RESUMO
Recently, we showed that double-transgenic rats overexpressing guanylin (Gn), a bioactive peptide, and its receptor, guanylyl cyclase-C (GC-C), specifically in macrophages demonstrate an antiobesity phenotype and low-expression levels of proinflammatory cytokines in the mesenteric fat even when fed a high-fat diet. Here, we examined the levels and mechanism of Gn and GC-C transcription following saturated fatty acid and lipopolysaccharide (LPS), an activator of Toll-like receptor 4 (TLR4), exposure by using the NR8383 macrophage cell line. In addition, the levels of guanylin and cGMP were increased by addition of either palmitic acid or LPS. Next, we investigated the interaction of the gene transcription and nuclear factor-κB (NF-κB) by using an NF-κB inhibitor and chromatin immunoprecipitation assay. We showed that palmitic acid induced Gn gene expression via TLR4 and NF-κB. Moreover, we demonstrated that NF-κB binding to the Gn promoter was responsible for the induction of gene transcription by palmitic acid or LPS. Our results indicate that saturated fatty acids such as palmitic acid activate Gn gene expression via the NF-κB pathway, raising the possibility that the activated Gn-GC-C system may contribute to the inhibition of high-fat diet-induced proinflammatory cytokines in macrophages.
Assuntos
Hormônios Gastrointestinais/genética , Lipopolissacarídeos/farmacologia , Macrófagos Alveolares/efeitos dos fármacos , NF-kappa B/genética , Peptídeos Natriuréticos/genética , Ácido Palmítico/farmacologia , Receptor 4 Toll-Like/genética , Animais , Linhagem Celular , GMP Cíclico/imunologia , GMP Cíclico/metabolismo , Hormônios Gastrointestinais/agonistas , Hormônios Gastrointestinais/imunologia , Regulação da Expressão Gênica , Genes Reporter , Humanos , Luciferases/genética , Luciferases/metabolismo , Macrófagos Alveolares/citologia , Macrófagos Alveolares/imunologia , Camundongos , NF-kappa B/imunologia , Peptídeos Natriuréticos/agonistas , Peptídeos Natriuréticos/imunologia , Células RAW 264.7 , Ratos , Receptores Acoplados a Guanilato Ciclase/genética , Receptores Acoplados a Guanilato Ciclase/imunologia , Transdução de Sinais , Células THP-1 , Receptor 4 Toll-Like/imunologiaRESUMO
NEW FINDINGS: What is the central question of this manuscript? What is the effect of food texture on fat accumulation, lipogenesis and proinflammatory factors in the adipose tissue and on energy balance in male rats? What is the main finding and its importance? Calorie intake and fat accumulation in rats fed soft pellets ad libitum increased, but their body weight did not. The data suggest that, even when BMI is normal, frequent consumption of soft food may contribute to the development of lifestyle-related diseases. ABSTRACT: Dietary factors such as food texture are known to affect feeding behaviour and energy metabolism. We recently found that rats fed soft pellets (SPs) on a 3 h restricted feeding schedule showed glucose intolerance, insulin resistance with disruption of insulin signalling, and hyperplasia of pancreatic ß-cells, even though there were no differences in energy intake and body weight between rats fed control pellets (CPs) and rats fed SPs. We investigated the effect of food texture on fat accumulation, lipogenesis and proinflammatory factors in the mesenteric fat, as well as on energy balance in male rats fed CPs or SPs. We used 7-week-old Wistar rats that were randomly divided into two groups, ad libitum fed either CPs or SPs for 27 weeks. Body weight and calorie intake were monitored once a week throughout the experiment. The calorie intake, lipogenesis and fat accumulation of the rats fed SPs increased, whereas their body weight did not. Additionally, SP rats used their fat mainly as a source of energy and increased their energy expenditure. Our data suggest that the habit of frequently eating soft food causes visceral fat accumulation without an increase in body weight. Further investigations using soft-textured foods could lead to the development of appropriate interventions for non-overweight patients with lifestyle-related diseases.
