bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cytokines Induce Deoxyribonucleic Acid Strand Breaks and Apoptosis in Human Pancreatic Islet Cells*
Authors: Delaney Carol A. , Pavlovic Dejan , Hoorens Anne , Pipeleers Daniel G. , Eizirik Décio L. 
Published: January 2014

Abstract
We have previously observed that a 6-day exposure of human pancreatic islets to a combination of cytokines (interleukin-1β 50 U/ml + tumour necrosis factor-α 1000 U/ml + interferon-γ 1000 U/ml) severely impairs β-cell functions. In the present study, we examined whether this condition affects DNA integrity and viability of human islet cells. Cells were studied after 3, 6, and 9 days of cytokine treatment by both single cell gel electrophoresis (the “comet assay,” a sensitive method for detection of DNA strand breaks) and by a cytotoxicity assay using the DNA binding dyes Hoechst 33342 and propidium iodide as indices for the number of viable, necrotic, and apoptotic cells. Cytokine treatment for 6 and 9 days resulted in a 50% increase in comet length (P &lt; 0.01 vs. controls), indicating DNA strand breaks, as well as in a significant increase in the number of apoptotic cells (P &lt; 0.02 vs. controls), but not in the number of necrotic cells. The arginine analogs NG-nitro-l-arginine and NG-monomethyl-l-arginine prevented nitric oxide formation by the cytokines but did not interfere with cytokine-induced DNA strand breaks and apoptosis. The present data suggest that prolonged (6–9 days) exposure of human pancreatic islets to a mixture of cytokines induces DNA strand breaks and cell death by apoptosis. These deleterious effects of cytokines appear to be independent of nitric oxide generation.
Identification of cis-Acting Deoxyribonucleic Acid Elements That Mediate Gonadotropin-Releasing Hormone Stimulation of the Rat Luteinizing Hormone β-Subunit Gene*
Authors: Kaiser Ursula B. , Sabbagh Elena , Saunders Brian D. , Chin William W. 
Published: January 2014

AbstractGnRH plays a critical role in reproductive development and function by regulating the biosynthesis and secretion of the pituitary gonadotropins, LH and FSH. Although it is known that GnRH induces gonadotropin subunit gene transcription, the mechanism by which this occurs has not been elucidated. Studies have been hindered by the lack of available cell lines that express the LH and FSH subunit genes and respond to GnRH. We have transfected the rat pituitary GH3 cell line with the rat GnRH receptor complementary DNA. These cells, when cotransfected with regulatory regions of the LH or FSH subunit genes fused to a luciferase reporter gene, respond to GnRH with an increase in promoter activity comparable to that seen in primary rat pituitary cells. In this study, we have used this cell model to identify cis-acting elements of the LHβ gene that mediate stimulation by GnRH. Analysis of a series of 5′-deletion and internal deletion constructs has revealed two regions of the rat LHβ gene promoter involved in mediating the response to GnRH, region A (−490/−352) and region B (−207/−82). Fusion of region A upstream of a heterologous minimal promoter linked to the luciferase gene conferred GnRH responsiveness to the promoter, whereas region B did not. However, the presence of both regions A and B conferred a greater GnRH response than region A alone. Electrophoretic mobility shift assay revealed the presence of a protein(s) binding to region A using GH3 as well as αT3–1 nuclear extracts. Thus, region A (−490/−352) confers GnRH responsiveness to the LHβ subunit gene and binds to a protein(s) present in pituitary cell lines. DNA sequences in region B (−207/−82) also contribute to GnRH responsiveness. The identification of putative GnRH response elements in the rat LHβ gene promoter will aid in elucidation of the mechanisms of regulation of gene expression by GnRH.
Induction of Oxytocin Receptor Gene Expression in Rabbit Amnion Cells*
Authors: Jeng Yow-Jiun , Lolait Stephen J. , Soloff Melvyn S. 
Published: January 2014

