RESUMO
AIMS/HYPOTHESIS: Repeated exposures to insulin-induced hypoglycaemia in people with diabetes progressively impairs the counterregulatory response (CRR) that restores normoglycaemia. This defect is characterised by reduced secretion of glucagon and other counterregulatory hormones. Evidence indicates that glucose-responsive neurons located in the hypothalamus orchestrate the CRR. Here, we aimed to identify the changes in hypothalamic gene and protein expression that underlie impaired CRR in a mouse model of defective CRR. METHODS: High-fat-diet fed and low-dose streptozocin-treated C57BL/6N mice were exposed to one (acute hypoglycaemia [AH]) or multiple (recurrent hypoglycaemia [RH]) insulin-induced hypoglycaemic episodes and plasma glucagon levels were measured. Single-nuclei RNA-seq (snRNA-seq) data were obtained from the hypothalamus and cortex of mice exposed to AH and RH. Proteomic data were obtained from hypothalamic synaptosomal fractions. RESULTS: The final insulin injection resulted in similar plasma glucose levels in the RH group and AH groups, but glucagon secretion was significantly lower in the RH group (AH: 94.5±9.2 ng/l [n=33]; RH: 59.0±4.8 ng/l [n=37]; p<0.001). Analysis of snRNA-seq data revealed similar proportions of hypothalamic cell subpopulations in the AH- and RH-exposed mice. Changes in transcriptional profiles were found in all cell types analysed. In neurons from RH-exposed mice, we observed a significant decrease in expression of Avp, Pmch and Pcsk1n, and the most overexpressed gene was Kcnq1ot1, as compared with AH-exposed mice. Gene ontology analysis of differentially expressed genes (DEGs) indicated a coordinated decrease in many oxidative phosphorylation genes and reduced expression of vacuolar H+- and Na+/K+-ATPases; these observations were in large part confirmed in the proteomic analysis of synaptosomal fractions. Compared with AH-exposed mice, oligodendrocytes from RH-exposed mice had major changes in gene expression that suggested reduced myelin formation. In astrocytes from RH-exposed mice, DEGs indicated reduced capacity for neurotransmitters scavenging in tripartite synapses as compared with astrocytes from AH-exposed mice. In addition, in neurons and astrocytes, multiple changes in gene expression suggested increased amyloid beta (Aß) production and stability. The snRNA-seq analysis of the cortex showed that the adaptation to RH involved different biological processes from those seen in the hypothalamus. CONCLUSIONS/INTERPRETATION: The present study provides a model of defective counterregulation in a mouse model of type 2 diabetes. It shows that repeated hypoglycaemic episodes induce multiple defects affecting all hypothalamic cell types and their interactions, indicative of impaired neuronal network signalling and dysegulated hypoglycaemia sensing, and displaying features of neurodegenerative diseases. It also shows that repeated hypoglycaemia leads to specific molecular adaptation in the hypothalamus when compared with the cortex. DATA AVAILABILITY: The transcriptomic dataset is available via the GEO ( http://www.ncbi.nlm.nih.gov/geo/ ), using the accession no. GSE226277. The proteomic dataset is available via the ProteomeXchange data repository ( http://www.proteomexchange.org ), using the accession no. PXD040183.
Assuntos
Diabetes Mellitus Tipo 2 , Hipoglicemia , Humanos , Camundongos , Animais , Glucagon/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Peptídeos beta-Amiloides , Proteômica , Camundongos Endogâmicos C57BL , Hipoglicemia/tratamento farmacológico , Insulina/metabolismo , Hipotálamo/metabolismo , Hipoglicemiantes/efeitos adversos , Perfilação da Expressão Gênica , RNA Nuclear Pequeno/metabolismo , Glicemia/metabolismoRESUMO
Stress-related psychiatric disorders and the stress system show prominent differences between males and females, as well as strongly divergent transcriptional changes. Despite several proposed mechanisms, we still lack the understanding of the molecular processes at play. Here, we explore the contribution of cell types to transcriptional sex dimorphism using single-cell RNA sequencing. We identify cell-type-specific signatures of acute restraint stress in the paraventricular nucleus of the hypothalamus, a central hub of the stress response, in male and female mice. Further, we show that a history of chronic mild stress alters these signatures in a sex-specific way, and we identify oligodendrocytes as a major target for these sex-specific effects. This dataset, which we provide as an online interactive app, offers the transcriptomes of thousands of individual cells as a molecular resource for an in-depth dissection of the interplay between cell types and sex on the mechanisms of the stress response.