Assuntos
Adiposidade/fisiologia , Ingestão de Alimentos/fisiologia , Ingestão de Energia/fisiologia , Metabolismo Energético/fisiologia , Tecido Adiposo/metabolismo , Tecido Adiposo/fisiopatologia , Animais , Glicemia/metabolismo , Composição Corporal/fisiologia , Peso Corporal/fisiologia , Gorduras na Dieta/efeitos adversos , Comportamento Alimentar/fisiologia , Alimentos , Insulina/metabolismo , Resistência à Insulina/fisiologia , Lipogênese/fisiologia , Masculino , Obesidade/metabolismo , Obesidade/fisiopatologia , Ratos , Ratos WistarRESUMO
Guanylin (Gn), a bioactive peptide, and its receptor, guanylyl cyclase-C (GC-C), are primarily present in the intestine and maintain homeostasis in body fluids. Recently, rats whose macrophages overexpress Gn and GC-C were found to be resistant to diet-induced obesity. Considering that obesity is strongly related to a chronic inflammatory state in white adipose tissues, it is possible that Gn-GC-C macrophages contribute to the regulation of inflammation. In the present study, we investigated the inflammatory state of mesenteric fat in rats transgenic for both Gn and GC-C (double-transgenic [dTg] rats) by evaluating the levels of cyclic guanosine monophosphate (cGMP), a second messenger of Gn-GC-C, cGMP-dependent protein kinase (PKG), and phosphorylated vasodilator-stimulated phosphoprotein (VASP), a target protein of PKG. The levels of cGMP in dTg rats was higher than in WT rats fed the same diet. Although there were no significant differences in levels of PKG and phosphorylated VASP between WT and dTg rats fed a standard diet (STD), these levels in dTg rats fed a high fat diet (HFD) were markedly increased compared with levels in HFD WT rats. Furthermore, mRNA levels of proinflammatory factors in mesenteric fat were lower in HFD dTg rats than in HFD WT rats and were similar to levels in STD WT and dTg rats. These results indicate that the Gn-GC-C system in macrophages regulates the cGMP-PKG-VASP pathway and controls obesity through the downregulation of proinflammatory factors.
Assuntos
GMP Cíclico/metabolismo , Hormônios Gastrointestinais/metabolismo , Gordura Intra-Abdominal/metabolismo , Macrófagos Peritoneais/metabolismo , Peptídeos Natriuréticos/metabolismo , Paniculite Peritoneal/metabolismo , Receptores Acoplados a Guanilato Ciclase/agonistas , Receptores de Peptídeos/agonistas , Sistemas do Segundo Mensageiro , Animais , Moléculas de Adesão Celular/metabolismo , Proteínas Quinases Dependentes de GMP Cíclico/metabolismo , Dieta Hiperlipídica/efeitos adversos , Hormônios Gastrointestinais/genética , Imuno-Histoquímica , Mediadores da Inflamação/metabolismo , Gordura Intra-Abdominal/enzimologia , Gordura Intra-Abdominal/imunologia , Gordura Intra-Abdominal/patologia , Macrófagos Peritoneais/enzimologia , Macrófagos Peritoneais/imunologia , Macrófagos Peritoneais/patologia , Masculino , Proteínas dos Microfilamentos/metabolismo , Peptídeos Natriuréticos/genética , Obesidade/etiologia , Obesidade/imunologia , Obesidade/metabolismo , Obesidade/patologia , Paniculite Peritoneal/etiologia , Paniculite Peritoneal/imunologia , Paniculite Peritoneal/patologia , Fosfoproteínas/metabolismo , Fosforilação , Processamento de Proteína Pós-Traducional , Distribuição Aleatória , Ratos , Ratos Transgênicos , Receptores de Enterotoxina , Receptores Acoplados a Guanilato Ciclase/genética , Receptores Acoplados a Guanilato Ciclase/metabolismo , Receptores de Peptídeos/genética , Receptores de Peptídeos/metabolismoRESUMO
CCK and leptin are anorectic hormones produced in the small intestine and white adipose tissue, respectively. Investigating how these hormones act together as an integrated anorectic signal is important for elucidating the mechanisms by which energy balance is maintained. We found here that coadministration of subthreshold CCK and leptin, which individually have no effect on feeding, dramatically reduced food intake in rats. Phosphorylation of AMP-activated protein kinase (AMPK) in the hypothalamus significantly decreased after coinjection of CCK and leptin. In addition, coadministration of these hormones significantly increased mRNA levels of anorectic cocaine- and amphetamine-regulated transcript (CART) and thyrotropin-releasing hormone (TRH) in the hypothalamus. The interactive effect of CCK and leptin on food intake was abolished by intracerebroventricular preadministration of the AMPK activator AICAR or anti-CART/anti-TRH antibodies. These findings indicate that coinjection of CCK and leptin reduces food intake via reduced AMPK phosphorylation and increased CART/TRH in the hypothalamus. Furthermore, by using midbrain-transected rats, we investigated the role of the neural pathway from the hindbrain to the hypothalamus in the interaction of CCK and leptin to reduce food intake. Food intake reduction induced by coinjection of CCK and leptin was blocked in midbrain-transected rats. Therefore, the neural pathway from hindbrain to hypothalamus plays an important role in transmitting the anorectic signals provided by coinjection of CCK and leptin. Our findings give further insight into the mechanisms of feeding and energy balance.
