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1.
Chem Biol Interact ; 328: 109144, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32653415

RESUMO

The debilitating nature of cognitive impairment in epilepsy and the potential of some traditional antiepileptics to further deteriorate cognitive function are areas of growing concern. Glucagon-like peptide-1 (GLP-1) deficiency has been linked to reduced seizure threshold as well as cognitive dysfunction. Here, we tested whether sitagliptin (SITA), by virtue of its neuroprotective properties, could alleviate both epilepsy and associated cognitive dysfunction in a rat model of kindling epilepsy. Chemical kindling was induced by subconvulsive doses of pentylenetetrazol (PTZ) (30 mg/kg; i.p). SITA (50 mg/kg; p.o) was administered 1 h before PTZ injections. SITA conceivably attenuated PTZ hippocampal histological insult, preserved neuronal integrity and amended neurotransmitter perturbations in rat hippocampi paralleled with enhanced hippocampal GLP-1 levels as well as the downstream cAMP content and protein kinase A (PKA) activity. Moreover, SITA improved cognitive functioning of rats in the Morris water maze which was coupled with hampered hippocampal p(Ser404)-tau and ß-amyloid proteins. SITA replenished p(Ser9)-glycogen synthase kinase-3ß (GSK-3ß). It also opposed the boosted matrix metalloproteinase-9 (MMP-9), brain-derived neurotrophic factor (BDNF), and insulin-like growth factor-1 (IGF-1) levels associated with PTZ administration along with mitigation of both ß-secretase-1 (BACE1) immunoreactivity and receptor for advanced glycation end products (RAGE) protein level in rat hippocampi. In conclusion, SITA subdues epileptic and cognitive upshots of PTZ kindling in rats, which might correspond to the modulation of BACE1, amyloidogenic/RAGE axis as well as GSK-3ß/MMP-9/BDNF signaling cascade. SITA effects are probably mediated via boosting GLP-1 and subsequently enhancing GLP-1/GLP-1R signaling.


Assuntos
Secretases da Proteína Precursora do Amiloide/metabolismo , Amiloide/metabolismo , Ácido Aspártico Endopeptidases/metabolismo , Transtornos Cognitivos/induzido quimicamente , Transtornos Cognitivos/metabolismo , Excitação Neurológica/efeitos dos fármacos , Receptor para Produtos Finais de Glicação Avançada/metabolismo , Transdução de Sinais , Fosfato de Sitagliptina/farmacologia , Peptídeos beta-Amiloides/metabolismo , Animais , Biomarcadores/metabolismo , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Transtornos Cognitivos/patologia , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Glicogênio Sintase Quinase 3 beta/metabolismo , Hipocampo/efeitos dos fármacos , Hipocampo/patologia , Fator de Crescimento Insulin-Like I/metabolismo , Masculino , Metaloproteinase 9 da Matriz/metabolismo , Inibição Neural/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Neurônios/patologia , Neurotransmissores/metabolismo , Pentilenotetrazol , Ratos Wistar , Convulsões/induzido quimicamente , Convulsões/metabolismo , Convulsões/patologia , Transdução de Sinais/efeitos dos fármacos , Memória Espacial/efeitos dos fármacos , Proteínas tau/metabolismo
2.
DNA Cell Biol ; 39(9): 1700-1710, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32721233

RESUMO

The increased secretion of glucagon-like peptide-1 (GLP-1) after Roux-en-Y gastric bypass (RYGB) is regarded as the main reason for the improvement of blood glucose. However, the single-nucleotide polymorphisms (SNPs) of GLP-1 Receptor (GLP1R) impair receptor function, subsequently affecting ß cell insulin secretion function, ultimately affecting the efficacy of RYGB. In this study, we revealed that two SNPs in GLP1R gene, rs3765467 and rs10305492, could significantly reduce the insulin secreted by ß cells and the cyclic AMP concentration, whereas promote ß cell apoptosis. Under high glucose exposure, rs3765467 and rs10305492 impaired ß cell secretion of insulin and ß cell viability in the same way; in other words, GLP1R rs3765467 and rs10305492 exert an effect on pancreatic ß cell glucose-stimulated insulin secretion. Moreover, GLP-1 antagonist Exendin (9-39) further enhanced, whereas GLP-1 agonist Exendin-4 partially attenuated the effects of SNPs on the functions and apoptosis of ß cells. In conclusion, the rs3765467 and rs10305492 SNPs in GLP1R show to exert a critical effect on regulating insulin secretory capacity of ß cells and ß cell mass. Through leading to the dysfunction and apoptosis of ß cells, GLP1R rs3765467 and rs10305492 might also impair GLP-1 interaction with GLP1R, therefore attenuating the therapeutic effect of RYGB.


