Diss. (sammanfattning) Uppsala : Uppsala universitet, 2008. / Härtill 4 uppsatser.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2018-11-01T15:30:56Z No. of bitstreams: 2 Dissertação - Daniel Pereira Cavalcante - 2018.pdf: 1689683 bytes, checksum: f7e099cdea49d38708f07e5f523e5d8b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-11-01T15:49:18Z (GMT) No. of bitstreams: 2 Dissertação - Daniel Pereira Cavalcante - 2018.pdf: 1689683 bytes, checksum: f7e099cdea49d38708f07e5f523e5d8b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-11-01T15:49:18Z (GMT). No. of bitstreams: 2 Dissertação - Daniel Pereira Cavalcante - 2018.pdf: 1689683 bytes, checksum: f7e099cdea49d38708f07e5f523e5d8b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-10-04 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Ghrelin is a recently discovered peptide, mainly produced in the stomach and involved in body's energy-maintenance processes. Ghrelin exerts its actions by activating the growth hormone secretagogue receptor (GHS-R). A number of studies have investigated the involvement of ghrelin in the modulation of emotional behavior. In this context, evidence shows the presence of GHS-R receptors in the dorsal raphe nucleus (DRN), the main source of serotonergic neurons that innervate encephalic structures involved in emotional control. Our study aims to evaluate the effects of the pharmacological manipulation of ghrelin receptors located in the DRN on the expression of the behavioral responses of Wistar rats. Such responses were assessed in the elevated T maze (ETM), an experimental model that allows the measurement, in the same animal, of two defensive behavioral strategies, inhibitory avoidance and escape. Our results showed that the intra-DRN infusion of ghrelin impaired the acquisition of inhibitory avoidance, an anxiolytic-like effect, and facilitated the expression of escape response in the ETM, indicating a panicogenic-like effect. The intra-DRN administration of the ghrelin receptor (GHS-R1a) antagonist PF-04628935 did not alter the behavioral tasks assessed in the ETM. Finally, our results revealed that intra-DRN infusions of PF-04628935 prior to the administration of ghrelin into this area neutralized the behavioral effects obtained in the ETM. Taken together, our data reveal an important involvement of the ghrelin central signaling system in the mediation of defensive behavioral responses that have been associated with generalized anxiety and panic disorders. / A grelina é um peptídeo recentemente descoberto, produzido principalmente no estômago e envolvido nos processos de manutenção de energia do organismo. A grelina exerce suas ações ao ativar o receptor secretagogo do hormônio do crescimento (GHS-R). Uma série de estudos tem investigado o envolvimento da grelina na modulação de comportamentos emocionais. Neste contexto, evidências mostram a presença de receptores GHS-R no núcleo dorsal da rafe (NDR), principal fonte de neurônios serotonérgicos que inervam estruturas encefálicas envolvidas no controle emocional. O objetivo deste trabalho foi avaliar os efeitos obtidos com a manipulação farmacológica dos receptores de grelina localizados no NDR sobre a expressão das respostas comportamentais de esquiva inibitória e fuga de ratos. Tais respostas foram avaliadas no labirinto em T elevado (LTE), modelo experimental que possibilita a medida, em um mesmo animal, de duas estratégias comportamentais defensivas, a esquiva inibitória e a fuga. Os dados de nosso estudo mostraram que a infusão intra-NDR de grelina prejudicou a aquisição da resposta de esquiva inibitória, um efeito ansiolítico, e facilitou a expressão da resposta de fuga dos animais no LTE, um efeito panicogênico. A administração intra-NDR do antagonista de receptores de grelina (GHS-R1a) PF-04628935 não modificou as respostas comportamentais defensivas avaliadas no LTE. Por fim, nossos dados mostraram que a infusão de PF-04628935 previamente à injeção de grelina no NDR foi capaz de bloquear os efeitos comportamentais obtidos no LTE. Tomadas em conjunto, as evidências obtidas em nosso estudo apontam para um importante envolvimento do sistema central de sinalização do peptídeo grelina na mediação de respostas comportamentais defensivas que têm sido associadas aos transtornos de ansiedade generalizada e do pânico.

