bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nongenomic Activity and Subsequent c-fos Induction by Estrogen Receptor Ligands Are Not Sufficient to Promote Deoxyribonucleic Acid Synthesis in Human Endometrial Adenocarcinoma Cells
Authors: Singleton David W. , Feng Yuxin , Burd Craig J. , Khan Sohaib A. 
Published: December 2002

Abstract
Estrogen 17β-estradiol (E2) rapidly modulates several signaling pathways related to cell growth, preservation, and differentiation. The physiological role of these nongenomic effects with regard to downstream outcomes, and the relationship with transcriptional estrogen activity are unclear. Furthermore, the ability of selective estrogen receptor modulators (SERMs) to trigger nongenomic actions is largely unknown. To determine whether estrogen receptor (ER) ligands exert nongenomic activity in endometrial adenocarcinoma cells, and whether this activity affects transcription and DNA synthesis, we challenged human Ishikawa cells with E2 or partial ER agonists 4-hydroxytamoxifen (OHT) and raloxifene (ral). Serum-starved Ishikawa cells exposed for 5 min to 0.1 nm E2 showed induced phosphorylation of MAPK (ERK1/2). Ral and 4-OHT each at 1 nm also stimulated ERK in a rapid transient manner. E2 and 4-OHT induced proto-oncogene c-fos mRNA expression in Ishikawa cells within 30 min, but ral had no effect. In contrast to nongenomic action, only E2 stimulated expression of an estrogen response element (ERE)-driven luciferase (LUC) reporter gene. To examine DNA synthesis, [3H]-thymidine incorporation was measured in serum-starved cultures exposed to E2 or partial agonists for 2 d. E2 at 1 nm stimulated thymidine uptake in an ERK-dependent manner, but 1 nm 4-OHT, 1 nm ral, and 0.1-nm concentrations of E2 had no significant effects. Taken together, these data indicate that both nongenomic and direct transcriptional ER effects are likely required to promote DNA synthesis.
Sex Difference in Hepatic Peroxisome Proliferator-Activated Receptor α Expression: Influence of Pituitary and Gonadal Hormones
Authors: Jalouli Masoumeh , Carlsson Linda , Améen Caroline , Lindén Daniel , Ljungberg Anna , Michalik Liliane , Edén Staffan , Wahli Walter , Oscarsson Jan 
Published: December 2002

AbstractPeroxisome proliferator-activated receptor (PPAR) α is a nuclear receptor that is mainly expressed in tissues with a high degree of fatty acid oxidation such as liver, heart, and skeletal muscle. Unsaturated fatty acids, their derivatives, and fibrates activate PPARα. Male rats are more responsive to fibrates than female rats. We therefore wanted to investigate if there is a sex difference in PPARα expression. Male rats had higher levels of hepatic PPARα mRNA and protein than female rats. Fasting increased hepatic PPARα mRNA levels to a similar degree in both sexes. Gonadectomy of male rats decreased PPARα mRNA expression to similar levels as in intact and gonadectomized female rats. Hypophysectomy increased hepatic PPARα mRNA and protein levels. The increase in PPARα mRNA after hypophysectomy was more pronounced in females than in males. GH treatment decreased PPARα mRNA and protein levels, but the sex-differentiated secretory pattern of GH does not determine the sex-differentiated expression of PPARα. The expression of PPARα mRNA in heart or soleus muscle was not influenced by gender, gonadectomy, hypophysectomy, or GH treatment. In summary, pituitary-dependent hormones specifically regulate hepatic PPARα expression. Sex hormones regulate the sex difference in hepatic PPARα levels, but not via the sexually dimorphic GH secretory pattern.
New Evidence of Similarity between Human and Plant Steroid Metabolism: 5α-Reductase Activity in Solanum malacoxylon
Authors: Rosati Fabiana , Danza Giovanna , Guarna Antonio , Cini Nicoletta , Racchi Milvia Luisa , Serio Mario 
Published: December 2002

