RESUMO
Adipose tissue is a multifunctional organ that regulates many physiological processes such as energy homeostasis, nutrition, the regulation of insulin sensitivity, body temperature, and immune response. In this review, we highlight the relevance of the different mediators that control adipose tissue activity through a systematic review of the main players present in white and brown adipose tissues. Among them, inflammatory mediators secreted by the adipose tissue, such as classical adipokines and more recent ones, elements of the immune system infiltrated into the adipose tissue (certain cell types and interleukins), as well as the role of intestinal microbiota and derived metabolites, have been reviewed. Furthermore, anti-obesity mediators that promote the activation of beige adipose tissue, e.g., myokines, thyroid hormones, amino acids, and both long and micro RNAs, are exhaustively examined. Finally, we also analyze therapeutic strategies based on those mediators that have been described to date. In conclusion, novel regulators of obesity, such as microRNAs or microbiota, are being characterized and are promising tools to treat obesity in the future.
Assuntos
Tecido Adiposo , Obesidade , Humanos , Animais , Obesidade/metabolismo , Tecido Adiposo/metabolismo , Adipocinas/metabolismo , MicroRNAs/metabolismo , MicroRNAs/genética , Microbioma Gastrointestinal , Tecido Adiposo Marrom/metabolismo , Tecido Adiposo Branco/metabolismo , Mediadores da Inflamação/metabolismo , Metabolismo EnergéticoRESUMO
BACKGROUND: Background: Perinatal malnutrition seems to provoke important neurochemical alterations in the brain that lead to higher vulnerability to develop neuropsychiatric disorders in the adulthood. OBJECTIVES: We have examined the persistence and reversibility of the changes induced by perinatal undernourishment on the expression of fumarate hydratase in the rat nucleus accumbens, bearing in mind that this expression has been previously linked with addictive disorders. Clusterin, a multifunctional protein known to be neuroprotective and possibly related to addiction in humans, was studied in parallel. METHODS: Female Wistar rats underwent a severe restriction of food during gestation and lactation. Upon weaning, a subgroup of undernourished animals was switched to normal chow and another one continued under food restriction. Control rats and their mothers were fed on chow along the experiment. Fumarate hydratase and clusterin were quantified by western blot after five months of postnatal life in the three experimental groups. RESULTS: Food restriction along the whole experimental period provoked a marked upregulation of both clusterin and fumarate hydratase in the mitochondrial fraction of the nucleus accumbens. In the case of clusterin, this upregulation was also observed in the cytosolic fraction of the nucleus accumbens. When undernourishment was limited to gestation and lactation the two proteins appeared downregulated with respect to controls. CONCLUSION: The results are consistent with the idea that perinatal malnutrition provokes marked changes in brain neurochemistry that are not fully corrected by the rehabilitation of normal feeding and could be linked to behavioural disturbances in the adulthood, that is, increased vulnerability to addiction.
Assuntos
Clusterina , Fumarato Hidratase , Desnutrição , Fenômenos Fisiológicos da Nutrição Materna , Núcleo Accumbens , Adulto , Animais , Clusterina/metabolismo , Feminino , Fumarato Hidratase/metabolismo , Humanos , Núcleo Accumbens/metabolismo , Gravidez , Ratos , Ratos WistarRESUMO
Because nonalcoholic steatohepatitis (NASH) is associated with impaired liver regeneration, we investigated the effects of G49, a dual glucagon-like peptide-1/glucagon receptor agonist, on NASH and hepatic regeneration. C57Bl/6 mice fed chow or a methionine and choline-deficient (MCD) diet for 1 week were divided into 4 groups: control (chow diet), MCD diet, chow diet plus G49, and M+G49 (MCD diet plus G49). Mice fed a high-fat diet (HFD) for 10 weeks were divided into groups: HFD and H+G49 (HFD plus G49). Following 2 (MCD groups) or 3 (HFD groups) weeks of treatment with G49, partial hepatectomy (PH) was performed, and all mice were maintained on the same treatment schedule for 2 additional weeks. Analysis of liver function, hepatic regeneration, and comprehensive genomic and metabolic profiling were conducted. NASH was ameliorated in the M+G49 group, manifested by reduced inflammation, steatosis, oxidative stress, and apoptosis and increased mitochondrial biogenesis. G49 treatment was also associated with replenishment of intrahepatic glucose due to enhanced gluconeogenesis and reduced glucose use through the pentose phosphate cycle and oxidative metabolism. Following PH, G49 treatment increased survival, restored the cytokine-mediated priming phase, and enhanced the proliferative capacity and hepatic regeneration ratio in mice on the MCD diet. NASH markers remained decreased in M+G49 mice after PH, and glucose use was shifted to the pentose phosphate cycle and oxidative metabolism. G49 administered immediately after PH was also effective at alleviating the pathological changes induced by the MCD diet. Benefits in terms of liver regeneration were also found in mice fed HFD and treated with G49. CONCLUSION: Dual-acting glucagon-like peptide-1/glucagon receptor agonists such as G49 represent a novel therapeutic approach for patients with NASH and particularly those requiring PH. (Hepatology 2017;65:950-968).