Abstract Ghrelin is a peptide hormone with anabolic functions. It increases growth hormone secretion and appetite, decreases fat utilisation as a metabolic fuel and increases fat storage in the adipose tissue. In addition, ghrelin exerts effects on glucose metabolism, heart function and inflammatory processes. Due to these characteristics ghrelin has become a hot topic for research focusing on obesity and its co-morbidities such as hypertension, type 2 diabetes and atherosclerosis. The aims of this study were to detect new sequential variations in the genes coding for the ghrelin receptor and ghrelin and to study whether these variations associate with obesity and metabolic risk factors for atherosclerosis. The roles of genetic and environmental factors in the determination of plasma ghrelin levels were also examined. In addition, the association of plasma ghrelin concentrations with disordered glucose regulation and type 2 diabetes was assessed in a longitudinal study. Five single nucleotide polymorphisms (SNPs) in the exons of the ghrelin receptor and 11 SNPs in the ghrelin gene 5´flanking area were found. The SNPs in the ghrelin receptor gene did not associate with plasma IGF-1 concentrations, but two of them did reveal an association with insulin and/or lipid metabolism related parameters. The SNPs found in the ghrelin gene 5´flanking area did not associate with plasma ghrelin levels, but one of them associated with body mass index (BMI). In monozygotic twins discordant for obesity, ghrelin levels were higher in the lean compared with the obese co-twins. Serum ghrelin levels at baseline did not differ between those who maintained normal glucose tolerance and those who developed impaired glucose regulation or type 2 diabetes during the follow up. In conclusion, the results suggest that two variations in the ghrelin receptor gene might be associated with glucose and lipid metabolism but not with IGF-1 levels. One SNP in the ghrelin gene might be associated with obesity. The results also indicate that plasma ghrelin levels are influenced by acquired obesity rather than genetic determinants. Finally, fasting serum ghrelin concentrations do not seem to have a significant predictive value on the incidence of impaired glucose tolerance and type 2 diabetes. / Tiivistelmä Greliini on peptidihormoni, jolla on osoitettu olevan anabolisia vaikutuksia. Se voimistaa kasvuhormonin eritystä, toimii ruokahalua ja ravinnonottoa lisäävänä signaalina, vähentää rasvahappojen käyttöä energian lähteenä ja lisää rasvakudoksen määrää. Lisäksi greliinillä on osoitettu olevan vaikutuksia sokeriaineenvaihduntaan, sydämen toimintaan ja tulehduksellisiin prosesseihin. Näiden ominaisuuksiensa ansiosta greliinistä on tullut tärkeä tutkimuskohde lihavuuteen ja sen liitännäissairauksiin, kuten verenpainetautiin, tyypin 2 diabetekseen ja ateroskleroosiin liittyvässä tutkimuksessa. Tässä väitöskirjatutkimuksessa oli tavoitteina etsiä uusia geneettisiä poikkeamia greliiniä ja greliinireseptoria koodaavista geeneistä ja tutkia löytyneiden poikkeamien kytkeytymistä lihavuuteen sekä ateroskleroosin aineenvaihdunnallisiin riskitekijöihin. Tavoitteina oli myös selvittää geneettisten- ja ympäristötekijöiden roolia greliinipitoisuuksien säätelyssä. Lisäksi greliinipitoisuuksien yhteyttä tyypin 2 diabetekseen ja sokeriaineenvaihdunnan häiriöihin tutkittiin seurantatutkimuksessa. Greliinireseptorin geenin eksoneista löytyi viisi ja greliinigeenin 5´reunustavilta alueilta yksitoista yhden nukleotidin geneettistä poikkeamaa. Löytyneillä greliinireseptorin geenin poikkeamilla ei havaittu olevan yhteyttä plasman IGF-1 pitoisuuksiin, mutta kahdella niistä oli yhteyttä insuliini- ja/tai lipidiaineenvaihduntaan liittyviin muuttujiin. Greliinigeenin 5´reunustavan alueen geneettiset poikkeamat eivät