AbstractThe physiological role of steroid hormones in humans is well known, and the metabolic pathway and mechanisms of action are almost completely elucidated. The role of plant steroid hormones, brassinosteroids, is less known, but an increasing amount of data on brassinosteroid biosynthesis is showing unexpected similarities between human and plant steroid metabolic pathways. Here we focus our attention on the enzyme 5α-reductase (5αR) for which a plant ortholog of the mammalian system, DET2, was recently described in Arabidopsis thaliana. We demonstrate that campestenone, the natural substrate of DET2, is reduced to 5α-campestanone by both human 5αR isozymes but with different affinities. Solanum malacoxylon, which is a calcinogenic plant very active in the biosynthesis of vitamin D-like molecules and sterols, was used to study 5αR activity. Leaves and calli were chosen as examples of differentiated and undifferentiated tissues, respectively. Two separate 5αR activities were found in calli and leaves of Solanum using campestenone as substrate. The use of progesterone allowed the detection of both activities in calli. Support for the existence of two 5αR isozymes in S. malacoxylon was provided by the differential actions of inhibitors of the human 5αR in calli and leaves. The evidence for the presence of two isozymes in different plant tissues extends the analogies between plant and mammalian steroid metabolic pathways.
α-Melanocyte Stimulating Hormone Prevents Lipopolysaccharide-Induced Vasculitis by Down-Regulating Endothelial Cell Adhesion Molecule Expression
Authors: Scholzen T. E. , Sunderkötter C. , Kalden D.-H. , Brzoska T. , Fastrich M. , Fisbeck T. , Armstrong C. A. , Ansel J. C. , Luger T. A. 
Published: December 2002

AbstractThe neuroendocrine hormone α-melanocyte stimulating hormone (MSH) has profound antiinflammatory and immunomodulating properties. Here we have examined the possibility that α-MSH may interfere with the expression and function of cell adhesion molecules (CAMs) expressed by human dermal microvascular endothelial cells (HDMECs) in response to lipopolysaccharide (LPS) or TNFα in vitro and in vivo. In HDMEC, α-MSH (10−8/10−12m) profoundly reduced the mRNA and protein expression of E-selectin, vascular CAM (VCAM)-1, and intercellular CAM (ICAM)-1 induced by LPS or TNFα as determined by semiquantitative RT-PCR, ELISA, and fluorescence-activated cell sorter analysis. In addition, α-MSH significantly impaired the LPS-induced ICAM-1 and VCAM-1-mediated adhesion of lymphocytes to HDMEC monolayer in a functional adhesion assay. Likewise, α-MSH effectively inhibited the transcription factor nuclear factor-κB activation in HDMEC, which is required for CAM gene expression. Importantly in vivo, in murine LPS-induced cutaneous vasculitis (local Shwartzman reaction), a single ip injection of α-MSH significantly suppressed the deleterious vascular damage and hemorrhage by inhibiting the sustained expression of vascular E-selectin and VCAM-1. This persistent expression has been implicated in the dysregulation of diapedesis and activation of leukocytes, which subsequently leads to hemorrhagic vascular damage. Our findings indicate that α-MSH may have an important therapeutical potential for the treatment of vasculitis, sepsis, and inflammatory diseases.
Lysyl Oxidase Gene Expression and Enzyme Activity in the Rat Ovary: Regulation by Follicle-Stimulating Hormone, Androgen, and Transforming Growth Factor-β Superfamily Members in Vitro
Authors: Harlow Christopher R. , Rae Mick , Davidson Lindsay , Trackman Philip C. , Hillier Stephen G. 
Published: December 2002

AbstractLysyl oxidase (LOX) catalyzes the final enzymatic reaction required for cross-linking of collagen and elastin fibers and therefore has a crucial role in regulating the formation and maintenance of extracellular matrix in the ovary. LOX mRNA is abundantly expressed in rat granulosa cells. To examine how regulation of LOX in the ovary might influence follicular development, we studied LOX mRNA expression and enzyme activity in rat granulosa cells from late preantral/early antral follicles in vitro. FSH dose dependently inhibited LOX mRNA and enzyme activity (50% reduction at 10 ng/ml) in vitro, and FSH action was mimicked by 8-bromo-cAMP, suggesting FSH action via elevation of cAMP. Dihydrotestosterone alone enhanced LOX mRNA and enzyme activity, but potentiated the effect of FSH, causing a further reduction. TGFβ1 alone dose dependently enhanced LOX mRNA (5-fold increase at 10 ng/ml) and activity (1.5-fold increase). FSH dose dependently inhibited the increase in LOX mRNA and activity caused by TGFβ1 (by up to 84% and 80%, respectively). Growth differentiation factor-9 (GDF-9) and activin A, at the same concentration as TGFβ1 (10 ng/ml), stimulated LOX mRNA and activity within 6 h, although overall expression was higher at 48 h. All three factors when combined with FSH further reduced both mRNA and enzyme activity (by up to 60%) compared with FSH alone. These findings indicate control of LOX at endocrine, paracrine, and autocrine levels within the ovary and suggest coordinated regulation of ovarian extracellular matrix during follicular development, with FSH determining whether local factors act as stimulators or inhibitors of LOX.
Immunolesion of Norepinephrine and Epinephrine Afferents to Medial Hypothalamus Alters Basal and 2-Deoxy-d-Glucose-Induced Neuropeptide Y and Agouti Gene-Related Protein Messenger Ribonucleic Acid Expression in the Arcuate Nucleus
Authors: Fraley G. S. , Ritter S. 
Published: December 2002