Assuntos
Proteínas Quinases Ativadas por AMP/biossíntese , Colecistocinina/farmacologia , Ingestão de Alimentos/efeitos dos fármacos , Hipotálamo/metabolismo , Leptina/farmacologia , Proteínas do Tecido Nervoso/biossíntese , Hormônio Liberador de Tireotropina/biossíntese , Proteína Relacionada com Agouti/biossíntese , Animais , Western Blotting , Hipotálamo/efeitos dos fármacos , Hipotálamo/enzimologia , Injeções Intraventriculares , Masculino , Mesencéfalo/fisiologia , Neuropeptídeo Y/biossíntese , Fosforilação , RNA Mensageiro/biossíntese , Ratos , Ratos Wistar , Reação em Cadeia da Polimerase em Tempo Real , Fator de Transcrição STAT3/biossínteseRESUMO
Dietary factors such as food texture affect feeding behavior and energy metabolism, potentially causing obesity and type 2 diabetes. We previously found that rats fed soft pellets (SPs) were neither hyperphagic nor overweight but demonstrated glucose intolerance, insulin resistance, and hyperplasia of pancreatic ß-cells. In the present study, we investigated the mechanism of muscle atrophy in rats that had been fed SPs on a 3-h time-restricted feeding schedule for 24 weeks. As expected, the SP rats were normal weight; however, they developed insulin resistance, glucose intolerance, and fat accumulation. In addition, skeletal muscles of SP rats were histologically atrophic and demonstrated disrupted insulin signaling. Furthermore, we learned that the muscle atrophy of the SP rats developed via the IL-6-STAT3-SOCS3 and ubiquitin-proteasome pathways. Our data show that the dietary habit of consuming soft foods can lead to not only glucose intolerance or insulin resistance but also muscle atrophy.
Assuntos
Diabetes Mellitus Tipo 2 , Intolerância à Glucose , Resistência à Insulina , Ratos , Animais , Resistência à Insulina/fisiologia , Intolerância à Glucose/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Insulina/metabolismo , Atrofia Muscular/etiologia , Atrofia Muscular/metabolismo , Músculo Esquelético/metabolismo , Dieta , Dieta HiperlipídicaRESUMO
A high-fat diet (HFD) is a well-known contributing factor in the development of obesity. Most rats fed HFDs become obese. Those that avoid obesity when fed HFDs are considered diet resistant (DR). We performed a microarray screen to identify genes specific to the mesenteric fat of DR rats and revealed high expression of guanylin and guanylyl cyclase C (GC-C) in some subjects. Our histologic studies revealed that the cellular source of guanylin and GC-C is macrophages. Therefore, we developed double-transgenic (Tg) rats overexpressing guanylin and GC-C in macrophages and found that they were resistant to the effects of HFDs. In the mesenteric fat of HFD-fed Tg rats, Fas and perilipin mRNAs were downregulated, and those of genes involved in fatty acid oxidation were upregulated, compared with the levels in HFD-fed wild-type rats. In vitro studies demonstrated that lipid accumulation was markedly inhibited in adipocytes cocultured with macrophages expressing guanylin and GC-C and that this inhibition was reduced after treatment with guanylin- and GC-C-specific siRNAs. Our results suggest that the macrophagic guanylin-GC-C system contributes to the altered expression of genes involved in lipid metabolism, leading to resistance to obesity.
Assuntos
Dieta Hiperlipídica/efeitos adversos , Hormônios Gastrointestinais/metabolismo , Macrófagos/metabolismo , Mesentério/citologia , Peptídeos Natriuréticos/metabolismo , Receptores Acoplados a Guanilato Ciclase/metabolismo , Receptores de Peptídeos/metabolismo , Adipócitos/metabolismo , Animais , Colesterol/sangue , Ácidos Graxos não Esterificados/sangue , Hormônios Gastrointestinais/deficiência , Hormônios Gastrointestinais/genética , Regulação da Expressão Gênica , Técnicas de Introdução de Genes , Insulina/sangue , Fígado/metabolismo , Macrófagos/enzimologia , Macrófagos Peritoneais/enzimologia , Macrófagos Peritoneais/metabolismo , Masculino , Peptídeos Natriuréticos/deficiência , Peptídeos Natriuréticos/genética , Oxirredução , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA Interferente Pequeno/genética , Ratos , Ratos Transgênicos , Receptores de Enterotoxina , Receptores Acoplados a Guanilato Ciclase/deficiência , Receptores Acoplados a Guanilato Ciclase/genética , Receptores de Peptídeos/deficiência , Receptores de Peptídeos/genética , Triglicerídeos/sangue , Triglicerídeos/metabolismoRESUMO
The CBP protein (cAMP response element binding protein (CREB) binding protein) is a co-activator for several transcription factors with a wide range of important biological functions, such as sterol regulatory element binding proteins (SREBPs), CCAAT/enhancer-binding proteins (C/EBPs), nuclear receptors (including peroxisome proliferator-activated receptors, PPARs), and signal transducers and activators of transcription (STATs). In contrast to these individual transcription factors, the biological roles of CBP are poorly understood. CBP enhances transcriptional activities via histone acetylation and the recruitment of additional co-activators such as SRC (steroid coactivator)-1 (ref. 9). To identify its physiological functions using a loss-of-function mutant, we analyzed CBP-deficient mice. As Crebbp null mice (Crebbp-/-) died during embryogenesis, we used Crebbp+/- mice. Unexpectedly, Crebbp+/- mice showed markedly reduced weight of white adipose tissue (WAT) but not of other tissues. Despite this lipodystrophy, Crebbp+/- mice showed increased insulin sensitivity and glucose tolerance and were completely protected from body weight gain induced by a high-fat (HF) diet. We observed increased leptin sensitivity and increased serum adiponectin levels in Crebbp+/- mice. These increased effects of insulin-sensitizing hormones secreted from WAT may explain, at least in part, the phenotypes of Crebbp+/- mice. This study demonstrates that CBP may function as a 'master-switch' between energy storage and expenditure.