Assuntos
Apoptose , Receptor do Peptídeo Semelhante ao Glucagon 1/genética , Secreção de Insulina , Células Secretoras de Insulina/metabolismo , Polimorfismo de Nucleotídeo Único , Animais , Linhagem Celular , Células Cultivadas , Exenatida/farmacologia , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Receptor do Peptídeo Semelhante ao Glucagon 1/metabolismo , Glucose/metabolismo , Glucose/farmacologia , Humanos , Células Secretoras de Insulina/efeitos dos fármacos , Camundongos , Mutação , Ratos
3.
Metabolism ; 109: 154290, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32522488

RESUMO

BACKGROUND: Males absent on the first (Mof) is implicated in gene control of diverse biological processes, such as cell growth, differentiation, apoptosis and autophagy. However, the relationship between glucose regulation and Mof-mediated transcription events remains unexplored. We aimed to unravel the role of Mof in glucose regulation by using global and pancreatic α-cell-specific Mof-deficient mice in vivo and α-TC1-6 cell line in vitro. METHODS: We used tamoxifen-induced temporal Mof-deficient mice first to show Mof regulate glucose homeostasis, islet cell proportions and hormone secretion. Then we used α-cell-specific Mof-deficient mice to clarify how α-cell subsets and ß-cell mass were regulated and corresponding hormone level alterations. Ultimately, we used small interfering RNA (siRNA) to knockdown Mof in α-TC1-6 and unravel the mechanism regulating α-cell mass and glucagon secretion. RESULTS: Mof was mainly expressed in α-cells. Global Mof deficiency led to lower glucose levels, attributed by decreased α/ß-cell ratio and glucagon secretion. α-cell-specific Mof-deficient mice exhibited similar alterations, with more reduced prohormone convertase 2 (PC2)-positive α-cell mass, responsible for less glucagon, and enhanced prohormone convertase 1 (PC1/3)-positive α-cell mass, leading to more glucagon-like peptide-1 (GLP-1) secretion, thus increased ß-cell mass and insulin secretion. In vitro, increased DNA damage, dysregulated autophagy, enhanced apoptosis and altered cell fate factors expressions upon Mof knockdown were observed. Genes and pathways linked to impaired glucagon secretion were uncovered through transcriptome sequencing. CONCLUSION: Mof is a potential interventional target for glucose regulation, from the aspects of both α-cell subset mass and glucagon, intra-islet GLP-1 secretion. Upon Mof deficiency, Up-regulated PC1/3 but down-regulated PC2-positive α-cell mass, leads to more GLP-1 and insulin but less glucagon secretion, and contributed to lower glucose level.


Assuntos
Glicemia/metabolismo , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Células Secretoras de Glucagon/citologia , Glucagon/metabolismo , Histona Acetiltransferases/fisiologia , Homeostase , Animais , Linhagem Celular , Histona Acetiltransferases/deficiência , Insulina/metabolismo , Ilhotas Pancreáticas/metabolismo , Camundongos , Pró-Proteína Convertase 1/metabolismo , Pró-Proteína Convertase 2/metabolismo
4.
Life Sci ; 254: 117752, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32387412

RESUMO

AIMS: To design and evaluate novel mono-PEGylated dimeric GLP-1 conjugate with enhanced GLP-1 receptor activation and prolonged anti-diabetes efficacies. MAIN METHODS: All these novel GLP-1 conjugates were produced by using solid-phase synthesis method and further specific cysteine-maleimide modification. In vitro GLP-1R activation assay was performed in CHO cells stably expressing human GLP-1 receptor. The binding affinity for human serum albumin (HSA) in vitro was also conducted using surface plasmon resonance measurement. Subsequently, selected GLP-1 conjugate was subjected to evaluate the acute and chronic efficacies in vivo. KEY FINDINGS: Four novel glucagon-like peptide-1 (GLP-1) conjugates, termed DIG-1 to DIG-4, were designed and prepared with high purity. Moreover, DIG-1(PEG-5 kDa) and DIG-2 (PEG-10 kDa) exerted ~3-fold and ~2-fold higher potencies of GLP-1R activation than native GLP-1, respectively, and both obviously higher than the DIG-3 (PEG-10 kDa) and DIG-4 (PEG-30 kDa). Then DIG-2 exhibited better in vivo glucose-stabilizing and insulinotropic efficacies than DIG-1 by using multiple oral glucose tests (OGTTs) in SD rats. Furthermore, prolonged glucose-lowering ability of DIG-2 exhibited in hypoglycemic duration test and multiple OGTTs in diabetic db/db mice. Pharmacokinetic data of DIG-2 in cynomolgus monkeys revealed a half-life of ~97.2 h and ~120.4 h after a single subcutaneous (s.c.) administration at doses of 100 and 150 nmol/kg, respectively. Chronic treatment of DIG-2 in db/db mice for consecutive 8-week significantly ameliorate the diabetic symptoms including deteriorative % hemoglobin A1C (HbA1C), glucose tolerance and pancreatic function. SIGNIFICANCE: DIG-2, as a novel mono-PEGylated dimeric GLP-1 conjugate, holds enhanced receptor activation and prolonged anti-diabetes efficacies.


Assuntos
Diabetes Mellitus Experimental/metabolismo , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Hipoglicemiantes/uso terapêutico , Polietilenoglicóis/metabolismo , Animais , Células CHO , Cricetulus , Dimerização , Humanos , Ratos
5.
Am J Physiol Gastrointest Liver Physiol ; 319(1): G23-G35, 2020 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-32421358

