bluuebunny/crossref_metadata_2025_split huggingface dataset:
Somatostatin binding to chicken adenohypophysial membranes
Authors: Harvey S. , Attardo D. , Baidwan J. S. 
Published: December 2008

ABSTRACT
[125I-Tyr1]-Somatostatin (SRIF)-binding sites were demonstrated on crude plasma membrane preparations from chicken pituitary glands. These binding sites were saturable and of high affinity (dissociation constant <1·0 nm) and low capacity (maximal binding capacity <200 fmol/mg protein) and were specific for SRIF moieties. The number and affinity of these binding sites in the caudal lobe of the pituitary, in which somatotrophs predominate, were similar to those in the cephalic lobe, in which lactotrophs and thyrotrophs are confined. Gonadotrophs are present in the caudal lobe, but whereas exogenous SRIF inhibited secretagogue-induced GH release from incubated pituitary glands, it had no effect on basal or secretagogue-induced LH release. The half-maximal binding of SRIF to the caudal lobe membranes (3 nm) was similar to that required for half-maximal suppression of TRH-induced GH release, suggesting a role for these binding sites in the regulation of GH secretion in birds.
Differential expression of inhibin α and βA subunit genes in rat and mouse ovarian follicles during pregnancy
Authors: Penschow J. D. , Aldred G. P. , Darling P. A. , Haralambidis J. , Hammond V. E. , van Leeuwen B. H. , Mason A. J. , Niall H. D. , Seeburg P. , Coghlan J. P. 
Published: December 2008

ABSTRACT
Relative levels of rat ovarian α inhibin (αI) and βA inhibin (βAI) mRNAs were measured during pregnancy by dot-blot hybridization of ovarian poly(A+) RNA. Follicular patterns of αI and βAI expression in contralateral ovaries from the same rats were also studied by hybridization histochemistry. Oligodeoxynucleotide probes specific for porcine αI and βAI were synthesized, 32P end-labelled and used as hybridization probes on dot-blots of ovarian RNA and frozen sections of ovarian tissue from pregnant rats. During pregnancy, levels of αI and βAI mRNAs remained fairly constant from day 7 after mating until parturition and then fell within 16 h post partum. In all ovaries observed, expression of inhibin genes was located in granulosa cells of healthy antral follicles. In general, the strongest signals for αI and βAI mRNAs were obtained in large follicles, with weaker signals in smaller follicles. Follicular patterns of αI and βAI expression during pregnancy were often dissimilar when βI and βAI were compared over a range of follicles. Considerable βI mRNA was detectable in some follicles in which βAI was reduced or undetectable, despite strong signals for both αI and βAI in an adjacent follicle. Essentially, αI mRNA levels were relatively consistent between groups of follicles, whereas βAI levels varied considerably. βAI mRNA was never observed in a follicle in the absence of αI mRNA, indicating that activin production in any follicle occurs in the presence of αI mRNA. Similar patterns of expression were observed in ovaries from pregnant mice. We have shown that expression of αI and βAI inhibin genes is not regulated uniformly within follicles of pregnant rat and mouse ovaries.
Structure of an interferon-α2 gene expressed in the bovine conceptus early in gestation
Authors: Stewart H. J. , McCann S. H. E. , Flint A. P. F. 
Published: December 2008

ABSTRACT
Genomic and cDNA clones for bovine trophoblast interferon (IFN) have been isolated by probing a bovine genomic library and a bovine embryonic (day-18 post coitus) cDNA library respectively with the ovine trophoblast IFN cDNA. The two DNA sequences were identical; sequence analysis demonstrated 80% identity between the amino acid sequence of bovine trophoblast IFN and ovine trophoblast IFN, and 70% identity with a previously identified bovine IFN-α2. Southern blotting of bovine genomic DNA indicated the presence of a minimum of three trophoblast IFN genes. Primer extension analysis identified the transcription start site in the 5′ flanking region of the bovine IFN gene. Computer-aided analysis of the 5′ flanking sequence demonstrated a similarity with that of bovine IFN-α2 and the existence of a possible viral induction sequence.
Cyclic AMP and calcium in mouse mammary tumour virus expression: effects and post-transcriptional site of action
Authors: Bolander F. F. , Blackstone M. E. , Bradham B. M. 
Published: December 2008