AbstractOxytocin (OT)-stimulated PGE2 release by rabbit amnion is enhanced by the up-regulation of oxytocin receptors (OTR), which increase about 200-fold at the end of pregnancy. As recent studies have shown that PGs are essential for parturition, the rise in amnion OTR and associated PGE2 synthesis are probably essential for labor initiation. The present work was directed toward understanding the mechanisms of OTR up-regulation. Levels of agents that stimulate adenylyl cyclase activity and cortisol are increased in amniotic fluid at the end of pregnancy. Addition of either forskolin or cortisol to cultured amnion cells caused an increase in OTR ligand-binding sites and steady state OTR messenger RNA (mRNA) levels. Forskolin treatment elevated OTR mRNA levels rapidly, but transiently, whereas cortisol’s effects were slower and sustained. Actinomycin or cycloheximide, added 3 h after forskolin, led to a sustained elevation in OTR mRNA levels, suggesting that forskolin increases the activities of OTR mRNA-destabilizing factors along with increasing OTR mRNA concentration. Cortisol did not appear to affect OTR mRNA stability. Measurement of OTR mRNA transcription rates showed that forskolin’s effects were maximal within 1 h of treatment. In contrast, cortisol-induced transcription was not apparent until 8 h. The effects of forskolin and cortisol on OTR gene transcription were synergistic. Thus, the increase in OTR mRNA levels occurring after either forskolin or cortisol treatments is the result of induction of OTR gene expression, but the effects of the two agents appear to occur at separate sites.
Effect of Epalrestat, an Aldose Reductase Inhibitor, on the Generation of Oxygen-Derived Free Radicals in Neutrophils from Streptozotocin-Induced Diabetic Rats*
Authors: Kashima Koji , Sato Noriyuki , Sato Ken , Shimizu Hiroyuki , Mori Masatomo 
Published: January 2014

AbstractNeutrophil function is impaired by a known mechanism in diabetic patients, thus increasing susceptibility to infections. We studied the effect of epalrestat, an aldose reductase inhibitor, on the generation of oxygen-derived free radicals and cytosolic sorbitol concentration in neutrophils from streptozotocin-induced diabetic rats. There were four groups: treated and untreated control and diabetic rats. Treated groups were given 0.075% epalrestat in their diet for 4 weeks from the induction of diabetes and were untreated for the subsequent 4 weeks. Oxygen radicals were measured as chemiluminescence amplified by a luciferin analog [Cypridina luciferin analog-dependent chemiluminescence (CLA-DCL), which is dependent on O2− generation] and luminol (L)-DCL, which is highly dependent on OCl− generation) in response to formyl-methonyl-leucyl-phenylalanine. Diabetes resulted in a significant decrease in CLA/L-DCL and a significant increase in sorbitol (P &lt; 0.01); there was a negative correlation between sorbitol and CLA-DCL (P &lt; 0.05) in diabetic groups. The 4-week treatment with epalrestat in the diabetic group completely prevented the increase in sorbitol and partially improved the CLA-DCL, although L-DCL was not significantly affected. After 4 weeks off treatment, CLA-DCL decreased and sorbitol increased. Treatment had no effect on serum insulin or glucose concentration. We conclude that an increase in sorbitol in neutrophils causes, in part, an impaired generation of O2−. Epalrestat improves the impaired O2− generation by preventing the sorbitol increase in streptozotocin-induced diabetic rats.
Repeated Intracerebroventricular Administration of Glucagon-Like Peptide-1-(7–36) Amide or Exendin-(9–39) Alters Body Weight in the Rat**This work was supported by the United Kingdom Medical Research Council.
Authors: Meeran Karim , O’Shea Donal , Edwards C. Mark B. , Turton Mandy D. , Heath Melanie M. , Gunn Irene , Abusnana Salahedeen , Rossi Michela , Small Caroline J. , Goldstone Anthony P. , Taylor Gillian M. , Sunter David , Steere Joanna , Choi Sang Jeon , Ghatei Mohammad A. , Bloom Stephen R. 
Published: January 2014

