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1.
J Vis Exp ; (175)2021 09 20.
Artigo em Inglês | MEDLINE | ID: mdl-34605820

RESUMO

This study describes a protocol for the multiplex in situ hybridization (ISH) of the mouse jugular-nodose ganglia, with a particular emphasis on detecting the expression of G protein-coupled receptors (GPCRs). Formalin-fixed jugular-nodose ganglia were processed with the RNAscope technology to simultaneously detect the expression of two representative GPCRs (cholecystokinin and ghrelin receptors) in combination with one marker gene of either nodose (paired-like homeobox 2b, Phox2b) or jugular afferent neurons (PR domain zinc finger protein 12, Prdm12). Labeled ganglia were imaged using confocal microscopy to determine the distribution and expression patterns of the aforementioned transcripts. Briefly, Phox2b afferent neurons were found to abundantly express the cholecystokinin receptor (Cck1r) but not the ghrelin receptor (Ghsr). A small subset of Prdm12 afferent neurons was also found to express Ghsr and/or Cck1r. Potential technical caveats in the design, processing, and interpretation of multiplex ISH are discussed. The approach described in this article may help scientists in generating accurate maps of the transcriptional profiles of vagal afferent neurons.


Assuntos
Neurônios Aferentes , Gânglio Nodoso , Animais , Proteínas de Transporte , Hibridização In Situ , Camundongos , Proteínas do Tecido Nervoso , Receptores de Grelina/metabolismo , Nervo Vago
2.
Mol Biol (Mosk) ; 55(4): 578-584, 2021.
Artigo em Russo | MEDLINE | ID: mdl-34432775

RESUMO

The review presents data on the expression of ghrelin receptor GHS-R1a in the brain in model animals (Danio rerio, rodents, primates), and in the human brain. Studies show widespread localization of GHS-R1a in the brain, which indicates the involvement of the receptor in many physiological processes. Using various models, information has been obtained regarding the participation of the receptor in the regulation of the pro- and anti-inflammatory response, apoptosis and proliferation. It is known that the ghrelin receptor plays an important role in eating behavior and is also involved in the pathogenetic mechanisms of obesity, drug addiction, and alcoholism. With this in mind, research is underway with the use of various therapeutic agents (receptor agonists and antagonists) that can be used for the pharmacological correction of these pathological conditions. This review also presents hypothetical mechanisms of intracellular signaling, in which GHS-R1a may participate; however, a complete understanding of these mechanisms has not yet been reached. The ghrelin intracellular pathways seem to be specific to brain region and, probably, also depend on the metabolic or stress status of the organism.


Assuntos
Alcoolismo , Receptores de Grelina , Animais , Encéfalo/metabolismo , Grelina/genética , Humanos , Receptores de Grelina/genética , Receptores de Grelina/metabolismo , Transdução de Sinais
3.
Nat Commun ; 12(1): 5064, 2021 08 20.
Artigo em Inglês | MEDLINE | ID: mdl-34417468

RESUMO

Ghrelin, also called "the hunger hormone", is a gastric peptide hormone that regulates food intake, body weight, as well as taste sensation, reward, cognition, learning and memory. One unique feature of ghrelin is its acylation, primarily with an octanoic acid, which is essential for its binding and activation of the ghrelin receptor, a G protein-coupled receptor. The multifaceted roles of ghrelin make ghrelin receptor a highly attractive drug target for growth retardation, obesity, and metabolic disorders. Here we present two cryo-electron microscopy structures of Gq-coupled ghrelin receptor bound to ghrelin and a synthetic agonist, GHRP-6. Analysis of these two structures reveals a unique binding pocket for the octanoyl group, which guides the correct positioning of the peptide to initiate the receptor activation. Together with mutational and functional data, our structures define the rules for recognition of the acylated peptide hormone and activation of ghrelin receptor, and provide structural templates to facilitate drug design targeting ghrelin receptor.


