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1.
Nat Commun ; 11(1): 4160, 2020 08 19.
Artigo em Inglês | MEDLINE | ID: mdl-32814772

RESUMO

Ghrelin is a gastric peptide hormone with important physiological functions. The unique feature of ghrelin is its Serine 3 acyl-modification, which is essential for ghrelin's activity. However, it remains to be elucidated why the acyl-modification of ghrelin is necessary for activity. To address these questions, we solved the crystal structure of the ghrelin receptor bound to antagonist. The ligand-binding pocket of the ghrelin receptor is bifurcated by a salt bridge between E124 and R283. A striking feature of the ligand-binding pocket of the ghrelin receptor is a wide gap (crevasse) between the TM6 and TM7 bundles that is rich in hydrophobic amino acids, including a cluster of phenylalanine residues. Mutagenesis analyses suggest that the interaction between the gap structure and the acyl acid moiety of ghrelin may participate in transforming the ghrelin receptor into an active conformation.


Assuntos
Grelina/metabolismo , Fenilalanina/metabolismo , Receptores de Grelina/metabolismo , Animais , Sítios de Ligação/genética , Células CHO , Cricetinae , Cricetulus , Cristalografia por Raios X , Grelina/química , Grelina/genética , Células HEK293 , Humanos , Ligantes , Camundongos Endogâmicos MRL lpr , Mutagênese Sítio-Dirigida , Fenilalanina/química , Fenilalanina/genética , Ligação Proteica , Conformação Proteica , Receptores de Grelina/antagonistas & inibidores , Receptores de Grelina/genética , Células Sf9 , Spodoptera
2.
Gene ; 752: 144774, 2020 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-32442579

RESUMO

BACKGROUND: Hypermethylation of the growth hormone secretagogue receptor gene (GHSR) is increasingly observed in human cancers, suggesting that it could represent a pan-cancer biomarker of clinical interest. However, little is still known concerning GHSR methylation levels in thymic epithelial tumors, and particularly in thymomas from patients with Myasthenia Gravis (TAMG). MATERIAL AND METHODS: In the present study we collected DNA samples from circulating lymphocytes and surgically resected tumor tissues of 65 TAMG patients, and from the adjacent healthy thymic tissue available from 43 of them. We then investigated GHSR methylation levels in the collected tissues searching for correlation with the clinical characteristics of the samples. RESULTS: GHSR hypermethylation was observed in 18 thymoma samples (28%) compared to the healthy thymic tissues (P < 1 × 10-4), and those samples were particularly enriched in advanced disease stages than stage I (94% were in stage II or higher). GHSR was demethylated in the remaining 47 thymomas, as well as in all the investigated healthy thymic samples and in circulating lymphocytes. CONCLUSIONS: GHSR hypermethylation is not a pan-cancer marker or an early event in TAMG, but occurs in almost 1/4 of them and mainly from stage II onward. Subsequent studies are required to clarify the molecular pathways leading to GHSR hypermethylation in TAMG tissues and their relevance to disease progression.


Assuntos
Miastenia Gravis/genética , Receptores de Grelina/genética , Adulto , Idoso , Metilação de DNA/genética , Feminino , Humanos , Linfócitos/patologia , Masculino , Pessoa de Meia-Idade , Miastenia Gravis/metabolismo , Neoplasias Epiteliais e Glandulares/genética , Receptores de Grelina/metabolismo , Timoma/genética , Neoplasias do Timo/genética
3.
Am J Physiol Regul Integr Comp Physiol ; 318(5): R1014-R1023, 2020 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-32292065

RESUMO

In rats, overnight fasting reduces the ability of systemic cholecystokinin-8 (CCK) to suppress food intake and to activate cFos in the caudal nucleus of the solitary tract (cNTS), specifically within glucagon-like peptide-1 (GLP-1) and noradrenergic (NA) neurons of the A2 cell group. Systemic CCK increases vagal sensory signaling to the cNTS, an effect that is amplified by leptin and reduced by ghrelin. Since fasting reduces plasma leptin and increases plasma ghrelin levels, we hypothesized that peripheral leptin administration and/or antagonism of ghrelin receptors in fasted rats would rescue the ability of CCK to activate GLP-1 neurons and a caudal subset of A2 neurons that coexpress prolactin-releasing peptide (PrRP). To test this, cFos expression was examined in ad libitum-fed and overnight food-deprived (DEP) rats after intraperitoneal CCK, after coadministration of leptin and CCK, or after intraperitoneal injection of a ghrelin receptor antagonist (GRA) before CCK. In fed rats, CCK activated cFos in ~60% of GLP-1 and PrRP neurons. Few or no GLP-1 or PrRP neurons expressed cFos in DEP rats treated with CCK alone, CCK combined with leptin, or GRA alone. However, GRA pretreatment increased the ability of CCK to activate GLP-1 and PrRP neurons and also enhanced the hypophagic effect of CCK in DEP rats. Considered together, these new findings suggest that reduced behavioral sensitivity to CCK in fasted rats is at least partially due to ghrelin-mediated suppression of hindbrain GLP-1 and PrRP neural responsiveness to CCK.