AbstractCentral nervous system glucagon-like peptide-1-(7–36) amide (GLP-1) administration has been reported to acutely reduce food intake in the rat. We here report that repeated intracerebroventricular (icv) injection of GLP-1 or the GLP-1 receptor antagonist, exendin-(9–39), affects food intake and body weight. Daily icv injection of 3 nmol GLP-1 to schedule-fed rats for 6 days caused a reduction in food intake and a decrease in body weight of 16 ± 5 g (P &lt; 0.02 compared with saline-injected controls). Daily icv administration of 30 nmol exendin-(9–39) to schedule-fed rats for 3 days caused an increase in food intake and increased body weight by 7 ± 2 g (P &lt; 0.02 compared with saline-injected controls). Twice daily icv injections of 30 nmol exendin-(9–39) with 2.4 nmol neuropeptide Y to ad libitum-fed rats for 8 days increased food intake and increased body weight by 28 ± 4 g compared with 14 ± 3 g in neuropeptide Y-injected controls (P &lt; 0.02). There was no evidence of tachyphylaxis in response to icv GLP-1 or exendin-(9–39). GLP-1 may thus be involved in the regulation of body weight in the rat.
Altered Expression of Agouti-Related Protein and Its Colocalization with Neuropeptide Y in the Arcuate Nucleus of the Hypothalamus during Lactation*
Authors: Chen Peilin , Li Chien , Haskell-Luevano Carrie , Cone Roger D. , Smith M. Susan 
Published: January 2014

AbstractDuring lactation, the levels of neuropeptide Y (NPY), which plays an important role in mediating food intake, are significantly elevated in a number of hypothalamic areas, including the arcuate nucleus (ARH). To identify additional hypothalamic systems that might be important in mediating the increase in food intake and alterations in energy homeostasis during lactation, the present studies examined the expression of agouti-related protein (AGRP), a recently described homologue of the skin agouti protein. AGRP is found in the hypothalamus and has been suggested to play an important role in the regulation of food intake. In the first experiment, animals were studied during diestrus of the estrous cycle, a stage of the cycle when estrogen levels are basal and similar to lactation, or during days 12–13 postpartum. Lactating animals had their litters adjusted to eight pups on day 2 postpartum. Brain tissue sections were used to measure AGRP messenger RNA (mRNA) levels by in situ hybridization. AGRP mRNA signal was found mostly in the ventromedial portion of the ARH, which has been shown to contain a high density of NPY neurons. A significant increase in AGRP mRNA content was observed in the mid- to caudal portion of the ARH of lactating animals compared with diestrous females. No difference was found in the rostral portion of the ARH. In the second experiment, double-label in situ hybridization for AGRP and NPY was performed in lactating animals to determine the extent of colocalization of the two peptides in the ARH, using 35S-labeled and digoxigenin-labeled antisense complementary RNA probes. It was found that almost all of the NPY-positive neurons throughout the ARH also expressed AGRP mRNA signal. Furthermore, AGRP expression was confined almost exclusively to NPY-positive neurons. Thus, the present study showed that during lactation, AGRP gene expression was significantly elevated in a subset of the AGRP neurons in the ARH. The high degree of colocalization of AGRP and NPY, coupled with previous reports from our laboratory demonstrating increased NPY expression in the ARH in response to suckling, suggests that AGRP and NPY are coordinately regulated and may be involved in the increase in food intake during lactation.
FKHR Binds the Insulin Response Element in the Insulin-Like Growth Factor Binding Protein-1 Promoter*
Authors: Durham Susan K. , Suwanichkul Adisak , Scheimann Ann O. , Yee Douglas , Jackson James G. , Barr Frederic G. , Powell David R. 
Published: January 2014