Assuntos
Oligopeptídeos/química , Receptores de Grelina/química , Sequência de Aminoácidos , Animais , Sítios de Ligação , Linhagem Celular , Microscopia Crioeletrônica , Subunidades alfa Gq-G11 de Proteínas de Ligação ao GTP/química , Subunidades alfa Gq-G11 de Proteínas de Ligação ao GTP/metabolismo , Grelina/metabolismo , Células HEK293 , Humanos , Modelos Moleculares , Oligopeptídeos/metabolismo , Ligação Proteica , Receptores de Grelina/metabolismo , Receptores de Grelina/ultraestrutura
4.
Int J Mol Sci ; 22(16)2021 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-34445634

RESUMO

Cannabinoids have been reported as orexigenic, i.e., as promoting food intake that, among others, is controlled by the so-called "hunger" hormone, ghrelin. The aim of this paper was to look for functional and/or molecular interactions between ghrelin GHSR1a and cannabinoid CB2 receptors at the central nervous system (CNS) level. In a heterologous system we identified CB2-GHSR1a receptor complexes with a particular heteromer print consisting of impairment of CB2 receptor/Gi-mediated signaling. The blockade was due to allosteric interactions within the heteromeric complex as it was reverted by antagonists of the GHSR1a receptor. Cannabinoids acting on the CB2 receptor did not affect cytosolic increases of calcium ions induced by ghrelin acting on the GHSR1a receptor. In situ proximity ligation imaging assays confirmed the expression of CB2-GHSR1a receptor complexes in both heterologous cells and primary striatal neurons. We tested heteromer expression in neurons from offspring of high-fat-diet mouse mothers as they have more risk to be obese. Interestingly, there was a marked upregulation of those complexes in striatal neurons from siblings of pregnant female mice under a high-fat diet.


Assuntos
Corpo Estriado/patologia , Dieta Hiperlipídica/efeitos adversos , Grelina/metabolismo , Neurônios/patologia , Obesidade/patologia , Receptor CB2 de Canabinoide/metabolismo , Receptores de Grelina/metabolismo , Animais , Canabinoides/farmacologia , Corpo Estriado/efeitos dos fármacos , Corpo Estriado/metabolismo , Feminino , Grelina/genética , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Obesidade/etiologia , Obesidade/metabolismo , Receptor CB2 de Canabinoide/genética , Receptores de Grelina/genética , Transdução de Sinais , Regulação para Cima
5.
Int J Mol Sci ; 22(16)2021 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-34445772

RESUMO

In this review we described the interactions between ghrelin and the growth hormone (GH)-insulin-like growth factor 1 (IGF-1) axis in children and adults with growth hormone deficiency (GHD). A possible involvement of these interactions in the pathogenesis of unexplained cases of GHD was suggested. Current research provides more and more details to the knowledge on the circadian rhythm of ghrelin. We gathered reports on the decreasing effect of Helicobacter pylori-related chronic gastritis on the number of ghrelin immunopositive cells and the consequent decrease in ghrelin serum concentration. The gastrointestinal tract microflora modification of the ghrelin action, by the mechanism of molecular mimicry, was also stressed. Moreover, the mutual relationships between ghrelin and the TSH-FT4/FT3 axis in growth and metabolic processes are described. It is to be recalled that FT4 and FT3 exert a permissive impact on IGF-1 action and, in turn, GH, in reaction mediated by IGF-1, enhances the monodeiodination of FT4 to FT3. Finally, we discussed the latest attempts to use the GH secretagogue receptor (GHS-R) analogues for possible diagnostic and therapeutic purposes.


Assuntos
Grelina/metabolismo , Hormônio do Crescimento/deficiência , Hormônio do Crescimento/metabolismo , Animais , Humanos , Fator de Crescimento Insulin-Like I/metabolismo , Receptores de Grelina/metabolismo
6.
Mol Med Rep ; 24(3)2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34296307

RESUMO

Ghrelin, an orexigenic hormone, is a peptide that binds to the growth hormone secretagogue receptor; it is secreted mainly by enteroendocrine cells in the oxyntic glands of the stomach. Ghrelin serves a role in both local and systemic physiological processes, and is implicated in various pathologies, including neoplasia, with tissue expression in several types of malignancies in both in vitro and in vivo studies. However, the precise implications of the ghrelin axis in metastasis, invasion and cancer progression regulation has yet to be established. In the case of gastrointestinal (GI) tract malignancies, ghrelin has shown potential to become a prognostic factor or even a therapeutic target, although data in the literature are inconsistent and unsystematic, with reports untailored to a specific histological subtype of cancer or a particular localization. The evaluation of immunohistochemical expression shows a limited outlook owing to the low number of cases analyzed, and in vivo analyses have conflicting data regarding differences in ghrelin serum levels in patients with cancer. The aim of this review was to examine the relationship between ghrelin and GI tract malignancies to demonstrate the inconsistencies in current results and to highlight its clinical significance in the outcome of these patients.