Assuntos
Caracteres Sexuais , Estresse Psicológico , Camundongos , Masculino , Feminino , Animais , Estresse Psicológico/metabolismo , HipotálamoRESUMO
Lipids comprise an extremely heterogeneous group of compounds that perform a wide variety of biological functions. Traditional view of lipids as important structural components of the cell and compounds playing a trophic role is currently being supplemented by information on the possible participation of lipids in signaling, not only intracellular, but also intercellular. The review article discusses current data on the role of lipids and their metabolites formed in glial cells (astrocytes, oligodendrocytes, microglia) in communication of these cells with neurons. In addition to metabolic transformations of lipids in each type of glial cells, special attention is paid to the lipid signal molecules (phosphatidic acid, arachidonic acid and its metabolites, cholesterol, etc.) and the possibility of their participation in realization of synaptic plasticity, as well as in other possible mechanisms associated with neuroplasticity. All these new data can significantly expand our knowledge about the regulatory functions of lipids in neuroglial relationships.
Assuntos
Comunicação Celular , Lipídeos , Neuroglia , Neurônios , Ácido Araquidônico/metabolismo , Astrócitos/citologia , Astrócitos/metabolismo , Colesterol/metabolismo , Microglia/citologia , Microglia/metabolismo , Neuroglia/citologia , Neuroglia/metabolismo , Plasticidade Neuronal , Neurônios/citologia , Neurônios/metabolismo , Oligodendroglia/citologia , Oligodendroglia/metabolismo , Ácidos Fosfatídicos/metabolismo , Transdução de Sinais , Humanos , AnimaisRESUMO
Accumulating evidences suggest a strong correlation between metabolic changes and neurodegeneration in CNS demyelinating diseases such as multiple sclerosis (MS). Biotin, an essential cofactor for five carboxylases, is expressed by oligodendrocytes and involved in fatty acid synthesis and energy production. The metabolic effect of biotin or high-dose-biotin (MD1003) has been reported on rodent oligodendrocytes in vitro, and in neurodegenerative or demyelinating animal models. However, clinical studies, showed mild or no beneficial effect of MD1003 in amyotrophic lateral sclerosis (ALS) or MS. Here, we took advantage of a mouse model of myelin deficiency to study the effects of MD1003 on the behavior of murine and grafted human oligodendrocytes in vivo. We show that MD1003 increases the number and the differentiation potential of endogenous murine oligodendroglia over time. Moreover, the levels of MD1003 are increased in the plasma and brain of pups born to treated mothers, indicating that MD1003 can pass through the mother's milk. The histological analysis of the grafted animals shows that MD1003 increased proliferation and accelerates differentiation of human oligodendroglia, but without enhancing their myelination potential. These findings provide important insights into the role of MD1003 on murine and human oligodendrocyte maturation/myelination that may explain the mitigated outcome of ALS/MS clinical trials.
Assuntos
Esclerose Lateral Amiotrófica , Biotina , Esclerose Múltipla , Células Precursoras de Oligodendrócitos , Animais , Humanos , Camundongos , Esclerose Lateral Amiotrófica/metabolismo , Biotina/farmacologia , Diferenciação Celular , Esclerose Múltipla/metabolismo , Bainha de Mielina , Oligodendroglia/metabolismoRESUMO
Alzheimer's disease (AD) is a degenerative cognitive condition that affects individuals with an increasing prevalence in older age groups. There are currently five drugs on the market for AD but no new effective ones have been discovered for decades. There has been increasing interest in the use of natural remedies such as special diets and plant extracts but these require further study. Based on the known effects on white matter and neuronal conductance in Alzheimer's disease, we present a protocol for proteomic analysis of myelin-enriched brain fractions as a way of identifying potential biomarkers of efficacy. This fingerprint could be used in screening assays for novel compounds for treatment of AD.
Assuntos
Doença de Alzheimer , Proteômica , Substância Branca , Idoso , Doença de Alzheimer/diagnóstico , Doença de Alzheimer/tratamento farmacológico , Biomarcadores/análise , Humanos , Bainha de Mielina , ProteomaRESUMO
Demyelination is the hallmark of multiple sclerosis (MS). Promoting remyelination is an important strategy to treat MS. Our previous study showed that Astragalus polysaccharides (APS), the main bioactive component of Astragalus membranaceus, could prevent demyelination in experimental autoimmune encephalomyelitis mice. To investigate the effects of APS on remyelination and the underlying mechanisms, in this study we set up a cuprizone-induced demyelination model in mice and treated them with APS. It was found that APS relieved the neurobehavioral dysfunctions caused by demyelination, and efficaciously facilitated remyelination in vivo. In order to determine whether the mechanism of enhancing remyelination was associated with the differentiation of neural stem cells (NSCs), biomarkers of NSCs, astrocytes, oligodendrocytes and neurons were measured in the corpus callosum tissues of mice through Real-time PCR, Western blot and immunohistochemistry assays. Data revealed that APS suppressed the stemness of NSCs, reduced the differentiation of NSCs into astrocytes, and promoted the differentiation into oligodendrocytes and neurons. This phenomenon was confirmed in the differentiation model of C17.2 NSCs cultured in vitro. Since Sonic hedgehog signaling pathway has been proven to be crucial to the differentiation of NSCs into oligodendrocytes, we examined expression levels of the key molecules in this pathway in vivo and in vitro, and eventually found APS activated this signaling pathway. Together, our results demonstrated that APS probably activated Sonic hedgehog signaling pathway first, then induced NSCs to differentiate into oligodendrocytes and promoted remyelination, which suggested that APS might be a potential candidate in treating MS.
