Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 21
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Sci Rep ; 14(1): 14405, 2024 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-38909138

RESUMO

Microglia, brain-resident macrophages, can acquire distinct functional phenotypes, which are supported by differential reprogramming of cell metabolism. These adaptations include remodeling in glycolytic and mitochondrial metabolic fluxes, potentially altering energy substrate availability at the tissue level. This phenomenon may be highly relevant in the brain, where metabolism must be precisely regulated to maintain appropriate neuronal excitability and synaptic transmission. Direct evidence that microglia can impact on neuronal energy metabolism has been widely lacking, however. Combining molecular profiling, electrophysiology, oxygen microsensor recordings and mathematical modeling, we investigated microglia-mediated disturbances in brain energetics during neuroinflammation. Our results suggest that proinflammatory microglia showing enhanced nitric oxide release and decreased CX3CR1 expression transiently increase the tissue lactate/glucose ratio that depends on transcriptional reprogramming in microglia, not in neurons. In this condition, neuronal network activity such as gamma oscillations (30-70 Hz) can be fueled by increased ATP production in mitochondria, which is reflected by elevated oxygen consumption. During dysregulated inflammation, high energy demand and low glucose availability can be boundary conditions for neuronal metabolic fitness as revealed by kinetic modeling of single neuron energetics. Collectively, these findings indicate that metabolic flexibility protects neuronal network function against alterations in local substrate availability during moderate neuroinflammation.


Assuntos
Metabolismo Energético , Glucose , Microglia , Doenças Neuroinflamatórias , Neurônios , Animais , Neurônios/metabolismo , Microglia/metabolismo , Camundongos , Doenças Neuroinflamatórias/metabolismo , Glucose/metabolismo , Mitocôndrias/metabolismo , Óxido Nítrico/metabolismo , Ácido Láctico/metabolismo , Rede Nervosa/metabolismo , Encéfalo/metabolismo , Consumo de Oxigênio , Trifosfato de Adenosina/metabolismo , Inflamação/metabolismo , Masculino , Camundongos Endogâmicos C57BL
2.
Trends Neurosci ; 45(12): 913-927, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36283867

RESUMO

Traditionally, lymphocytic interferon γ (IFN-γ) was considered to be a simple 'booster' of proinflammatory responses by microglia (brain-resident macrophages) during bacterial or viral infection. Recent slice culture (in situ) and in vivo studies suggest, however, that IFN-γ has a unique role in microglial activation. Priming by IFN-γ results in proliferation (microgliosis), enhanced synapse elimination, and moderate nitric oxide release sufficient to impair synaptic transmission, gamma rhythm activity, and cognitive functions. Moreover, IFN-γ is pivotal for driving Toll-like receptor (TLR)-activated microglia into neurotoxic phenotypes that induce energetic and oxidative stress, severe network dysfunction, and neuronal death. Pharmacological targeting of activated microglia could be beneficial during elevated IFN-γ levels, blood-brain barrier leakage, and parenchymal T lymphocyte infiltration associated with, for instance, encephalitis, multiple sclerosis, and Alzheimer's disease.


Assuntos
Interferon gama , Microglia , Interferon gama/farmacologia , Citocinas , Óxido Nítrico , Redes Neurais de Computação
3.
J Neuroimmunol ; 368: 577881, 2022 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-35537331

RESUMO

Immunological priming by type II interferon (IFN-γ) is crucial for evoking neurotoxic phenotypes of microglia (tissue-resident macrophages). We report that serial exposure of hippocampal slice cultures to IFN-γ and lipopolysaccharide (Toll-like receptor 4 ligand) induces high release of IL-6, TNF-α and nitric oxide, concomitant loss of electrical network activity (neuronal gamma oscillations) and neurodegeneration. Notably, these effects are still present after 3 days of IFN-γ removal but neither mimicked by IFN-α nor attenuated by anti-inflammatory cytokine, IL-10. Our findings might be relevant for brain diseases featuring elevated IFN-γ levels, such as viral and bacterial infections, multiple sclerosis and Alzheimer's disease.