Assuntos
Resistência à Insulina/genética , Lipodistrofia/genética , Proteínas Nucleares/genética , Transativadores/genética , Adipócitos/metabolismo , Adipócitos/patologia , Tecido Adiposo/patologia , Tecido Adiposo Marrom/patologia , Animais , Proteínas Estimuladoras de Ligação a CCAAT/metabolismo , Proteína de Ligação a CREB , Tamanho Celular , Proteínas de Ligação a DNA/metabolismo , Gorduras na Dieta/administração & dosagem , Metabolismo Energético , Heterozigoto , Resistência à Insulina/fisiologia , Lipodistrofia/patologia , Lipodistrofia/fisiopatologia , Camundongos , Camundongos Mutantes , Proteínas Nucleares/deficiência , Proteínas Nucleares/fisiologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteína de Ligação a Elemento Regulador de Esterol 1 , Transativadores/deficiência , Transativadores/fisiologia , Fatores de Transcrição/metabolismoRESUMO
Glucagon-like peptide-1 (GLP-1) and leptin are anorectic hormones produced in the small intestine and white adipose tissue, respectively. Investigating how these hormones act together as an integrated anorectic signal is important to elucidate a mechanism to maintain energy balance. In the present study, coadministration of subthreshold GLP-1 and leptin dramatically reduced feeding in rats. Although coadministration of GLP-1 with leptin did not enhance leptin signal transduction in the hypothalamus, it significantly decreased phosphorylation of AMP-activated protein kinase (AMPK). In addition, coadministration of GLP-1 with leptin significantly increased proopiomelanocortin (POMC) mRNA levels. Considering that α-melanocortin stimulating hormone (α-MSH) is derived from POMC and functions through the melanocortin-4-receptor (MC4-R) as a key molecule involved in feeding reduction, the interaction of GLP-1 and leptin on feeding reduction may be mediated through the α-MSH/MC4-R system. As expected, the interaction of GLP-1 and leptin was abolished by intracerebroventricular preadministration of the MC4-R antagonists agouti-related peptide and SHU9119. Taken together, GLP-1 and leptin cooperatively reduce feeding at least in part via inhibition of AMPK following binding of α-MSH to MC4-R.
Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Interações Medicamentosas , Ingestão de Alimentos/efeitos dos fármacos , Comportamento Alimentar/efeitos dos fármacos , Peptídeo 1 Semelhante ao Glucagon/administração & dosagem , Leptina/administração & dosagem , Receptor Tipo 4 de Melanocortina/metabolismo , Animais , Masculino , Hormônios Estimuladores de Melanócitos/farmacologia , Ratos , Ratos Wistar , Receptor Tipo 4 de Melanocortina/antagonistas & inibidores , alfa-MSH/metabolismoRESUMO
Ghrelin, a gastrointestinal peptide, stimulates feeding when administered peripherally. Blockade of the vagal afferent pathway abolishes ghrelin-induced feeding, indicating that the vagal afferent pathway may be a route conveying orexigenic ghrelin signals to the brain. Here, we demonstrate that peripheral ghrelin signaling, which travels to the nucleus tractus solitarius (NTS) at least in part via the vagus nerve, increases noradrenaline (NA) in the arcuate nucleus of the hypothalamus, thereby stimulating feeding at least partially through alpha-1 and beta-2 noradrenergic receptors. In addition, bilateral midbrain transections rostral to the NTS, or toxin-induced loss of neurons in the hindbrain that express dopamine beta hydroxylase (an NA synthetic enzyme), abolished ghrelin-induced feeding. These findings provide new evidence that the noradrenergic system is necessary in the central control of feeding behavior by peripherally administered ghrelin.