RESUMO

Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are released from enteroendocrine cells (EECs) in response to nutrient ingestion and lower blood glucose levels by stimulation of insulin secretion and thus are defined as incretins. GLP-1 receptor (GLP-1R) expression has been identified on enteric neurons that include intrinsic afferent neurons, extrinsic spinal, and vagal sensory afferents but has not been shown to have an incretin effect through these nerves. GLP-1 and GIP enter the mesenteric lymphatic fluid (MLF) after a meal via the interstitial fluid (IF) from local tissue secretion and/or blood capillaries. We tested if MLF could induce diet-dependent intransient increases in intracellular calcium ([Ca2+]i) in cultured sensory neurons. Postprandial rat MLF, collected from the superior mesenteric lymphatic duct, induced a significant twofold higher intransient increase in [Ca2+]i in primary-cultured sensory neurons than MLF from fasted rats. Inhibition of transient receptor potential vanilloid 1 (TRPV1) and TRPV1 and ankyrin 1 cation channels (TRPA1) with ruthenium red eliminated the difference. Substance P (SP) (a peptide that stimulates insulin secretion) sensor cells cocultured with sensory neurons showed both the GLP-1R agonist exendin-4 (Ex-4) and GIP induced transient increases in [Ca2+]i directly coupled to SP secretion in the sensory nerves. Ex-4-induced release of SP required expression of either TRPA1 or TRPV1. These data identify unrecognized actions of GLP-1 and GIP as incretins by acting as neurolymphocrines and suggest a mechanism for sensory nerves to respond to the postprandial state through MLF.NEW & NOTEWORTHY Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are secreted upon eating to lower blood sugar. GLP-1 and GIP were found to induce the secretion of substance P (SP) from cultured sensory nerves. SP enhances insulin secretion. Mesenteric lymphatic fluid (MLF) also stimulates sensory neurons in a diet-dependent manner. These studies identify new actions of GLP-1 and GIP as incretins and suggest a mechanism for sensory nerves to respond to diet through MLF.


Assuntos
Polipeptídeo Inibidor Gástrico/metabolismo , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Glucose/metabolismo , Substância P/metabolismo , Canal de Cátion TRPA1/metabolismo , Animais , Glicemia/metabolismo , Células Enteroendócrinas/metabolismo , Receptor do Peptídeo Semelhante ao Glucagon 1/metabolismo , Incretinas/metabolismo , Período Pós-Prandial , Ratos , Receptores dos Hormônios Gastrointestinais
6.
Am J Physiol Gastrointest Liver Physiol ; 319(1): G36-G42, 2020 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-32463335

RESUMO

After 50% proximal small bowel resection (SBR) in mice, we have demonstrated hepatic steatosis, impaired glucose metabolism without insulin resistance, and increased pancreatic islet area. We sought to determine the consequences of SBR on pancreatic ß-cell morphology, proliferation, and expression of a key regulatory hormone, glucagon-like peptide-1 (GLP-1). C57BL/6 mice underwent 50% SBR or sham operation. At 10 wk, pancreatic insulin content and secretion was measured by ELISA. Immunohistochemistry was performed to determine structural alterations in pancreatic α-and ß-cells. Western blot analysis was used to measure GLP-1R expression, and immunoassay was used to measure plasma insulin and GLP-1. Experiments were repeated by administering a GLP-1 agonist (exendin-4) to a cohort of mice following SBR. After SBR, there was pancreatic islet hypertrophy and impaired glucose tolerance. The proportion of α and ß cells was not grossly altered. Whole pancreas and pancreatic islet insulin content was not significantly different; however, SBR mice demonstrated decreased insulin secretion in both static incubation and islet perfusion experiments. The expression of pancreatic GLP-1R was decreased approximately twofold after SBR, compared with sham and serum GLP-1, was decreased. These metabolic derangements were mitigated after administration of the GLP-1 agonist. Following massive SBR, there is significant hypertrophy of pancreatic islet cells with morphologically intact α- and ß-cells. Significantly reduced pancreatic insulin release in both static and dynamic conditions demonstrate a perturbed second phase of insulin secretion. GLP-1 is a key mediator of this amplification pathway. Decreased expression of serum GLP-1 and pancreatic GLP-1R in face of no change in insulin content presents a novel pathway for enteropancreatic glucose regulation following SBR.NEW & NOTEWORTHY Metabolic changes occur following intestinal resection; however, the effects on pancreatic function are unknown. Prior studies have demonstrated that glucagon-like protein-1 (GLP-1) signaling is a crucial player in the improved insulin sensitivity after bariatric surgery. In this study, we explore the effect of massive small bowel resection on gut hormone physiology and provide novel insights into the enteropancreatic axis.


Assuntos
Peptídeo 1 Semelhante ao Glucagon/metabolismo , Intestinos/lesões , Ilhotas Pancreáticas/metabolismo , Pâncreas/metabolismo , Animais , Glucagon/metabolismo , Receptor do Peptídeo Semelhante ao Glucagon 1/metabolismo , Insulina/sangue , Células Secretoras de Insulina/metabolismo , Camundongos Endogâmicos C57BL , Pâncreas Exócrino/metabolismo
7.
Clin Sci (Lond) ; 134(9): 1081-1094, 2020 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-32352510

RESUMO

The relationship between disturbances in glucose homeostasis and heart failure (HF) progression is bidirectional. However, the mechanisms by which HF intrinsically impairs glucose homeostasis remain unknown. The present study tested the hypothesis that the bioavailability of intact glucagon-like peptide-1 (GLP-1) is affected in HF, possibly contributing to disturbed glucose homeostasis. Serum concentrations of total and intact GLP-1 and insulin were measured after an overnight fast and 15 min after the ingestion of a mixed breakfast meal in 49 non-diabetic patients with severe HF and 40 healthy control subjects. Similarly, fasting and postprandial serum concentrations of these hormones were determined in sham-operated rats, and rats with HF treated with an inhibitor of the GLP-1-degrading enzyme dipeptidyl peptidase-4 (DPP4), vildagliptin, or vehicle for 4 weeks. We found that HF patients displayed a much lower increase in postprandial intact and total GLP-1 levels than controls. The increase in postprandial intact GLP-1 in HF patients correlated negatively with serum brain natriuretic peptide levels and DPP4 activity and positively with the glomerular filtration rate. Likewise, the postprandial increases in both intact and total GLP-1 were blunted in HF rats and were restored by DPP4 inhibition. Additionally, vehicle-treated HF rats displayed glucose intolerance and hyperinsulinemia, whereas normal glucose homeostasis was observed in vildagliptin-treated HF rats. We conclude that the postprandial increase in GLP-1 is blunted in non-diabetic HF. Impaired GLP-1 bioavailability after meal intake correlates with poor prognostic factors and may contribute to the establishment of a vicious cycle between glucose disturbance and HF development and progression.