Assuntos
Peptídeo 1 Semelhante ao Glucagon/antagonistas & inibidores , Regeneração Hepática/efeitos dos fármacos , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológico , Receptores de Glucagon/antagonistas & inibidores , Animais , Biópsia por Agulha , Modelos Animais de Doenças , Peptídeo 1 Semelhante ao Glucagon/farmacologia , Humanos , Imuno-Histoquímica , Peroxidação de Lipídeos , Regeneração Hepática/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Hepatopatia Gordurosa não Alcoólica/patologia , Estresse Oxidativo , Distribuição Aleatória , Receptores de Glucagon/administração & dosagem , Resultado do TratamentoRESUMO
Human studies have suggested that early undernutrition increases the risk of obesity, thereby explaining the increase in overweight among individuals from developing countries who have been undernourished as children. However, this conclusion is controversial, given that other studies do not concur. This study sought to determine whether rehabilitation after undernutrition increases the risk of obesity and metabolic disorders. We employed a published experimental food-restriction model. Wistar female rats subjected to severe food restriction since fetal stage and controls were transferred to a moderately high-fat diet (cafeteria) provided at 70 days of life to 6.5 months. Another group of undernourished rats were rehabilitated with chow. The energy intake of undernourished animals transferred to cafeteria formula exceeded that of the controls under this regime and was probably driven by hypothalamic disorders in insulin and leptin signal transduction. The cafeteria diet resulted in greater relative increases in both fat and lean body mass in the undernourished rats when compared with controls, enabling the former group to completely catch up in length and body mass index. White adipose tissues of undernourished rats transferred to the high-lipid regime developed a browning which, probably, contributed to avoid the obesigenic effect observed in controls. Nevertheless, the restricted group rehabilitated with cafeteria formula had greater accretion of visceral than subcutaneous fat, showed increased signs of macrophage infiltration and inflammation in visceral pad, dyslipidemia, and ectopic fat accumulation. The data indicate that early long-term undernutrition is associated with increased susceptibility to the harmful effects of nutritional rehabilitation, without causing obesity.
Assuntos
Desnutrição/complicações , Obesidade/etiologia , Efeitos Tardios da Exposição Pré-Natal/etiologia , Tecido Adiposo Branco/metabolismo , Tecido Adiposo Branco/patologia , Adiposidade , Animais , Dieta Hiperlipídica/efeitos adversos , Ingestão de Energia , Feminino , Hiperfagia/etiologia , Hiperfagia/metabolismo , Hipotálamo/metabolismo , Resistência à Insulina , Leptina/metabolismo , Fígado/metabolismo , Fígado/patologia , Masculino , Desnutrição/metabolismo , Desnutrição/reabilitação , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Neuropeptídeo Y/metabolismo , Obesidade/metabolismo , Oxirredução , Gravidez , Efeitos Tardios da Exposição Pré-Natal/metabolismo , Pró-Opiomelanocortina/metabolismo , Ratos Wistar , Fatores de RiscoRESUMO
The loss of functional beta-cell mass in diabetes is directly linked to the development of diabetic complications. Although dietary flavonoids have demonstrated antidiabetic properties, their potential effects on pancreatic beta-cell preservation and their synergistic benefits with antidiabetic drugs remain underexplored. We have developed a potential functional food enriched in flavonoids by combining cocoa powder and carob flour (CCB), which has shown antidiabetic effects. Here, we investigated the ability of the CCB, alone or in combination with metformin, to preserve pancreatic beta cells in an established diabetic context and their potential synergistic effect. Zucker diabetic fatty rats (ZDF) were fed a CCB-rich diet or a control diet, with or without metformin, for 12 weeks. Markers of pancreatic oxidative stress and inflammation, as well as relative beta-cell mass and beta-cell apoptosis, were analyzed. Results demonstrated that CCB feeding counteracted pancreatic oxidative stress by enhancing the antioxidant defense and reducing reactive oxygen species. Moreover, the CCB suppressed islet inflammation by preventing macrophage infiltration into islets and overproduction of pro-inflammatory cytokines, along with the inactivation of nuclear factor kappa B (NFκB). As a result, the CCB supplementation prevented beta-cell apoptosis and the loss of beta cells in ZDF diabetic animals. The observed additive effect when combining the CCB with metformin underscores its potential as an adjuvant therapy to delay the progression of type 2 diabetes.