Abstract
Neuropeptide Y (NPY) and agouti gene-related protein (AGRP) are orexigenic peptides of special importance for control of food intake. In situ hybridization studies have shown that NPY and AGRP mRNAs are increased in the arcuate nucleus of the hypothalamus (ARC) by glucoprivation. Other work has shown that glucoprivation stimulates food intake by activation of hindbrain glucoreceptor cells and requires the participation of rostrally projecting norepinephrine (NE) or epinephrine (E) neurons. Here we determine the role of hindbrain catecholamine afferents in glucoprivation-induced increase in ARC NPY and AGRP gene expression. The selective NE/E immunotoxin saporin-conjugated antidopamineβ-hydroxylase (anti-dβh) was microinjected into the medial hypothalamus and expression of AGRP and NPY mRNA was analyzed subsequently in the ARC under basal and glucoprivic conditions using 33P-labeled in situ hybridization. Saporin-conjugated anti-dβh virtually eliminated dβh-immunoreactive terminals in the ARC without causing nonspecific damage. These lesions significantly increased basal but eliminated 2-deoxy-d-glucose-induced increases in AGRP and NPY mRNA expression. Results indicate that hindbrain catecholaminergic neurons contribute to basal NPY and AGRP gene expression and mediate the responsiveness of NPY and AGRP neurons to glucose deficit. Our results also suggest that catecholamine neurons couple potent orexigenic neural circuitry within the hypothalamus with hindbrain glucose sensors that monitor brain glucose supply.
Central Administration of Neuropeptide Y Reduces α-Melanocyte-Stimulating Hormone-Induced Cyclic Adenosine 5′-Monophosphate Response Element Binding Protein (CREB) Phosphorylation in Pro-Thyrotropin-Releasing Hormone Neurons and Increases CREB Phosphorylation in Corticotropin-Releasing Hormone Neurons in the Hypothalamic Paraventricular Nucleus
Authors: Sarkar Sumit , Lechan Ronald M. 
Published: December 2002

AbstractNeuropeptide Y (NPY) has a potent inhibitory effect on TRH gene expression in the paraventricular nucleus (PVN) and contributes to the fall in circulating thyroid hormone levels during fasting mediated by a reduction in serum leptin levels. Because α-MSH activates the TRH gene by increasing the phosphorylation of CREB in the nucleus of these neurons, we raised the possibility that at least one of the mechanisms by which NPY reduces TRH mRNA in hypophysiotropic neurons is by antagonizing the ability of α-MSH to phosphorylate CREB. As NPY increases CRH mRNA in the hypothalamus, we further determined whether intracerebroventricular (icv) administration of NPY regulates the phosphorylation of CREB in hypophysiotropic CRH neurons. NPY [10 μg in artificial CSF (aCSF)] was administered into the lateral ventricle icv 30 min before the icv administration of aCSF or α-MSH (10 μg in aCSF), the latter in a dose previously demonstrated to increase proTRH mRNA and phosphorylate CREB in TRH neurons. By double-labeling immunocytochemistry, only few TRH neurons in the PVN contained phosphoCREB (PCREB) in animals treated only with aCSF (4 ± 0.2%) or with NPY followed by aCSF (9.7 ± 2.5), whereas α-MSH-infused animals dramatically increased the percentage of TRH neurons containing PCREB (75.3 ± 6.9%). Pretreatment with NPY before α-MSH infusion, however, significantly reduced the percentage of TRH neurons containing PCREB (40.8 ± 3.5%) compared with α-MSH infused animals (P = 0.01). Only 12.2 ± 0.9% of CRH neurons of the medial parvocellular neurons contained PCREB nuclei in vehicle-treated animals, whereas 30 min following NPY infusion, the number of CRH neurons containing PCREB increased dramatically to 88 ± 2.9%. Whereas α-MSH infusion increased the percentage of CRH neurons that contained PCREB to 56 ± 2.2% compared with control, animals pretreated with NPY further increased the number of CRH neurons colocalizing with PCREB to 87 ± 2.5%. These data demonstrate a functional interaction between NPY and α-MSH in the regulation of proTRH neurons in the PVN, suggesting that NPY can antagonize α-MSH induced activation of the TRH gene by interfering with melanocortin signaling at the postreceptor level, preventing the phosphorylation of CREB. In contrast, NPY infusion increases the phosphorylation of CREB in CRH neurons, indicating that NPY has independent effects on discrete populations of neurons in the PVN, presumably mediated through different signaling mechanisms.
Lysophosphatidic Acid Inhibits C-Type Natriuretic Peptide Activation of Guanylyl Cyclase-B
Authors: Abbey Sarah E. , Potter Lincoln R. 
Published: December 2002