liittyneet plasman greliinipitoisuuksiin, mutta yhdellä variaatiolla oli yhteyttä kehon painoindeksiin. Kaksostutkimukimuksissa greliinipitoisuudet olivat korkeammat hoikilla kaksosilla verrattuna lihaviin kaksospareihinsa, huolimatta samasta geeniperimästä. Seurantatutkimuksen alussa mitatut seerumin greliinipitoisuudet eivät ennustaneet tyypin 2 diabeteksen tai muun sokeriaineenvaihdunnan häiriön ilmaantumista. Yhteenvetona voidaan sanoa, että tutkimuksessa löytyneet greliinireseptorin geneettiset poikkeamat saattavat liittyä sokeri- ja rasva-aineenvaihduntaan, mutta eivät niinkään muihin tunnettuihin ateroskleroosin riskitekijöihin. Yksi greliinigeenin variaatioista näyttäisi liittyvän lihavuuteen. Tutkimukset osoittavat, että geneettiset tekijät säätelisivät plasman greliinipitoisuutta vähemmän kuin hankittu lihavuus. Lisäksi serumin greliinipitoisuuksilla ei ole merkittävää ennusteellista arvoa tyypin 2 diabeteksen ilmaantuvuuden suhteen.

Η γκρελίνη είναι ένα ακυλιωμένο πεπτίδιο που κατά κύριο λόγο παράγεται από το στόμαχο και αποτελεί το φυσικό μόριο-αγωνιστή του μέχρι πρόσφατα ορφανού υποδοχέα GHSR-1a (growth hormone secretagogue receptor type 1a).Η γκρελίνη διαθέτει ισχυρή ικανότητα απελευθέρωσης της αυξητικής ορμόνης καθώς επίσης ασκεί πολλαπλές δράσεις στο ΚΝΣ και σε άλλους ιστούς και όργανα που προκαλούν διέγερση της όρεξης, ρύθμιση του ενεργειακού ισοζυγίου, επίδραση στο γαστρεντερικό σύστημα και στην παγκρεατική λειτουργία.Επιπρόσ- θετα διαμεσολαβεί καρδιαγγειακές δράσεις όπως μείωση των περιφερικών αντιστάσεων, αύξηση της καρδιακής παροχής σε υγιή άτομα και σε ασθενείς με καρδιακή ανεπάρκεια,εξα- σθένηση της καρδιακής καχεξίας, αντιαποπτωτική δράση στην καρδιακή ανεπάρκεια και αντιφλεγμονώδη δράση στο σχηματισμό της αθηρωματικής πλάκας. Η παρούσα εργασία,προσδιορίζοντας τα επίπεδα της γκρελίνης σε ασθενείς με οξεία πρωτοεμφανιζόμενη ή απορρύθμιση χρόνιας συστολικής καρδιακής ανεπάρκειας και μετά την συσχέτισή τους με διάφορες κλινικές,αιμοδυναμικές και υπερηχογραφικές παραμέτρους σε μια περίοδο παρακολούθησης 6 μηνών-1 έτους και την εφαρμογή βέλτιστης εξατομικευμένης φαρμακευτικής αγωγής ,κατέληξε στο συμπέρασμα ότι η παρατηρούμενη διαχρονική αύξηση των επιπέδων της γκρελίνης σε συνδυασμό με την βελτίωση των ανωτέρω παραμέτρων προτείνει στην γκρελίνη ρόλο αιτίου ή αποτελέσματος στην πορεία βελτίωσης της καρδιακής ανεπάρκειας. / Ghrelin is an acylated peptide that mainly is produced from the stomach and constitutes the natural molecule-ligand of until recently orphan receptor GHSR-1a(growth hormone secretagogue receptor type 1a).Ghrelin allocates powerful ability of release of the growth hormone and also practices multiple actions in the CNS and in other tissues and organs that cause excitation of apetite, regulation of energy balance, effect in the gastrointestinal system and in function of pancreas.In addition, ghrelin mediates cardiovascular actions as reductions of systemic resistances, increase of cardiac output in healthy individuals and in patients with heart failure, attenuation of cardiac cachexia, inhibition of the apoptosis of myocardial cells in the heart failure and anti-inflammatory action in the progression of atherosclerosis. The present work, determining the levels of ghrelin in patients with acute de novo or decompensation of chronis systolic heart failure and afterwards their cross-correlation with various clinics, haemodynamic, and other parameters of the cardiac ultrasound in a period of follow-up of 6 months-1 year and the application of most optimal individualized pharmaceutical treatment, led to conclusion that the observed diachronic increase of levels of ghrelin in combination with the improvement of above parameters proposes in ghrelin role of reason or result in the course of improvement of heart failure.