ABSTRACT
The role of cyclic AMP (cAMP), calcium, calmodulin and protein kinase C (PKC) in the expression of both mouse mammary tumour virus (MMTV) RNA and an MMTV glycoprotein, gp58, was investigated in normal mammary epithelium in culture. None of these second messengers had any effect on MMTV RNA. Dibutyryl cAMP alone had no effect on gp58 levels but, at low concentrations (0·05–0·1 mm), it nearly doubled the induction seen with insulin, cortisol and prolactin; higher concentrations were inhibitory. Although a calcium ionophore (A23187), either alone or with hormones, was ineffective, a calcium channel blocker (verapamil) reduced hormonal induction of gp58 by 80%, and a calmodulin inhibitor (W-13) reduced it by 90%. Two PKC activators, a phorbol ester and a diacylglyceride, were ineffective alone, with hormones or with the calcium ionophore. The following conclusions can be made: (1) cAMP, calcium and calmodulin play an important role in MMTV expression, (2) these second messengers all act post-transcriptionally, since they do not affect MMTV RNA, and (3) PKC does not appear to have a role in MMTV production in normal mammary epithelium.
Adenosine and its analogue ( − )-N6-R-phenyl-isopropyladenosine modulate anterior pituitary adenylate cyclase activity and prolactin secretion in the rat
Authors: Schettini G. , Landolfi E. , Meucci O. , Florio T. , Grimaldi M. , Ventra C. , Marino A. 
Published: December 2008

ABSTRACT
The effect of adenosine and its analogue ( − )-N6-R-phenylisopropyladenosine (PIA) on both anterior pituitary adenylate cyclase activity and prolactin secretion was examined in the rat. Adenosine inhibited basal adenylate cyclase activity in a dose-dependent manner and also reduced the stimulation of the enzyme by vasoactive intestinal peptide (VIP). Likewise, in primary cultures of anterior pituitary cells, adenosine decreased prolactin secretion in both basal and VIP-stimulated conditions. In perifusion experiments, adenosine also inhibited prolactin release in both basal and TRH-stimulated conditions. PIA produced a biphasic pattern of response of basal adenylate cyclase activity, being inhibitory at low and stimulatory at high concentrations. In VIP-stimulated conditions, low concentrations of PIA inhibited both adenylate cyclase activity and prolactin release from primary cultures of pituitary cells, while no additive stimulatory effect was seen at high concentrations. Similarly, low concentrations of PIA reduced both basal and TRH-stimulated prolactin release from perifused pituitaries, while increasing PIA concentrations restored prolactin release. These data show that adenosine affects basal and stimulated prolactin secretion from anterior pituitary cells. Adenosine receptors seem to be coupled to the adenylate cyclase system in the anterior pituitary gland, suggesting a possible relationship between the effect of adenosine on adenylate cyclase activity and prolactin secretion.
Trypsin stimulation of aldosterone and 18-hydroxycorticosterone production by rat adrenal zona glomerulosa tissue is mediated by activation of protein kinase C
Authors: Vinson G. P. , Laird S. M. , Hinson J. P. , Mallick N. , Marsigliante S. , Teja R. 
Published: December 2008

ABSTRACT
When rat adrenal whole capsules, containing the zona glomerulosa, were incubated, addition of the protein kinase C inhibitors TMB-8 (10 μmol/l), W7, H7, polymyxin-B and sphingosine (all 1 μmol/l) was found to inhibit the steroidogenic response to trypsin. Aldosterone and 18-hydroxycorticosterone were strongly, and corticosterone moderately, affected, while the production of 18-hydroxydeoxycorticosterone was neither stimulated by trypsin nor inhibited by the protein kinase C inhibitors. Addition of neomycin, which prevents substrate interaction with phospholipase C, also inhibited the response to trypsin, while addition of phospholipase C itself stimulated aldosterone, 18-hydroxycorticosterone and corticosterone production with the same tissue sensitivity as trypsin. Addition of phospholipase A2 had no effect. Direct assay of protein kinase C activity showed that trypsin stimulation effected the translocation of Ca2+/phospholipid-activated protein kinase C from the cytosolic to the membrane fraction. When glomerulosa tissue was incubated with [32P]ATP, and cytosolic proteins were subjected to isoelectric focusing on polyacrylimide gels, autoradiography showed that incorporation of 32P into several protein components was increased by trypsin stimulation.
It was concluded that trypsin exerts its stimulatory effects on steroidogenesis by activating protein kinase C; not, however, by generating the Ca2+/phospholipid-independent fragment, but possibly by enhancing the activity of phospholipase C.
Site-specific mutagenesis of human chorionic gonadotrophin (hCG)-β subunit: influence of mutation on hCG production
Authors: Azuma C. , Miyai K. , Saji F. , Kamiura S. , Tokugawa Y. , Kimura T. , Ohashi K. , Koyama M. , Iijima Y. , Kashiwai T. , Hayashizaki Y. , Tanizawa O. 
Published: December 2008