Assuntos
Glicemia/metabolismo , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Insuficiência Cardíaca/etiologia , Período Pós-Prandial/fisiologia , Idoso , Animais , Peptídeo C/sangue , Feminino , Intolerância à Glucose/fisiopatologia , Insuficiência Cardíaca/fisiopatologia , Humanos , Insulina/sangue , Masculino , Pessoa de Meia-Idade , Obesidade/metabolismo , Obesidade/fisiopatologia , Fragmentos de Peptídeos/sangue , Ratos Wistar
8.
Food Chem ; 324: 126857, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32344342

RESUMO

Glucagon-like peptide-1 (GLP-1) is an important signal in the peripheral and neural systems, which contributes to the maintenance of glucose and energy homeostasis. In this study, 1H NMR validated polyphenols and polysaccharides extracted from sprouted quinoa yoghurt were used as isolates and conjugates to upregulate the stimulation of GLP-1 release in NCI-H716 cells. In addition, we explored their effect on proglucagon and prohormone convertase 3 mRNA expressions, HNF-3γ and CCK-2R gene protein expression, as well as cytosolic calcium release. Variations in concentration showed a dose-dependent GLP-1 stimulation, and were significantly optimized by germination. Proglucagon mRNA expression in NCI-H716 cells was upregulated, and was relatively highest with QYPSP1 treatments in a 2.68 fold. The results suggested that the conjugates had greater potential to stimulate GLP-1 release than their isolates. Sprouted quinoa yoghurt could therefore be a potential functional food useful to regulate glucose and energy homeostasis.


Assuntos
Chenopodium quinoa/química , Inibidores da Dipeptidil Peptidase IV/química , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Polifenóis/química , Polissacarídeos/química , Iogurte/análise , Cálcio/metabolismo , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Chenopodium quinoa/crescimento & desenvolvimento , Chenopodium quinoa/metabolismo , Cromatografia Líquida de Alta Pressão , Inibidores da Dipeptidil Peptidase IV/metabolismo , Inibidores da Dipeptidil Peptidase IV/farmacologia , Germinação , Humanos , Polifenóis/análise , Polifenóis/isolamento & purificação , Polissacarídeos/análise , Polissacarídeos/isolamento & purificação , Proglucagon/antagonistas & inibidores , Proglucagon/genética , Proglucagon/metabolismo , Pró-Proteína Convertase 1/antagonistas & inibidores , Pró-Proteína Convertase 1/genética , Pró-Proteína Convertase 1/metabolismo
9.
PLoS One ; 15(4): e0231543, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32282828

RESUMO

Dipeptidyl peptidase-4 (DPP-4) is a proteolytic enzyme responsible for the rapid degradation of Glucagon-like peptide 1 (GLP-1) that is required for the secretion of insulin. DPP-4 also influences activation of node like receptor family, pyrin domain containing 3 (NLRP3) inflammasome under diabetic conditions. Although several polyphenols are reported for various bioactivities, they are consumed as part of the food matrix and not in isolation. Horsegram (Macrotyloma uniflorum) is a rich source of myricetin (Myr) (35 µg/g flour), reported for its anti-hyperglycemic effect. In this investigation, we aimed to study the effect of Myr, singly, and in the presence of co-nutrient horsegram protein (HP) on DPP-4 activity and its consequential impact on GLP-1, insulin, and NLRP3 inflammasome in high-fat diet and single low dose streptozotocin (STZ)-induced diabetic male Wistar rats. In diabetic control (DC), the activity of DPP-4 and its expression were higher compared to treated groups. The consequential decrease in the circulating GLP-1 levels in the DC group, but not treated groups, further indicated the effectiveness of our test molecules under diabetic conditions. Specifically, Myr decreased DPP-4 activity and its expression levels with enhanced circulating GLP-1 and insulin levels. Myr administration also resulted in a lessening of diabetes-induced NLRP3 inflammasome activation and enhanced antioxidant enzyme activities. HP also proved to be efficient in reducing elevated blood glucose levels and enhancing antioxidant enzyme activities. However, Myr, in the presence of HP as a co-nutrient, had diminished capacity to inhibit DPP-4 and, consequently, reduced potential in ameliorating diabetic conditions. Myr proved to be a potent inhibitor of DPP-4 in vitro and in vivo, resulting in enhanced circulating GLP-1 and insulin levels, thereby improving diabetic conditions. Though Myr and HP, individually ameliorate diabetic conditions, their dietary combination had reduced efficiency.