No description available.

Ghrelin is a 28 amino acid peptide hormone with a unique octanoic acid modification that has an extensive range of physiological effects, including stimulation of growth hormone (GH) release, appetite regulation, and modulation of reproductive functions. The cognate receptor for ghrelin is the growth hormone secretagogue receptor (GHS-R), a G protein-coupled receptor with two documented isoforms, the functional GHS-R type 1a and the C-terminally truncated GHS-R type 1b. Several ghrelin variants have also been identified in addition to the n-octanoylated form of ghrelin. In our laboratory, we have identified a novel exon 3-deleted preproghrelin variant that retains sequence for the mature ghrelin hormone and also encodes a novel C-terminal peptide (designated as C-terminal 3 peptide). There is emerging evidence to suggest that the ghrelin axis, encompassing ghrelin, several ghrelin variants and both forms of the GHS-R, is implicated in tumour growth. The objective of this project is to investigate the role of the ghrelin axis in hormone-dependent cancer and to further characterise the expression and function of the novel exon 3-deleted preproghrelin isoform. Hormone-dependent cancers, including prostate and breast cancers, are significant causes of morbidity and mortality in the Western world. Improved diagnoses and treatments earlier in the progression of the disease are urgently required to improve patient outcomes. Growth factors play an integral role in prostate and breast cancer, particularly in the emergence of aggressive, hormone-refractory disease that is resistant to standard therapies. We have previously identified ghrelin as being a novel growth factor for prostate cancer cells in vitro and have hypothesised that this may be extended to other hormone-dependent cancer types including breast cancer. In the current study, techniques including real-time quantitative RT-PCR, Western blot analysis and immunohistochemistry have been used to determine and quantitate ghrelin, exon 3-deleted preproghrelin and GHS-R expression in prostate and breast cancer. Ghrelin and exon 3-deleted preproghrelin are highly expressed in prostate cancer tissues compared to expression levels in normal prostate glands. Similarly, breast carcinoma specimens display greater immunoreactivity for ghrelin and exon 3-deleted preproghrelin than normal breast tissues. Expression of the exon 3-deleted preproghrelin mRNA isoform is upregulated in the oestrogen-independent, highly malignant MDA-MB-435 breast cancer cell line compared to the non-tumourigenic MCF-10A breast epithelial cell line, suggesting that augmented transcription of the isoform is associated with an increased malignant potential in breast cancer. The functional GHS-R type 1a is expressed in normal breast tissue and breast cancer specimens and cell lines. In contrast, the truncated GHS-R type 1b isoform is exclusively expressed in breast carcinoma. These data suggest that GHS-R type 1b, ghrelin and exon 3-deleted preproghrelin display potential as novel diagnostic markers for prostate and breast cancer. These studies have been the first to demonstrate that ghrelin may have an important role in cell proliferation in breast and prostate cancer. Functional assays demonstrated that (10nM) ghrelin stimulated proliferation in the LNCaP prostate cancer cell lines (45.0 ± 1.7% above control, P &lt0.01) and rapidly activated the ERK 1/2 mitogen-activated kinase (MAPK) pathway in both PC3 and LNCaP cell lines. It does not, however, protect these cells from chemically-induced apoptosis. The MAPK inhibitors PD98059 and U0126 blocked ghrelin-induced MAPK activation, as well as cell proliferation, in both cell lines. Prostate cancer cells secrete mature ghrelin in vitro, and may therefore stimulate MAPK pathways in an autocrine manner. Ghrelin also appears to act as a growth factor in breast cancer cell proliferation, as the growth of MDA-MB-435 and MDA-MB-231 breast cancer cell lines is significantly increased by ghrelin