AbstractC-type natriuretic peptide (CNP), found in endothelial cells, chondrocytes, and neurons, binds its cognate transmembrane receptor, natriuretic peptide receptor-B (NPR-B/GC-B), and stimulates the synthesis of the intracellular signaling molecule, cGMP. The known physiologic consequences of this binding event are vasorelaxation, inhibition of cell proliferation, and the stimulation of long bone growth. Here we report that 10% fetal bovine serum markedly reduced CNP-dependent cGMP elevations in NIH3T3 fibroblast. The purified serum components platelet-derived growth factor and lysophosphatidic acid (LPA) mimicked the effect of serum on CNP-dependent cGMP elevations, but the latter factor resulted in the most dramatic reductions. The LPA-dependent inhibition was rapid and dose dependent, having t1/2 and IC50 values of approximately 5 min and 3.0 μm LPA, respectively. The decreased cGMP concentrations resulted from reduced CNP-dependent NPR-B guanylyl cyclase activity that did not require losses in receptor protein or activation of protein kinase C, indicating a previously undescribed desensitization pathway. These data suggest that NPR-B is repressed by LPA and that one mechanism by which LPA exerts its effects is through the heterologous desensitization of the CNP/NPR-B/cGMP pathway. We hypothesize that cross-talk between the LPA and CNP signaling pathway maximizes the response of fibroblasts in the wound-healing process.
The Morphometry of Astrocytes in the Rostral Preoptic Area Exhibits a Diurnal Rhythm on Proestrus: Relationship to the Luteinizing Hormone Surge and Effects of Age
Authors: Cashion Adrienne B. , Smith Matthew J. , Wise Phyllis M. 
Published: December 2002

Abstract
The morphometry of astrocytes in the arcuate nucleus exhibits cyclic changes during the estrous cycle leading to dynamic changes in the communication between neurotransmitters and neuropeptides that regulate pituitary hormone secretion. Data suggest that remodeling of direct and/or indirect inputs into GnRH neurons may influence the timing and/or amplitude of the preovulatory LH surge in young rats. We have previously found that aging alters the timing and amplitude of the LH surge. Therefore, the purpose of this study was to focus on the rostral preoptic area where GnRH cell bodies reside. We assessed the possibility that the morphometry of astrocytes in the rostral preoptic area displays time-related and age-dependent changes on proestrus.
Our results demonstrate that, in young rats, astrocyte cell surface area decreases between 0800 h and 1200 h, before the initiation of the LH surge. Changes in surface area over the cycle were specific to astrocytes in close apposition to GnRH neurons. In contrast, in middle-aged rats astrocyte surface area was significantly less than in young rats and did not change during the day. These findings suggest that a loss of astrocyte plasticity could lead to the delayed and attenuated LH surge that has been previously observed in middle-aged rats.
Menkes Protein Contributes to the Function of Peptidylglycine α-Amidating Monooxygenase
Authors: Steveson Tami C. , Ciccotosto Giuseppe D. , Ma Xin-Ming , Mueller Gregory P. , Mains Richard E. , Eipper Betty A. 
Published: December 2002