Assuntos
Cacau , Chocolate , Diabetes Mellitus Tipo 2 , Galactanos , Células Secretoras de Insulina , Mananas , Metformina , Gomas Vegetais , Ratos , Animais , Metformina/farmacologia , Ratos Zucker , Flavonoides/farmacologia , Diabetes Mellitus Tipo 2/tratamento farmacológico , Hipoglicemiantes/farmacologia , Alimento Funcional , InflamaçãoRESUMO
Mother's milk contains a unique microbiome that plays a relevant role in offspring health. We hypothesize that maternal malnutrition during lactation might impact the microbial composition of milk and affect adequate offspring gut colonization, increasing the risk for later onset diseases. Then, Wistar rats were fed ad libitum (Control, C) food restriction (Undernourished, U) during gestation and lactation. After birth, offspring feces and milk stomach content were collected at lactating day (L)4, L14 and L18. The V3-V4 region of the bacterial 16S rRNA gene was sequenced to characterize bacterial communities. An analysis of beta diversity revealed significant disparities in microbial composition between groups of diet at L4 and L18 in both milk, and fecal samples. In total, 24 phyla were identified in milk and 18 were identified in feces, with Firmicutes, Proteobacteria, Actinobacteroidota and Bacteroidota collectively representing 96.1% and 97.4% of those identified, respectively. A higher abundance of Pasteurellaceae and Porphyromonas at L4, and of Gemella and Enterococcus at L18 were registered in milk samples from the U group. Lactobacillus was also significantly more abundant in fecal samples of the U group at L4. These microbial changes compromised the number and variety of milk-feces or feces-feces bacterial correlations. Moreover, increased offspring gut permeability and an altered expression of goblet cell markers TFF3 and KLF3 were observed in U pups. Our results suggest that altered microbial communication between mother and offspring through breastfeeding may explain, in part, the detrimental consequences of maternal malnutrition on offspring programming.
Assuntos
Microbioma Gastrointestinal , Desnutrição , Microbiota , Ratos , Feminino , Animais , Leite/metabolismo , Lactação/metabolismo , Ratos Wistar , RNA Ribossômico 16S/genética , Microbioma Gastrointestinal/genética , Leite Humano/microbiologia , Dieta , Fezes/microbiologia , Bactérias/genética , Desnutrição/metabolismoRESUMO
Developing brains are vulnerable to nutritional insults. Early undernutrition alters their structure and neurochemistry, inducing long-term pathological effects whose causal pathways are not well defined. During suckling, the brain uses glucose and ketone bodies as substrates. Milk is a high-fat low-carbohydrate diet, and the liver must maintain high rates of gluconeogenesis and ketogenesis to address the needs of these substrates. Insulin and glucagon play major roles in this adaptation: throughout suckling, their blood concentrations are low and high, respectively, and the liver maintains low insulin sensitivity and increased glucagon responsiveness. We propose that disturbances in the endocrine profile and available plasma substrates along with undernutrition-related changes in brain cortex capacity for ketone utilization may cause further alterations in some brain functions. We explored this hypothesis in 10-day-old suckling rats whose mothers were severely food restricted from the 14th day of gestation. We measured the plasma/serum concentrations of glucose, ketone body, insulin and glucagon, and hepatic insulin and glucagon responses. Undernutrition led to hypoglycemia and hyperketonemia to 84% (P < 0.001) and 144% (P < 0.001) of control values, respectively. Liver responsiveness to insulin and glucagon became increased and reduced, respectively; intraperitoneal glucagon reduced liver glycogen by 90% (P < 0.01) in control and by 35% (P < 0.05) in restricted. Cortical enzymes of ketone utilization remained unchanged, but their carrier proteins were altered: monocarboxylate transporter (MCT) 1 increased: 73 ± 14, controls; 169 ± 20, undernourished (P < 0.01; densitometric units); MCT2 decreased: 103 ± 3, controls; 37 ± 4, undernourished (P < 0.001; densitometric units). All of these changes, coinciding with the brain growth spurt, may cause some harmful effects associated with early undernutrition.
Assuntos
Metabolismo Energético/fisiologia , Glucagon/metabolismo , Insulina/metabolismo , Fígado/metabolismo , Desnutrição/metabolismo , Adaptação Fisiológica , Fatores Etários , Análise de Variância , Animais , Animais Lactentes , Glicemia/metabolismo , Córtex Cerebral/crescimento & desenvolvimento , Córtex Cerebral/metabolismo , Feminino , Corpos Cetônicos/metabolismo , Desnutrição/fisiopatologia , Transportadores de Ácidos Monocarboxílicos/metabolismo , Gravidez , Efeitos Tardios da Exposição Pré-Natal , Ratos , Ratos WistarRESUMO
Type 2 diabetes (T2D) results from impaired beta-cell function and insufficient beta-cell mass compensation in the setting of insulin resistance. Current therapeutic strategies focus their efforts on promoting the maintenance of functional beta-cell mass to ensure appropriate glycemic control. Thus, understanding how beta-cells communicate with metabolic and non-metabolic tissues provides a novel area for investigation and implicates the importance of inter-organ communication in the pathology of metabolic diseases such as T2D. In this review, we provide an overview of secreted factors from diverse organs and tissues that have been shown to impact beta-cell biology. Specifically, we discuss experimental and clinical evidence in support for a role of gut to beta-cell crosstalk, paying particular attention to bacteria-derived factors including short-chain fatty acids, lipopolysaccharide, and factors contained within extracellular vesicles that influence the function and/or the survival of beta cells under normal or diabetogenic conditions.