Assuntos
Interferon gama , Microglia , Hipocampo/metabolismo , Interferon gama/metabolismo , Interferon gama/farmacologia , Interleucina-10 , Lipopolissacarídeos/farmacologia , Microglia/metabolismo , Neurônios/metabolismo , Óxido Nítrico , Fator de Necrose Tumoral alfa/metabolismo
4.
Brain Behav Immun ; 96: 80-91, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34015428

RESUMO

Recognition of pathogen- or damage-associated molecular patterns (PAMPs, DAMPs) by innate Toll-like receptors (TLRs) is central to the activation of microglia (brain macrophages) in many CNS diseases. Notably, TLR-mediated microglial activation is complex and modulated by additional exogenous and endogenous immunological signals. The impact of different microglial reactive phenotypes on electrical activity and neurotransmission is widely unknown, however. We explored the effects of TLR ligands on microglia and neuronal network function in rat organotypic hippocampal slice cultures (in situ), i.e., postnatal cortical tissue lacking adaptive immunity. Single exposure of slice cultures to TLR2 or TLR3 ligands [PGN, poly(I:C)] for 2-3 days induced moderate microglial activation featuring IL-6 and TNF-α release and only mild alterations of fast neuronal gamma band oscillations (30-70 Hz) that are fundamental to higher cognitive functions, such as perception, memory and behavior. Paired exposure to TLR3/TLR2 or TLR3/TLR4 ligands (LPS) induced nitric oxide (NO) release, enhanced TNF-α release, and associated with advanced network dysfunction, including slowing to the beta frequency band (12-30 Hz) and neural bursts (hyperexcitability). Paired exposure to a TLR ligand and the leukocyte cytokine IFN-γ enhanced NO release and associated with severe network dysfunction, albeit sensitive parvalbumin- and somatostatin-positive inhibitory interneurons were preserved. Notably, the neuronal disturbance was prevented by either microglial depletion or pharmacological inhibition of oxidant-producing enzymes, inducible NO synthase (iNOS) and NADPH oxidase. In conclusion, TLR-activated microglia can induce different levels of neuronal network dysfunction, in which severe dysfunction is mainly caused by reactive oxygen and nitrogen species rather than proinflammatory cytokines. Our findings provide a mechanistic insight into microglial activation and functional neuronal network impairment, with relevance to neuroinflammation and neurodegeneration observed in, e.g., meningoencephalitis, multiple sclerosis and Alzheimer's disease.


Assuntos
Microglia , Receptor 2 Toll-Like , Animais , Células Cultivadas , Macrófagos , Neurônios , Ratos , Receptor 3 Toll-Like
5.
Semin Cell Dev Biol ; 112: 137-144, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-32807643

RESUMO

Microglia are universal sensors of alterations in CNS physiology. These cells integrate complex molecular signals and undergo comprehensive phenotypical remodeling to adapt inflammatory responses. In the last years, single-cell analyses have revealed that microglia exhibit diverse phenotypes during development, growth and disease. Emerging evidence suggests that such phenotype transitions are mediated by reprogramming of cell metabolism. Indeed, metabolic pathways are distinctively altered in activated microglia and are central nodes controlling microglial responses. Microglial lipid metabolism has been specifically involved in the control of microglial activation and effector functions, such as migration, phagocytosis and inflammatory signaling, and minor disturbances in microglial lipid handling associates with altered brain function in disorders featuring neuroinflammation. In this review, we explore new and relevant aspects of microglial metabolism in health and disease. We give special focus on how different branches of lipid metabolism, such as lipid sensing, synthesis and oxidation, integrate and control essential aspects of microglial biology, and how disturbances in these processes associate with aging and the pathogenesis of, for instance, multiple sclerosis and Alzheimer's disease. Finally, challenges and advances in microglial lipid research are discussed.


Assuntos
Encéfalo/imunologia , Imunidade Inata/genética , Metabolismo dos Lipídeos/imunologia , Doenças Neuroinflamatórias/imunologia , Encéfalo/metabolismo , Humanos , Metabolismo dos Lipídeos/genética , Lipídeos/genética , Lipídeos/imunologia , Microglia/imunologia , Microglia/metabolismo , Doenças Neuroinflamatórias/genética , Doenças Neuroinflamatórias/patologia , Fagocitose/genética
6.
Metabolism ; 114: 154429, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33166579