Assuntos
Regulação do Apetite/efeitos dos fármacos , Colecistocinina/administração & dosagem , Ingestão de Alimentos/efeitos dos fármacos , Jejum/metabolismo , Comportamento Alimentar/efeitos dos fármacos , Grelina/sangue , Neurônios/efeitos dos fármacos , Rombencéfalo/efeitos dos fármacos , Animais , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Leptina/sangue , Masculino , Neurônios/metabolismo , Hormônio Liberador de Prolactina/metabolismo , Proteínas Proto-Oncogênicas c-fos/metabolismo , Ratos Sprague-Dawley , Receptores de Grelina/metabolismo , Rombencéfalo/metabolismo , Transdução de Sinais
4.
Endocrinology ; 161(4)2020 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-32049280

RESUMO

The ghrelin receptor (GhrR) is known for its strong orexigenic effects in pharmacological doses and has long been considered as a promising target for the treatment of obesity. Several antagonists have been developed to decrease the orexigenic signaling, but none of these have been approved for the treatment of obesity because of adverse effects and lack of efficacy. Heterodimerization and biased signaling are important concepts for G-protein coupled receptor (GPCR) signaling, and the influence of these aspects on the GhrR may be important for feeding behavior and obesity. GhrR has been described to heterodimerize with other GPCRs, such as the dopamine receptors 1 and 2, leading to a modulation of the signaling properties of both dimerization partners. Another complicating factor of GhrR-mediated signaling is its ability to activate several different signaling pathways on ligand stimulation. Importantly, some ligands have shown to be "biased" or "functionally selective," implying that the ligand favors a particular signaling pathway. These unique signaling properties could have a sizeable impact on the physiological functions of the GhrR system. Importantly, heterodimerization may explain why the GhrR is expressed in areas of the brain that are difficult for peptide ligands to access. One possibility is that the purpose of GhrR expression is to modulate the function of other receptors in addition to merely being independently activated. We suggest that a deeper understanding of the signaling properties of the GhrR will facilitate future drug discovery in the areas of obesity and weight management.


Assuntos
Grelina/metabolismo , Receptores de Grelina/metabolismo , Transdução de Sinais/fisiologia , Animais , Humanos , Obesidade/metabolismo , Receptores de Orexina/metabolismo , Multimerização Proteica/fisiologia , Receptores Dopaminérgicos/metabolismo , Receptores de Serotonina/metabolismo
5.
Arch Physiol Biochem ; 126(1): 31-40, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30320517

RESUMO

This study investigated the effect of acylated ghrelin (AG) deficiency after sleeve gastrectomy (SG) or chronic administration in control and SG-indiuced rats on platelet function, coagulation, and fibrinolysis. Administration of AG (100 µg/kg, subcutaneously) to control or SG rats significantly inhibited platelets aggregation and lowered levels of Von-Willebrand factor (vWF), fibrinogen, and thromboxane B2. Concomitantly, it decreased circulatory levels and aortic expression levels of plasminogen activator inhibitor-1 (PAI-1) and tissue factor (TF) and increased the aortic expression of the endothelial nitric oxidase (eNOS). However, AG inhibited angiotensin-II (ANGII)-induced upregulation of tissue factor pathway inhibitor (TPAI) and TF and increased activity of TF and increases eNOS expression in cultured endothelial cells, an effect that was abolished by the addition of D-[lys3]-GHRP-6, a selective AG receptor (GHSR-1a) blocker or L-Name, a potent eNOS inhibitor. In conclusion, AG has an anti-platelet, anti-coagulant, and fibrinolytic roles mediated through GHSR-1a to enhance nitric oxide synthesis.


Assuntos
Aorta/efeitos dos fármacos , Coagulação Sanguínea/efeitos dos fármacos , Células Endoteliais/efeitos dos fármacos , Gastrectomia/métodos , Grelina/farmacologia , Hemostáticos/farmacologia , Acilação , Angiotensina II/farmacologia , Animais , Aorta/citologia , Aorta/metabolismo , Esquema de Medicação , Células Endoteliais/citologia , Células Endoteliais/metabolismo , Fibrinogênio/metabolismo , Expressão Gênica/efeitos dos fármacos , Grelina/análogos & derivados , Injeções Subcutâneas , Masculino , NG-Nitroarginina Metil Éster/farmacologia , Óxido Nítrico/antagonistas & inibidores , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase Tipo III/genética , Óxido Nítrico Sintase Tipo III/metabolismo , Oligopeptídeos/farmacologia , Inibidor 1 de Ativador de Plasminogênio/genética , Inibidor 1 de Ativador de Plasminogênio/metabolismo , Agregação Plaquetária/efeitos dos fármacos , Cultura Primária de Células , Ratos , Ratos Sprague-Dawley , Receptores de Grelina/antagonistas & inibidores , Receptores de Grelina/genética , Receptores de Grelina/metabolismo , Tromboxano B2/metabolismo , Fator de von Willebrand/metabolismo
6.
Anat Histol Embryol ; 49(1): 112-120, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31568599

RESUMO

In this study, we aimed to observe the localization and expression of peptide hormones-leptin, ghrelin and obestatin-in the sheep tongue by immunohistochemistry. For that purpose, tongues of ten adult sheep were used. Leptin expression of moderate intensity was observed in the basal and parabasal epithelial cells of the luminal epithelium, and leptin was strongly expressed in the taste buds of the circumvallate and fungiform papillae and in von Ebner's glands. Ghrelin was primarily expressed in some of the skeletal muscle cells and the smooth muscle cells of the middle layer of blood vessels. A strong expression was observed in the epithelial cells lining the base of the groove surrounding the circumvallate papillae. Obestatin expression was particularly strong in the epithelial cells of the salivary ducts. It was also stronger in the von Ebner's glands than in the seromucous glands. Leptin, ghrelin and obestatin were shown to be produced at varying levels in different cell types, including epithelial, stromal and skeletal muscle cells, as well as in ganglion neurons, neural plexuses and blood vessels in the sheep tongue. Cellular localization and expression of these peptide hormones have not been investigated in many species including sheep.