AbstractThe insulin response element (IRE) in the IGFBP-1 promoter, and in other gene promoters, contains a T(A/G)TTT motif essential for insulin inhibition of transcription. Studies presented here test whether FKHR may be the transcription factor that confers insulin inhibition through this IRE motif. Immunoblots using antiserum to the synthetic peptide FKHR413–430, RNase protection, and Northerns blots show that FKHR is expressed in HEP G2 human hepatoma cells. Southwestern blots, electromobility shift assays, and DNase I protection assays show that Escherichia coli-expressed GST-FKHR binds specifically to IREs from the IGFBP-1, PEPCK and TAT genes; however, unlike HNF3β, another protein proposed to be the insulin regulated factor, GST-FKHR does not bind the insulin unresponsive G/C-A/C mutation of the IGFBP-1 IRE. When HEP G2 cells were cotransfected with FKHR expression vectors and with IGFBP-1 promoter plasmids containing either native or mutant IREs, FKHR expression induced a 5-fold increase in activity of the native IGFBP-1 promoter but no increase in activity of promoter constructs containing insulin unresponsive IRE mutants. These data suggest that FKHR, and/or a related family member, is the important T(G/A)TTT binding protein that confers the inhibitory effect of insulin on gene transcription.
Glycosylation-Dependent Cell Adhesion Molecule 1 (GlyCAM 1) Is Induced by Prolactin and Suppressed by Progesterone in Mammary Epithelium**This work was supported by National Institutes of Health.
Authors: Hou Zhaoyuan , Bailey Jason P. , Vomachka Archie J. , Matsuda Manabu , Lockefeer Jason A. , Horseman Nelson D. 
Published: January 2014

AbstractGlycosylation-dependent cell adhesion molecule 1 (GlyCAM 1), a mucin-like endothelial glycoprotein, was induced by PRL and suppressed by progesterone in the mammary gland of mice, and in HC11 mouse mammary epithelial cells. Complementary DNA microarray analysis revealed that expression of GlyCAM 1 was reduced in the mammary gland of PRL-gene disrupted mice (PRL−/−) compared with control (PRL+/−) littermates. This result was confirmed by in situ hybridization and immunostaining. The messenger RNA (mRNA) encoding GlyCAM 1 was present in mammary epithelia of PRL-stimulated mice. Immunohistochemistry indicated that GlyCAM 1 protein was detectable both in mammary epithelia and in the ductal lumen in PRL+/− virgin mice, but not in PRL−/− mice. GlyCAM 1 mRNA was highly induced by grafting pituitary glands from normal littermates. Trace amounts of mRNA for GlyCAM 1 were detected by RT-PCR in mammary tissue of PRL−/− mice. Progesterone inhibited both basal and PRL-stimulated GlyCAM 1 transcription. In HC11 cells, GlyCAM 1 mRNA was induced in cells treated with insulin, dexamethasone, and PRL. Similar to the in vivo studies, progesterone inhibited the induction of GlyCAM 1 transcription. In CHO cells, PRL stimulated transcription of a luciferase reporter gene containing an 800-bp promoter fragment of GlyCAM 1, and progesterone partially suppressed the PRL effect. These data demonstrate that expression of GlyCAM 1 in mammary gland is under the control of both PRL and progesterone.
A1 Adenosine Receptor Activation Increases Adipocyte Leptin Secretion*
Authors: Rice Alan M. , Fain John N. , Rivkees Scott A. 
Published: January 2014

