the groups in hypothalamic content of TRH but TRH release in the incubation medium was increased by OE2 (30·2 ± 6·5 vs 10·0 ± 1·3 pg/mg protein per 30 min; P<0·01). In summary, physiological levels of OE2 stimulated prolactin secretion without change in TSH and this was associated with a threefold increase in hypothalamic release of TRH. These findings suggest that the stimulating effect of OE2 on prolactin secretion may, in part, be mediated by hypothalamic TRH. J. Endocr. (1984) 103, 257–261

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Modulation of prolactin secretion by contraceptive progestins in cultured rat pituitary cells in vitro

Acta Endocrinologica ◽

10.1530/acta.0.117s188 ◽

1988 ◽

Vol 117 (4_Suppl) ◽

pp. S188-S189

Author(s):

L. KIESEL ◽

T. RABE ◽

D. SCHOLZ ◽

V. KIRSCHNER ◽

B. RUNNEBAUM

Keyword(s):

Prolactin Secretion ◽

Pituitary Cells ◽

Rat Pituitary ◽

Rat Pituitary Cells

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PRV UL13 inhibits cGAS–STING-mediated IFN-β production by phosphorylating IRF3

Veterinary Research ◽

10.1186/s13567-020-00843-4 ◽

2020 ◽

Vol 51 (1) ◽

Author(s):

Zongyi Bo ◽

Yurun Miao ◽

Rui Xi ◽

Qiuping Zhong ◽

Chenyi Bao ◽

...

Keyword(s):

Transcriptional Activation ◽

Pseudorabies Virus ◽

Nuclear Translocation ◽

Economic Loss ◽

Inhibitory Effect ◽

Poly I:C ◽

Interferon Response ◽

Type I ◽

Creb Binding Protein ◽

Swine Industry

Abstract Cyclic GMP-AMP (cGAMP) synthase (cGAS) is an intracellular sensor of cytoplasmic viral DNA created during virus infection, which subsequently activates the stimulator of interferon gene (STING)-dependent type I interferon response to eliminate pathogens. In contrast, viruses have developed different strategies to modulate this signalling pathway. Pseudorabies virus (PRV), an alphaherpesvirus, is the causative agent of Aujeszky’s disease (AD), a notable disease that causes substantial economic loss to the swine industry globally. Previous reports have shown that PRV infection induces cGAS-dependent IFN-β production, conversely hydrolysing cGAMP, a second messenger synthesized by cGAS, and attenuates PRV-induced IRF3 activation and IFN-β secretion. However, it is not clear whether PRV open reading frames (ORFs) modulate the cGAS–STING-IRF3 pathway. Here, 50 PRV ORFs were screened, showing that PRV UL13 serine/threonine kinase blocks the cGAS–STING-IRF3-, poly(I:C)- or VSV-mediated transcriptional activation of the IFN-β gene. Importantly, it was discovered that UL13 phosphorylates IRF3, and its kinase activity is indispensable for such an inhibitory effect. Moreover, UL13 does not affect IRF3 dimerization, nuclear translocation or association with CREB-binding protein (CBP) but attenuates the binding of IRF3 to the IRF3-responsive promoter. Consistent with this, it was discovered that UL13 inhibits the expression of multiple interferon-stimulated genes (ISGs) induced by cGAS–STING or poly(I:C). Finally, it was determined that PRV infection can activate IRF3 by recruiting it to the nucleus, and PRVΔUL13 mutants enhance the transactivation level of the IFN-β gene. Taken together, the data from the present study demonstrated that PRV UL13 inhibits cGAS–STING-mediated IFN-β production by phosphorylating IRF3.

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Role of Curing Temperature of Poly(Glycerol Sebacate) Substrates on Protein-Cell Interaction and Early Cell Adhesion

Polymers ◽

10.3390/polym13030382 ◽

2021 ◽

Vol 13 (3) ◽

pp. 382

Author(s):

Rubén Martín-Cabezuelo ◽

José Carlos Rodríguez-Hernández ◽

Guillermo Vilariño-Feltrer ◽

Ana Vallés-Lluch

Keyword(s):

Protein Interactions ◽

Chemical Properties ◽

Focal Adhesions ◽

Collagen Type I ◽

Inhibitory Effect ◽

Synthesis Temperature ◽

Curing Temperature ◽

Cell Protein ◽

Preliminary Treatment ◽

Type I

A novel procedure to obtain smooth, continuous polymeric surfaces from poly(glycerol sebacate) (PGS) has been developed with the spin-coating technique. This method proves useful for separating the effect of the chemistry and morphology of the networks (that can be obtained by varying the synthesis parameters) on cell-protein-substrate interactions from that of structural variables. Solutions of the PGS pre-polymer can be spin-coated, to then be cured. Curing under variable temperatures has been shown to lead to PGS networks with different chemical properties and topographies, conditioning their use as a biomaterial. Particularly, higher synthesis temperatures yield denser networks with fewer polar terminal groups available on the surface. Material-protein interactions were characterised by using extracellular matrix proteins such as fibronectin (Fn) and collagen type I (Col I), to unveil the biological interface profile of PGS substrates. To that end, atomic force microscopy (AFM) images and quantification of protein adsorbed in single, sequential and competitive protein incubations were used. Results reveal that Fn is adsorbed in the form of clusters, while Col I forms a characteristic fibrillar network. Fn has an inhibitory effect when incubated prior to Col I. Human umbilical endothelial cells (HUVECs) were also cultured on PGS surfaces to reveal the effect of synthesis temperature on cell behaviour. To this effect, early focal adhesions (FAs) were analysed using immunofluorescence techniques. In light of the results, 130 °C seems to be the optimal curing temperature since a preliminary treatment with Col I or a Fn:Col I solution facilitates the formation of early focal adhesions and growth of HUVECs.