Assuntos
Hormônios Peptídicos/metabolismo , Língua , Animais , Vasos Sanguíneos/metabolismo , Células Epiteliais/metabolismo , Grelina/metabolismo , Imuno-Histoquímica , Leptina/metabolismo , Células Musculares/metabolismo , Neurônios/metabolismo , Receptores de Grelina/metabolismo , Ovinos , Papilas Gustativas/metabolismo , Língua/citologia , Língua/metabolismo
7.
Cell Physiol Biochem ; 53(5): 851-864, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31714043

RESUMO

BACKGROUND/AIMS: The growth promoting effect of lysine and betaine as well as the expression of candidate genes reflecting their efficacy, such as ghrelin, leptin, Growth Hormone Secretagogue Receptor (GHS-R), Insulin like Growth Factor (IGF- 1) and Growth Hormone Releasing Hormone (GHRH) was examined in Labeo rohita fingerlings. METHODS: One hundred eighty healthy juveniles from a homologous population were randomly distributed to 15 rectangular tanks of 150 litres capacity. The experiment was carried out for 60 days with five treatment groups consisting T1 (0.25% Betaine), T2 (0.5% Betaine), T3 (0.75% Lysine) and T4 (1.5% Lysine) and control group. The experiment was carried out for 60 days with five treatment groups consisting T1 (0.25% Betaine), T2 (0.5% Betaine), T3 (0.75% Lysine) and T4 (1.5% Lysine) and control group. At the end of trial, the growth parameters such as weight gain, SGR, PER were estimated from the weight of the triplicate groups. The digestive, metabolic and antioxidant enzymes were analysed using spectrophotometric methods. The intestine, brain and liver were sampled from the treatments and expression of different genes ghrelin, leptin, GHSR, IGF-1 and GHRH was also performed by realtime PCR. RESULTS: A significant (P<0.05) increase in weight gain, SGR, PER and lowest FCR was found in T4 group which was significantly (p < 0.05) different from other experimental groups. The highest mRNA expression levels of expression were found in T4 group which was similar to that of ghrelin gene mRNA of T2 group. The significantly (p<0.05) highest GHSR, GHRH and IGF-1 gene expression levels were found in T4 treatment group compared to other groups. CONCLUSION: The present study reveals that the lysine and betaine stimulate growth and expression of ghrelin GHRH, GHS-R and IGF-1 genes. The increase of IGF-I mRNA expression with lysine and betaine supplementation revealed that these compounds act as growth modulators. However, lysine was found to be a more potent modulator of growth compared to betaine.


Assuntos
Betaína/farmacologia , Cyprinidae/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Lisina/farmacologia , Ração Animal , Animais , Catalase/metabolismo , Cyprinidae/crescimento & desenvolvimento , Grelina/genética , Grelina/metabolismo , Hormônio Liberador de Hormônio do Crescimento/genética , Hormônio Liberador de Hormônio do Crescimento/metabolismo , Fator de Crescimento Insulin-Like I/genética , Fator de Crescimento Insulin-Like I/metabolismo , Mucosa Intestinal/efeitos dos fármacos , Mucosa Intestinal/metabolismo , Leptina/genética , Leptina/metabolismo , Fígado/enzimologia , Fígado/metabolismo , Receptores de Grelina/genética , Receptores de Grelina/metabolismo , Superóxido Dismutase/metabolismo
8.
Mol Med Rep ; 20(6): 5050-5058, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31638214

RESUMO

Ghrelin is an orexigenic hormone that is produced by gastric cells. Ghrelin stimulates food intake and increases gastric movement. In rat model, injected ß­hydroxybutyric acid (ß­HB) leads to a decrease in body weight. It has been reported that patients with gastric erosions are slower to evacuate the stomach. The aim of the present study was to investigate the effects of ghrelin and ß­HB on motility and inflammation in rat gastric antral smooth muscle cells (GASMCs). GASMCs were extracted from rat gastric antrum. Cell viability was determined using the Cell Counting Kit­8 assay. A reactive oxygen species (ROS) assay kit was used to analyze the levels of ROS using flow cytometry. Protein levels were determined using western blotting, and the expression levels of mRNAs were evaluated using reverse transcription­quantitative PCR. ß­HB inhibited the expression of myosin regulatory light polypeptide 9 (MYL9), myosin light chain kinase (MLCK), transforming protein RhoA (RhoA), Rho­associated protein kinase­1 (ROCK­1) and growth hormone secretagogue receptor (GHS­R). By contrast, ghrelin increased the expression of MYL9, MLCK, RhoA, ROCK­1 and GHS­R in ß­HB­treated GASMCs. ß­HB increased the levels of tumor necrosis factor (TNF)­α, interleukin (IL)­6 and ROS, and decreased the levels of manganese (Mn) superoxide dismutase (SOD), copper/zinc (Cu/Zn)SOD and catalase. Ghrelin decreased the expression of TNF­α, IL­6, ROS and catalase, whereas ghrelin promoted the expression of MnSOD and Cu/ZnSOD in ß­HB­treated GASMCs. Short interfering RNA targeting GHS­R inhibited the expression of MYL9, MLCK, RhoA and ROCK­1, and increased the levels of TNF­α, IL­6 and ROS in ß­HB­treated or ghrelin­treated GASMCs. The present study provided preliminary evidence that ß­HB inhibits the motility of GASMCs and promotes inflammation in GASMCs, whereas ghrelin decreases these effects. GHS­R acted as a primary regulator of motility and inflammation in GASMCs treated with ß­HB and ghrelin.