Assuntos
Neoplasias Gastrointestinais , Grelina/metabolismo , Animais , Neoplasias Gastrointestinais/metabolismo , Humanos , Mesoderma/metabolismo , Tumores Neuroendócrinos/metabolismo , Receptores de Grelina/metabolismo , Transdução de Sinais
7.
Nat Commun ; 12(1): 3938, 2021 06 24.
Artigo em Inglês | MEDLINE | ID: mdl-34168117

RESUMO

The membrane is an integral component of the G protein-coupled receptor signaling machinery. Here we demonstrate that lipids regulate the signaling efficacy and selectivity of the ghrelin receptor GHSR through specific interactions and bulk effects. We find that PIP2 shifts the conformational equilibrium of GHSR away from its inactive state, favoring basal and agonist-induced G protein activation. This occurs because of a preferential binding of PIP2 to specific intracellular sites in the receptor active state. Another lipid, GM3, also binds GHSR and favors G protein activation, but mostly in a ghrelin-dependent manner. Finally, we find that not only selective interactions but also the thickness of the bilayer reshapes the conformational repertoire of GHSR, with direct consequences on G protein selectivity. Taken together, this data illuminates the multifaceted role of the membrane components as allosteric modulators of how ghrelin signal could be propagated.


Assuntos
Fosfatidilinositol 4,5-Difosfato/metabolismo , Receptores de Grelina/química , Receptores de Grelina/metabolismo , Regulação Alostérica , Sítios de Ligação , Membrana Celular/química , Membrana Celular/metabolismo , Cisteína/genética , Transferência Ressonante de Energia de Fluorescência , Gangliosídeo G(M3)/metabolismo , Humanos , Bicamadas Lipídicas/química , Bicamadas Lipídicas/metabolismo , Metabolismo dos Lipídeos , Lipídeos/química , Mutação , Fosfatidilinositol 4,5-Difosfato/química , Conformação Proteica , Receptores de Grelina/genética , Transdução de Sinais
8.
Nutrients ; 13(4)2021 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-33804920

RESUMO

Ghrelin is a major appetite-stimulating neuropeptide found in circulation. While its role in increasing food intake is well known, its role in affecting taste perception, if any, remains unclear. In this study, we investigated the role of the growth hormone secretagogue receptor's (GHS-R; a ghrelin receptor) activity in the peripheral taste system using feeding studies and conditioned taste aversion assays by comparing wild-type and GHS-R-knockout models. Using transgenic mice expressing enhanced green fluorescent protein (GFP), we demonstrated GHS-R expression in the taste system in relation phospholipase C ß2 isotype (PLCß2; type II taste cell marker)- and glutamate decarboxylase type 67 (GAD67; type III taste cell marker)-expressing cells using immunohistochemistry. We observed high levels of co-localization between PLCß2 and GHS-R within the taste system, while GHS-R rarely co-localized in GAD67-expressing cells. Additionally, following 6 weeks of 60% high-fat diet, female Ghsr-/- mice exhibited reduced responsiveness to linoleic acid (LA) compared to their wild-type (WT) counterparts, while no such differences were observed in male Ghsr-/- and WT mice. Overall, our results are consistent with the interpretation that ghrelin in the taste system is involved in the complex sensing and recognition of fat compounds. Ghrelin-GHS-R signaling may play a critical role in the recognition of fatty acids in female mice, and this differential regulation may contribute to their distinct ingestive behaviors.


Assuntos
Apetite/fisiologia , Gorduras/administração & dosagem , Comportamento Alimentar/fisiologia , Receptores de Grelina/metabolismo , Paladar/fisiologia , Ração Animal , Animais , Feminino , Camundongos , Camundongos Transgênicos , Modelos Animais
9.
Int J Mol Sci ; 22(7)2021 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-33916403

RESUMO

Growth hormone secretagogue receptor 1a (GHS-R1a), which is one of the G protein-coupled receptors (GPCRs), is involved in various physiological actions such as energy consumption, growth hormone secretion promoting action, and cardiovascular protective action. The ligand was searched for as an orphan receptor for a while, but the ligand was found to be acylated ghrelin (ghrelin) discovered by Kangawa and Kojima et al. in 1999. Recently, it has also been reported that dysregulation of GHS-R1a mediates reduced feeding in various diseases. On the other hand, since the physiological effects of ghrelin have been studied exclusively in male mice, few studies have been conducted on gender differences in ghrelin reactivity. In this review, we describe (1) the characteristics of GHS-R1a, (2) the role of ghrelin in hypophagia due to stress or anticancer drugs, and (3) the gender differences in the physiological effects of GHS-R1a and the influence of stress on it.