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Camelina Oil Supplementation Improves Bone Parameters in Ovariectomized Rats

Animals ◽

10.3390/ani11051343 ◽

2021 ◽

Vol 11 (5) ◽

pp. 1343

Author(s):

Iwona Puzio ◽

Dorota Graboś ◽

Marek Bieńko ◽

Radosław P. Radzki ◽

Aneta Nowakiewicz ◽

...

Keyword(s):

Serum Level ◽

Recovery Period ◽

Physiological Saline ◽

Ovariectomized Rats ◽

Control Group ◽

Sham Operation ◽

Type I ◽

Camelina Oil ◽

Bone Parameters ◽

Ovx Rats

The aim of the present study was to determine the effect of administration of Camelina sativa oil (CO) as a source of polyunsaturated fatty acids (PUFA) on bone parameters in ovariectomized rats (OVX). Overall, 40 10-week-old healthy female Wistar rats were divided into 4 groups with 10 animals in each. Rats in the control group (SHO) were subjected to a sham operation, whereas experimental rats (OVX) were ovariectomized. After a 7-day recovery period, the SHO the rats received orally 1 mL of physiological saline for the next 6 weeks. The OVX rats received orally 1 mL of physiological saline (OVX-PhS), 5 g/kg BW (OVX-CO5), or 9 g/kg BW (OVX-CO9) of camelina oil. The use of camelina oil had a significant effect on body weight, lean mass, and fat mass. The camelina oil administration suppressed the decrease in the values of some densitometric, tomographic, and mechanical parameters of femur caused by estrogen deficiency. The CO treatment increased significantly the serum level of osteocalcin and decreased the serum level of C-terminal telopeptide of type I collagen in the OVX rats. In conclusion, camelina oil exerts a positive osteotropic effect by inhibiting ovariectomy-induced adverse changes in bones. Camelina oil supplementation can be used as an efficient method for improving bone health in a disturbed state. However, further research must be carried out on other animal species supplemented with the oil.

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CircAgtpbp1 Acts as a Molecular Sponge of miR-543-5p to Regulate the Secretion of GH in Rat Pituitary Cells

Animals ◽

10.3390/ani11020558 ◽

2021 ◽

Vol 11 (2) ◽

pp. 558

Author(s):

ZeWen Yu ◽

WenZhi Ren ◽

Tian Wang ◽

WeiDi Zhang ◽

ChangJiang Wang ◽

...

Keyword(s):

Pituitary Gland ◽

Inhibitory Effect ◽

Pituitary Cells ◽

Sequencing Analysis ◽

Hormone Regulation ◽

Gh Secretion ◽

Qrt Pcr ◽

Rat Pituitary ◽

Rat Pituitary Cells

CircRNAs have been identified to be expressed differently and stably in numerous species and tissues, but their functions in growth hormone (GH) secretion are still largely unknown. In summary, we have revealed a circRNA-miRNA-mRNA network that may play a biological role in the rat pituitary gland. First, we verified the chromosome location information of circAgtpbp1 according to sequencing analysis. The circAgtpbp1 characteristics were authenticated through PCR, qRT–PCR, treating with RNase and fluorescent in situ hybridization (FISH). Second, we detected the expression pattern of circAgtpbp1 in the rat anterior pituitary by qRT–PCR. We also designed circAgtpbp1 siRNA and constructed overexpression plasmid to evaluate the effect of circAgtpbp1 function on GH secretion by qRT–PCR, ELISA and Western blot. CircAgtpbp1 is a stable, truly circular molecule. We found that circAgtpbp1 interacted with miR-543-5p and can regulate GH secretion in pituitary cells through a circAgtpbp1-miR-543-5p-GH axis. Overall, the evidence generated by our study suggests that circAgtpbp1 can act as a sponge of miR-543-5p to reduce the inhibitory effect of miR-543-5p on Gh1 and further promote GH secretion. These findings expand our existing knowledge on the mechanisms of hormone regulation in the pituitary gland.

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Effect of Anticonvulsants on the Uptake of 5-Methyltetrahydrofolic Acid by the Choroid Plexus in Rabbits

Clinical Science ◽

10.1042/cs0530075 ◽

1977 ◽

Vol 53 (1) ◽

pp. 75-80

Author(s):

H. Taguchi ◽

Z. Abdul-Cader ◽

J. Perry ◽

E. H. Reynolds ◽

I. Chanarin

Keyword(s):

Folic Acid ◽

Low Temperature ◽

Choroid Plexus ◽

Incubation Medium ◽

Pernicious Anaemia ◽

Inhibitory Effect ◽

Anaerobic Conditions ◽

Acid Therapy ◽

Pteroylglutamic Acid

1. The isolated choroid plexus of the rabbit takes up 5-methyltetrahydrofolate from the incubation medium. 2. Other folate analogues (pteroylglutamic acid, methotrexate, 5-formyltetrahydrofolate = folinic acid) inhibited the uptake of 5-methyltetrahydrofolate. 3. The uptake of 5-methyltetrahydrofolate was inhibited by low temperature, anaerobic conditions and dinitrophenol. 4. The anticonvulsant drugs, diphenylhydantoin and phenobarbital, had no effect on 5-methyltetrahydrofolate uptake. 5. The inhibitory effect of pteroylglutamic acid on the uptake of 5-methyltetrahydrofolate by the choroid plexus may explain the effect of long-term folic acid therapy in aggravating vitamin B12 neuropathy in pernicious anaemia.

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