RESUMO

OBJECTIVE: The systemic function of CETP has been well characterized. CETP plasma activity reduces HDL cholesterol and thus increases the risk of atherosclerosis. Here, we investigated whether CETP expression modulate adiposity. METHODS: Body adiposity and energy metabolism related assays and gene/protein expression were compared in CETP transgenic and non-transgenic mice and in hamsters treated with CETP neutralizing antibody. RESULTS: We found that transgenic mice expressing human CETP present less white adipose tissue mass and lower leptinemia than nontransgenic (NTg) littermates. No differences were found in physical activity, food intake, fat fecal excretion, lipogenesis or exogenous lipid accumulation in adipose depots. Nonetheless, adipose lipolysis rates and whole-body energy expenditure were elevated in CETP mice. In accordance, lipolysis-related gene expression and protein content were increased in visceral and brown adipose tissue (BAT). In addition, we verified increased BAT temperature and oxygen consumption. These results were confirmed in two other animal models: 1) hamsters treated with CETP neutralizing antibody and 2) an independent line of transgenic mice expressing simian CETP. CONCLUSIONS: These findings reveal a novel anti-adipogenic role for CETP.


Assuntos
Tecido Adiposo Marrom/metabolismo , Adiposidade/fisiologia , Proteínas de Transferência de Ésteres de Colesterol/metabolismo , Lipólise/fisiologia , Fígado/metabolismo , Animais , Anticorpos Neutralizantes , Proteínas de Transferência de Ésteres de Colesterol/genética , Cricetinae , Ingestão de Alimentos/fisiologia , Metabolismo Energético/fisiologia , Leptina/sangue , Camundongos , Camundongos Transgênicos , Atividade Motora/fisiologia
7.
J Neuroinflammation ; 17(1): 235, 2020 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-32782006

RESUMO

BACKGROUND: The granulocyte-macrophage colony-stimulating factor (GM-CSF) (or CSF-2) is involved in myeloid cell growth and differentiation, and, possibly, a major mediator of inflammation in body tissues. The role of GM-CSF in the activation of microglia (CNS resident macrophages) and the consequent impacts on neuronal survival, excitability, and synaptic transmission are widely unknown, however. Here, we focused on electrical neuronal network rhythms in the gamma frequency band (30-70 Hz). Gamma oscillations are fundamental to higher brain functions, such as perception, attention, and memory, and they are exquisitely sensitive to metabolic and oxidative stress. METHODS: We explored the effects of chronic GM-CSF exposure (72 h) on microglia in male rat organotypic hippocampal slice cultures (in situ), i.e., postnatal cortex tissue lacking leukocyte invasion (adaptive immunity). We applied extracellular electrophysiological recordings of local field potential, immunohistochemistry, design-based stereology, biochemical analysis, and pharmacological ablation of microglia. RESULTS: GM-CSF triggered substantial proliferation of microglia (microgliosis). By contrast, the release of proinflammatory cytokines (IL-6, TNF-α) and nitric oxide, the hippocampal cytoarchitecture as well as the morphology of parvalbumin-positive inhibitory interneurons were unaffected. Notably, GM-CSF induced concentration-dependent, long-lasting disturbances of gamma oscillations, such as slowing (beta frequency band) and neural burst firing (hyperexcitability), which were not mimicked by the T lymphocyte cytokine IL-17. These disturbances were attenuated by depletion of the microglial cell population with liposome-encapsulated clodronate. In contrast to priming with the cytokine IFN-γ (type II interferon), GM-CSF did not cause inflammatory neurodegeneration when paired with the TLR4 ligand LPS. CONCLUSIONS: GM-CSF has a unique role in the activation of microglia, including the potential to induce neuronal network dysfunction. These immunomodulatory properties might contribute to cognitive impairment and/or epileptic seizure development in disease featuring elevated GM-CSF levels, blood-brain barrier leakage, and/or T cell infiltration.


Assuntos
Fator Estimulador de Colônias de Granulócitos e Macrófagos/farmacologia , Hipocampo/efeitos dos fármacos , Interneurônios/efeitos dos fármacos , Microglia/efeitos dos fármacos , Animais , Proliferação de Células/efeitos dos fármacos , Hipocampo/metabolismo , Interleucina-6/metabolismo , Interneurônios/metabolismo , Masculino , Microglia/metabolismo , Óxido Nítrico/metabolismo , Ratos , Ratos Wistar , Fator de Necrose Tumoral alfa/metabolismo
8.
J Neurosci Res ; 98(10): 1953-1967, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32638411