Assuntos
Diabetes Mellitus Tipo 2 , Microbioma Gastrointestinal , Resistência à Insulina , Células Secretoras de Insulina , Doenças Metabólicas , Diabetes Mellitus Tipo 2/metabolismo , Microbioma Gastrointestinal/fisiologia , Humanos , Células Secretoras de Insulina/metabolismo , Doenças Metabólicas/metabolismoRESUMO
Cocoa constitutes one of the richest sources of dietary flavonoids with demonstrated anti-diabetic potential. However, the metabolic impact of cocoa intake in a diabetic context remains unexplored. In this study, metabolomics tools have been used to investigate the potential metabolic changes induced by cocoa in type 2 diabetes (T2D). To this end, male Zucker diabetic fatty rats were fed on standard (ZDF) or 10% cocoa-rich diet (ZDF-C) from week 10 to 20 of life. Cocoa supplementation clearly decreased serum glucose levels, improved glucose metabolism and produced significant changes in the urine metabolome of ZDF animals. Fourteen differential urinary metabolites were identified, with eight of them significantly modified by cocoa. An analysis of pathways revealed that butanoate metabolism and the synthesis and degradation of branched-chain amino acids and ketone bodies are involved in the beneficial impact of cocoa on diabetes. Moreover, correlation analysis indicated major associations between some of these urine metabolites (mainly valine, leucine, and isoleucine) and body weight, glycemia, insulin sensitivity, and glycated hemoglobin levels. Overall, this untargeted metabolomics approach provides a clear metabolic fingerprint associated to chronic cocoa intake that can be used as a marker for the improvement of glucose homeostasis in a diabetic context.
Assuntos
Cacau , Diabetes Mellitus Experimental , Diabetes Mellitus Tipo 2 , Aminoácidos de Cadeia Ramificada/metabolismo , Animais , Glicemia/metabolismo , Cacau/química , Flavonoides/metabolismo , Hemoglobinas Glicadas/metabolismo , Isoleucina , Corpos Cetônicos/metabolismo , Leucina/metabolismo , Masculino , Metabolômica , Espectroscopia de Prótons por Ressonância Magnética , Ratos , Ratos Zucker , Valina/metabolismoRESUMO
Protein tyrosine phosphatase 1B (PTP1B) is a negative regulator of insulin and tyrosine kinase growth factor signaling. We have recently demonstrated that PTP1B deficiency increases GLUT2/insulin receptor (IR) A complexes and glucose uptake in suckling, but not adult, primary hepatocytes. Herein we have investigated intrahepatic glucose utilization in 3-5 days old wild-type and PTP1B(-/-) mice. PTP1B deficiency decreased glycogen, lactate, and pyruvate content in the livers from suckling mice. Conversely, the activity of glucose 6-phosphate dehydrogenase (G6PD), the rate limiting enzyme of the pentose phosphate cycle (PPC) which provides substrates for DNA synthesis, was enhanced in the liver of PTP1B(-/-) animals. Liver weight, liver-to-body mass ratio, DNA content, and PCNA expression were increased in PTP1B(-/-) suckling mice compared to the wild-type controls. At the molecular level, STAT 5B phosphorylation, IGF-I mRNA, and protein levels as well as IGF-IR tyrosine phosphorylation were increased in the livers of PTP1B-deficient neonates. Unexpectedly, hepatic and serum triglycerides (TG) were increased by PTP1B deficiency, although the expression of lipogenic enzymes remained as in the wild-type controls. However, the analysis of milk composition revealed higher TG content in lactating females lacking PTP1B. The effects of PTP1B deficiency on G6PD activity, STAT 5B/IGF-I/IGF-IR axis, PCNA expression and liver growth during suckling were maintained by transferring PTP1B(-/-) embryos (PTP1B(-/-T)) to a wild-type female. Conversely, PTP1B(-/-T) mice did not show hepatic fat accumulation. In conclusion, the present study suggests that PTP1B plays a unique role in the control of the physiological liver development after birth.