Assuntos
Hipotálamo/metabolismo , Norepinefrina/metabolismo , Hormônios Peptídicos/metabolismo , Rombencéfalo/metabolismo , Transdução de Sinais/fisiologia , Animais , Dopamina beta-Hidroxilase/metabolismo , Relação Dose-Resposta a Droga , Ingestão de Alimentos , Comportamento Alimentar/efeitos dos fármacos , Comportamento Alimentar/fisiologia , Grelina , Masculino , Neurônios/metabolismo , Neuropeptídeo Y/metabolismo , Hormônios Peptídicos/farmacologia , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Receptores Adrenérgicos alfa 1/metabolismo , Receptores Adrenérgicos beta 2/metabolismoRESUMO
Although orexin-A peptide was recently found to inhibit the brain reward system, the exact neural substrates for this phenomenon remain unclear. The aim of the present study was to investigate the role of orexin neurons in intra-cranial self-stimulation behavior and to clarify the pathways through which orexin-A inhibits the brain reward system. Immunohistochemical examination using Fos, a neuronal activation marker, revealed that the percentage of activated orexin cells was very low in the lateral hypothalamus even in the hemisphere ipsilateral to self-stimulation, suggesting that orexin neurons play only a small part, if any, in performing intra-cranial self-stimulation behavior. Intra-ventral tegmental area administration of orexin-A (1.0 nmol) significantly increased the intra-cranial self-stimulation threshold. Furthermore, the threshold-increasing effects of intra-ventral tegmental area or intracerebroventricular orexin-A were inhibited by administration of the nonspecific corticotropin-releasing factor receptor antagonist, d-Phe-CRF(12-41) (20 µg). Following intra-ventral tegmental area infusion of orexin-A, the percentage of cells double-labeled with corticotropin-releasing factor and Fos antibodies increased in the central nucleus of the amygdala but not in the bed nucleus of the stria terminalis, and brain microdialysis analyses indicated that dopamine efflux in both the central nucleus of the amygdala and bed nucleus of the stria terminalis were enhanced. Taken together, the present findings suggest that intra-ventral tegmental area or intracerebroventricular administration of orexin-A exerts its threshold-increasing effect via subsequent activation of the corticotropin-releasing factor system.
Assuntos
Comportamento Animal/efeitos dos fármacos , Hormônio Liberador da Corticotropina/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/farmacologia , Neuropeptídeos/farmacologia , Autoestimulação/fisiologia , Área Tegmentar Ventral/efeitos dos fármacos , Tonsila do Cerebelo/anatomia & histologia , Tonsila do Cerebelo/efeitos dos fármacos , Tonsila do Cerebelo/fisiologia , Animais , Hormônio Liberador da Corticotropina/antagonistas & inibidores , Dopamina/metabolismo , Infusões Intraventriculares , Peptídeos e Proteínas de Sinalização Intracelular/administração & dosagem , Masculino , Neuropeptídeos/administração & dosagem , Neurotransmissores/farmacologia , Orexinas , Proteínas Proto-Oncogênicas c-fos/metabolismo , Ratos , Ratos Wistar , Recompensa , Autoestimulação/efeitos dos fármacos , Área Tegmentar Ventral/anatomia & histologia , Área Tegmentar Ventral/fisiologiaRESUMO
Neuroendocrine regulatory peptide (NERP)-1 and NERP-2 are biologically active peptides recently discovered by peptidomic analysis. NERPs are processed out from the 594-residue VGF protein which contains many prohormone convertase cleavage motifs. VGF-deficient mice exhibit a hypermetabolic and infertile phenotype, for which VGF protein-derived peptides including NERPs are presumably responsible. To provide a solid basis for elucidating physiological roles of NERPs, we investigated rat VGF protein processing by chromatographic and mass spectrometric analysis, and immunoblotting, using antibodies against NERPs and the VGF protein C-terminus (VGF-C). Cellular and tissue distribution of immunoreactive (ir) NERPs were also analyzed in the rat. Both ir-NERP-1 and ir-NERP-2, which occur abundantly in the CNS and pituitary, moderately in the gastrointestinal (GI) tract, were mainly localized in neuronal structures. Major endogenous forms of ir-NERPs in the brain and GI tract were identified as NERP-1, NERP-2, and big NERP-2 (NERP-1 + NERP-2), with NERP-1 and big NERP-2 being predominant. Regarding ir-VGF-C peptides, VGF[588-617], VGF[556-617], and VGF[509-617] were found to be major forms. Immunoblotting with the NERP-2 and VGF-C antibodies revealed processing intermediates of 10-37 kDa. Taken together, we deduce that VGF protein is primarily cleaved at 10 sites through the processing pathway common to the brain and GI tract.
Assuntos
Química Encefálica , Trato Gastrointestinal/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Neuropeptídeos/metabolismo , Precursores de Proteínas/metabolismo , Processamento de Proteína Pós-Traducional , Animais , Química Encefálica/fisiologia , Trato Gastrointestinal/citologia , Proteínas do Tecido Nervoso/química , Neuropeptídeos/química , Peptídeos/química , Peptídeos/metabolismo , Hipófise/química , Hipófise/citologia , Hipófise/metabolismo , Precursores de Proteínas/química , Ratos , Ratos Sprague-Dawley , Ratos Wistar , Distribuição Tecidual/fisiologiaRESUMO
Orexin-A and -B (identical to hypocretin-1 and -2) are hypothalamic neuropeptides that regulate appetite and arousal. Orexins-producing neurons project their axons to various brain regions, including the olfactory bulb. In the present study, to understand the relationship between orexins and olfaction, we investigated the distribution of the orexin-A- and -B-immunoreactive (ir) fibers in the rat olfactory bulb and the contents of orexin-A and -B in the rat olfactory bulb after food deprivation for 48 h by using immunohistochemistry and radioimmunoassay, respectively. Both orexin-A- and -B-ir fibers are similarly wide spread from the glomerular layer of the olfactory bulb where the terminals of the peripheral olfactory nerves make synapses with the mitral cells or the tufted cells, to the piriform cortex. Dense orexin-A- and -B-ir fibers were observed mainly in the granular cell layer and anterior olfactory nucleus. The contents of orexin-A and -B (pg/10 mg wet weight tissue) in fed rats (mean+/-S.E.M., n=6) were 2.72+/-0.24 and 6.31+/-0.63, respectively. Fasting for 48 h significantly reduced the contents of orexin-B, but not orexin-A. Orexins in the rat olfactory bulb may be involved in not only olfactory system but also energy balance.