Assuntos
Ácido 3-Hidroxibutírico/farmacologia , Movimento Celular/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Grelina/farmacologia , Miócitos de Músculo Liso/efeitos dos fármacos , Miócitos de Músculo Liso/metabolismo , Receptores de Grelina/genética , Animais , Biomarcadores , Sobrevivência Celular/efeitos dos fármacos , Suscetibilidade a Doenças , Feminino , Motilidade Gastrointestinal/efeitos dos fármacos , Motilidade Gastrointestinal/genética , Humanos , Masculino , Oxirredução , Ratos , Espécies Reativas de Oxigênio/metabolismo , Receptores de Grelina/metabolismo
9.
Neuropeptides ; 78: 101972, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31610887

RESUMO

OBJECTIVES: This study aimed to explore the involvement of the ghrelin pathway from the arcuate nucleus (ARC) to the dorsal vagal complex (DVC) and to determine its role in the regulation of glycolipid metabolism. METHODS: The protein and mRNA expression of ghrelin and growth hormone (GH) secretagogue receptor type 1a (GHSR-1a) were measured using immunohistochemistry and the polymerase chain reaction (PCR) method, respectively. Ghrelin fiber projections arising from the ARC and projecting into the DVC were investigated using retrograde tracing, combined with fluorescence immunohistochemical staining. The effects of electrical stimulation (ES) of the ARC on ghrelin-responsive, glucose-sensitive DVC neurons, glycolipid metabolism, and liver lipid enzymes were determined using electrical physiological method, biochemical analysis, quantitative real-time PCR (qRT-PCR) and Western blot analysis. RESULTS: GHSR-1a was expressed in the DVC neurons. Ghrelin fibers originating from the ARC projected into the DVC. ES of the ARC-activated the ghrelin-responsive glucose-excited (GE) and glucose-inhibited (GI) neurons in the DVC. ES of the ARC significantly elevated the serum triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and glucose levels; it reduced the serum high-density lipoprotein (HDLC) and insulin levels. Moreover, ES of the ARC increased liver acetyl-CoA carboxylase-1 (ACC-1) and decreased carnitine palmitoyltransferase-1 (CPT-1) expression, resulting in lipid accumulation in the liver. All the aforementioned effects were partially blocked by pretreatment with the ghrelin receptor antagonist [D-Lys-3]-GHRP-6 in the DVC and were reduced by vagotomy. ES of the ARC increased agouti-related protein (AgRP)/neuropeptide Y (NPY) expression in the ARC and ghrelin expression in the DVC. CONCLUSION: Ghrelin fiber projections arising from the ARC and projecting into the DVC play a role in the regulation of afferent glucose metabolism and glycolipid metabolism via the ghrelin receptor GHSR-1a in the DVC.


Assuntos
Núcleo Arqueado do Hipotálamo/metabolismo , Grelina/metabolismo , Glicolipídeos/metabolismo , Bulbo/metabolismo , Neurônios/metabolismo , Receptores de Grelina/metabolismo , Animais , Grelina/genética , Imuno-Histoquímica , Lipídeos/sangue , Masculino , Fibras Nervosas/metabolismo , Vias Neurais/metabolismo , Ratos , Ratos Wistar , Receptores de Grelina/genética
10.
Proc Jpn Acad Ser B Phys Biol Sci ; 95(8): 459-467, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31611501

RESUMO

Ghrelin, a growth hormone-releasing peptide first discovered in rat stomach in 1999, is a ligand for the growth hormone secretagogue receptor. It participates in the regulation of diverse processes, including energy balance and body weight maintenance, and appears to be beneficial for the treatment of cardiovascular diseases. In animal models of chronic heart failure, ghrelin improves cardiac function and remodeling; these findings have been recapitulated in human patients. In other animal models, ghrelin effectively diminishes pulmonary hypertension. Moreover, ghrelin administration early after myocardial infarction decreased the frequency of fatal arrhythmia and improved survival rate. In ghrelin-deficient mice, endogenous ghrelin protects against fatal arrhythmia and promotes remodeling after myocardial infarction. Although the mechanisms underlying the effects of ghrelin on the cardiovascular system have not been fully elucidated, its beneficial effects appear to be mediated through regulation of the autonomic nervous system. Ghrelin is a promising therapeutic agent for cardiac diseases.