Assuntos
Animais Lactentes , Fator de Crescimento Insulin-Like I/metabolismo , Fígado/crescimento & desenvolvimento , Fígado/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 1/deficiência , Animais , Feminino , Glucose/metabolismo , Fator de Crescimento Insulin-Like I/genética , Lactação/fisiologia , Fígado/citologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Antígeno Nuclear de Célula em Proliferação/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 1/genética , Receptor IGF Tipo 1/genética , Receptor IGF Tipo 1/metabolismo , Fator de Transcrição STAT5/genética , Fator de Transcrição STAT5/metabolismo , Triglicerídeos/metabolismoRESUMO
Exposure to maternal undernutrition during development increases the risk for neurological and cognitive defects. However, little is known about the underlying mechanisms involved. Peripheral responses to insulin are increased following food-restriction, thus the possibility arises that brain insulin actions are affected by undernutrition, causing damages to the higher cerebral functions. In this study, we examined the effects of early undernutriton on molecular targets of insulin actions such as glucose transporters, glycogen, glycogen synthase kinase-3 (GSK3) and mitogen-activated protein kinases, as well as proteins involved in apoptosis in the cortex from 10-day-old rats. We show that undernutrition results in an enhanced glycogen content which is confined to astrocytes, according to our histochemical approaches. Cortical phospho-GSK3 is also increased. In addition to glycogen synthesis, GSK3 regulates crucial cellular processes. Therefore, its elevated degree of phosphorylation may have an impact on these processes and, consequently, on the cortical development. Phospho-p38 and both total JNK and phospho-JNK, which regulate apoptosis, are reduced following undernutrition. However, cleaved caspase 3 is not altered, which suggests that this condition does not induce extensive modifications to the cortical apoptosis. Thus, our results indicate that undernutrition gives rise to molecular alterations that may have repercussions on cerebral cortex development and functions.
Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Córtex Cerebral/enzimologia , Quinase 3 da Glicogênio Sintase/metabolismo , Glicogênio/biossíntese , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Desnutrição/enzimologia , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo , Proteínas Quinases Ativadas por AMP/antagonistas & inibidores , Fatores Etários , Animais , Animais Recém-Nascidos , Animais Lactentes/crescimento & desenvolvimento , Animais Lactentes/metabolismo , Peso Corporal/fisiologia , Ativação Enzimática/fisiologia , Feminino , Tamanho do Órgão/fisiologia , Gravidez , Fenômenos Fisiológicos da Nutrição Pré-Natal/fisiologia , Ratos , Ratos WistarRESUMO
Maternal malnutrition plays a critical role in the developmental programming of later metabolic diseases susceptibility in the offspring, such as obesity and type 2 diabetes. Because the liver is the major organ that produces and supplies blood glucose, we aimed at defining the potential role of liver glycogen autophagy in the programming of glucose metabolism disturbances. To this end, newborns were obtained from pregnant Wistar rats fed ad libitum with a standard diet or 65% food-restricted during the last week of gestation. We found that newborns from undernourished mothers showed markedly high basal insulin levels whereas those of glucagon were decreased. This unbalance led to activation of the mTORC1 pathway and inhibition of hepatic autophagy compromising the adequate handling of glycogen in the very early hours of extrauterine life. Restoration of autophagy with rapamycin but not with glucagon, indicated no defect in autophagy machinery per se, but in signals triggered by glucagon. Taken together, these results support the notion that hyperinsulinemia is an important mechanism by which mobilization of liver glycogen by autophagy is defective in food-restricted animals. This early alteration in the hormonal control of liver glycogen autophagy may influence the risk of developing metabolic diseases later in life.
Assuntos
Autofagia , Retardo do Crescimento Fetal/metabolismo , Hiperinsulinismo/metabolismo , Glicogênio Hepático/metabolismo , Animais , Animais Recém-Nascidos/metabolismo , Feminino , Glucose/metabolismo , Fígado/metabolismo , Desnutrição/metabolismo , Gravidez , Ratos , Ratos WistarRESUMO
Cocoa supplementation improves glucose metabolism in Zucker diabetic fatty (ZDF) rats via multiple mechanisms. Furthermore, cocoa rich-diets modify the intestinal microbiota composition both in humans and rats in healthy conditions. Accordingly, we hypothesized that cocoa could interact with the gut microbiota (GM) in ZDF rats, contributing to their antidiabetic effects. Therefore, here we investigate the effect of cocoa intake on gut health and GM in ZDF diabetic rats. Male ZDF rats were fed with standard (ZDF-C) or 10% cocoa-rich diet (ZDF-Co) during 10 weeks. Zucker Lean animals (ZL) received the standard diet. Colon tissues were obtained to determine the barrier integrity and the inflammatory status of the intestine and faeces were analysed for microbial composition, short-chain fatty acids (SCFA) and lactate levels. We found that cocoa supplementation up-regulated the levels of the tight junction protein Zonula occludens-1 (ZO-1) and the mucin glycoprotein and reduced the expression of pro-inflammatory cytokines such as tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6) and monocyte chemoattractant protein 1 (MCP-1) in the colon of ZDF diabetic animals. Additionally, cocoa modulated the microbial composition of the ZDF rats to values similar to those of the lean group. Importantly, cocoa treatment increased the relative abundance of acetate-producing bacteria such as Blautia and prevented the increase in the relative amount of lactate-producing bacteria (mainly Enterococcus and Lactobacillus genera) in ZDF diabetic animals. Accordingly, the total levels of SCFA (mainly acetate) increased significantly in the faeces of ZDF-Co diabetic rats. Finally, modified GM was closely associated with improved biochemical parameters related to glucose homeostasis and intestinal integrity and inflammation. These findings demonstrate for the first time that cocoa intake modifies intestinal bacteria composition towards a healthier microbial profile in diabetic animals and suggest that these changes could be associated with the improved glucose homeostasis and gut health induced by cocoa in ZDF diabetic rats.