Assuntos
Ingestão de Alimentos , Transtornos da Alimentação e da Ingestão de Alimentos/metabolismo , Grelina/metabolismo , Receptores de Grelina/metabolismo , Caracteres Sexuais , Transdução de Sinais , Animais , Transtornos da Alimentação e da Ingestão de Alimentos/patologia , Feminino , Humanos , Masculino , Camundongos
10.
Int J Mol Sci ; 22(8)2021 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-33920473

RESUMO

Growth hormone secretagogue receptor (GHS-R) is widely known to regulate food intake and adiposity, but its role in glucose homeostasis is unclear. In this study, we investigated the expression of GHS-R in mouse pancreatic islets and its role in glycemic regulation. We used Ghsr-IRES-tauGFP mice, with Green Fluorescent Protein (GFP) as a surrogate for GHS-R, to demonstrate the GFP co-localization with insulin and glucagon expression in pancreatic islets, confirming GHS-R expression in ß and α cells. We then generated ß-cell-specific GHSR-deleted mice with MIP-Cre/ERT and validated that GHS-R suppression was restricted to the pancreatic islets. MIP-Cre/ERT;Ghsrf/f mice showed normal energy homeostasis with similar body weight, body composition, and indirect calorimetry profile. Interestingly, MIP-Cre/ERT;Ghsrf/f mice exhibited an impressive phenotype in glucose homeostasis. Compared to controls, MIP-Cre/ERT;Ghsrf/f mice showed lower fasting blood glucose and insulin; reduced first-phase insulin secretion during a glucose tolerance test (GTT) and glucose-stimulated insulin secretion (GSIS) test in vivo. The isolated pancreatic islets of MIP-Cre/ERT;Ghsrf/f mice also showed reduced insulin secretion during GSIS ex vivo. Further, MIP-Cre/ERT;Ghsrf/f mice exhibited improved insulin sensitivity during insulin tolerance tests (ITT). Overall, our results confirmed GHS-R expression in pancreatic ß and α cells; GHS-R cell-autonomously regulated GSIS and modulated systemic insulin sensitivity. In conclusion, ß cell GHS-R was an important regulator of glucose homeostasis, and GHS-R antagonists may have therapeutic potential for Type 2 Diabetes.


Assuntos
Secreção de Insulina , Células Secretoras de Insulina/metabolismo , Receptores de Grelina/metabolismo , Animais , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/metabolismo , Camundongos , Camundongos Knockout , Receptores de Grelina/genética
11.
Transl Psychiatry ; 11(1): 230, 2021 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-33879778

RESUMO

Most psychiatric disorders are characterized by deficits in the ability to interact socially with others. Ghrelin, a hormone normally associated with the regulation of glucose utilization and appetite, is also implicated in the modulation of motivated behaviors including those associated with food and sex rewards. Here we hypothesized that deficits in ghrelin receptor (growth hormone secretagogue receptor; GHSR) signaling are also associated with deficits in social motivation in male mice. To test this hypothesis, we compared social motivation in male mice lacking GHSR or mice treated with the GHSR antagonist JMV2959 with that of WT or vehicle-treated mice. GHSR signaling in dopamine cells of the ventral tegmental area (VTA) has been implicated in the control of sexual behavior, thus we further hypothesized that GHSR signaling in the VTA is important for social motivation. Thus, we conducted studies where we delivered JMV2959 to block GHSR in the VTA of mice, and studies where we rescued the expression of GHSR in the VTA of GHSR knockout (KO) mice. Mice lacking GHSR or injected with JMV2959 peripherally for 3 consecutive days displayed lower social motivation as reflected by a longer latency to approach a novel conspecific and shorter interaction time compared to WT or vehicle-treated controls. Furthermore, intra-VTA infusion of JMV2959 resulted in longer latencies to approach a novel conspecific, whereas GHSR KO mice with partial rescue of the GHSR showed decreased latencies to begin a novel social interaction. Together, these data suggest that GHSR in the VTA facilitate social approach in male mice, and GHSR-signaling deficits within the VTA result in reduced motivation to interact socially.