Assuntos
Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Fibras Nervosas/metabolismo , Neuropeptídeos/metabolismo , Bulbo Olfatório/citologia , Bulbo Olfatório/metabolismo , Animais , Córtex Cerebral/citologia , Córtex Cerebral/metabolismo , Interpretação Estatística de Dados , Técnica Indireta de Fluorescência para Anticorpo , Privação de Alimentos/fisiologia , Glutamato Descarboxilase/metabolismo , Imuno-Histoquímica , Masculino , Vias Neurais/citologia , Vias Neurais/metabolismo , Orexinas , Radioimunoensaio , Ratos , Ratos WistarRESUMO
Neuropeptide W (NPW), a novel endogenous peptide for G protein-coupled receptors GPR7 and GPR8, is expressed in the gastric antral mucosa of rat, mouse, and human stomachs. Here, we studied the ontogeny of NPW in the developing rat stomach. Real-time RT-PCR showed that NPW gene expression was initially detectable in embryonic day 14 (E14) stomach and gradually increased during the progress of age until birth, postnatal day 1 (P1). NPW mRNA level in the stomach increased again from the weaning period (P21) until reaching adulthood. Immunohistochemistry using polyclonal antibodies raised against rat NPW revealed that NPW-positive cells were detected in the P1 antral stomach and gradually increased during the development of age. Furthermore, double immunohistochemistry demonstrated that NPW colocalized with gastrin in P1 rat stomach. These data will provide clues to physiological functions of NPW in the development of rat stomach.
Assuntos
Mucosa Gástrica/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Neuropeptídeos/classificação , Neuropeptídeos/metabolismo , Animais , Feminino , Imuno-Histoquímica , Masculino , Neuropeptídeos/genética , Ratos , Ratos Wistar , Estômago/embriologia , Estômago/crescimento & desenvolvimentoRESUMO
Neuropeptide W (NPW) was recently discovered as the endogenous ligand for GPR7 and GPR8, which are orphan G protein-coupled receptors isolated from the porcine brain. These receptors are assumed to be involved in feeding regulation and/or energy homeostasis. Recent anatomical studies have revealed that high levels of GPR7 mRNA are distributed in the brain, including the hypothalamus and amygdala. However immunohistochemical studies on the distribution and localization of NPW have revealed differing results concerning whether or not NPW-containing cell bodies and their processes are present in the hypothalamus. Only a few immunohistochemical reports have been published concerning the presence of NPW-containing neurons in the brains of rodents, while there have been no anatomical studies of the co-localization of this neuropeptide with other transmitters. On this basis, we used a specific antiserum against NPW to determine immunohistochemically the presence of NPW-containing neurons in the rat hypothalamus. Many NPW-like immunoreactive cell bodies and their processes could be detected in the caudal region of the lateral hypothalamus but not in its anterior or middle regions. Given this positive identification of NPW-containing neurons in the lateral hypothalamus, we further studied the nature of interaction between NPW-containing neurons and neurons containing feeding regulating peptides such as orexin- and melanin-concentrating hormone (MCH). Very close interactions between NPW-containing nerve processes and orexin- and MCH-containing neuronal cell bodies and processes could be observed. These morphological findings strongly suggest that NPW is involved in the regulation of feeding and/or sleep/arousal behavior through orexin- and/or MCH-mediated neuronal pathways.
Assuntos
Hormônios Hipotalâmicos/metabolismo , Hipotálamo/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Melaninas/metabolismo , Neurônios/metabolismo , Neuropeptídeos/metabolismo , Hormônios Hipofisários/metabolismo , Animais , Masculino , Orexinas , Ratos , Ratos WistarRESUMO
Neuropeptide W (NPW) is an endogenous ligand for GPR7, a member of the G-protein-coupled receptor family. NPW plays an important role in the regulation of both feeding and energy metabolism, and is also implicated in modulating responses to an acute inflammatory pain through activation of the hypothalamus-pituitary-adrenal axis. GPR7 mRNA has been shown to be expressed in the hypothalamus, pituitary gland and adrenal cortex. Similarly, NPW expression has been demonstrated in the brain and pituitary gland. However, the precise distribution of NPW-producing cells in the adrenal gland remains unknown. The aim of this study was to explore the distribution and localization of NPW immunoreactivity in the rat adrenal gland. Total RNA was prepared from the hypothalamus, pituitary gland and adrenal gland. RT-PCR revealed the expression of NPW mRNA in these tissues, while in situ hybridization demonstrated the presence of NPW mRNA in the adrenal medulla. When immunohistochemistry was performed on sections of adrenal gland, NPW-like immunoreactivity (NPW-LI) was observed in the medulla but not in the cortex. Moreover, NPW-LI was found to be co-localized in cells which expressed dopamine beta hydroxylase but not phenylethanolamine-N-methyltransferase. The finding that NPW is expressed in noradrenalin-containing cells in the adrenal medulla suggests that it may play an important role in endocrine function in the adrenal gland.