Assuntos
Cacau , Diabetes Mellitus Experimental/dietoterapia , Dieta , Microbioma Gastrointestinal/efeitos dos fármacos , Animais , Bactérias/classificação , Glicemia , Quimiocina CCL2 , Colo/microbiologia , Colo/patologia , Ácidos Graxos Voláteis , Teste de Tolerância a Glucose , Homeostase/efeitos dos fármacos , Hipoglicemiantes/farmacologia , Interleucina-6 , Masculino , Ratos , Ratos Zucker , Fator de Necrose Tumoral alfa , Proteína da Zônula de Oclusão-1/metabolismoRESUMO
The Goto-Kakizaki (GK) rat is a type 2 diabetes model with a defective beta-cell mass detectable in late fetal development. Diminished IGF-2 production seems to be involved in this effect. Herein, we analyzed the effect of maternal food-restriction on the beta-cell mass of GK fetuses and the involvement of the IGF system, highly responsive to nutritional status in this process. To this end, in undernourished GK fetuses (U-GK), we measured serum GH/IGF levels, beta-cell mass, replication and differentiation, and IGF-1/-2 protein content in liver and pancreas tissue. Pregnant GK females were food restricted (65% restriction) during the last week of gestation. Our results show that maternal malnutrition ameliorates beta-cell mass in U-GK fetuses and a specific pancreatic IGF-2 increase may be instrumental in this effect. Further studies are needed to determine whether maternal undernutrition is sufficient to delay or decrease the risk of the GK rat for developing diabetes.
Assuntos
Diabetes Mellitus Tipo 2 , Modelos Animais de Doenças , Feto/metabolismo , Fator de Crescimento Insulin-Like II/metabolismo , Células Secretoras de Insulina , Desnutrição , Pâncreas , Animais , Diferenciação Celular , Proliferação de Células , Feminino , Feto/citologia , Regulação da Expressão Gênica no Desenvolvimento , Humanos , Células Secretoras de Insulina/citologia , Células Secretoras de Insulina/metabolismo , Fígado/embriologia , Fígado/metabolismo , Pâncreas/embriologia , Pâncreas/metabolismo , Gravidez , Prenhez , Ratos , Ratos WistarRESUMO
Type 2 diabetes mellitus is a complex metabolic disease and its pathogenesis involves abnormalities in both peripheral insulin action and insulin secretion. Previous in vitro data showed that insulin receptor isoform A, but not B, favours basal glucose uptake through its specific association with endogenous GLUT1/2 in murine hepatocytes and beta cells. With this background, we hypothesized that hepatic expression of insulin receptor isoform A in a mouse model of type 2 diabetes could potentially increase the glucose uptake of these cells, decreasing the hyperglycaemia and therefore ameliorating the diabetic phenotype. To assure this hypothesis, we have developed recombinant adeno-associated viral vectors expressing insulin receptor isoform A (IRA) or isoform B (IRB) under the control of a hepatocyte--specific promoter. Our results demonstrate that in the long term, hepatic expression of IRA in diabetic mice is more efficient than IRB in ameliorating glucose intolerance. Consequently, it impairs the induction of compensatory mechanisms through beta cell hyperplasia and/or hypertrophy that finally lead to beta cell failure, reverting the diabetic phenotype in about 8â weeks. Our data suggest that long-term hepatic expression of IRA could be a promising therapeutic approach for the treatment of type 2 diabetes mellitus.