ABSTRACT
The heterodimeric glycoprotein hormones, human chorionic gonadotrophin (hCG), LH, TSH and FSH, consist of two non-covalently linked subunits, the α and β subunits. The β subunit is specific for each hormone and is responsible for the biological specificity, but the β subunits of different hormones show some degree of structural homology. The CAGY (cysteine-alanine-glycine-tyrosine) region is one of the amino acid sequences that is homologous in different β subunits and is highly conserved between species. In the present study, site-specific in-vitro mutagenesis was used to change three individual nucleotides in the centre of the CAGY region of the hCG-β subunit, and the effects of these mutations on hCG production was determined by in-vitro transcription and then translation in Xenopus laevis oocytes. The results indicate that the CAGY region, particularly the glycine residue at position 36 in the β subunit, is essential for the production of hCG. This finding is consistent with previous studies showing that this region is necessary for the biological activity of human TSH.
Steroid hormones induce macrophage colony-stimulating factor (MCSF) and MCSF receptor mRNAs in the human endometrium
Authors: Azuma C. , Saji F. , Kimura T. , Tokugawa Y. , Takemura M. , Samejima Y. , Tanizawa O. 
Published: December 2008

ABSTRACT
We investigated the biological effects of sex-steroid hormones, secreted from the corpus luteum and placenta, on the induction of mRNAs encoding macrophage colony-stimulating factor (MCSF) and c-fms proto-oncogene (MCSF receptor) in human endometrium. RNA was extracted from the placenta and endometrium of both pregnant and non-pregnant women, and Northern blot analysis was performed on poly(A)+ RNA using MCSF or c-fms proto-oncogene cDNA as the probe. Results showed: (1) that MCSF mRNA was expressed in the placenta and endometrium of the pregnant uterus, (2) that c-fms proto-oncogene mRNA was also expressed in the placenta and endometrium of the pregnant uterus, and (3) that exogenous sex-steroid hormones could induce the expression of MCSF and c-fms proto-oncogene mRNAs in the endometrium of non-pregnant women. These results indicate that sex-steroid hormones secreted by the corpus luteum and/or placenta influence endometrial and placental growth and differentiation via a mechanism of action involving local production of MCSF and its receptor.
Thyrotrophin-releasing hormone stimulates polyphosphoinositide metabolism in the frog neurointermediate lobe
Authors: Desrues L. , Tonon M. C. , Vaudry H. 
Published: December 2008

ABSTRACT
Previous studies have demonstrated that TRH is a potent stimulator of α-MSH secretion from frog pituitary melanotrophs. In order to determine the intracellular events responsible for TRH-evoked α-MSH release, we have investigated the effect of TRH on polyphosphoinositide breakdown in frog pars intermedia. Neurointermediate lobes were labelled to isotopic equilibrium with myo-[3H]inositol.
TRH stimulated the rate of incorporation of [3H]inositol into the phospholipid fraction. The effect of TRH was concentration-dependent; half-maximal stimulation of α-MSH release and inositol incorporation occurred at 12 and 28 nmol TRH/1 respectively. In prelabelled neurointermediate lobes, lithium (10 mmol/l) enhanced the radioactivity in inositol monophosphate, bisphosphate (IP2) and trisphosphate (IP3). LiCl (10 mmol/l) induced a 38% inhibition of α-MSH release from perifused neurointermediate lobes but did not impair TRH-induced α-MSH secretion. In the presence of LiCl, TRH (1 μmol/l) induced a transient increase of the radioactivity in IP3, which was evident by 30 s and maximal by 1 min (+ 100%). TRH treatment also increased the radioactivity in IP2, which reached a plateau after 5 min (+ 100%). The increase in radioactivity in IP3 induced by TRH was closely paralleled by a rapid loss of [3H]phosphatidylinositol bisphosphate (PIP2), which was maximal by 1 min (−70%).
These results indicate that, in frog pars intermedia, TRH-evoked α-MSH secretion is coupled to breakdown of PIP2. The data suggest that, in amphibian melanotrophs, as previously shown in GH3 tumour cells and in rat pituitary mammotrophs, TRH causes rapid stimulation of polyphosphoinositide-hydrolysing phospholipase C.
The Booroola F gene mutation in sheep is not located close to the FSH-β gene
Authors: Montgomery G. W. , Sise J. A. , Greenwood P. J. , Fleming J. S. 
Published: December 2008