Assuntos
Receptores de Grelina , Área Tegmentar Ventral , Animais , Grelina , Masculino , Camundongos , Camundongos Knockout , Motivação , Receptores de Grelina/metabolismo , Secretagogos , Área Tegmentar Ventral/metabolismo
12.
Arch Biochem Biophys ; 704: 108872, 2021 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-33857472

RESUMO

The gastric peptide ghrelin has important functions in energy metabolism and cellular homeostasis by activating growth hormone secretagogue receptor type 1a (GHSR1a). The N-terminal residues of ghrelin orthologs from all vertebrates are quite conserved; however, in orthologs from Cavia porcellus and Phyllostomus discolor, Ser2 and Leu5 are replaced by a smaller Ala and a positively charged Arg, respectively. In the present study, we first demonstrated that the hydrophobic Leu5 is essential for the function of human ghrelin, because Ala replacement caused an approximately 100-fold decrease in activity. However, replacement of Leu5 by an Arg residue caused much less disruption; further replacement of Ser2 by Ala almost restored full activity, although the [S2A] mutation itself showed slight detriments, implying that the positively charged Arg5 in the [S2A,L5R] mutant might form alternative interactions with certain receptor residues to compensate for the loss of the essential Leu5. To identify the responsible receptor residues, we screened GHSR1a mutants in which all conserved negatively charged residues in the extracellular regions and all aromatic residues in the ligand-binding pocket were mutated separately. According to the decrease in selectivity of the mutant receptors towards [S2A,L5R]ghrelin, we deduced that the positively charged Arg5 of the ghrelin mutant primarily interacts with the essential aromatic Phe286 at the extracellular end of the sixth transmembrane domain of GHSR1a by forming cation-π and π-π interactions. The present study provided new insights into the binding mechanism of ghrelin with its receptor, and thus would facilitate the design of novel ligands for GHSR1a.


Assuntos
Grelina/química , Receptores de Grelina/química , Animais , Quirópteros , Grelina/genética , Grelina/metabolismo , Cobaias , Células HEK293 , Humanos , Ligação Proteica , Domínios Proteicos , Receptores de Grelina/genética , Receptores de Grelina/metabolismo
13.
Eur J Pharmacol ; 899: 174039, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33737011

RESUMO

The orexigenic peptide ghrelin increases the release of dopamine in the nucleus accumbens (NAc) shell via central ghrelin receptors, especially those located in the ventral tegmental area (VTA). The activity of the VTA dopamine neurons projecting to NAc shell, involves somatodendritic dopamine release within the VTA. However, the effects of ghrelin on the concomitant dopamine release in the VTA and NAc shell is unknown. It is further unknown whether addictive drugs, such as alcohol and amphetamine, enhance the dopamine levels in both these areas via ghrelin receptor dependent mechanisms. Thus, the effects of a ghrelin receptor antagonist, JMV2959, on the ability of i) central ghrelin ii) systemic alcohol or iii) systemic amphetamine to increase the dopamine release in the VTA and in the NAc shell in rats by using in vivo microdialysis was explored. We showed that systemic administration of JMV2959 blocks the ability of central ghrelin to increases dopamine release in the VTA and the NAc shell, and reduces the alcohol- and amphetamine-induced dopamine release in both these areas. Locomotor activity studies was then conducted in an attempt to correlate the ghrelin-induced dopamine release in the VTA to a behavioural outcome. These revealed that local infusion of a dopamine D1 receptor antagonist into the VTA blocks the ability of central ghrelin to cause a locomotor stimulation in mice. Collectively, this study adds to the growing body of evidence indicating that ghrelin signalling modulates the ability of ghrelin, and addictive drugs, to activate the mesoaccumbal dopamine pathway.


Assuntos
Anfetamina/farmacologia , Dopamina/metabolismo , Etanol/farmacologia , Grelina/farmacologia , Glicina/análogos & derivados , Antagonistas de Hormônios/farmacologia , Núcleo Accumbens/efeitos dos fármacos , Receptores de Grelina/antagonistas & inibidores , Triazóis/farmacologia , Área Tegmentar Ventral/efeitos dos fármacos , Animais , Comportamento Animal/efeitos dos fármacos , Glicina/farmacologia , Locomoção/efeitos dos fármacos , Masculino , Camundongos , Núcleo Accumbens/metabolismo , Ratos Wistar , Receptores de Dopamina D1/metabolismo , Receptores de Grelina/metabolismo , Recompensa , Área Tegmentar Ventral/metabolismo
14.
Physiol Behav ; 228: 113208, 2021 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-33068562