AbstractMenkes protein (ATP7A) is a P-type ATPase involved in copper uptake and homeostasis. Disturbed copper homeostasis occurs in patients with Menkes disease, an X-linked disorder characterized by mental retardation, neurodegeneration, connective tissue disorders, and early childhood death. Mutations in ATP7A result in malfunction of copper-requiring enzymes, such as tyrosinase and copper/zinc superoxide dismutase. The first step of the two-step amidation reaction carried out by peptidylglycine α-amidating monooxygenase (PAM) also requires copper. We used tissue from wild-type rats and mice and an ATP7A-specific antibody to determine that ATP7A is expressed at high levels in tissues expressing high levels of PAM. ATP7A is largely localized to the trans Golgi network in pituitary endocrine cells. The Atp7a mouse, bearing a mutation in the Atp7a gene, is an excellent model system for examining the consequences of ATP7A malfunction. Despite normal levels of PAM protein, levels of several amidated peptides were reduced in pituitary and brain extracts of Atp7a mice, demonstrating that PAM function is compromised when ATP7A is inactive. Based on these results, we conclude that a reduction in the ability of PAM to produce bioactive end-products involved in neuronal growth and development could contribute to many of the biological effects associated with Menkes disease.
Anion Selectivity by the Sodium Iodide Symporter
Authors: Van Sande J. , Massart C. , Beauwens R. , Schoutens A. , Costagliola S. , Dumont J. E. , Wolff J. 
Published: December 2002

Abstract
The iodide transporter of the thyroid (NIS) has been cloned by the group of Carrasco. The NIS-mediated transport was studied by electrophysiological methods in NIS-expressing Xenopus oocytes. Using this method, the anion selectivity of NIS was different from that previously reported for thyroid cells, whereas perchlorate and perrhenate were found not transported. In this study we compared the properties of human NIS, stably transfected in COS-7 cells to those of the transport in a thyroid cell line, the FRTL5 cells, by measuring the transport directly. We measured the uptake of 125I−, 186ReO4−, and 99mTcO4− and studied the effect on it of known competing anions, i.e. ClO4−, SCN−, ClO3−, ReO4−, and Br−. We conclude that the properties of the NIS transporter account by themselves for the properties of the thyroid iodide transporter as described previously in thyroid slices. The order of affinity was: ClO4− &gt; ReO4− &gt; I− ≥ SCN− &gt; ClO3− &gt; Br−. NIS is also inhibited by dysidenin (as in dog thyroid).
Ghrelin Protects Against Ethanol-Induced Gastric Ulcers in Rats: Studies on the Mechanisms of Action
Authors: Sibilia V. , Rindi G. , Pagani F. , Rapetti D. , Locatelli V. , Torsello A. , Campanini N. , Deghenghi R. , Netti C. 
Published: December 2002

Abstract
Ghrelin, the endogenous ligand for GH secretagogue receptors, has been reported to influence acid gastric secretion and motility, but its potential gastroprotective effect is unknown. The aims of this study were 1) to examine the effects of central and peripheral administration of ghrelin on ethanol-induced gastric ulcers in conscious rats, and 2) to investigate the possible roles of nitric oxide (NO), vagal nerve, and sensory fibers in the gastric effects of ghrelin.
Ghrelin was administered either intracerebroventricularly or sc 30 min before ethanol, and mucosal lesions were examined macroscopically. Additionally, rats were either treated with the inhibitor of NO synthesis Nω-nitro-l-arginine methyl ester (L-NAME) or underwent bilateral cervical vagotomy or capsaicin-induced sensory denervation. Conventional histology and immunohistochemistry for ghrelin, gastrin, and somatostatin were performed on gastric specimens from representative rats.
Central ghrelin (4–4000 ng/rat) dose-dependently reduced ethanol-induced gastric ulcers by 39–77%. Subcutaneous ghrelin administration (80 μg/kg) reduced ulcer depth only. L-NAME and capsaicin, but not vagotomy, prevented the gastroprotective effect of central ghrelin (4000 ng/rat).
This is the first evidence that ghrelin exerts a potent central gastroprotective activity against ethanol-induced lesions. The gastroprotective effect of ghrelin is mediated by endogenous NO release and requires the integrity of sensory nerve fibers.