AbstractA1 adenosine receptors (A1ARs) are heavily expressed in adipocytes and influence fat cell metabolism. Because increasing evidence suggests a role for leptin in mediating appetite and fat cell metabolism, we tested whether A1ARs regulate leptin production. Rats were treated with the A1AR agonist N6-cyclopentyladenosine (CPA), and changes in circulating levels of leptin and leptin gene expression were examined. Serum leptin levels rose 2- to 10-fold, with peak increases seen 8–16 h after injection of CPA (P &lt; 0.05). In contrast, CPA did not alter steady state levels of adipose tissue leptin mRNA. To assess the influence of endogenous adenosine on circulating leptin levels, rats were also injected with dipyridamole (DPY), an adenosine reuptake blocker. DPY induced 80% increases in serum levels at 8 h after injections (P &lt; 0.05). Supporting the idea that stimulation of leptin production is A1AR mediated, pretreatment with the A1AR antagonist 8-cyclopentyl-1,3-dipropylxanthine completely blocked increases in leptin levels after DPY treatment. To complement in vivo studies, the effect of A1AR activation on leptin secretion was also studied in epididymal fat pad cultures. In cultures, CPA treatment increased leptin secretion by 37% (P &lt; 0.05). Collectively, these data show that the adenosinergic system can increase leptin secretion by directly activating A1ARs in fat tissue.
The in Vivo and in Vitro Effects of Exogenous Leptin on Ovulation in the Rat*
Authors: Duggal Priya S. , Van der Hoek Kylie H. , Milner Clyde R. , Ryan Natalie K. , Armstrong David T. , Magoffin Denis A. , Norman Robert J. 
Published: January 2014

Abstract
Leptin, a hormonal product of the Lep gene, is expressed by adipocytes and is thought to play a role in regulating food intake and reproduction. The leptin protein has been localized in many reproductive tissues, including the ovary. Several publications indicate that the ovary is directly affected by leptin and that leptin may be a factor linking obesity and reproductive dysfunction. In this study, the effect of systemic leptin administration on ovulation in the rat ovary, both in vivo and in vitro, was investigated. Ip administration of leptin (30 μg at 3 hourly intervals for 15 h) to immature gonadotropin-primed rats caused a decline in ovulation in vivo, from 15.9 ± 2.0 oocytes in the control animals to 5.3 ± 1.6 oocytes in the leptin-treated animals (P &lt; 0.001). Plasma progesterone and estradiol levels were analyzed immediately before ovulation, and neither was altered significantly in animals receiving the leptin treatment. Food consumption and body weight decreased following leptin treatment; however, a loss in body weight alone (pair-fed controls) was insufficient to explain the decrease in ovulation observed in the leptin-treated animals. In vitro perfusion of FSH-primed whole ovaries showed that treatment with leptin in combination with LH significantly decreased ovulations from 5.7 ± 1.6 per ovary perfused with LH alone to 1.3 ± 0.6 in those with LH and 1 μg/ml leptin (P &lt; 0.05). Progesterone and estradiol levels in the samples taken during the perfusion period were unaffected by leptin treatment. In summary, leptin administration resulted in fewer ovulations, both in vivo and in vitro, but did not influence steroid levels. Systemic leptin administration at these doses can therefore inhibit ovulation, a process that occurs through a direct effect on the ovary.
Interactions between the Prohormone Convertase 2 Promoter and the Thyroid Hormone Receptor*
Authors: Li Qiao-Ling , Jansen Erik , Brent Gregory A. , Naqvi Syed , Wilber John F. , Friedman Theodore C. 
Published: January 2014

AbstractThe majority of prohormones are cleaved at paired basic residues to generate bioactive hormones by prohormone convertases (PCs). As PC1 and PC2, two neuroendocrine-specific PCs, appear to be the key enzymes capable of processing a variety of prohormones, alterations of PC2 and/or PC1 levels will probably have a profound effect on hormonal homeostasis. We investigated the regulation of PC2 messenger RNA (mRNA) by thyroid hormone using GH3 cells to demonstrate that T3 negatively regulated PC2 mRNA levels in a dose- and time-dependent fashion. Functional analysis of progressive 5′-deletions of the human (h) PC2 promoter luciferase constructs in GH3 cells demonstrated that the regulation probably occurs at the transcriptional level, and that putative negative thyroid hormone response elements were located within the region from −44 to +137 bp relative to the transcriptional start site. Transient transfections in JEG-3 cells and COS-1 cells showed that the suppressive effect of T3 was equally mediated by the thyroid hormone receptor (TR) isoforms TRα1 and TRβ1. Electrophoretic mobility shift assays using purified TRα1 and retinoid X receptor-β protein as well as GH3 nuclear extracts showed that regions from +51 to +71 bp and from +118 to +137 bp of the hPC2 promoter bind to TRα1 as both a monomer and a homodimer and with TRα1/retinoid X receptor-β as a heterodimer. Finally, the in vivo regulation of pituitary PC2 mRNA by thyroid status was demonstrated in rats. These results demonstrate that T3 negatively regulates PC2 expression at the transcriptional level and that functional negative thyroid hormone response elements exist in the hPC2 promoter. We postulate that the alterations of PC2 activity may mediate some of the pathophysiological consequences of hypo- or hyperthyroidism.
Coexpression of ERβ with ERα and Progestin Receptor Proteins in the Female Rat Forebrain: Effects of Estradiol Treatment
Authors: Gréco Béatrice , Allegretto E. A. , Tetel M. J. , Blaustein J. D. 
Published: January 2014