Assuntos
Medula Suprarrenal/metabolismo , Regulação da Expressão Gênica , Neuropeptídeos/genética , Norepinefrina/metabolismo , Animais , Imuno-Histoquímica , Hibridização In Situ , Masculino , RNA Mensageiro/genética , Ratos , Ratos Sprague-DawleyRESUMO
Recently we found that guanylin (Gn) and its receptor, guanylyl cyclase C (GC-C), are uniquely expressed in the mesenteric macrophages of some diet-resistant rats and that double-transgenic (dTg) rats overexpressing Gn and GC-C in macrophages demonstrate reduced fatty acid synthase and fat accumulation in fat tissue even when fed a high-fat diet (HFD). Lipid accumulation and fatty acid synthase mRNA levels in cocultured dTg rat adipocytes and macrophages were reduced compared with those in adipocytes cultured with WT rat macrophages. Here, we investigated whether Interleukin-15 (IL-15) derived from Gn-GC-C-expressing macrophages regulates lipid accumulation in adipocytes. IL-15 inhibited fatty acid synthase and lipid accumulation via STAT5 in cultured adipocytes. IL-15 mRNA and protein levels in the mesenteric fat of HFD-fed dTg rats were significantly higher than those of HFD-fed WT rats. Phosphorylated STAT5 levels in the mesenteric fat of HFD-fed dTg rats were increased compared with those of HFD-fed WT rats. In addition, the mRNA level of fatty acid synthase in the mesenteric fat was lower in HFD-fed dTg rats than in HFD-fed WT rats. These results support the hypothesis that IL-15 secreted from Gn-GC-C-expressing macrophages contributes to the inhibition of fatty acid synthase and lipid accumulation in adipocytes, leading to obesity resistance.
Assuntos
Adipócitos/metabolismo , Ácido Graxo Sintase Tipo I/metabolismo , Hormônios Gastrointestinais/biossíntese , Interleucina-15/biossíntese , Macrófagos/metabolismo , Peptídeos Natriuréticos/biossíntese , Receptores de Enterotoxina/biossíntese , Adipócitos/citologia , Animais , Gorduras na Dieta/efeitos adversos , Gorduras na Dieta/farmacologia , Ácido Graxo Sintase Tipo I/genética , Hormônios Gastrointestinais/genética , Interleucina-15/genética , Macrófagos/citologia , Peptídeos Natriuréticos/genética , Ratos , Ratos Transgênicos , Receptores de Enterotoxina/genéticaRESUMO
Age-related decreases in energy expenditure have been associated with the loss of skeletal muscle and decline of food intake, possibly through a mechanism involving changes of growth hormone (GH) secretion and feeding behavior. Age-related declines of growth hormone secretion and food intake have been termed the somatopause and anorexia of ageing, respectively. Ghrelin, a 28-amino-acid peptide, was isolated from human and rat stomachs as an endogenous ligand of growth hormone secretagogue receptor. Ghrelin stimulates growth hormone release and food intake when peripherally administered to rodents and humans. Here, we investigate the relationship between age-related decline of growth hormone secretion and/or food intake and ghrelin function. Ghrelin (10 nmol/kg body weight) was administered intravenously to male 3-, 12-, 24-and 27-month-old Long-Evans rats, after which growth hormone concentrations and 2 h food intake were measured. An intravenous administration of ghrelin to rats increased food intake in all generations. In addition, to orexigenic effect by ghrelin, intravenous administration of ghrelin elicited a marked increase in plasma GH levels, with the peak occurring 15 min after administration. These findings suggest that the aged rats maintain the reactivity to administered exogenous ghrelin.
Assuntos
Envelhecimento/fisiologia , Ingestão de Alimentos/efeitos dos fármacos , Hormônio do Crescimento/metabolismo , Hormônios Peptídicos/farmacologia , Fatores Etários , Envelhecimento/efeitos dos fármacos , Animais , Peso Corporal/efeitos dos fármacos , Grelina , Masculino , Ratos , Ratos Endogâmicos LECRESUMO
Guanylyl cyclase C (GC-C) is a member of a family of enzymes that metabolize GTP to cGMP and was first identified as a receptor for heat-stable enterotoxin. Guanylin (GNY) has since been identified as an endogenous ligand for GC-C in the intestine of several mammalian species. The GNY/GC-C system regulates ion transportation and pH in the mucosa. Recently, it was reported that GC-C and GNY are involved in lipid metabolism in rat mesenteric adipose tissue macrophages. To examine the role of GC-C and GNY in lipid metabolism in cattle, we used a bovine mesenteric adipocyte primary culture system and a coculture system for bovine adipocytes and GNY-/GC-C-expressing macrophages. Fat droplets were observed to accumulate in bovine mesenteric adipocytes cultured alone, whereas few fat droplets accumulated in adipocytes indirectly cocultured with macrophages. We also observed that GC-C was present in bovine mesenteric adipose tissue, and that fat droplet accumulation decreased after in vitro GNY administration. Expressions of mRNAs encoding lipogenic factors decreased significantly in adipocytes after either coculture or GNY administration. These results suggest that the GNY/GC-C system is part of the control system for lipid accumulation in bovine mesenteric adipose tissue.