treatment. Our findings suggest that the ghrelin axis could provide an important new target for adjunctive therapies for both breast and prostate cancer. The C-terminal 3 peptide derived from exon 3-deleted preproghrelin may be an important new component of the ghrelin axis and studies into its function are currently in progress. Although it did not induce MAPK cascades or stimulate proliferation in prostate or breast cancer cell lines, the discovery of a murine counterpart, exon 4-deleted preproghrelin, indicates that it is highly conserved. Exon 4-deleted preproghrelin is expressed in all mouse tissues examined, with stomach being the predominant site of synthesis. Other components of the ghrelin axis were also found to be present in a wide-range of mouse tissues including brain, ovary and prostate. This comprehensive report has paved the way for future work with in vivo mouse models of cancer. This study has provided a substantial basis for the further evaluation of ghrelin, exon 3-deleted preproghrelin and the GHS-R type 1b as novel diagnostic/prognostic markers for prostate and breast cancer and supports the rationale for targeting the ghrelin axis for treatment of these tumours. Keywords: Ghrelin, exon 3-deleted preproghrelin, GHS-R, growth factors, MAPK, ERK 1/2, hormone-dependent cancer, prostate, breast, diagnostic/prognostic marker, therapeutic targets.

Ghrelin is a gut-brain peptide hormone that induces appetite, stimulates the release of growth hormone, and has recently been shown to ameliorate inflammation. Recent studies have suggested that ghrelin may play a potential role in inflammation-related diseases such as inflammatory bowel diseases (IBD). A previous study with ghrelin in the TNBS mouse model of colitis demonstrated that ghrelin treatment decreased the clinical severity of colitis and inflammation and prevented the recurrence of disease. Ghrelin may be acting at the immunological and epithelial level as the ghrelin receptor (GHSR) is expressed by immune cells and intestinal epithelial cells. The current project investigated the effect of ghrelin in a different mouse model of colitis using dextran sodium sulphate (DSS) – a luminal toxin. Two molecular weight forms of DSS were used as they give differing effects (5kDa and 40kDa). Ghrelin treatment significantly improved clinical colitis scores (p=0.012) in the C57BL/6 mouse strain with colitis induced by 2% DSS (5kDa). Treatment with ghrelin suppressed colitis in the proximal colon as indicated by reduced accumulative histopathology scores (p=0.03). Whilst there was a trend toward reduced scores in the mid and distal colon in these mice this did not reach significance. Ghrelin did not affect histopathology scores in the 40kDa model. There was no significant effect on the number of regulatory T cells or TNF-α secretion from cultured lymph node cells from these mice. The discovery of C-terminal ghrelin peptides, for example, obestatin and the peptide derived from exon 4 deleted proghrelin (Δ4 preproghrelin peptide) have raised questions regarding their potential role in biological functions. The current project investigated the effect of Δ4 peptide in the DSS model of colitis however no significant suppression of colitis was observed. In vitro epithelial wound healing assays were also undertaken to determine the effect of ghrelin on intestinal epithelial cell migration. Ghrelin did not significantly improve wound healing in these assays. In conclusion, ghrelin treatment displays a mild anti-inflammatory effect in the 5kDa DSS model. The potential mechanisms behind this effect and the disparity between these results and those published previously will be discussed.

Thesis (Ph.D.) -- University of Rhode Island, 2008. / Typescript. Includes bibliographical references (leaves 227-239).

Thesis (M.S.)--Ohio University, June, 2005. / Includes bibliographical references (p. 88-96)

Thesis (Ph. D.)--University of Texas at Austin, 2005. / Supervisor: Jeanne Freeland-Graves. Vita. Includes bibliographical references.