Abstract
Estrogen and progestin receptors (ER, PgR) play a critical role in the regulation of neuroendocrine functions in females. The neuroanatomical distribution of the recently cloned, ERβ, overlaps with both ERα and PgR. To determine whether ERβ is found within ERα- or PgR-containing neurons in female rat, we used dual label immunocytochemistry. ERβ-immunoreactivity (ERβ-ir) was primarily detected in the nuclei of cells in the periventricular preoptic area (PvPO), the bed nucleus of the stria terminalis (BNSTpr), the paraventricular nucleus, the supraoptic nucleus, and the medial amygdala (MEApd). Coexpression of ERβ-ir with ERα-ir or PgR-ir was observed in the PvPO, BNSTpr, and MEApd in ovariectomized rats. E2 treatment decreased the number of ERβ-ir cells in the PvPO and BNSTpr and the number of ERα-ir cells in the MEApd and paraventricular nucleus, and therefore decreased the number of cells coexpressing ERβ-ir and ERα-ir in the PvPO, BNSTpr, and MEApd. E2 treatment increased the amount of PgR-ir in cells of the PvPO, BNSTpr, and MEApd, a portion of which also contained ERβ. These results demonstrate that ERβ is expressed in ERα- or PgR-containing cells, and they suggest that E can modulate the ratios of these steroid receptors in a brain region-specific manner.
Distribution of Chimeric IGF Binding Protein (IGFBP)-3 and IGFBP-4 in the Rat Heart: Importance of C-Terminal Basic Region
Authors: Knudtson K. L. , Boes M. , Sandra A. , Dake B. L. , Booth B. A. , Bar R. S. 
Published: January 2014

AbstractIGF binding proteins-3 and -4, whether given in the perfused rat heart or given iv in the intact animal, cross the microvascular endothelium of the heart and distribute in subendothelial tissues. IGF binding protein-3, like IGF-I/II, localizes in cardiac muscle, with lesser concentrations in CT elements. In contrast, IGFBP-4 preferentially localizes in CT. In this study, chimeric IGF binding proteins were prepared in which a basic 20-amino-acid C-terminal region of IGF binding protein-3 was switched with the homologous region of IGF binding protein-4, and vice-versa, to create IGF binding protein-34 and IGF binding protein-43. Perfused IGF binding protein-34 behaved like IGF binding protein-4, localizing in connective tissue elements, whereas IGF binding protein-43 now localized in cardiac muscle at concentrations identical to perfused IGF binding protein-3. To determine whether these small mutations altered the affinity of the chimera for cells, the ability of 125I-IGF binding protein-34 and 125I-IGF binding protein-43 to bind to microvascular endothelial cells was determined and compared with IGF binding protein-3. IGF binding protein-34 retained 15% of the binding capacity of IGF binding protein-3, whereas IGF binding protein-43 bound to microvessel endothelial cells with higher affinity and greater total binding than that of IGF binding protein-3. We conclude that small changes in the C-terminal basic domain of IGF binding protein-3 and the corresponding region of IGF binding protein-4 can alter their affinity for cultured cells and influence their tissue distribution in the rat heart.