Assuntos
Diabetes Mellitus Experimental/terapia , Dipeptidil Peptidase 4/metabolismo , Flavonoides/administração & dosagem , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Hipoglicemiantes/administração & dosagem , Proteínas de Plantas/administração & dosagem , Animais , Antioxidantes/metabolismo , Glicemia , Diabetes Mellitus Experimental/metabolismo , Fabaceae , Feminino , Flavonoides/metabolismo , Inflamassomos/metabolismo , Insulina/sangue , Fígado/enzimologia , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Estresse Oxidativo , Proteínas de Plantas/metabolismo , Gravidez , Ratos Wistar
10.
Am J Physiol Gastrointest Liver Physiol ; 318(5): G980-G987, 2020 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-32308039

RESUMO

Glucagon-like peptide (GLP)-1 and -2-secreting L cells have been shown to express the bile acid receptor Takeda G protein-receptor-5 (TGR5) and increase secretion upon receptor activation. Previous studies have explored GLP-1 secretion following acute TGR5 activation, but chronic activation and GLP-2 responses have not been characterized. In this study, we aimed to investigate the consequences of pharmacological TGR5 receptor activation on L cell hormone production in vivo using the specific TGR5 agonist RO5527239 and the GLP-2 receptor knockout mouse. Here, we show that 1) TGR5 receptor activation led to increased GLP-1 and GLP-2 content in the colon, which 2) was associated with an increased small intestinal weight that 3) was GLP-2 dependent. Additionally, we report that TGR5-mediated gallbladder filling occurred independently of GLP-2 signaling. In conclusion, we demonstrate that pharmacological TGR5 receptor activation stimulates L cells, triggering GLP-2-dependent intestinal adaption in mice.NEW & NOTEWORTHY Using the specific Takeda G protein-receptor-5 (TGR5) agonist RO5527239 and GLP-2 receptor knockout mice, we show that activation of TGR5 led to the increase in colonic GLP-1 and GLP-2 concomitant with a GLP-2 dependent growth response in the proximal portion of the small intestine.


Assuntos
Proliferação de Células/efeitos dos fármacos , Células Enteroendócrinas/efeitos dos fármacos , Peptídeo 2 Semelhante ao Glucagon/metabolismo , Intestino Delgado/efeitos dos fármacos , Ácidos Isonipecóticos/farmacologia , Oximas/farmacologia , Receptores Acoplados a Proteínas-G/agonistas , Animais , Colo/efeitos dos fármacos , Colo/crescimento & desenvolvimento , Colo/metabolismo , Células Enteroendócrinas/metabolismo , Feminino , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Receptor do Peptídeo Semelhante ao Glucagon 2/genética , Receptor do Peptídeo Semelhante ao Glucagon 2/metabolismo , Intestino Delgado/crescimento & desenvolvimento , Intestino Delgado/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores Acoplados a Proteínas-G/metabolismo , Transdução de Sinais
11.
J Pharmacol Sci ; 143(2): 65-73, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32229084

RESUMO

Glucagon-like peptide 1 (GLP-1) released from enteroendocrine (L) cells regulates insulin secretion. Intestinal inflammation and impaired GLP-1 release have been found in type 2 diabetes mellitus (T2DM) patients. Fructo-oligosaccharides (FOS), a known prebiotic, improve GLP-1 release and glucose homeostasis in T2DM models. This study aimed to investigate the effect of tumor necrosis factor-α (TNF-α), a proinflammatory cytokine associated with intestinal inflammation in T2DM, on L cell apoptosis and the effect of FOS on inflammation-associated impairment of GLP-1 secretion. Herein, using cell death assays, immunofluorescence staining, real time PCR and Western blot analyses, we found that TNF-α induced L cell apoptosis via nuclear factor kappa B (NF-κB)- inducible nitric oxide synthase (iNOS)-cleaved caspase-3-dependent pathways. Interestingly, FOS did not suppress TNF-α-induced NF-κB nuclear translocation, but inhibited expression of iNOS and cleaved caspase-3. In addition, FOS alleviated apoptosis and rescued impaired GLP-1 release in TNF-α-treated L cells. Altogether, our data indicate that TNF-α induces L cell apoptosis via an NF-κB-iNOS-caspase-3-dependent pathway. FOS may be useful in suppressing inflammation-associated L cell apoptosis and maintaining GLP-1 level in T2DM patients.


Assuntos
Apoptose/efeitos dos fármacos , Caspase 3/genética , Caspase 3/metabolismo , Células Enteroendócrinas/metabolismo , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Óxido Nítrico Sintase Tipo II/genética , Óxido Nítrico Sintase Tipo II/metabolismo , Oligossacarídeos/farmacologia , Apoptose/genética , Diabetes Mellitus Tipo 2/metabolismo , Humanos , Inflamação , NF-kappa B/metabolismo , Transdução de Sinais/efeitos dos fármacos , Fator de Necrose Tumoral alfa/metabolismo
12.
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
13.
PLoS Genet ; 16(3): e1008650, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32196486

RESUMO

Stem cell systems are essential for the development and maintenance of polarized tissues. Intercellular signaling pathways control stem cell systems, where niche cells signal stem cells to maintain the stem cell fate/self-renewal and inhibit differentiation. In the C. elegans germline, GLP-1 Notch signaling specifies the stem cell fate, employing the sequence-specific DNA binding protein LAG-1 to implement the transcriptional response. We undertook a comprehensive genome-wide approach to identify transcriptional targets of GLP-1 signaling. We expected primary response target genes to be evident at the intersection of genes identified as directly bound by LAG-1, from ChIP-seq experiments, with genes identified as requiring GLP-1 signaling for RNA accumulation, from RNA-seq analysis. Furthermore, we performed a time-course transcriptomics analysis following auxin inducible degradation of LAG-1 to distinguish between genes whose RNA level was a primary or secondary response of GLP-1 signaling. Surprisingly, only lst-1 and sygl-1, the two known target genes of GLP-1 in the germline, fulfilled these criteria, indicating that these two genes are the primary response targets of GLP-1 Notch and may be the sole germline GLP-1 signaling protein-coding transcriptional targets for mediating the stem cell fate. In addition, three secondary response genes were identified based on their timing following loss of LAG-1, their lack of a LAG-1 ChIP-seq peak and that their glp-1 dependent mRNA accumulation could be explained by a requirement for lst-1 and sygl-1 activity. Moreover, our analysis also suggests that the function of the primary response genes lst-1 and sygl-1 can account for the glp-1 dependent peak protein accumulation of FBF-2, which promotes the stem cell fate and, in part, for the spatial restriction of elevated LAG-1 accumulation to the stem cell region.