Assuntos
Sistema Cardiovascular/metabolismo , Grelina/metabolismo , Sequência de Aminoácidos , Animais , Sistema Nervoso Autônomo/metabolismo , Sistema Nervoso Autônomo/fisiologia , Sistema Cardiovascular/efeitos dos fármacos , Sistema Cardiovascular/fisiopatologia , Grelina/química , Grelina/farmacologia , Grelina/uso terapêutico , Cardiopatias/tratamento farmacológico , Cardiopatias/fisiopatologia , Humanos , Receptores de Grelina/metabolismo
11.
Curr Diab Rep ; 19(10): 102, 2019 09 10.
Artigo em Inglês | MEDLINE | ID: mdl-31506846

RESUMO

PURPOSE OF REVIEW: Obesity is affecting over 600 million adults worldwide and has numerous negative effects on health. Since ghrelin positively regulates food intake and body weight, targeting its signaling to induce weight loss under conditions of obesity seems promising. Thus, the present work reviews and discusses different possibilities to alter ghrelin signaling. RECENT FINDINGS: Ghrelin signaling can be altered by RNA Spiegelmers, GHSR/Fc, ghrelin-O-acyltransferase inhibitors as well as antagonists, and inverse agonists of the ghrelin receptor. PF-05190457 is the first inverse agonist of the ghrelin receptor tested in humans shown to inhibit growth hormone secretion, gastric emptying, and reduce postprandial glucose levels. Effects on body weight were not examined. Although various highly promising agents targeting ghrelin signaling exist, so far, they were mostly only tested in vitro or in animal models. Further research in humans is thus needed to further assess the effects of ghrelin antagonism on body weight especially under conditions of obesity.


Assuntos
Grelina/metabolismo , Obesidade/tratamento farmacológico , Receptores de Grelina/metabolismo , Perda de Peso/fisiologia , Animais , Fármacos Antiobesidade/farmacologia , Fármacos Antiobesidade/uso terapêutico , Peso Corporal/efeitos dos fármacos , Modelos Animais de Doenças , Grelina/antagonistas & inibidores , Humanos , Obesidade/metabolismo , Receptores de Grelina/agonistas , Receptores de Grelina/antagonistas & inibidores
12.
Anal Cell Pathol (Amst) ; 2019: 9627810, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31360627

RESUMO

This study investigated the effect of acylated synthetic ghrelin (AG) on the survival and proliferation of human chemosensitive ovarian cancer cells (A2780) and explored some mechanisms of action with a focus on the p53 apoptotic pathway and PI3K/Akt and NF-κB survival pathways. Human A2780 ovarian cancer cells were cultured with or without AG treatment in the presence or absence of cisplatin. In some cases, cisplatin+AG-treated cells were pre-incubated either with [D-Lys3]-GHRP-6, a ghrelin receptor antagonist, or with LY294002, a PI3K inhibitor. mRNA of ghrelin receptors(GHS-R1a and GHS-R1b), as well as, protein levels of GHS-R1a, were expressed abundantly in A2780 cells. AG treatment did not affect the mRNA and protein levels of GHS-R1a and GHS-R1b in both control and Cis-treated cells. However, while AG treatment had no effect on control cell viability, it significantly increased cell viability and proliferation and inhibited cell death in Cis-treated cells. In both control and Cis-treated cells, AG treatment significantly increased PI3K/Akt/mTOR signaling and enhanced the nuclear accumulation of NF-κB. Concomitantly, in both control and Cis-treated cells, AG significantly lowered the protein levels of p53, p-p53 (Ser16), PUMA, cytochrome C, and cleaved caspase-3. Interestingly, pre-incubating the cells with either [D-Lys3]-GHRP-6 or LY294002 completely abolished the above-mentioned effect of AG in both control and Cis-treated cells. In conclusion, the findings of this study show that AG promotes cell survival of the OC cells and renders them resistat to Cis therapy, an effect that is mediated by the activation of PI3K/Akt/mTOR and activation of NF-κB, and requires GHS-R1a.


Assuntos
Cisplatino/farmacologia , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Grelina/farmacologia , Neoplasias Ovarianas/patologia , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais , Serina-Treonina Quinases TOR/metabolismo , Acilação , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/metabolismo , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Feminino , Humanos , NF-kappa B/metabolismo , Proteínas de Neoplasias/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores de Grelina/genética , Receptores de Grelina/metabolismo , Transdução de Sinais/efeitos dos fármacos
13.
Mol Cells ; 42(6): 470-479, 2019 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-31250620

RESUMO

Interstitial cells of Cajal (ICCs) are pacemaker cells that exhibit periodic spontaneous depolarization in the gastrointestinal (GI) tract and generate pacemaker potentials. In this study, we investigated the effects of ghrelin and motilin on the pacemaker potentials of ICCs isolated from the mouse small intestine. Using the whole-cell patch-clamp configuration, we demonstrated that ghrelin depolarized pacemaker potentials of cultured ICCs in a dose-dependent manner. The ghrelin receptor antagonist [D-Lys] GHRP-6 completely inhibited this ghrelin-induced depolarization. Intracellular guanosine 5'-diphosphate-ß-S and pre-treatment with Ca2+free solution or thapsigargin also blocked the ghrelin-induced depolarization. To investigate the involvement of inositol triphosphate (IP3), Rho kinase, and protein kinase C (PKC) in ghrelin-mediated pacemaker potential depolarization of ICCs, we used the IP3 receptor inhibitors 2-aminoethoxydiphenyl borate and xestospongin C, the Rho kinase inhibitor Y-27632, and the PKC inhibitors staurosporine, Go6976, and rottlerin. All inhibitors except rottlerin blocked the ghrelin-induced pacemaker potential depolarization of ICCs. In addition, motilin depolarized the pacemaker potentials of ICCs in a similar dose-dependent manner as ghrelin, and this was also completely inhibited by [D-Lys] GHRP-6. These results suggest that ghrelin induced the pacemaker potential depolarization through the ghrelin receptor in a G protein-, IP3-, Rho kinase-, and PKC-dependent manner via intracellular and extracellular Ca2+ regulation. In addition, motilin was able to depolarize the pacemaker potentials of ICCs through the ghrelin receptor. Therefore, ghrelin and its receptor may modulate GI motility by acting on ICCs in the murine small intestine.