RESUMO

Microglial cells (resident macrophages) feature rapid activation in CNS disease and can acquire multiple phenotypes exerting neuroprotection or neurotoxicity. The functional impact of surveying ("resting") microglia on neural excitability and neurotransmission in physiology is widely unknown, however. We addressed this issue in male rat hippocampal slice cultures (in situ) by pharmacological microglial ablation within days and by characterizing neuronal gamma-band oscillations (30-70 Hz) that are highly sensitive to neuromodulators and disturbances in ion and energy regulation. Gamma oscillations support action potential timing and synaptic plasticity, associate with higher brain functions like perception and memory, and require precise communication between excitatory pyramidal cells and inhibitory (GABAergic) interneurons. The slice cultures featured well-preserved hippocampal cytoarchitecture and parvalbumin-positive interneuron networks, microglia with ramified morphology, and low basal levels of IL-6, TNF-α, and nitric oxide (NO). Stimulation of slice cultures with the pro-inflammatory cytokine IFN-γ or bacterial LPS serving as positive controls for microglial reactivity induced MHC-II expression and increased cytokine and NO release. Chronic exposure of slice cultures to liposome-encapsulated clodronate reduced the microglial cell population by about 96%, whereas neuronal structures, astrocyte GFAP expression, and basal levels of cytokines and NO were unchanged. Notably, the properties of gamma oscillations reflecting frequency, number and synchronization of synapse activity were regular after microglial depletion. Also, electrical stimulus-induced transients of the extracellular potassium concentration ([K+ ]o ) reflecting cellular K+ efflux, clearance and buffering were unchanged. This suggests that nonreactive microglia are dispensable for neuronal homeostasis and neuromodulation underlying network signaling and rhythm generation in cortical tissue.


Assuntos
Ritmo Gama/fisiologia , Hipocampo/fisiologia , Microglia/fisiologia , Neurônios/fisiologia , Potássio/fisiologia , Animais , Animais Recém-Nascidos , Córtex Cerebral/citologia , Córtex Cerebral/fisiologia , Hipocampo/citologia , Masculino , Técnicas de Cultura de Órgãos , Ratos , Ratos Wistar
9.
Brain Behav Immun ; 88: 802-814, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32446944

RESUMO

Microglia are tissue resident macrophages (innate immunity) and universal sensors of alterations in CNS physiology. In response to pathogen or damage signals, microglia feature rapid activation and can acquire different phenotypes exerting neuroprotection or neurotoxicity. Although transcriptional aspects of microglial phenotypic transitions have been described, the underlying metabolic reprogramming is widely unknown. Employing postnatal organotypic hippocampal slice cultures, we describe that microglia transformed into a mild reactive phenotype by single TLR4 stimulation with lipopolysaccharide (LPS), which was boosted into a severe neurotoxic phenotype by IFN-γ (LPS + INF-γ). The two reactive phenotypes associated with reduction of microglial homeostatic "surveillance" markers, increase of cytokine release (IL-6, TNF-α) as well as enhancement of tissue energy demand and lactate production. These reactive phenotypes differed in the pattern of inhibition of the respiratory chain in mitochondria, however. TLR4 stimulation induced succinate dehydrogenase (complex II) inhibition by the metabolite itaconate. By contrast, TLR4 + IFN-γ receptor stimulation mainly resulted in complex IV inhibition by nitric oxide (NO) that also associated with severe oxidative stress, neuronal dysfunction and death. Notably, pharmacological depletion of microglia or treatment with itaconate resulted in effective neuroprotection reflected by well-preserved cytoarchitecture and electrical network activity, i.e., neuronal gamma oscillations (30-70 Hz) that underlie higher cognitive functions in vivo. Our findings provide in situ evidence that (i) proinflammatory microglia can substantially alter brain energy metabolism and (ii) fine-tuning of itaconate and NO metabolism determines microglial reactivity, impairment of neural network function and neurodegeneration. These data add mechanistic insights into microglial activation, with relevance to disorders featuring neuroinflammation and to drug discovery.