ABSTRACT
A cDNA probe for the β subunit of bovine FSH (FSH-β) detects multiple restriction fragment length polymorphisms (RFLPs) in sheep genomic DNA consistent with an insertion/deletion polymorphism around the FSH-β locus. The presence of the insertion/deletion was confirmed by screening over 100 individuals with two restriction enzymes detecting RFLPs. All individuals showed the same patterns of fragments with both enzymes. A partial restriction map of the FSH-β gene in sheep suggests that the insertion/deletion is approximately 2 kb in size and located downstream from the third exon. Individual DNA samples were analysed from two flocks where the Booroola F gene is known to be segregating. Individuals that were heterozygous for the F gene were shown to be homozygous for one or other of the two alleles. Genetic recombination between the FSH-β locus and the F gene was observed in four pedigrees and there was no evidence that the insertion/deletion is closely linked genetically to the Booroola F gene. A major gene transcript of 2·2–2·3 kb was detected on Northern blots of sheep RNA. Neither the insertion/deletion polymorphism nor the presence of the F gene appeared to influence the size of the FSH-β gene transcript.
Glucocorticoids regulate the amount of G proteins in rat aorta
Authors: Haigh R. M. , Jones C. T. , Milligan G. 
Published: December 2008

ABSTRACT
Glucocorticoids are known to influence cardiovascular sensitivity to catecholamines but the molecular mechanisms are undefined. We recently showed that glucocorticoids control the coupling of adrenergic receptors to G protein. Alterations in the amount of G protein is one mechanism by which receptor-G protein coupling may be controlled. Therefore, we set out to measure the levels of G proteins in aorta from normal, adrenalectomized and dexamethasonetreated adrenalectomized rats. G proteins were measured in plasma membrane preparations by immunoblotting and horseradish peroxidase staining. After adrenalectomy there was a 53% (n = 5) decrease in the density of staining for Gi (ANOVA; P<0.05 compared to controls). Conversely, there was a 210% (n = 5) increase in the density of staining for Gs. The levels of Go and the β-subunit of G proteins were not changed by adrenalectomy. Dexamethasone-replacement treatment after adrenalectomy returned Gi and Gs close to control values. Go remained unaltered compared to controls but was 24% (n=3) less than the adrenalectomized values (ANOVA; P<0.05). The levels of β-subunit after dexamethasone replacement were significantly greater (ANOVA; P<0.05) than both the controls and adrenalectomized values. These results show that glucocorticoids can differentially regulate the amounts of G proteins in rat aorta as in other tissues. This may be an important mechanism by which steroids control receptor-G protein coupling and hence transmembrane signalling pathways in vascular smooth muscle.
Internalization of human sex steroid-binding protein in the monkey epididymis
Authors: Gerard A. , Egloff M. , Gerard H. , Harate A. El , Domingo M. , Gueant J. L. , Dang C. D. , Degrelle H. 
Published: December 2008