RESUMO

Ghrelin is a 28 amino acid peptide hormone that targets the brain to promote feeding and adiposity. The ghrowth hormone secretagogue receptor 1a (GHSR1a) is expressed within many hypothalamic nuclei, including the ventral premammillary nucleus (PMV), but the role of GHSR1a signaling in this region is unknown. In order to investigate whether GHSR1a signaling within the PMV modulates energy balance, we implanted osmotic minipumps connected to cannulae that were implanted intracranially and aiming at the PMV. The cannulae delivered either saline or ghrelin (10 µg/day at a flow rate of 0.11µL/h for 28 days) into the PMV of adult male C57BLJ6 mice. We found that chronic infusion of ghrelin into the PMV increased weight gain, promoted the oxidation of carbohydrates as a fuel source and resulted in hyperglycemia, without affecting food intake, or body fat. This suggests that ghrelin signaling in the PMV contributes to the modulation of metabolic fuel utilization and glucose homeostasis.


Assuntos
Grelina , Hipotálamo , Animais , Metabolismo Energético , Grelina/metabolismo , Homeostase , Hipotálamo/metabolismo , Masculino , Camundongos , Obesidade , Receptores de Grelina/metabolismo
15.
Nat Prod Res ; 35(1): 57-62, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31135190

RESUMO

Teaghrelins, identified originally in Chin-shin oolong tea, are unique acylated flavonoid tetraglycosides and proposed to be potential oral analogues of ghrelin. In the present study, two new teaghrelin-like compounds were characterized from tea cultivars (TTES No. 12), and their chemical structures were established by the spectroscopic and spectrometric analysis. However, due to the different location of rhamnose, these two teaghrelin-like compounds may not show significant ghrelin receptor affinity.[Figure: see text].


Assuntos
Camellia sinensis/química , Flavonoides/química , Acilação , Flavonoides/metabolismo , Grelina/química , Grelina/farmacologia , Espectroscopia de Ressonância Magnética , Simulação de Acoplamento Molecular , Estrutura Molecular , Extratos Vegetais/química , Receptores de Grelina/metabolismo , Espectrometria de Massas por Ionização por Electrospray , Chá/química
16.
Mol Cell Endocrinol ; 521: 111098, 2021 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-33278490

RESUMO

Mice carrying an RGS-insensitive Gαi2 mutation display growth retardation early after birth. Although the growth hormone (GH)-axis is a key endocrine modulator of postnatal growth, its functional state in these mice has not been characterized. The present study was undertaken to address this issue. Results revealed that pituitary mRNA levels for GH, prolactin (PRL), somatostatin (SST), GH-releasing-hormone receptor (GHRH-R) and GH secretagogue receptor (GHS-R) were decreased in mutants compared to controls. These changes were reflected by a significant decrease in plasma levels of GH, IGF-1 and IGF-binding protein-3 (IGFBP-3). Mutants were also less responsive to GHRH and ghrelin (GhL) on GH stimulation of release from pituitary primary cell cultures. In contrast, they were more sensitive to the inhibitory effect of SST. These data provide the first evidence for an alteration of the functional state of the GH-axis in Gαi2G184S mice that likely contributes to their growth retardation.


Assuntos
Subunidade alfa Gi2 de Proteína de Ligação ao GTP/genética , Transtornos do Crescimento/genética , Transtornos do Crescimento/metabolismo , Proteínas RGS/metabolismo , Transdução de Sinais/genética , Animais , Células Cultivadas , Feminino , Subunidade alfa Gi2 de Proteína de Ligação ao GTP/metabolismo , Grelina/farmacologia , Hormônio do Crescimento/sangue , Hormônio do Crescimento/genética , Hormônio do Crescimento/metabolismo , Hormônio Liberador de Hormônio do Crescimento/sangue , Hormônio Liberador de Hormônio do Crescimento/genética , Hormônio Liberador de Hormônio do Crescimento/farmacologia , Proteína 3 de Ligação a Fator de Crescimento Semelhante à Insulina/sangue , Proteína 3 de Ligação a Fator de Crescimento Semelhante à Insulina/genética , Fator de Crescimento Insulin-Like I/genética , Fator de Crescimento Insulin-Like I/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Mutação , Hipófise/efeitos dos fármacos , Hipófise/metabolismo , Prolactina/genética , Prolactina/metabolismo , Proteínas RGS/genética , Reação em Cadeia da Polimerase em Tempo Real , Receptores de Grelina/metabolismo , Receptores de Neuropeptídeos/genética , Receptores de Neuropeptídeos/metabolismo , Receptores de Hormônios Reguladores de Hormônio Hipofisário/genética , Receptores de Hormônios Reguladores de Hormônio Hipofisário/metabolismo , Transdução de Sinais/efeitos dos fármacos , Somatostatina/genética , Somatostatina/metabolismo , Somatostatina/farmacologia
17.
Life Sci ; 266: 118909, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33333047