Assuntos
Astrágalo/química , Encefalomielite Autoimune Experimental/tratamento farmacológico , Células-Tronco Neurais/efeitos dos fármacos , Oligodendroglia/citologia , Polissacarídeos/uso terapêutico , Remielinização/efeitos dos fármacos , Animais , Diferenciação Celular/efeitos dos fármacos , Quelantes/farmacologia , Cuprizona/farmacologia , Encefalomielite Autoimune Experimental/induzido quimicamente , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Células-Tronco Neurais/citologia , Polissacarídeos/farmacologiaRESUMO
Extracellular amyloid-beta deposition and intraneuronal Tau-laden neurofibrillary tangles are prime features of Alzheimer's disease (AD). The pathology of AD is very complex and still not fully understood, since different neural cell types are involved in the disease. Although neuronal function is clearly deteriorated in AD patients, recently, an increasing number of evidences have pointed towards glial cell dysfunction as one of the main causative phenomena implicated in AD pathogenesis. The complex disease pathology together with the lack of reliable disease models have precluded the development of effective therapies able to counteract disease progression. The discovery and implementation of human pluripotent stem cell technology represents an important opportunity in this field, as this system allows the generation of patient-derived cells to be used for disease modeling and therapeutic target identification and as a platform to be employed in drug discovery programs. In this review, we discuss the current studies using human pluripotent stem cells focused on AD, providing convincing evidences that this system is an excellent opportunity to advance in the comprehension of AD pathology, which will be translated to the development of the still missing effective therapies.
Assuntos
Doença de Alzheimer/metabolismo , Técnicas de Cultura de Células/métodos , Avaliação Pré-Clínica de Medicamentos/métodos , Células-Tronco Pluripotentes Induzidas/metabolismo , Microglia/patologia , Células-Tronco Neurais/metabolismo , Organoides/metabolismo , Doença de Alzheimer/patologia , Doença de Alzheimer/terapia , Peptídeos beta-Amiloides/metabolismo , Astrócitos/metabolismo , Humanos , Células-Tronco Pluripotentes Induzidas/citologia , Microglia/citologia , Oligodendroglia/metabolismo , Proteínas tau/metabolismoRESUMO
The hypothalamic-pituitary-gonadal axis is controlled by gonadotropin-releasing hormone (GnRH) released by the hypothalamus. Disruption of this system leads to impaired reproductive maturation and function, a condition known as hypogonadotropic hypogonadism (HH). Most studies to date have focused on genetic causes of HH that impact neuronal development and function. However, variants may also impact the functioning of non-neuronal cells known as glia. Glial cells make up 50% of brain cells of humans, primates, and rodents. They include radial glial cells, microglia, astrocytes, tanycytes, oligodendrocytes, and oligodendrocyte precursor cells. Many of these cells influence the hypothalamic neuroendocrine system controlling fertility. Indeed, glia regulate GnRH neuronal activity and secretion, acting both at their cell bodies and their nerve endings. Recent work has also made clear that these interactions are an essential aspect of how the HPG axis integrates endocrine, metabolic, and environmental signals to control fertility. Recognition of the clinical importance of interactions between glia and the GnRH network may pave the way for the development of new treatment strategies for dysfunctions of puberty and adult fertility.
Assuntos
Células Endócrinas/fisiologia , Hipogonadismo/etiologia , Animais , Hormônio Liberador de Gonadotropina/metabolismo , Humanos , Hipogonadismo/metabolismo , Hipotálamo/metabolismo , Neurônios/fisiologia , Sistemas Neurossecretores/metabolismo , Sistemas Neurossecretores/fisiologia , Reprodução/fisiologiaRESUMO
An evolutionarily conserved function of glia is to provide metabolic and structural support for neurons. To identify molecules generated by glia and with vital functions for neurons, we used Drosophila melanogaster as a screening tool, and subsequently translated the findings to mice. We found that a cargo receptor operating in the secretory pathway of glia was essential to maintain axonal integrity by regulating iron buffering. Ferritin heavy chain was identified as the critical secretory cargo, required for the protection against iron-mediated ferroptotic axonal damage. In mice, ferritin heavy chain is highly expressed by oligodendrocytes and secreted by employing an unconventional secretion pathway involving extracellular vesicles. Disrupting the release of extracellular vesicles or the expression of ferritin heavy chain in oligodendrocytes causes neuronal loss and oxidative damage in mice. Our data point to a role of oligodendrocytes in providing an antioxidant defense system to support neurons against iron-mediated cytotoxicity.