ABSTRACT
Human sex steroid-binding protein (hSBP) has been purified from late-pregnancy serum and labelled either by iodination (125I) or by photoaffinity with [3H]Δ6-testosterone. Using a micromanipulator, each labelled protein was separately injected into the lumen of epididymal tubules isolated from the head epididymis of the cynomolgus monkey (Macaca fascicularis). Tubules were sampled from 3 to 90 min after the injection and processed for electron microscope autoradiography. Localization of the label occurred over the epididymal epithelium whichever tracer was used. The labelling was not randomly distributed over the different cell types constituting the epithelium, since only the 'principal cells' exhibited a silver grain count significantly greater than the background count. In these cells, labelled protein was found over endocytic organelles (coated structures, endosomes, multivesicular bodies and the trans Golgi network) and nuclei (including the nuclear envelope). Quantitative analysis demonstrated the same pattern of cellular and subcellular distribution for each tracer. Pretreatment with excess unlabelled protein significantly reduced the uptake of radioactivity by the principal cells, demonstrating the specificity of this phenomenon. This is the first study to show direct histological evidence for the internalization of hSBP in the primate epididymis, consistent with earlier immunohistochemical or biochemical localization of this protein. It is concluded that head epididymal cells are able to take up labelled hSBP across their apical membrane. The mechanism of internalization seems to involve endocytosis by the principal cells and leads to labelling of the nuclear compartment. This is strikingly similar to the pattern of uptake of rat androgen-binding protein (rABP) by rat epididymal cells previously demonstrated by our group. To what extent the chemical and structural homology between hSBP and rABP can be held responsible for the common cytophysiological behaviour of these sex steroid-binding proteins remains to be determined.
Hypothalamo-pituitary regulation of the c-myc gene in rat liver
Authors: Hällstöm I. Porsch , Gustafsson J.-Å. , Blanck A. 
Published: December 2008

ABSTRACT
Expression of the c-myc gene was studied in the livers of male and female Wistar rats. Furthermore, the effects on hepatic c-myc expression of neonatal and adult castration, with or without testosterone supplementation, as well as of continuous administration of GH to intact males, were analysed. Expression of c-myc was low in 6-day-old animals of both sexes, reached a maximum at 35 days of age and declined to the level of adult animals at 70 days. In prepubertal animals, expression was higher in females, but was higher in males after the onset of puberty, the postpubertal female rat liver exhibiting 50–70% of the expression in males.
Treatment of adult male rats with bovine GH in osmotic minipumps for 1 week reduced c-myc expression to the level of female rats. Castration, both neonatally and of adults, also feminized hepatic c-myc expression. Testosterone supplementation of the castrated animals increased the expression towards the level in sham-operated controls.
These results indicate that the c-myc gene is regulated by the hypothalamo-pituitary-liver axis via the sex-differentiated pattern of GH secretion, in analogy with other sex-differentiated hepatic functions, such as metabolism of steroids and xenobiotics. Neuroendocrine regulation of a gene such as c-myc, which is involved in the control of cell proliferation and differentiation, represents another aspect of the complex influence of GH on various somatic functions.
Modulation of inositol lipid hydrolysis in human breast cancer cells by two classes of bombesin antagonist
Authors: Patel K. V. , Schrey M. P. 
Published: December 2008

ABSTRACT
Inositol lipid hydrolysis was monitored in the human breast cancer cell line MCF-7 in response to various bombesin (BN) and substance P (SP) analogues. Both members of the BN family of peptides, i.e. BN and gastrin-releasing peptide (GRP), stimulated a dose-related increase in total inositol phosphate production, with a similar half-maximal effective dose (ED50) around 1 nm. The BN receptor antagonist [Leu13-Ψ-CH2NH-Leu14]-BN (LLBN) at 1 μm was devoid of agonist activity and displaced the BN dose—response to the right, resulting in a tenfold increase in the ED50 for BN. BN also stimulated a dose-related increase in 45Ca2+ efflux which was also inhibited by LLBN. Two SP analogues [dArg1, d-Pro2, d-Trp7,9,Leu11]-SP and [d-Arg1, d-Phe5, d-Trp7,9,Leu11]-SP ([APheTL]-SP), both antagonized BN-stimulated inositol lipid hydrolysis. [APheTL]-SP (60 and 80 μm) alone also exhibited considerable agonist activity which was not antagonized by LLBN. Indeed, a sub-threshold dose of [APheTL]-SP (40 μm) in the presence of LLBN (10 μm) potentiated the inositol lipid hydrolysis response. BN, GRP, LLBN and [APheTL]-SP all inhibited binding of 125I-labelled GRP to MCF-7 cells, to 50% of that occurring in the absence of the peptides, at concentrations of 150 pm, 150 pm, 150 nm and 600 nm respectively. These data are consistent with the presence of separate but interacting receptors or binding sites for BN and SP analogues, which are coupled to a common signal transduction pathway in human breast cancer cells.