Assuntos
Microglia , Mitocôndrias , Células Cultivadas , Lipopolissacarídeos/metabolismo , Microglia/metabolismo , Óxido Nítrico/metabolismo , Fenótipo
10.
Biosci Rep ; 39(4)2019 04 30.
Artigo em Inglês | MEDLINE | ID: mdl-30867255

RESUMO

Microglial activation by oleate and palmitate differentially modulates brain inflammatory status. However, the metabolic reprogramming supporting these reactive phenotypes remains unknown. Employing real-time metabolic measurements and lipidomic analysis, we show that both fatty acids promote microglial oxidative metabolism, while lipopolysaccharide (LPS) enhances glycolytic rates. Interestingly, oleate treatment was followed by enrichment in storage lipids bound to polyunsaturated fatty acids (PUFA), in parallel with protection against oxidative imbalance. Palmitate, in turn, induced a distinct lipid distribution defined by PUFA linked to membrane phospholipids, which are more susceptible to lipid peroxidation and inflammatory signaling cascades. This distribution was mirrored by LPS treatment, which led to a strong pro-inflammatory phenotype in microglia. Thus, although both oleate and palmitate preserve mitochondrial function, a contrasting lipid distribution supports differences in fatty acid-induced neuroinflammation. These data reinforce the concept that reactive microglial profiles are achieved by stimulus-evoked remodeling in cell metabolism.


Assuntos
Encéfalo/patologia , Microglia/metabolismo , Mitocôndrias/metabolismo , Ácido Oleico/metabolismo , Palmitatos/metabolismo , Animais , Linhagem Celular , Glicólise/fisiologia , Inflamação/patologia , Peroxidação de Lipídeos/fisiologia , Lipopolissacarídeos/farmacologia , Lipídeos de Membrana/metabolismo , Camundongos , Microglia/citologia , Neuroimunomodulação/fisiologia , Oxirredução , Fosforilação Oxidativa
11.
Proc Natl Acad Sci U S A ; 116(10): 4637-4642, 2019 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-30782788

RESUMO

Type II IFN (IFN-γ) is a proinflammatory T lymphocyte cytokine that serves in priming of microglia-resident CNS macrophages-during the complex microglial activation process under pathological conditions. Priming generally permits an exaggerated microglial response to a secondary inflammatory stimulus. The impact of primed microglia on physiological neuronal function in intact cortical tissue (in situ) is widely unknown, however. We explored the effects of chronic IFN-γ exposure on microglia in hippocampal slice cultures, i.e., postnatal parenchyma lacking leukocyte infiltration (adaptive immunity). We focused on fast neuronal network waves in the gamma-band (30-70 Hz). Such gamma oscillations are fundamental to higher brain functions, such as perception, attention, and memory, and are exquisitely sensitive to metabolic and oxidative stress. IFN-γ induced substantial morphological changes and cell population expansion in microglia as well as moderate up-regulation of activation markers, MHC-II, CD86, IL-6, and inducible nitric oxide synthase (iNOS), but not TNF-α. Cytoarchitecture and morphology of pyramidal neurons and parvalbumin-positive inhibitory interneurons were well-preserved. Notably, gamma oscillations showed a specific decline in frequency of up to 8 Hz, which was not mimicked by IFN-α or IL-17 exposure. The rhythm disturbance was caused by moderate microglial nitric oxide (NO) release demonstrated by pharmacological microglia depletion and iNOS inhibition. In conclusion, IFN-γ priming induces substantial proliferation and moderate activation of microglia that is capable of slowing neural information processing. This mechanism might contribute to cognitive impairment in chronic brain disease featuring elevated IFN-γ levels, blood-brain barrier leakage, and/or T cell infiltration, well before neurodegeneration occurs.


Assuntos
Interferon gama/metabolismo , Microglia/metabolismo , Neurônios/citologia , Animais , Proliferação de Células , Hipocampo/química , Hipocampo/citologia , Hipocampo/metabolismo , Microglia/química , Microglia/citologia , Plasticidade Neuronal , Neurônios/química , Neurônios/metabolismo , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase Tipo II/metabolismo , Ratos , Ratos Wistar
12.
PLoS One ; 14(2): e0211733, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30716103

RESUMO

Obesity-derived inflammation and metabolic dysfunction has been related to the activity of the inducible nitric oxide synthase (iNOS). To understand the interrelation between metabolism, obesity and NO., we evaluated the effects of obesity-induced NO. signaling on liver mitochondrial function. We used mouse strains containing mitochondrial nicotinamide transhydrogenase activity, while prior studies involved a spontaneous mutant of this enzyme, and are, therefore, more prone to oxidative imbalance. Wild-type and iNOS knockout mice were fed a high fat diet for 2, 4 or 8 weeks. iNOS knockout did not protect against diet-induced metabolic changes. However, the diet decreased fatty-acid oxidation capacity in liver mitochondria at 4 weeks in both wild-type and knockout groups; this was recovered at 8 weeks. Interestingly, other mitochondrial functional parameters were unchanged, despite significant modifications in insulin resistance in wild type and iNOS knockout animals. Overall, we found two surprising features of obesity-induced metabolic dysfunction: (i) iNOS does not have an essential role in obesity-induced insulin resistance under all experimental conditions and (ii) liver mitochondria are resilient to functional changes in obesity-induced metabolic dysfunction.