Assuntos
Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Intolerância à Glucose/metabolismo , Receptor de Insulina/metabolismo , Animais , Proliferação de Células , Dependovirus/metabolismo , Diabetes Mellitus Experimental/patologia , Diabetes Mellitus Tipo 2/patologia , Glucose/metabolismo , Intolerância à Glucose/patologia , Proteínas de Fluorescência Verde/metabolismo , Homeostase , Hiperplasia , Insulina/metabolismo , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/patologia , Fígado/metabolismo , Camundongos Knockout , Isoformas de Proteínas/metabolismoRESUMO
We have recently shown that cocoa flavanols may have anti-diabetic potential by promoting survival and function of pancreatic beta-cells in vitro. In this work, we investigated if a cocoa-rich diet is able to preserve beta-cell mass and function in an animal model of type 2 diabetes and the mechanisms involved. Our results showed that cocoa feeding during the prediabetic state attenuates hyperglycaemia, reduces insulin resistant, and increases beta cell mass and function in obese Zucker diabetic rats. At the molecular level, cocoa-rich diet prevented beta-cell apoptosis by increasing the levels of Bcl-xL and decreasing Bax levels and caspase-3 activity. Cocoa diet enhanced the activity of endogenous antioxidant defenses, mainly glutathione peroxidase, preventing thus oxidative injury induced by the pre-diabetic condition and leading to apoptosis prevention. These findings provide the first in vivo evidence that a cocoa-rich diet may delay the loss of functional beta-cell mass and delay the progression of diabetes by preventing oxidative stress and beta-cell apoptosis.
Assuntos
Apoptose/efeitos dos fármacos , Cacau/química , Dieta , Células Secretoras de Insulina/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Polifenóis/farmacologia , Animais , Antioxidantes/farmacologia , Caspase 3/genética , Caspase 3/metabolismo , Diabetes Mellitus Experimental/tratamento farmacológico , Glutationa Peroxidase/metabolismo , Hiperglicemia/tratamento farmacológico , Células Secretoras de Insulina/metabolismo , Masculino , Extratos Vegetais/farmacologia , Ratos , Ratos Zucker , Proteína X Associada a bcl-2/genética , Proteína X Associada a bcl-2/metabolismo , Proteína bcl-X/genética , Proteína bcl-X/metabolismoRESUMO
SCOPE: Mice with deletion of insulin receptor substrate (IRS) 2 develop hyperglycaemia, impaired hepatic insulin signaling and elevated gluconeogenesis. Protein tyrosine phosphatase 1B (PTP1B) inhibition by resveratrol improves peripheral insulin sensitivity of these mice. Although resveratrol activates Sirtuin1 (Sirt1), the mechanisms underlying its beneficial effects are not totally elucidated. In this study, we have investigated whether Sirt1 mediates the effects of resveratrol in controlling insulin resistance in diabetic mice. METHODS AND RESULTS: We attempted to ameliorate peripheral insulin resistance in two diabetic models, Irs2-deficient (Irs2(-/-)) mice and streptozotocin (STZ)-injected mice by resveratrol treatment or Sirt1 overexpression. Resveratrol improved systemic insulin sensitivity of Irs2-deficient mice. Irs2-deficient mice are characterized by high levels of PTP1B expression in liver and muscle. Interestingly, resveratrol decreased PTP1B in both tissues, thereby restoring IRS1-mediated insulin signaling. Moreover, resveratrol also restored insulin sensitivity and hepatic insulin signaling in STZ-diabetic mice. In contrast, moderate overexpression of Sirt1 neither normalized PTP1B levels nor restored insulin signaling in Irs2-deficient mice or STZ-diabetic mice. CONCLUSION: Resveratrol improves peripheral insulin signaling independently of Sirt1 in diabetic mice in association with the inhibition of PTP1B and, therefore, this polyphenol could be an effective adjuvant for the treatment of diabetes.
Assuntos
Antioxidantes/uso terapêutico , Diabetes Mellitus Tipo 2/dietoterapia , Suplementos Nutricionais , Resistência à Insulina , Músculo Esquelético/metabolismo , Sirtuína 1/metabolismo , Estilbenos/uso terapêutico , Animais , Cruzamentos Genéticos , Diabetes Mellitus Experimental/dietoterapia , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/patologia , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/patologia , Inibidores Enzimáticos/uso terapêutico , Feminino , Hipoglicemiantes/uso terapêutico , Proteínas Substratos do Receptor de Insulina/genética , Proteínas Substratos do Receptor de Insulina/metabolismo , Ilhotas Pancreáticas/metabolismo , Ilhotas Pancreáticas/patologia , Fígado/enzimologia , Fígado/metabolismo , Masculino , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Músculo Esquelético/enzimologia , Proteína Tirosina Fosfatase não Receptora Tipo 1/antagonistas & inibidores , Proteína Tirosina Fosfatase não Receptora Tipo 1/genética , Proteína Tirosina Fosfatase não Receptora Tipo 1/metabolismo , Resveratrol , Sirtuína 1/genéticaRESUMO
SCOPE: Diabetes mellitus is associated with reductions in glutathione, supporting the critical role of oxidative stress in its pathogenesis. Antioxidant food components such as flavonoids have a protective role against oxidative stress-induced degenerative and age-related diseases. Flavonoids such as epicatechin (EC) constitute an important part of the human diet; they can be found in green tea, grapes, and cocoa and possess multiple biological activities. This study investigates the chemo-protective effect of EC against oxidative stress induced by tert-butylhydroperoxide (t-BOOH) on Ins-1E pancreatic beta cells. METHODS AND RESULTS: Cell viability, oxidative status, phosphorylated Jun kinase (p-JNK) expression, and insulin secretion were evaluated. Ins-1E cells treatment with 5-20 µM EC for 20 h evoked no cell damage and enhanced antioxidant enzymes and insulin secretion. Addition of 50 µM t-BOOH for 2 h induced reactive oxygen species, p-JNK, and carbonyl groups and decreased GSH and insulin secretion. Pretreatment of cells with EC prevented the t-BOOH-induced reactive oxygen species, carbonyl groups, p-JNK expression and cell death, and recovered insulin secretion. CONCLUSION: Ins-1E cells treated with EC showed a remarkable recovery of cell viability and insulin secretion damaged by t-BOOH, indicating that integrity of secreting and surviving machineries in the EC-treated cells was notably protected against the oxidative insult.