Assuntos
Antioxidantes/metabolismo , Apoferritinas/metabolismo , Neurônios/metabolismo , Oligodendroglia/metabolismo , Animais , Masculino , Camundongos , Camundongos Endogâmicos C57BLRESUMO
BACKGROUND: Although historically microglia were thought to be immature in the fetal brain, evidence of purposeful interactions between these immune cells and nearby neural progenitors is becoming established. Here, we examined the influence of embryonic microglia on gliogenesis within the developing tuberal hypothalamus, a region later important for energy balance, reproduction, and thermoregulation. METHODS: We used immunohistochemistry to quantify the location and numbers of glial cells in the embryonic brain (E13.5-E17.5), as well as a pharmacological approach (i.e., PLX5622) to knock down fetal microglia. We also conducted cytokine and chemokine analyses on embryonic brains in the presence or absence of microglia, and a neurosphere assay to test the effects of the altered cytokines on hypothalamic progenitor behaviors. RESULTS: We identified a subpopulation of activated microglia that congregated adjacent to the third ventricle alongside embryonic Olig2+ neural progenitor cells (NPCs) that are destined to give rise to oligodendrocyte and astrocyte populations. In the absence of microglia, we observed an increase in Olig2+ glial progenitor cells that remained at the ventricle by E17.5 and a concomitant decrease of these Olig2+ cells in the mantle zone, indicative of a delay in migration of these precursor cells. A further examination of maturing oligodendrocytes in the hypothalamic grey and white matter area in the absence of microglia revealed migrating oligodendrocyte progenitor cells (OPCs) within the grey matter at E17.5, a time point when OPCs begin to slow their migration. Finally, quantification of cytokine and chemokine signaling in ex vivo E15.5 hypothalamic cultures +/- microglia revealed decreases in the protein levels of several cytokines in the absence of microglia. We assayed the influence of two downregulated cytokines (CCL2 and CXCL10) on neurosphere-forming capacity and lineage commitment of hypothalamic NPCs in culture and showed an increase in NPC proliferation as well as neuronal and oligodendrocyte differentiation. CONCLUSION: These data demonstrate that microglia influence gliogenesis in the developing tuberal hypothalamus.
Assuntos
Astrócitos/citologia , Hipotálamo/citologia , Hipotálamo/embriologia , Microglia/citologia , Oligodendroglia/citologia , Animais , Diferenciação Celular/fisiologia , Camundongos , Células-Tronco Neurais/citologiaRESUMO
OBJECTIVE: To explore the mechanism of electroacupuncture (EA) in accelerating the aggregation of microglia and promoting the remyelination at the location of demyelination. METHODS: C57BL/6 mice were randomly divided into 4 groups: normal, control, model (LPC) and LPCï¼EA. The demyelination model was established by microinjection of Lysolecithin (LPC, 1 µL) into the left corpus callosum. EA (2 Hz/15 Hz, 2ï¼4 mA) was applied to "Baihui"(GV20)and "Zhiyang"(GV9)for 30 minï¼once daily for 3 days, then, once every other day for 18 days. Immuno-fluorescence staining was used to observe the expression of myelin basic protein (MBP) and Axl tyrosine kinase receptor (Axl), Iba1 and numbers of Olig2-positive oligodendrocytes in the corpus callosum. Western blot was employed to detect the expression of MBP in the corpus callosum, and Oil Red O staining was used to observe changes of number of myelin pieces. RESULTS: Following modeling, the expression levels of MBP on day 5 and 10 after modeling were significantly decreased (P<0.05, P<0.01), Iba1 expression and Olig2-positive oligodendrocyte numbers on day 10 apparently increased (P<0.001, P<0.01). On day 21 after modeling, the levels of the above mentioned indexes returned to normal. After EA intervention, the levels of MBP expression on day 5 and 10, Axl, Iba1 protein expression and Olig2-positive oligodendrocyte numbers on day 5 were markedly increased (P<0.001ï¼P<0.01ï¼P<0.05), while Iba1 expression on day 10 was considerably decreased in comparison with the model group (P<0.01)ï¼Oil Red O staining showed that on day 5 after modeling, the number of red lipid droplets were obviously increased in the corpus callosum tissue on the injection side, and apparently reduced in the EA group, suggesting a clearance of the accumulated myelin fragments by EA. CONCLUSION: EA intervention may reduce myelin debris and promote the aggregation of microglial cells and oligodendrocytes to the injured site, accelerate the myelin regeneration and up-regulate the expression of MBP and Axl of corpus callosum in demyelination mice.