Assuntos
Resistência à Insulina/fisiologia , Fígado/metabolismo , Fígado/fisiologia , Mitocôndrias Hepáticas/metabolismo , Mitocôndrias Hepáticas/fisiologia , Óxido Nítrico Sintase Tipo II/metabolismo , Animais , Dieta Hiperlipídica , Metabolismo dos Lipídeos/fisiologia , Masculino , Doenças Metabólicas/metabolismo , Doenças Metabólicas/fisiopatologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Obesidade/metabolismo , Obesidade/fisiopatologia
13.
Mol Cell Endocrinol ; 460: 238-245, 2018 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-28760600

RESUMO

Hypothalamic dysfunction is a common feature of experimental obesity. Studies have identified at least three mechanisms involved in the development of hypothalamic neuronal defects in diet-induced obesity: i, inflammation; ii, endoplasmic reticulum stress; and iii, mitochondrial abnormalities. However, which of these mechanisms is activated earliest in response to the consumption of large portions of dietary fats is currently unknown. Here, we used immunoblot, real-time PCR, mitochondrial respiration assays and transmission electron microscopy to evaluate markers of inflammation, endoplasmic reticulum stress and mitochondrial abnormalities in the hypothalamus of Swiss mice fed a high-fat diet for up to seven days. In the present study we show that the expression of the inflammatory chemokine fractalkine was the earliest event detected. Its hypothalamic expression increased as early as 3 h after the introduction of a high-fat diet and was followed by the increase of cytokines. GPR78, an endoplasmic reticulum chaperone, was increased 6 h after the introduction of a high-fat diet, however the actual triggering of endoplasmic reticulum stress was only detected three days later, when IRE-1α was increased. Mitofusin-2, a protein involved in mitochondrial fusion and tethering of mitochondria to the endoplasmic reticulum, underwent a transient reduction 24 h after the introduction of a high-fat diet and then increased after seven days. There were no changes in hypothalamic mitochondrial respiration during the experimental period, however there were reductions in mitochondria/endoplasmic reticulum contact sites, beginning three days after the introduction of a high-fat diet. The inhibition of TNF-α with infliximab resulted in the normalization of mitofusin-2 levels 24 h after the introduction of the diet. Thus, inflammation is the earliest mechanism activated in the hypothalamus after the introduction of a high-fat diet and may play a mechanistic role in the development of mitochondrial abnormalities in diet-induced obesity.


Assuntos
Hipotálamo/patologia , Inflamação/patologia , Mitocôndrias/patologia , Obesidade/patologia , Animais , Biomarcadores/metabolismo , Dieta Hiperlipídica , Chaperona BiP do Retículo Endoplasmático , Estresse do Retículo Endoplasmático , GTP Fosfo-Hidrolases/metabolismo , Hipotálamo/ultraestrutura , Camundongos , Mitocôndrias/ultraestrutura , Testes de Neutralização , Fator de Necrose Tumoral alfa/metabolismo
14.
Biochim Biophys Acta Mol Cell Biol Lipids ; 1863(2): 143-151, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29155055

RESUMO

High plasma levels of fatty acids occur in a variety of metabolic diseases. Cellular effects of fatty acid overload resulting in negative cellular responses (lipotoxicity) are often studied in vitro, in an attempt to understand mechanisms involved in these diseases. Fatty acids are poorly soluble, and thus usually studied when complexed to albumins such as bovine serum albumin (BSA). The conjugation of fatty acids to albumin requires care pertaining to preparation of the solutions, effective free fatty acid concentrations, use of different fatty acid species, types of BSA, appropriate controls and ensuring cellular fatty acid uptake. This review discusses lipotoxicity models, the potential problems encountered when using these cellular models, as well as practical solutions for difficulties encountered.