Assuntos
Células-Tronco Germinativas Adultas/metabolismo , Proteínas de Caenorhabditis elegans/metabolismo , Proteínas de Ligação a DNA/metabolismo , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Receptores Notch/metabolismo , Células-Tronco Germinativas Adultas/citologia , Animais , Caenorhabditis elegans , Proteínas de Caenorhabditis elegans/genética , Diferenciação Celular/fisiologia , Linhagem da Célula , Proteínas de Ligação a DNA/genética , Células Germinativas/metabolismo , Peptídeo 1 Semelhante ao Glucagon/genética , RNA/metabolismo , RNA Mensageiro/metabolismo , Receptores Notch/genética , Transdução de Sinais , Células-Tronco/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
14.
Endocrinology ; 161(4)2020 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-32166324

RESUMO

Genetic research has revealed pro-opiomelanocortin (POMC) to be a fundamental regulator of energy balance and body weight in mammals. Within the brain, POMC is primarily expressed in the arcuate nucleus of the hypothalamus (ARC), while a smaller population exists in the brainstem nucleus of the solitary tract (POMCNTS). We performed a neurochemical characterization of this understudied population of POMC cells using transgenic mice expressing green fluorescent protein (eGFP) under the control of a POMC promoter/enhancer (PomceGFP). Expression of endogenous Pomc mRNA in the nucleus of the solitary tract (NTS) PomceGFP cells was confirmed using fluorescence-activating cell sorting (FACS) followed by quantitative PCR. In situ hybridization histochemistry of endogenous Pomc mRNA and immunohistochemical analysis of eGFP revealed that POMC is primarily localized within the caudal NTS. Neurochemical analysis indicated that POMCNTS is not co-expressed with tyrosine hydroxylase (TH), glucagon-like peptide 1 (GLP-1), cholecystokinin (CCK), brain-derived neurotrophic factor (BDNF), nesfatin, nitric oxide synthase 1 (nNOS), seipin, or choline acetyltransferase (ChAT) cells, whereas 100% of POMCNTS is co-expressed with transcription factor paired-like homeobox2b (Phox2b). We observed that 20% of POMCNTS cells express receptors for adipocyte hormone leptin (LepRbs) using a PomceGFP:LepRbCre:tdTOM double-reporter line. Elevations in endogenous or exogenous leptin levels increased the in vivo activity (c-FOS) of a small subset of POMCNTS cells. Using ex vivo slice electrophysiology, we observed that this effect of leptin on POMCNTS cell activity is postsynaptic. These findings reveal that a subset of POMCNTS cells are responsive to both changes in energy status and the adipocyte hormone leptin, findings of relevance to the neurobiology of obesity.


Assuntos
Tronco Encefálico/metabolismo , Neurônios/metabolismo , Pró-Opiomelanocortina/metabolismo , Receptores para Leptina/metabolismo , Animais , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Colecistocinina/metabolismo , Colina O-Acetiltransferase/metabolismo , Subunidades gama da Proteína de Ligação ao GTP/metabolismo , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Camundongos , Camundongos Transgênicos , Óxido Nítrico Sintase Tipo I/metabolismo , Nucleobindinas/metabolismo , Regiões Promotoras Genéticas , Receptores para Leptina/genética , Tirosina 3-Mono-Oxigenase/metabolismo
15.
Diabetes ; 69(4): 614-623, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32041793

RESUMO

Glucagon-like peptide 1 (GLP-1) mimetics are effective drugs for treatment of type 2 diabetes, and there is consequently extensive interest in increasing endogenous GLP-1 secretion and L-cell abundance. Here we identify G-protein-coupled bile acid receptor 1 (GPBAR1) as a selective regulator of intestinal L-cell differentiation. Lithocholic acid and the synthetic GPBAR1 agonist, L3740, selectively increased L-cell density in mouse and human intestinal organoids and elevated GLP-1 secretory capacity. L3740 induced expression of Gcg and transcription factors Ngn3 and NeuroD1 L3740 also increased the L-cell number and GLP-1 levels and improved glucose tolerance in vivo. Further mechanistic examination revealed that the effect of L3740 on L cells required intact GLP-1 receptor and serotonin 5-hydroxytryptamine receptor 4 (5-HT4) signaling. Importantly, serotonin signaling through 5-HT4 mimicked the effects of L3740, acting downstream of GLP-1. Thus, GPBAR1 agonists and other powerful GLP-1 secretagogues facilitate L-cell differentiation through a paracrine GLP-1-dependent and serotonin-mediated mechanism.