Assuntos
Doenças Desmielinizantes , Eletroacupuntura , Animais , Corpo Caloso , Camundongos , Camundongos Endogâmicos C57BL , Bainha de MielinaRESUMO
In the case of neurodegenerative pathologies, the therapeutic arsenal available is often directed towards the consequences of the disease. The purpose of this study is, therefore, to evaluate the ability of docosahexaenoic acid (DHA), a molecule present in certain foods and considered to have health benefits, to inhibit the cytotoxic effects of very long-chain fatty acids (C24:0, C26:0), which can contribute to the development of some neurodegenerative diseases. The effect of DHA (50 µM) on very long-chain fatty acid-induced toxicity was studied by several complementary methods: phase contrast microscopy to evaluate cell viability and morphology, the MTT test to monitor the impact on mitochondrial function, propidium iodide staining to study plasma membrane integrity, and DHE staining to measure oxidative stress. A Western blot assay was used to assess autophagy through modification of LC3 protein. The various experiments were carried out on the cellular model of 158N murine oligodendrocytes. In 158N cells, our data establish that DHA is able to inhibit all tested cytotoxic effects induced by very long-chain fatty acids.
Assuntos
Ácidos Docosa-Hexaenoicos/farmacologia , Ácidos Graxos/análise , Mitocôndrias/efeitos dos fármacos , Oligodendroglia/citologia , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Camundongos , Mitocôndrias/metabolismo , Modelos Animais , Oligodendroglia/efeitos dos fármacos , Oligodendroglia/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismoRESUMO
In schizophrenia, decreased hippocampal volume, reduced oligodendrocyte numbers in hippocampal cornu ammonis (CA) subregions and reduced neuron number in the dentate gyrus have been reported; reduced oligodendrocyte numbers were significantly related to cognitive deficits. The hippocampus is involved in cognitive functions and connected to the hypothalamus, anterior thalamus, and cingulate cortex, forming the Papez circuit, and to the mediodorsal thalamus. The relationship between the volume of these interconnected regions and oligodendrocyte and neuron numbers in schizophrenia is unknown. Therefore, we used stepwise logistic regression with subsequent multivariate stepwise linear regression and bivariate correlation to analyze oligodendrocyte and neuron numbers in the posterior hippocampal subregions CA1, CA2/3, CA4, dentate gyrus, and subiculum and volumes of the hippocampal CA region, cingulum, anterior and mediodorsal thalamus and hypothalamus in postmortem brains of 10 schizophrenia patients and 11 age- and gender-matched healthy controls. Stepwise logistic regression identified the following predictors for diagnosis, in order of inclusion: (1) oligodendrocyte number in CA4, (2) hypothalamus volume, (3) oligodendrocyte number in CA2/3, and (4) mediodorsal thalamus volume. Subsequent stepwise linear regression analyses identified the following predictors: (1) for oligodendrocyte number in CA4: (a) oligodendrocyte number in CA2/3, (b) diagnostic group, (c) hypothalamus volume, and (d) neurons in posterior subiculum; (2) for hypothalamus volume: (a) mediodorsal thalamus volume; (3) for oligodendrocyte number in CA2/3: oligodendrocyte number (a) in posterior CA4 and (b) in posterior subiculum; (4) for mediodorsal thalamus volume: volumes of (a) anterior thalamus and (b) hippocampal CA. In conclusion, we found a positive relationship between hippocampal oligodendrocyte number and the volume of the hypothalamus, a brain region connected to the hippocampus, which is important for cognition.
Assuntos
Hipocampo/patologia , Hipotálamo/patologia , Rede Nervosa/patologia , Oligodendroglia/citologia , Esquizofrenia/patologia , Tálamo/patologia , Adulto , Autopsia , Feminino , Hipocampo/citologia , Humanos , Hipotálamo/citologia , Masculino , Pessoa de Meia-Idade , Esquizofrenia/diagnósticoRESUMO
OBJECTIVE: To explore the mechanism of electroacupuncture (EA) in accelerating the aggregation of microglia and promoting the remyelination at the location of demyelination. METHODS: C57BL/6 mice were randomly divided into 4 groups: normal, control, model (LPC) and LPC+EA. The demyelination model was established by microinjection of Lysolecithin (LPC, 1 µL) into the left corpus callosum. EA (2 Hz/15 Hz, 2-4 mA) was applied to "Baihui"(GV20)and "Zhiyang"(GV9)for 30 min,once daily for 3 days, then, once every other day for 18 days. Immuno-fluorescence staining was used to observe the expression of myelin basic protein (MBP) and Axl tyrosine kinase receptor (Axl), Iba1 and numbers of Olig2-positive oligodendrocytes in the corpus callosum. Western blot was employed to detect the expression of MBP in the corpus callosum, and Oil Red O staining was used to observe changes of number of myelin pieces. RESULTS: Following modeling, the expression levels of MBP on day 5 and 10 after modeling were significantly decreased (P<0.05, P<0.01), Iba1 expression and Olig2-positive oligodendrocyte numbers on day 10 apparently increased (P<0.001, P<0.01). On day 21 after modeling, the levels of the above mentioned indexes returned to normal. After EA intervention, the levels of MBP expression on day 5 and 10, Axl, Iba1 protein expression and Olig2-positive oligodendrocyte numbers on day 5 were markedly increased (P<0.001,P<0.01,P<0.05), while Iba1 expression on day 10 was considerably decreased in comparison with the model group (P<0.01).Oil Red O staining showed that on day 5 after modeling, the number of red lipid droplets were obviously increased in the corpus callosum tissue on the injection side, and apparently reduced in the EA group, suggesting a clearance of the accumulated myelin fragments by EA. CONCLUSION: EA intervention may reduce myelin debris and promote the aggregation of microglial cells and oligodendrocytes to the injured site, accelerate the myelin regeneration and up-regulate the expression of MBP and Axl of corpus callosum in demyelination mice.