Assuntos
Técnicas de Cultura de Células/métodos , Ácidos Graxos/metabolismo , Transtornos do Metabolismo dos Lipídeos/metabolismo , Modelos Biológicos , Animais , Bovinos , Humanos , Soroalbumina Bovina/metabolismo
15.
Aging Cell ; 16(1): 73-81, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27619151

RESUMO

Caloric restriction (CR) protects against many cerebral pathological conditions that are associated with excitotoxic damage and calcium overload, although the mechanisms are still poorly understood. Here we show that CR strongly protects against excitotoxic insults in vitro and in vivo in a manner associated with significant changes in mitochondrial function. CR increases electron transport chain activity, enhances antioxidant defenses, and favors mitochondrial calcium retention capacity in the brain. These changes are accompanied by a decrease in cyclophilin D activity and acetylation and an increase in Sirt3 expression. This suggests that Sirt3-mediated deacetylation and inhibition of cyclophilin D in CR promote the inhibition of mitochondrial permeability transition, resulting in enhanced mitochondrial calcium retention. Altogether, our results indicate that enhanced mitochondrial calcium retention capacity underlies the beneficial effects of CR against excitotoxic conditions. This protection may explain the many beneficial effects of CR in the aging brain.


Assuntos
Cálcio/metabolismo , Restrição Calórica , Mitocôndrias/metabolismo , Fármacos Neuroprotetores/metabolismo , Neurotoxinas/toxicidade , Acetilação/efeitos dos fármacos , Animais , Antioxidantes/farmacologia , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Morte Celular/efeitos dos fármacos , Peptidil-Prolil Isomerase F , Ciclofilinas/metabolismo , Transporte de Elétrons/efeitos dos fármacos , Ácido Glutâmico/toxicidade , Masculino , Camundongos , Ratos Sprague-Dawley , Soro/metabolismo
16.
FEBS J ; 283(5): 822-33, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26732506

RESUMO

ß-cells quickly adjust insulin secretion to oscillations in nutrients carried by the blood, acting as fuel sensors. However, most studies of ß-cell responses to nutrients do not discriminate between fuel levels and signaling components present in the circulation. Here we studied the effect of serum from calorie-restricted rats versus serum from rats fed ad libitum, diluted tenfold in the medium, which did not contribute significantly to the pool of nutrients, on ß-cell mitochondrial function and dynamics under regular and high-nutrient culture conditions. Insulin secreting beta-cell derived line (INS1) cells incubated with serum from calorie-restricted rats (CR serum) showed higher levels of peroxisome proliferator-activated receptor gamma coactivator 1-α (PGC-1α) and active nitric oxide synthase. The expression of mitofusin-2 (Mfn-2) and optic atrophy 1 (OPA-1), proteins involved in mitochondrial fusion, was increased, while the levels of the mitochondrial fission mediator dynamin related protein 1 (DRP-1) were reduced. Consistent with changes in mitochondrial dynamics protein levels, CR serum treatment increased mitochondrial fusion rates, as well as their length and connectivity. These changes in mitochondrial morphology were associated with prolonged glucose-stimulated insulin secretion and mitochondrial respiration. When combining CR serum and high levels of glucose and palmitate (20 and 0.4 mm, respectively), an in vitro model of type II diabetes, we observed that signaling promoted by CR serum was enough to overcome glucolipotoxicity, as indicated by CR-mediated prevention of mitochondrial fusion arrest and reduced respiratory function in INS1 cells under glucolipotoxicity. Overall, our results provide evidence that non-nutrient factors in serum have a major impact on ß-cell mitochondrial adaptations to changes in metabolism.


Assuntos
Restrição Calórica , Glucose/metabolismo , Células Secretoras de Insulina/metabolismo , Mitocôndrias/metabolismo , Animais , Linhagem Celular , Respiração Celular , Separação Celular , Dinaminas/metabolismo , Citometria de Fluxo , GTP Fosfo-Hidrolases/metabolismo , Insulina/metabolismo , Masculino , Dinâmica Mitocondrial , Óxido Nítrico Sintase Tipo III/metabolismo , Consumo de Oxigênio , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo , Ratos , Ratos Sprague-Dawley , Fatores de Transcrição/metabolismo
18.
PLoS One ; 10(3): e0120413, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25749501