Assuntos
Grelina/farmacologia , Células Intersticiais de Cajal/efeitos dos fármacos , Potenciais da Membrana/efeitos dos fármacos , Motilina/farmacologia , Acetofenonas/farmacologia , Amidas/farmacologia , Animais , Benzopiranos/farmacologia , Compostos de Boro/metabolismo , Cálcio/metabolismo , Carbazóis/farmacologia , Motilidade Gastrointestinal/fisiologia , Receptores de Inositol 1,4,5-Trifosfato/antagonistas & inibidores , Células Intersticiais de Cajal/fisiologia , Intestino Delgado/fisiologia , Compostos Macrocíclicos/farmacologia , Camundongos , Camundongos Endogâmicos ICR , Oligopeptídeos/metabolismo , Oxazóis/farmacologia , Proteína Quinase C/antagonistas & inibidores , Proteína Quinase C/metabolismo , Piridinas/farmacologia , Receptores de Grelina/antagonistas & inibidores , Receptores de Grelina/metabolismo , Transdução de Sinais , Estaurosporina/farmacologia , Tapsigargina/farmacologia , Quinases Associadas a rho/antagonistas & inibidores , Quinases Associadas a rho/metabolismo
14.
Neuroscience ; 412: 94-104, 2019 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-31185255

RESUMO

Ghrelin is an important orexigenic brain-gut hormone that regulates feeding, metabolism and glucose homeostasis in human and rodents at multiple levels. Ghrelin functions by binding to its receptor, the growth hormone secretagogue receptor 1a (GHS-R1a), which is widely expressed both inside and outside of the brain. Both acute and chronic calorie restrictions (CRs) were reported to increase endogenous ghrelin levels and lead to beneficial effects on brain functions, including anti-anxiety effects, anti-depressive effects, and memory improvement. However, the causal relationship and underlying mechanisms are not fully understood. Here, we introduced acute or chronic CR to both GHS-R1a KO (Ghsr-/-) mice and WT (Ghsr+/+) littermates, and investigated anxiety- and despair-related behaviors in the elevated plus maze (EPM), open field (OF) and forced swimming (FS) tests. We found that acute and chronic CR produced similar anxiolytic and anti-despair responses in Ghsr+/+ mice but opposite responses in Ghsr-/- mice. In particular, acute CR enhanced while chronic CR reduced anxiety- and despair-like behaviors in Ghsr-/- mice. Acute CR triggered anxiolytic and anti-despair responses in Ghsr+/+ mice. This effect was abolished by a GHS-R1a antagonist, suggesting a GHS-R1a dependent mechanism. Ad-libitum refeeding masked behavioral responses induced by acute CR in both Ghsr-/- and Ghsr+/+ mice. Altogether, our findings indicate that acute and chronic CRs mitigate anxiety- and despair-like behaviors with different physiological mechanisms, with the former being dependent on endogenous ghrelin release and GHS-R1a signaling, while the latter may not be.


Assuntos
Ansiedade/prevenção & controle , Restrição Calórica/métodos , Receptores de Grelina/metabolismo , Estresse Psicológico/prevenção & controle , Animais , Ansiedade/metabolismo , Comportamento Animal/fisiologia , Emoções/fisiologia , Camundongos , Camundongos Knockout , Receptores de Grelina/genética , Estresse Psicológico/metabolismo
15.
Diabetes ; 68(9): 1795-1805, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31201280

RESUMO

Exogenous ghrelin reduces glucose-stimulated insulin secretion and endogenous ghrelin protects against hypoglycemia during starvation. Islet ε-cells produce ghrelin and δ-cells express growth hormone secretagogue receptor (GHSR), suggesting the possibility of a paracrine mechanism for islet ghrelin to reach high local concentrations and affect insulin secretion. GHSR has high constitutive activity and may act independently of ghrelin. The objective in this study was to determine whether an intraislet ghrelin-GHSR axis modulates insulin secretion and glucose metabolism using mouse models lacking ghrelin (Ghrl-/- ) or GHSR (Ghsr-/- ). Ghsr-/- and Ghsr+/+ mice had comparable islet ghrelin concentrations. Exogenous ghrelin decreased insulin secretion in perifused isolated islets in a GHSR-dependent manner. Islets isolated from Ghrl-/- or Ghsr-/- mice did not differ from controls in glucose-, alanine-, or GLP-1-stimulated insulin secretion during perifusion. Consistent with this finding, Ghrl-/- and Ghsr-/- male mice studied after either 6 or 16 h of fasting had blood glucose concentrations comparable with those of controls following intraperitoneal glucose, or insulin tolerance tests, or after mixed nutrient meals. Collectively, our data provide strong evidence against a paracrine ghrelin-GHSR axis mediating insulin secretion or glucose tolerance in lean, chow-fed adult mice.