Assuntos
Ácidos e Sais Biliares/farmacologia , Diferenciação Celular/efeitos dos fármacos , Células Enteroendócrinas/efeitos dos fármacos , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Comunicação Parácrina/fisiologia , Receptores Acoplados a Proteínas-G/metabolismo , Serotonina/metabolismo , Animais , Células Enteroendócrinas/fisiologia , Feminino , Receptor do Peptídeo Semelhante ao Glucagon 1/metabolismo , Humanos , Jejuno/efeitos dos fármacos , Jejuno/metabolismo , Masculino , Camundongos , Comunicação Parácrina/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos
16.
J Mol Biol ; 432(5): 1367-1394, 2020 03 06.
Artigo em Inglês | MEDLINE | ID: mdl-31954131

RESUMO

Pancreatic α-cells are the major source of glucagon, a hormone that counteracts the hypoglycemic action of insulin and strongly contributes to the correction of acute hypoglycemia. The mechanisms by which glucose controls glucagon secretion are hotly debated, and it is still unclear to what extent this control results from a direct action of glucose on α-cells or is indirectly mediated by ß- and/or δ-cells. Besides its hyperglycemic action, glucagon has many other effects, in particular on lipid and amino acid metabolism. Counterintuitively, glucagon seems also required for an optimal insulin secretion in response to glucose by acting on its cognate receptor and, even more importantly, on GLP-1 receptors. Patients with diabetes mellitus display two main alterations of glucagon secretion: a relative hyperglucagonemia that aggravates hyperglycemia, and an impaired glucagon response to hypoglycemia. Under metabolic stress states, such as diabetes, pancreatic α-cells also secrete GLP-1, a glucose-lowering hormone, whereas the gut can produce glucagon. The contribution of extrapancreatic glucagon to the abnormal glucose homeostasis is unclear. Here, I review the possible mechanisms of control of glucagon secretion and the role of α-cells on islet function in healthy state. I discuss the possible causes of the abnormal glucagonemia in diabetes, with particular emphasis on type 2 diabetes, and I briefly comment the current antidiabetic therapies affecting α-cells.


Assuntos
Diabetes Mellitus Tipo 2/metabolismo , Células Secretoras de Glucagon/metabolismo , Glucagon/metabolismo , Animais , Diabetes Mellitus Tipo 2/terapia , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Receptor do Peptídeo Semelhante ao Glucagon 1/metabolismo , Glucose/metabolismo , Humanos , Hipoglicemia/fisiopatologia , Hipoglicemia/terapia , Insulina/metabolismo
17.
Endocrinology ; 161(2)2020 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-31905402

RESUMO

Characterization of enteroendocrine L cells in diabetes is critical for better understanding of the role of glucagon-like peptide-1 (GLP-1) in physiology and diabetes. We studied L-cell transcriptome changes including microRNA (miRNA) dysregulation in obesity and diabetes. We evaluated the regulation of miRNAs through microarray analyses on sorted enteroendocrine L cells from control and obese glucose-intolerant (I-HFD) and hyperglycemic (H-HFD) mice after 16 weeks of respectively low-fat diet (LFD) or high-fat diet (HFD) feeding. The identified altered miRNAs were studied in vitro using the mouse GLUTag cell line to investigate their regulation and potential biological functions. We identified that let-7e-5p, miR-126a-3p, and miR-125a-5p were differentially regulated in L cells of obese HFD mice compared with control LFD mice. While downregulation of let-7e-5p expression was observed in both I-HFD and H-HFD mice, levels of miR-126a-3p increased and of miR-125a-5p decreased significantly only in I-HFD mice compared with controls. Using miRNA inhibitors and mimics we observed that modulation of let-7e-5p expression affected specifically GLP-1 cellular content and basal release, whereas Gcg gene expression and acute GLP-1 secretion and cell proliferation were not affected. In addition, palmitate treatment resulted in a decrease of let-7e-5p expression along with an increase in GLP-1 content and release, suggesting that palmitate acts on GLP-1 through let-7e-5p. By contrast, modulation of miR-125a-5p and miR-126a-3p in the same conditions did not affect content or secretion of GLP-1. We conclude that decrease of let-7e-5p expression in response to palmitate may constitute a compensatory mechanism contributing to maintaining constant glycemia in obese mice.


Assuntos
Células Enteroendócrinas/metabolismo , Peptídeo 1 Semelhante ao Glucagon/metabolismo , MicroRNAs/metabolismo , Obesidade/metabolismo , Animais , Linhagem Celular , Dieta Hiperlipídica , Masculino , Camundongos Transgênicos , Palmitatos
18.
Arterioscler Thromb Vasc Biol ; 40(3): e65-e77, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31893947

RESUMO

OBJECTIVE: In patients with diabetes mellitus, increased platelet reactivity predicts cardiac events. Limited evidence suggests that DPP-4 (dipeptidyl peptidase 4) influences platelets via GLP-1 (glucagon-like peptide 1)-dependent effects. Because DPP-4 inhibitors are frequently used in diabetes mellitus to improve the GLP-1-regulated glucose metabolism, we characterized the role of DPP-4 inhibition and of native intact versus DPP-4-cleaved GLP-1 on flow-dependent thrombus formation in mouse and human blood. Approach and Results: An ex vivo whole blood microfluidics model was applied to approach in vivo thrombosis and study collagen-dependent platelet adhesion, activation, and thrombus formation under shear-flow conditions by multiparameter analyses. In mice, in vivo inhibition or genetic deficiency of DPP-4 (Dpp4-/-), but not of GLP-1-receptors (Glp1r-/-), suppressed flow-dependent platelet aggregation. In human blood, GLP-1(7-36), but not DPP-4-cleaved GLP-1(9-36), reduced thrombus volume by 32% and impaired whole blood thrombus formation at both low/venous and high/arterial wall-shear rates. These effects were enforced upon ADP costimulation and occurred independently of plasma factors and leukocytes. Human platelets did not contain detectable levels of GLP-1-receptor transcripts. Also, GLP-1(7-36) did not inhibit collagen-induced aggregation under conditions of stirring or stasis of platelets, pointing to a marked flow-dependent role. CONCLUSIONS: Native, intact GLP-1 is a natural suppressor of thrombus growth under physiological flow conditions, with DPP-4 inhibition and increased intact GLP-1 suppressing platelet aggregation under flow without a main relevance of GLP-1-receptor on platelets.