RESUMO
BACKGROUND: Hypothalamic inflammation including astrogliosis and microglia activation occurs after intake of high fat diet (HFD) in rodent models or in obese individuals. However, the effect of chronic HFD feeding on oligodendrocytes (OLGs), a myelin-producing glial population in the central nervous system (CNS), remains unclear. In this study, we used 8-week old male C57BL/6 mice fed by HFD for 3-6 months to induce chronic obesity. RESULTS: The transmission electron microscopy imaging analysis showed that the integrity of hypothalamic myelin was disrupted after HFD feeding for 4 and 6 months. Moreover, the accumulation of Iba1+-microglia with an amoeboid hypertrophic form was continually observed in arcuate nucleus of HFD-fed mice during the entire feeding time period. Interleukin-33 (IL-33), a tissue alarmin upon injury to the CNS, was detected with an increased level in hypothalamus after HFD feeding for 3 and 4 months. Furthermore, the in vitro study indicated that exposure of mature OLGs to IL-33 impaired OLG cell structure along with a decline in the expression of myelin basic protein. CONCLUSIONS: Altogether, our findings demonstrate that chronic HFD feeding triggers hypothalamic myelin disruption in accompany with IL-33 upregulation and prolonged microglial activation in hypothalamus. Given that the addition of exogenous IL-33 was harmful for the maturation of OLGs, an increase in IL-33 by chronic HFD feeding might contribute to the induction of hypothalamic myelin disruption.
Assuntos
Dieta Hiperlipídica/efeitos adversos , Hipotálamo/metabolismo , Interleucina-33/metabolismo , Bainha de Mielina/patologia , Regulação para Cima , Animais , Núcleo Arqueado do Hipotálamo/metabolismo , Núcleo Arqueado do Hipotálamo/patologia , Hipotálamo/patologia , Masculino , Camundongos , Proteína Básica da Mielina/biossíntese , Bainha de Mielina/metabolismo , Oligodendroglia/metabolismo , Oligodendroglia/patologia , Cultura Primária de Células , Ratos , Fatores de TempoRESUMO
OBJECTIVE: Age-related diseases, including neurodegenerative diseases, are associated with oxidative stress and lipid peroxidation, and increase the levels of cholesterol auto-oxidation products such as 7ß-hydroxycholesterol (7ß-OHC). Thus, it is imperative to identify agents that can prevent 7ß-OHC-induced side-effects. METHODS: We evaluated the potential protective effects of Carpobrotus edulis ethanol-water extract (EWe) on murine oligodendrocytes (158N) cultured in the absence or presence of 7ß-OHC (20 µg/mL, 24 h). The cells were incubated with EWe (20-200 µg/mL) 2 h before 7ß-OHC treatment. Mitochondrial activity and cell growth were evaluated with the MTT assay. Photometric methods were used to analyze antioxidant enzyme [catalase (CAT) and glutathione peroxidase (GPx)] activities and the generation of lipid and protein oxidation products [malondialdehyde (MDA), conjugated diene (CD), and carbonylated proteins (CPs)]. RESULTS: Treatment with 7ß-OHC induced cell death and oxidative stress (reflected by alteration in CAT and SOD activities). Overproduction of lipid peroxidation products (MDA and CDs) and CPs was also reported. The cytotoxic effects associated with 7ß-OHC were attenuated by 160 µg/mL of EWe of C. edulis. Cell death induced by 7ß-OHC treatment was ameliorated, GPx and CAT activities were restored to normal, and MDA, CD, and CP levels were reduced following C. edulis extract treatment. CONCLUSION: These data demonstrate the protective activities of C. edulis EWe against 7ß-OHC-induced disequilibrium in the redox status of 158N cells, indicative of the potential role of this plant extract in the prevention of neurodegenerative diseases.