Assuntos
Glicemia/metabolismo , Grelina/metabolismo , Secreção de Insulina/fisiologia , Ilhotas Pancreáticas/metabolismo , Receptores de Grelina/metabolismo , Transdução de Sinais/fisiologia , Animais , Feminino , Grelina/sangue , Grelina/genética , Insulina/metabolismo , Masculino , Camundongos , Camundongos Knockout , Receptores de Grelina/genética
16.
Can J Physiol Pharmacol ; 97(10): 909-915, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31100203

RESUMO

Molecular hydrogen (H2) showed protection against various kinds of oxidative-stress-related diseases. First, it was reported that the mechanism of therapeutic effects of H2 was antioxidative effect due to inhibition of the most cytotoxic reactive oxygen species, hydroxy radical (•OH). However, after chronic administration of H2 in drinking water, oxidative-stress-induced nerve injury is significantly attenuated even in the absence of H2. It suggests indirect signaling of H2 and gastrointestinal tract is involved. Indirect effects of H2 could be tested by giving H2 water only before nerve injury, as preconditioning. For example, preconditioning of H2 for certain a period (∼7 days) in Parkinson's disease model mice shows significant neuroprotection. As the mechanism of indirect effect, H2 in drinking water induces ghrelin production and release from the stomach via ß1-adrenergic receptor stimulation. Released ghrelin circulates in the body, being transported across the blood-brain barrier, activates its receptor, growth-hormone secretagogue receptor. H2-induced upregulation of ghrelin mRNA is also shown in ghrelin-producing cell line, SG-1. These observations help with understanding the chronic effects of H2 and raise intriguing preventive and therapeutic options using H2.


Assuntos
Grelina/metabolismo , Hidrogênio/administração & dosagem , Doenças Neurodegenerativas/terapia , Neuroproteção/efeitos dos fármacos , Traumatismos dos Nervos Periféricos/terapia , Animais , Barreira Hematoencefálica/metabolismo , Modelos Animais de Doenças , Ingestão de Líquidos , Mucosa Gástrica/efeitos dos fármacos , Mucosa Gástrica/metabolismo , Grelina/sangue , Humanos , Doenças Neurodegenerativas/sangue , Estresse Oxidativo/efeitos dos fármacos , Traumatismos dos Nervos Periféricos/sangue , Receptores de Grelina/metabolismo , Transdução de Sinais/efeitos dos fármacos , Resultado do Tratamento , Água/química
17.
Psychoneuroendocrinology ; 106: 183-194, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-30999229

RESUMO

Motivation alters behaviour in a complex manner and nucleus accumbens (NAc) shell has been implied as a key structure regulating such behaviour. Recent studies show that acute ghrelin signalling enhances motivation when assessed in a simple motor task. The aim of the present study was to define the role of ghrelin signalling on motivation in a more complex motor behaviour. Rats were tested in the Montoya staircase, an animal model of skilled reach foraging assessed by the number of sucrose pellets consumed. Electrophysiological recordings were conducted to explore the neurophysiological correlates of ghrelin signalling. The initial electrophysiological results displayed that ex vivo administration of ghrelin increased NAc shell output in brain slices from drug- and training-naïve rats. In rats with an acquired skilled reach performance, acute as well as repeated treatment with a ghrelin receptor (GHSR-1 A) antagonist (JMV2959) decreased the number of sucrose pellets consumed. Moreover, infusion of JMV2959 into NAc shell reduced this consumption. Sub-chronic, during ten days, JMV2959 treatment during training on the Montoya staircase reduced the number of pellets consumed, whereas ghrelin improved this behaviour. In addition, field potential and whole cell recordings were conducted in NAc shell of rats that had been treated with ghrelin or GHSR-1 A antagonist during training on the Montoya staircase. Sub-chronic administration of ghrelin during motor-skill learning selectively increased the frequency of inhibitory transmission in the NAc shell, resulting in a net suppression of accumbal output. Collectively these data suggest that ghrelin signalling in NAc shell enhances skilled reached foraging tentatively by increasing the motivation.


Assuntos
Comportamento Alimentar/efeitos dos fármacos , Grelina/farmacologia , Núcleo Accumbens/metabolismo , Animais , Grelina/metabolismo , Glicina/análogos & derivados , Glicina/farmacologia , Masculino , Núcleo Accumbens/fisiologia , Ratos , Ratos Wistar , Receptores de Grelina/metabolismo , Transdução de Sinais/efeitos dos fármacos , Triazóis/farmacologia , Área Tegmentar Ventral/metabolismo
18.
Int J Mol Sci ; 20(7)2019 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-30934667

RESUMO

Gastrointestinal motility is regulated by neural factors and humoral factors. Both motilin and ghrelin improve gastrointestinal motility, but many issues remain unclear. We prepared human motilin receptor transgenic (Tg) mice and performed experiments evaluating the effects of motilin, erythromycin (EM), and ghrelin. EM and ghrelin promoted gastric emptying (GE) when administered either peripherally or centrally to Tg mice. Atropine (a muscarinic receptor antagonist) counteracted GE induced by centrally administered EM, but not that induced by peripherally administered EM. The administration of EM in this model promoted the effect of mosapride (a selective serotonin 5-hydroxytryptamine 4 (5-HT4) receptor agonist), and improved loperamide (a µ-opioid receptor agonist)-induced gastroparesis. The level of acyl-ghrelin was significantly attenuated by EM administration. Thus, we have established an animal model appropriate for the evaluation of motilin receptor agonists. These data and the model are expected to facilitate the identification of novel compounds with clinical potential for relieving symptoms of dyspepsia and gastroparesis.