RESUMO

OBJECTIVE: To investigate the mechanism of Ghrelin/GHS-R signaling pathway in small intestine injury induced by NSAIDs related enteropathy. To clarify the mechanism network of intestinal mucosal repair with naringin as a new therapeutic method. METHODS: Naringin was used as the intervention method, observed the damage of small intestinal mucosa and detected the expression of ghrelin, GHS-R, leptin and TNF-α by electron microscopy, HE staining and immunohistochemistry. RESULTS: Compared with the control group, the weight of rats in the model group decreased, the thickness of intestinal mucosa became thinner, the structure of intestinal mucosa changed, the expression of ghrelin, GHS-R and leptin decreased, the expression of TNF-α increased. Compared with the model group, the intestinal mucosa of the treatment group was repaired, the expression of ghrelin, GHS-R and leptin was increased, and the expression TNF-α was decreased. CONCLUSION: The mechanism of intestinal mucosal damage in patients with NSAIDs related enteropathy may be related to the decreased expression of ghrelin, GHS-R and leptin, and promotion of TNF-α secretion. Naringin can effectively promote the secretion of ghrelin and leptin, the expression of GSH-R, and inhibit the release of TNF-α, so as to repair intestinal mucosa naringin will become a new method to treat and prevent NSAIDs related intestinal diseases.


Assuntos
Anti-Inflamatórios não Esteroides/toxicidade , Flavanonas/farmacologia , Grelina/metabolismo , Enteropatias/tratamento farmacológico , Intestino Delgado/efeitos dos fármacos , Substâncias Protetoras/farmacologia , Receptores de Grelina/metabolismo , Animais , Enteropatias/induzido quimicamente , Enteropatias/metabolismo , Enteropatias/patologia , Intestino Delgado/lesões , Intestino Delgado/metabolismo , Intestino Delgado/patologia , Leptina/metabolismo , Masculino , Ratos , Ratos Sprague-Dawley , Fator de Necrose Tumoral alfa/metabolismo
18.
FASEB J ; 35(1): e21269, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33368660

RESUMO

Obese individuals often show low growth hormone (GH) secretion, which leads to reduced lipid mobilization and further fat accumulation. Pharmacological approaches to increase GH levels in obese individuals by GH injection or GH-releasing hormone receptor agonist showed promising effects on fat reduction. However, side effects on glucose metabolism and the heavy costs on making large peptides hindered their clinical application. Here, we tested whether stimulation of endogenous GH secretion by a synthetic GH secretagogue receptor (GHSR) agonist, hexarelin, improved the metabolism in a hyperphagic obese mouse model. Male melanocortin 4 receptor knockout mice (MC4RKO) were pair-fed and received continuous hexarelin (10.56 µg/day) or vehicle infusion by an osmotic pump for 3-4 weeks. Hexarelin treatment significantly increased the pulsatile GH secretion without detectable alteration on basal GH secretion in MC4RKO mice. The treated mice showed increased lipolysis and lipid oxidation in the adipose tissue, and reduced de novo lipogenesis in the liver, leading to reduced visceral fat mass, reduced triglyceride content in liver, and unchanged circulating free fatty acid levels. Importantly, hexarelin treatment improved the whole-body insulin sensitivity but did not alter glucose tolerance, insulin levels, or insulin-like growth factor 1 (IGF-1) levels. The metabolic effects of hexarelin were likely through the direct action of GH, as indicated by the increased expression level of genes involved in GH signaling pathways in visceral adipose tissues and liver. In conclusion, hexarelin treatment stimulated the pulsatile GH secretion and reduced the fat accumulation in visceral depots and liver in obese MC4RKO mice with improved insulin sensitivity without altered levels of insulin or IGF-1. It provides evidence for managing obesity by enhancing pulsatile GH secretion through activation of GHSR in the pituitary gland.