Assuntos
Aizoaceae , Doenças Neurodegenerativas/prevenção & controle , Oligodendroglia/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Extratos Vegetais/farmacologia , Animais , Linhagem Celular , Avaliação Pré-Clínica de Medicamentos , Hidroxicolesteróis , Camundongos , Neuroproteção , Oligodendroglia/metabolismo , Fitoterapia , Extratos Vegetais/uso terapêuticoRESUMO
BACKGROUND: Humans are widely exposed to acrylamide (ACR) and its neurotoxicity is a significant public health issue attracting wide attention. The aim of the study was to investigate ACR-induced adverse cerebellar changes in rats and study the possible oligodendrogenic effect of omega 3 and green tea. MATERIALS AND METHODS: Twenty-four adult albino rats weighing 150-200 g were randomly divided into four equal groups (6 rats each): control group (Group I), the rats that received ACR 45 mg/kg/day (Group II), the rats that received ACR concomitant with omega 3 at a dosage of 200 mg/kg/day (Group III), the rats that received ACR concomitant with green tea dissolved in drinking water at a dosage of 5 g/L (Group IV). The rats were euthanized after 8 weeks of the experiment. Malondialdehyde (MDA) and glutathione (GSH) were measured in cerebellar homogenates. Sections of 5 µm thickness from specimens from the cerebellum were stained with haematoxylin and eosin, silver stain and immunohistochemical stains: platelet-derived growth factor alpha (PDGFα; for oligodendrocytes), glial fibrillary acidic protein (GFAP; for astrocytes) and BCL2 (antiapoptotic). RESULTS: Omega 3 and green tea had improved MDA and GSH as compared to the ACR group. Histologically, the ACR group showed variable degrees of cellular degeneration. Omega 3 had induced oligodendrogenesis in Group III. The optical density of silver stain was significantly (p < 0.05) increased in Groups III and IV as compared to the ACR group. Area per cent of positive PDGFα was significantly increased in the ACR + omega 3 group as compared to the ACR group. Area per cent of positive GFAP was significantly decreased in Groups III and IV as compared to the ACR group. Area per cent of positive BCL2 was significantly increased in the omega 3-trated group as compared to the ACR group. CONCLUSIONS: Concomitant administration of omega 3 or green tea with ACR might mitigate the adverse cerebellar changes caused by ACR thanks to an oligodendrogenic effect of omega 3.
Assuntos
Acrilamida/toxicidade , Cerebelo/patologia , Ácidos Graxos Ômega-3/farmacologia , Oligodendroglia/patologia , Chá/química , Animais , Antioxidantes/metabolismo , Astrócitos/efeitos dos fármacos , Astrócitos/metabolismo , Biomarcadores/metabolismo , Peso Corporal/efeitos dos fármacos , Cerebelo/efeitos dos fármacos , Masculino , Oligodendroglia/efeitos dos fármacos , Células PC12 , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Células de Purkinje/efeitos dos fármacos , Células de Purkinje/patologia , RatosRESUMO
OBJECTIVE@#Age-related diseases, including neurodegenerative diseases, are associated with oxidative stress and lipid peroxidation, and increase the levels of cholesterol auto-oxidation products such as 7β-hydroxycholesterol (7β-OHC). Thus, it is imperative to identify agents that can prevent 7β-OHC-induced side-effects.@*METHODS@#We evaluated the potential protective effects of Carpobrotus edulis ethanol-water extract (EWe) on murine oligodendrocytes (158N) cultured in the absence or presence of 7β-OHC (20 μg/mL, 24 h). The cells were incubated with EWe (20-200 µg/mL) 2 h before 7β-OHC treatment. Mitochondrial activity and cell growth were evaluated with the MTT assay. Photometric methods were used to analyze antioxidant enzyme [catalase (CAT) and glutathione peroxidase (GPx)] activities and the generation of lipid and protein oxidation products [malondialdehyde (MDA), conjugated diene (CD), and carbonylated proteins (CPs)].@*RESULTS@#Treatment with 7β-OHC induced cell death and oxidative stress (reflected by alteration in CAT and SOD activities). Overproduction of lipid peroxidation products (MDA and CDs) and CPs was also reported. The cytotoxic effects associated with 7β-OHC were attenuated by 160 μg/mL of EWe of C. edulis. Cell death induced by 7β-OHC treatment was ameliorated, GPx and CAT activities were restored to normal, and MDA, CD, and CP levels were reduced following C. edulis extract treatment.@*CONCLUSION@#These data demonstrate the protective activities of C. edulis EWe against 7β-OHC-induced disequilibrium in the redox status of 158N cells, indicative of the potential role of this plant extract in the prevention of neurodegenerative diseases.