Assuntos
Plaquetas/efeitos dos fármacos , Dipeptidil Peptidase 4/metabolismo , Inibidores da Dipeptidil Peptidase IV/farmacologia , Fibrinolíticos/farmacologia , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Linagliptina/farmacologia , Fosfato de Sitagliptina/farmacologia , Trombose/prevenção & controle , Animais , Plaquetas/metabolismo , Dipeptidil Peptidase 4/genética , Peptídeo 1 Semelhante ao Glucagon/análogos & derivados , Receptor do Peptídeo Semelhante ao Glucagon 1/genética , Receptor do Peptídeo Semelhante ao Glucagon 1/metabolismo , Humanos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fragmentos de Peptídeos/metabolismo , Agregação Plaquetária/efeitos dos fármacos , Transdução de Sinais , Trombose/enzimologia , Trombose/genética
19.
Am J Physiol Endocrinol Metab ; 318(1): E33-E43, 2020 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-31770015

RESUMO

Energy homeostasis is crucial for all physiological processes. Thus, when there is low energy intake, negative health effects may arise, including in reproductive function. We propose to study whether caloric restriction (CR) changes testicular metabolic profile and ultimately sperm quality. Male Wistar rats (n = 12) were randomized into a CR group fed with 30% fewer calories than weight-matched, ad libitum-fed animals (control group). Circulating hormonal profile, testicular glucagon-like peptide-1 (GLP-1), ghrelin and leptin receptors expression, and sperm parameters were analyzed. Testicular metabolite abundance and glycolysis-related enzymes were studied by NMR and Western blot, respectively. Oxidative stress markers were analyzed in testicular tissue and spermatozoa. Expressions of mitochondrial complexes and mitochondrial biogenesis in testes were determined. CR induced changes in body weight along with altered GLP-1, ghrelin, and leptin circulating levels. In testes, CR led to changes in receptor expression that followed those of the hormone levels; modified testicular metabolome, particularly amino acid content; and decreased oxidative stress-induced damage in testis and spermatozoa, although sperm head defects increased. In sum, CR induced changes in body weight, altering circulating hormonal profile and testicular metabolome and increasing sperm head defects. Ultimately, our data highlight that conditions of CR may compromise male fertility.


Assuntos
Restrição Calórica , Grelina/metabolismo , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Leptina/metabolismo , Espermatozoides/metabolismo , Testículo/metabolismo , Animais , Western Blotting , Masculino , Metaboloma , Mitocôndrias/metabolismo , Biogênese de Organelas , Estresse Oxidativo , Espectroscopia de Prótons por Ressonância Magnética , Distribuição Aleatória , Ratos , Ratos Wistar , Receptores para Leptina/metabolismo , Análise do Sêmen , Cabeça do Espermatozoide/patologia , Espermatozoides/patologia
20.
Food Chem Toxicol ; 135: 110886, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31626838

RESUMO

Diabetes mellitus has become a worldwide concern in recent years. In this study, the effect of Holothuria leucospilota polysaccharide (HLP) on type 2 diabetes mellitus (T2DM) was investigated in Goto-Kakizaki (GK) rats. The results showed that HLP significantly improved glucose intolerance and regulated blood lipid and hormone levels (p < 0.05). Pathological analysis showed that HLP repaired the impairments of the pancreas and colon in diabetic rats. In addition, a high dose of HLP (200 mg/kg) significantly upregulated the gene expression of peroxisome proliferator-activated receptor-α (PPAR-α), peroxisome proliferator-activated receptor-γ (PPAR-γ), phosphoinositide 3-kinase (PI3K), protein kinase B (PKB/AKT), glucose transporter-4 (GLUT4) and anti-apoptotic (Bcl-2), and downregulated the mRNA levels of pro-apoptotic (Bax) and cluster of differentiation 36 (CD36) in diabetic rats (p < 0.05). Furthermore, HLP treatment increased the short-chain fatty acid-producing bacteria and decreased the opportunistic bacterial pathogen in the feces of diabetic rats. These results demonstrated that HLP has the potential to ameliorate T2DM in GK rats.


Assuntos
Diabetes Mellitus Experimental/microbiologia , Diabetes Mellitus Tipo 2/microbiologia , Microbioma Gastrointestinal/efeitos dos fármacos , Polissacarídeos/farmacologia , Adiponectina/metabolismo , Animais , Glicemia/metabolismo , Diabetes Mellitus Experimental/sangue , Diabetes Mellitus Tipo 2/sangue , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Insulina/metabolismo , Leptina/metabolismo , Lipídeos/sangue , Masculino , Receptores Ativados por Proliferador de Peroxissomo/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Ratos , Pepinos-do-Mar , Transdução de Sinais
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