Assuntos
Hormônio Liberador de Hormônio do Crescimento/metabolismo , Hormônio do Crescimento/metabolismo , Metabolismo dos Lipídeos/efeitos dos fármacos , Obesidade/metabolismo , Oligopeptídeos/farmacologia , Receptores de Grelina/metabolismo , Animais , Modelos Animais de Doenças , Gordura Intra-Abdominal/metabolismo , Fígado/metabolismo , Camundongos , Camundongos Obesos , Receptores de Grelina/agonistas
19.
J Cell Physiol ; 236(7): 5121-5133, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33345314

RESUMO

Whether the stomach influences the progression of nonalcoholic steatohepatitis (NASH) remains largely unknown. Ghrelin, a 28-amino acid gastric hormone, is critical for the regulation of energy metabolism and inflammation. We investigated whether ghrelin affects the progression of NASH. NASH was induced with lipopolysaccharide (LPS; 240 µg/kg/day) in male C57BL/6J mice with high-fat diet (HFD). Ghrelin (11 nmol/kg/day) was administrated by a subcutaneous mini-pump. Liver steatosis, inflammation, and fibrosis were assessed. Kupffer cells and hepatocytes isolated from wild type, GHSR1a-/- or PPARγ+/- mice were cocultured to determine the cellular and molecular mechanism by which ghrelin ameliorates NASH. A low concentration of LPS activates the Kupffer cells, leading to the development of NASH in mice fed HFD. Ghrelin blocked the progression of NASH induced by LPS via GHSR1a-mediated attenuation of Kupffer cells M1 polarization. GHSR1a was detected in Kupffer cells isolated from wild-type mice but not in GHSR1a deficient animals. Upon binding with ghrelin, internalization of GHSR1a occurred. Ghrelin reduced levels of tumor necrosis factor-α and inducible nitricoxide synthase while increasing Arg1 in Kupffer cells treated with LPS. Ghrelin markedly attenuated the upregulation of lipid accumulation induced by the supernatant of Kupffer cells under both basal and LPS-treated conditions. Deficiency of PPARγ significantly reduced the effect of LPS on the hepatic steatosis in mice and in cultured hepatocytes. Our studies indicate that the stomach may improve the development of NASH via ghrelin. Ghrelin may serve as a marker and therapeutic target for NASH.


Assuntos
Grelina/farmacologia , Macrófagos do Fígado/metabolismo , Hepatopatia Gordurosa não Alcoólica/prevenção & controle , Receptores de Grelina/metabolismo , Estômago/fisiologia , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Animais , Arginase/metabolismo , Polaridade Celular , Células Cultivadas , Dieta Hiperlipídica , Grelina/metabolismo , Hepatócitos/metabolismo , Lipopolissacarídeos , Fígado/patologia , Cirrose Hepática/patologia , Ativação de Macrófagos/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Óxido Nítrico Sintase Tipo II/metabolismo , Hepatopatia Gordurosa não Alcoólica/patologia , PPAR gama/genética , Receptores de Grelina/genética
20.
J Mol Model ; 26(11): 294, 2020 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-33015729

RESUMO

Ghrelin is a peptide hormone involved in multiple functions, including growth hormone release stimulation, food intake regulation, and metabolic and cytoprotective effect. A novel family of peptides with internal cycles was designed as ghrelin analogs and the biological activity of two of them (A228 and A233) was experimentally studied in-depth. In this work, an in silico strategy was developed for describing and assessing the binding modes of A228 and A233 to GHS-R1a (ghrelin receptor) comparing it with ghrelin and GHRP-6 peptides. Several reported structures of different G protein coupled receptors were used as templates, to obtain a good quality model of GHS-R1a. The best model was selected by preliminary molecular docking with ghrelin and GHRP-6. Docking was used to estimate peptide orientations in the binding site of the best model, observing a superposition of its N-terminal and its first aromatic residue. To test the complex stability in time, the C-terminal fragments of each peptide were added and the complexes were inserted a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) membrane, performing a molecular dynamic simulation for 100 ns using the CHARMM36 force field. Despite of the structural differences, the studied peptides share a common binding mode; the N-terminal interacts with E124 and the aromatic residue close to it, with the aromatic cluster (F279, F309, and F312). A preliminary pharmacophore model, consisting in a positive charged amine and an aromatic ring at an approximate distance of 0.79 nm, can be proposed. The results here described could represent a step forward in the efficient search of new ghrelin analogs.


Assuntos
Simulação por Computador , Peptídeos/metabolismo , Peptídeos/farmacologia , Receptores de Grelina/agonistas , Sequência de Aminoácidos , Animais , Humanos , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Peptídeos/química , Ligação Proteica/efeitos dos fármacos , Receptores de Grelina/química , Receptores de Grelina/metabolismo
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