Assuntos
Animais , Camundongos , Aizoaceae , Linhagem Celular , Avaliação Pré-Clínica de Medicamentos , Hidroxicolesteróis , Doenças Neurodegenerativas , Neuroproteção , Oligodendroglia , Metabolismo , Estresse Oxidativo , Fitoterapia , Extratos Vegetais , Farmacologia , Usos TerapêuticosRESUMO
Gap junctions (GJs) coupling oligodendrocytes to astrocytes and to other oligodendrocytes are formed mainly by connexin47 (Cx47) and a smaller portion by connexin32 (Cx32). Mutations in both connexins cause inherited demyelinating disorders, but their expression is also disrupted in multiple sclerosis (MS). To clarify whether the loss of either Cx47 or Cx32 could modify the outcome of inflammation and myelin loss, we induced experimental autoimmune encephalomyelitis (EAE) in fully backcrossed Cx32 knockout (KO) and Cx47KO mice and compared their outcome with wild type (WT, C57BI/6 N) mice. Cx47KO EAE mice developed the most severe phenotype assessed by clinical scores and behavioral testing, followed by Cx32KO and WT mice. Cx47KO more than Cx32KO EAE mice developed more microglial activation, myelin, and axonal loss than did WT mice. Oligodendrocyte apoptosis and precursor proliferation was also higher in Cx47KO than in Cx32KO or WT EAE mice. Similarly, blood-spinal cord barrier (BSCB) disruption and inflammatory infiltrates of macrophages, T- and B-cells were more severe in Cx47KO than either Cx32KO or WT EAE groups. Finally, expression profiling revealed that several proinflammatory cytokines were higher at the peak of inflammation in the Cx47KO mice and persisted at later stages of EAE in contrast to reduction of their levels in WT EAE mice. Thus, loss of oligodendrocyte GJs aggravates BSCB disruption and inflammatory myelin loss, likely due to dysregulation of proinflammatory cytokines. This mechanism may play an important role in MS brain with reduced connexin expression, as well as in patients with inherited mutations in oligodendrocyte connexins and secondary inflammation.
Assuntos
Citocinas/metabolismo , Encefalomielite Autoimune Experimental/patologia , Junções Comunicantes/metabolismo , Regulação da Expressão Gênica/fisiologia , Força da Mão/fisiologia , Oligodendroglia/metabolismo , Animais , Apoptose/genética , Astrócitos/metabolismo , Astrócitos/patologia , Barreira Hematoencefálica/efeitos dos fármacos , Barreira Hematoencefálica/fisiopatologia , Proteínas de Ligação ao Cálcio/metabolismo , Proliferação de Células/genética , Conexinas/genética , Conexinas/metabolismo , Modelos Animais de Doenças , Encefalomielite Autoimune Experimental/induzido quimicamente , Encefalomielite Autoimune Experimental/genética , Encefalomielite Autoimune Experimental/fisiopatologia , Adjuvante de Freund/toxicidade , Junções Comunicantes/patologia , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/genética , Macrófagos/patologia , Camundongos , Camundongos Endogâmicos C57BL , Proteínas dos Microfilamentos/metabolismo , Atividade Motora/efeitos dos fármacos , Atividade Motora/genética , Glicoproteína Mielina-Oligodendrócito/toxicidade , Oligodendroglia/patologia , Fragmentos de Peptídeos/toxicidade , Proteína beta-1 de Junções ComunicantesRESUMO
BACKGROUND: Tumor necrosis factor (TNF) is associated with several neurodegenerative disorders including multiple sclerosis (MS). Although TNF-targeted therapies have been largely unsuccessful in MS, recent preclinical data suggests selective soluble TNF inhibition can promote remyelination. This has renewed interest in regulation of TNF signaling in demyelinating disease, especially given the limited treatment options for progressive MS. Using a mouse model of progressive MS, this study evaluates the effects of sustained TNF on oligodendrocyte (OLG) apoptosis and OLG precursor cell (OPC) differentiation. METHODS: Induction of experimental autoimmune encephalomyelitis (EAE) in transgenic mice expressing a dominant-negative interferon-γ receptor under the human glial fibrillary acidic protein promoter (GFAPγR1Δ) causes severe non-remitting disease associated with sustained TNF. Therapeutic effects in GFAPγR1Δ mice treated with anti-TNF compared to control antibody during acute EAE were evaluated by assessing demyelinating lesion size, remyelination, OLG apoptosis, and OPC differentiation. RESULTS: More severe and enlarged demyelinating lesions in GFAPγR1Δ compared to wild-type (WT) mice were associated with increased OLG apoptosis and reduced differentiated CC1+Olig2+ OLG within lesions, as well as impaired upregulation of TNF receptor-2, suggesting impaired OPC differentiation. TNF blockade during acute EAE in GFAPγR1Δ both limited OLG apoptosis and enhanced OPC differentiation consistent with reduced lesion size and clinical recovery. TNF neutralization further limited increasing endothelin-1 (ET-1) expression in astrocytes and myeloid cells noted in lesions during disease progression in GFAPγR1Δ mice, supporting inhibitory effects of ET-1 on OPC maturation. CONCLUSION: Our data implicate that IFNγ signaling to astrocytes is essential to limit a detrimental positive feedback loop of TNF and ET-1 production, which increases OLG apoptosis and impairs OPC differentiation. Interference of this cycle by TNF blockade promotes repair independent of TNFR2 and supports selective TNF targeting to mitigate progressive forms of MS.