Assuntos
Grelina/farmacologia , Receptores dos Hormônios Gastrointestinais/agonistas , Receptores de Neuropeptídeos/agonistas , Animais , Benzamidas/farmacologia , Eritromicina/administração & dosagem , Eritromicina/farmacologia , Esvaziamento Gástrico/efeitos dos fármacos , Gastroparesia/sangue , Gastroparesia/induzido quimicamente , Gastroparesia/tratamento farmacológico , Gastroparesia/fisiopatologia , Grelina/sangue , Humanos , Loperamida/efeitos adversos , Masculino , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Morfolinas/farmacologia , Período Pós-Prandial , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores dos Hormônios Gastrointestinais/genética , Receptores dos Hormônios Gastrointestinais/metabolismo , Receptores de Grelina/genética , Receptores de Grelina/metabolismo , Receptores de Neuropeptídeos/genética , Receptores de Neuropeptídeos/metabolismo , Estômago/efeitos dos fármacos , Estômago/patologia , Estômago/fisiopatologia , Nervo Vago/efeitos dos fármacos , Nervo Vago/fisiologia
19.
Gen Comp Endocrinol ; 279: 174-183, 2019 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-30914266

RESUMO

OBJECTIVE: Cisplatin is an important antineoplastic drug and has side effects such as nausea, vomiting, and dyspepsia. The detailed mechanisms for its side effects are yet not well be illustrated. Our purpose was to investigate the discharges of gastric distention (GD) sensitive neurons regulated by ghrelin and electrical stimulation of the lateral hypothalamus area (LHA) via the dorsal vagal complex (DVC) in cisplatin-treated rats. MATERIALS AND METHODS: Extracellular discharge recording was performed to observe the effects of ghrelin and electrical stimulation of the LHA on discharges of GD neurons in the DVC. RESULTS: GD neurons were recorded in DVC in saline-treated and cisplatin-treated rats and identified as GD-excitatory (GD-E) neurons, which are excited by gastric distension, and GD-inhibitory (GE-I) neurons, which are inhibited by gastric distension. Microinjection of ghrelin into the DVC increased the firing frequency of most GD neurons, while the ratios of excited GD-E and GD-I neurons in cisplatin-treated rats were significantly lower than those in saline-treated rats. The excitatory effect of ghrelin was eliminated completely by DVC pretreatment with ghrelin receptor antagonist [D-Lys-3]-GHRP-6. After electrical stimulation of the LHA, the firing frequency of these neurons significantly increased. This excitatory effect was weaker in cisplatin-treated rats than in saline-treated rats and could be partly blocked by DVC pretreatment with [D-Lys-3]-GHRP-6. CONCLUSION: GD neurons in the DVC could be excited by microinjecting ghrelin into the DVC and electrical stimulation of the LHA, respectively. The excitatory effect was attenuated by cisplatin injected intraperitoneally.


Assuntos
Cisplatino/farmacologia , Grelina/farmacologia , Região Hipotalâmica Lateral/fisiologia , Neurônios/fisiologia , Estômago/inervação , Nervo Vago/fisiologia , Potenciais de Ação/efeitos dos fármacos , Animais , Estimulação Elétrica , Grelina/metabolismo , Região Hipotalâmica Lateral/efeitos dos fármacos , Masculino , Neurônios/efeitos dos fármacos , Ratos Wistar , Receptores de Grelina/metabolismo , Nervo Vago/efeitos dos fármacos
20.
PLoS One ; 14(3): e0214626, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30921423

RESUMO

We estimated the effect of oligosaccharide supplementation and feed restriction on calves. The study was divided into two experimental periods of 28 days each with 20 crossbred calves that had initial body weight of 37 Kg and housed in individual pens. The animals were split in four experimental groups: animals fed 6 L milk/day (CON) in the two periods, animals fed milk restricted (3 L milk/day) in the first period and followed by CON feeding in the second period (RES), animals receiving supplementation of 5 g/day of mannanoligosaccharide (MOS) and animals receiving supplementation of 5 g/day mannan and frutoligosaccharide (MFOS). At the end of the study, all the animals were slaughtered. The average weight gain was lower in the restricted group when compared with CON and MFOS groups in the first period (P < 0.05) and there were no difference among the groups in the second period. Animals supplemented with MOS showed a significant increases in jejunal villus height and rumen papillae, which were not observed for MFOS group (P < 0.05) compared with RES and CON groups. There were no difference in ghrelin and leptin levels among treatments during periods 1 and 2 (P > 0.05). Also, the expression of ghrelin receptors in the paraventricular region of the hypothalamus did not differ among groups. We conclude that milk restriction during the first weeks of life in calves resulted in compensatory gain and did not modify the hormonal profile and expression of the ghrelin receptor in the hypothalamus. Moreover, a prebiotic supplementation changed the development of intestinal and ruminal epithelium.


Assuntos
Ração Animal/análise , Peso Corporal/efeitos dos fármacos , Suplementos Nutricionais/análise , Trato Gastrointestinal/efeitos dos fármacos , Trato Gastrointestinal/crescimento & desenvolvimento , Leite , Oligossacarídeos/farmacologia , Animais , Bovinos , Ingestão de Alimentos/efeitos dos fármacos , Epitélio/efeitos dos fármacos , Epitélio/metabolismo , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Hormônios/metabolismo , Hipotálamo/efeitos dos fármacos , Hipotálamo/metabolismo , Receptores de Grelina/metabolismo
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