RESUMO

Intermittent fasting (IF) is a dietary intervention often used as an alternative to caloric restriction (CR) and characterized by 24 hour cycles alternating ad libitum feeding and fasting. Although the consequences of CR are well studied, the effects of IF on redox status are not. Here, we address the effects of IF on redox state markers in different tissues in order to uncover how changes in feeding frequency alter redox balance in rats. IF rats displayed lower body mass due to decreased energy conversion efficiency. Livers in IF rats presented increased mitochondrial respiratory capacity and enhanced levels of protein carbonyls. Surprisingly, IF animals also presented an increase in oxidative damage in the brain that was not related to changes in mitochondrial bioenergetics. Conversely, IF promoted a substantial protection against oxidative damage in the heart. No difference in mitochondrial bioenergetics or redox homeostasis was observed in skeletal muscles of IF animals. Overall, IF affects redox balance in a tissue-specific manner, leading to redox imbalance in the liver and brain and protection against oxidative damage in the heart.


Assuntos
Lesões Encefálicas , Encéfalo , Metabolismo Energético , Jejum/metabolismo , Fígado , Mitocôndrias Hepáticas , Animais , Encéfalo/metabolismo , Encéfalo/patologia , Lesões Encefálicas/metabolismo , Lesões Encefálicas/patologia , Fígado/lesões , Fígado/metabolismo , Fígado/patologia , Masculino , Mitocôndrias Hepáticas/metabolismo , Mitocôndrias Hepáticas/patologia , Oxirredução , Consumo de Oxigênio , Ratos , Ratos Sprague-Dawley
19.
Endocrinology ; 155(7): 2456-66, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24797627

RESUMO

Intermittent fasting (IF) is an often-used intervention to decrease body mass. In male Sprague-Dawley rats, 24 hour cycles of IF result in light caloric restriction, reduced body mass gain, and significant decreases in the efficiency of energy conversion. Here, we study the metabolic effects of IF in order to uncover mechanisms involved in this lower energy conversion efficiency. After 3 weeks, IF animals displayed overeating during fed periods and lower body mass, accompanied by alterations in energy-related tissue mass. The lower efficiency of energy use was not due to uncoupling of muscle mitochondria. Enhanced lipid oxidation was observed during fasting days, whereas fed days were accompanied by higher metabolic rates. Furthermore, an increased expression of orexigenic neurotransmitters AGRP and NPY in the hypothalamus of IF animals was found, even on feeding days, which could explain the overeating pattern. Together, these effects provide a mechanistic explanation for the lower efficiency of energy conversion observed. Overall, we find that IF promotes changes in hypothalamic function that explain differences in body mass and caloric intake.


Assuntos
Peso Corporal/fisiologia , Jejum/fisiologia , Comportamento Alimentar/fisiologia , Hiperfagia/fisiopatologia , Hipotálamo/metabolismo , Proteína Relacionada com Agouti/genética , Proteína Relacionada com Agouti/metabolismo , Animais , Ingestão de Alimentos/efeitos dos fármacos , Metabolismo Energético/fisiologia , Expressão Gênica , Immunoblotting , Leptina/farmacologia , Metabolismo dos Lipídeos/fisiologia , Masculino , Mitocôndrias Musculares/metabolismo , Neuropeptídeo Y/genética , Neuropeptídeo Y/metabolismo , Oxirredução , Ratos , Ratos Sprague-Dawley , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Hormônio Liberador de Tireotropina/genética , Hormônio Liberador de Tireotropina/metabolismo , Fatores de Tempo
20.
Free Radic Biol Med ; 52(11-12): 2201-8, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22564526

RESUMO

Knowledge of location and intracellular subcompartmentalization is essential for the understanding of redox processes, because oxidants, owing to their reactive nature, must be generated close to the molecules modified in both signaling and damaging processes. Here we discuss known redox characteristics of various mitochondrial microenvironments. Points covered are the locations of mitochondrial oxidant generation, characteristics of antioxidant systems in various mitochondrial compartments, and diffusion characteristics of oxidants in mitochondria. We also review techniques used to measure redox state in mitochondrial subcompartments, antioxidants targeted to mitochondrial subcompartments, and methodological concerns that must be addressed when using these tools.


Assuntos
Compartimento Celular , Mitocôndrias/fisiologia , Estresse Oxidativo , Animais , Apoptose , Humanos , Oxirredução , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...