Assuntos
Cacau/química , Catequina/farmacologia , Células Secretoras de Insulina/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Animais , Antioxidantes/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Glutationa/metabolismo , Glutationa Peroxidase/metabolismo , Glutationa Redutase/metabolismo , Insulina/metabolismo , Secreção de Insulina , Células Secretoras de Insulina/metabolismo , Substâncias Protetoras/farmacologia , Ratos , Espécies Reativas de Oxigênio/metabolismo , terc-Butil Hidroperóxido/toxicidadeRESUMO
Oxidative stress is accepted as one of the causes of beta cell failure in type 2 diabetes. Therefore, identification of natural antioxidant agents that preserve beta cell mass and function is considered an interesting strategy to prevent or treat diabetes. Recent evidences indicated that colonic metabolites derived from flavonoids could possess beneficial effects on various tissues. The aim of this work was to establish the potential anti-diabetic properties of the microbial-derived flavonoid metabolites 3,4-dihydroxyphenylacetic acid (DHPAA), 2,3-dihydroxybenzoic acid (DHBA) and 3-hydroxyphenylpropionic acid (HPPA). To this end, we tested their ability to influence beta cell function and to protect against tert-butyl hydroperoxide-induced beta cell toxicity. DHPAA and HPPA were able to potentiate glucose-stimulated insulin secretion (GSIS) in a beta cell line INS-1E and in rat pancreatic islets. Moreover, pre-treatment of cells with both compounds protected against beta cell dysfunction and death induced by the pro-oxidant. Finally, experiments with pharmacological inhibitors indicate that these effects were mediated by the activation of protein kinase C and the extracellular regulated kinases pathways. Altogether, these findings strongly suggest that the microbial-derived flavonoid metabolites DHPAA and HPPA may have anti-diabetic potential by promoting survival and function of pancreatic beta cells.
Assuntos
MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Glucose/farmacologia , Insulina/metabolismo , Ilhotas Pancreáticas/efeitos dos fármacos , Fenóis/farmacologia , Proteína Quinase C/metabolismo , terc-Butil Hidroperóxido/toxicidade , Animais , Linhagem Celular , Secreção de Insulina , Ilhotas Pancreáticas/enzimologia , Ilhotas Pancreáticas/metabolismo , Ratos , Espécies Reativas de Oxigênio/metabolismoRESUMO
Replication, neogenesis, and apoptosis play a main role in neonatal endocrine pancreas remodeling. IGFs are major contributors to beta-cell growth and function and are highly sensitive to nutritional status. We previously showed that maternal malnutrition caused an increase in beta-cell mass in fetuses related to the stimulation of beta-cell proliferation due to increased pancreatic IGF-1. At 4 days of life, the beta-cell mass was decreased in undernourished neonates and persisted until adult age. To clarify whether undernutrition disrupts islet remodeling, we quantified beta-cell mass, neogenesis, replication, and apoptosis on days 4, 14, and 23. To determine the impact of food restriction on IGF ontogeny and the consequences for beta-cell growth, we measured IGF-1/-2 protein content in pancreas and liver and pancreatic IGF-1 receptor (IGF-1R)-signaling pathway at the same days. Our results indicate that undernutrition alters the timing and intensity of neonatal beta-cell ontogeny. However, although malnutrition causes beta-cell deficiency in neonates, an active process of beta-cell neogenesis and a lower incidence of beta-cell apoptosis maintain the regenerative capacity of the endocrine pancreas. Interestingly, our data provide evidence that local production of IGFs seems to be instrumental in these processes. In particular, increased pancreatic IGF-2 in undernourished rats may contribute to the partial suppression of the developmental wave of beta-cell apoptosis probably through the inhibition of glycogen synthase kinase-3. In addition, decreased pancreatic levels of IGFBP-1/-2/-3 in undernourished neonates could enhance IGF availability for interacting with IGF-1R/IR.