Assuntos
Tecido Adiposo/efeitos dos fármacos , Hormônios Gastrointestinais/farmacologia , Peptídeos Natriuréticos/farmacologia , Receptores de Enterotoxina/metabolismo , Adipócitos/efeitos dos fármacos , Adipócitos/metabolismo , Tecido Adiposo/citologia , Tecido Adiposo/metabolismo , Animais , Bovinos , Técnicas de Cocultura/veterinária , Guanilato Ciclase , Metabolismo dos Lipídeos/efeitos dos fármacos , Metabolismo dos Lipídeos/fisiologia , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Reação em Cadeia da Polimerase em Tempo Real/veterináriaRESUMO
The CT-R [calcitonin (CT) receptor] is expressed in the central nervous system and is involved in the regulation of food intake, thermogenesis, and behaviors. CT-R-stimulating peptide-1 (CRSP-1), a potent ligand for the CT-R, was recently isolated from the porcine brain. In this study, we first confirmed that porcine CRSP-1 (pCRSP-1) enhanced the cAMP production in COS-7 cells expressing recombinant rat CT-R, and then we examined the central effects of pCRSP-1 on feeding and energy homeostasis in rats. Intracerebroventricular (icv) administration of pCRSP-1 to free-feeding rats suppressed food intake in a dose-dependent manner. Chronic icv infusion of pCRSP-1 suppressed body weight gain over the infusion period. Furthermore, icv administration of pCRSP-1 increased body temperature and decreased locomotor activity. The central effects of pCRSP-1 were more potent than those of porcine CT in rats. In contrast, ip administration of pCRSP-1 did not elicit any anorectic or catabolic effects. Administration icv of pCRSP-1 also induced mild dyskinesia of the lower extremities and decreased gastric acid output. Fos expression induced by icv administration of pCRSP-1 was detected in the neurons of the paraventricular nucleus, dorsomedial hypothalamic nucleus, arcuate nucleus, locus coeruleus, and nucleus of solitary tract, areas that are known to regulate feeding and energy homeostasis. Administration icv of pCRSP-1 increased plasma concentrations of ACTH and corticosterone, implying that the hypothalamic-pituitary-adrenocortical axis might be involved in catabolic effects of pCRSP-1. These results suggest that CRSP-1 can function as a ligand for the CT-R and may act as a catabolic signaling molecule in the central nervous system.
Assuntos
Encéfalo/efeitos dos fármacos , Peptídeo Relacionado com Gene de Calcitonina/farmacologia , Metabolismo Energético/efeitos dos fármacos , Receptores da Calcitonina/agonistas , Hormônio Adrenocorticotrópico/sangue , Animais , Temperatura Corporal/efeitos dos fármacos , Corticosterona/sangue , Ingestão de Alimentos/efeitos dos fármacos , Homeostase/efeitos dos fármacos , Humanos , Ligantes , Masculino , Atividade Motora/efeitos dos fármacos , Ratos , Ratos Wistar , Aumento de Peso/efeitos dos fármacosRESUMO
Ghrelin, an acylated peptide serving as an endogenous ligand for GH secretagogue receptor (GHS-R), was originally isolated from rat and human stomach. In this study, we report the critical role of maternal ghrelin in fetal development. High levels of ghrelin receptor (GHS-R) mRNA were detected in various peripheral fetal tissues beginning at embryonic d 14 and lasting until birth. Fetal GHS-R expression was also confirmed in fetal tissues by immunohistochemistry. Autoradiography revealed that both des-acyl ghrelin and acyl ghrelin bind to fetal tissues. Chronic treatment of mothers with ghrelin resulted in a significant increase in birth weight in comparison to newborns from saline-treated mothers. Even when maternal food intake after ghrelin treatment was restricted through paired feeding, significant stimulation of fetal development still occurred. Conversely, active immunization of mothers against ghrelin decreased fetal body weight during pregnancy. A single ghrelin injection into the mother increased circulating ghrelin levels in the fetus within 5 min of injection, suggesting that maternal ghrelin transits easily to the fetal circulation. High levels of des-acyl ghrelin were detected in fetal blood and amniotic fluid. Both acylated and des-acyl ghrelin increased [3H]thymidine and 5-bromo-2'-deoxyuridine incorporation of cultured fetal skin cells in a dose-dependent manner, and calcium-imaging analysis revealed that acyl and des-acyl ghrelin increased the Ca2+ influx in discrete cultured fetal skin cells, respectively. These results indicate that maternal ghrelin regulates fetal development during the late stages of pregnancy.