RESUMO
Perturbations of lipid homeostasis manifest as dyslipidemias and obesity, which are significant risk factors for atherosclerosis and diabetes. Lipoprotein receptors in the liver are key players in the regulation of lipid homeostasis, among which the hepatic lipolysis stimulated lipoprotein receptor, LSR, was recently shown to play an important role in the removal of lipoproteins from the circulation during the postprandial phase. Since heterozygous LSR+/- mice demonstrate moderate dyslipidemia and develop higher body weight gain in response to high-fat diet compared with littermate LSR+/+ controls, we questioned if LSR heterozygosity could affect genes related to hepatic lipid metabolism. A target-specific qPCR array for 84 genes related to lipid metabolism was performed on mRNA isolated from livers of 6 mo old female LSR+/- mice and LSR+/+ littermates following a 6 wk period on a standard (STD) or high-fat diet (60% kcal, HFD). Of the 84 genes studied, 32 were significantly downregulated in STD-LSR+/- mice compared with STD-LSR+/+, a majority of which were PPARα target genes involved in lipid metabolism and transport, and insulin and adipokine-signaling pathways. Of these 32 genes, 80% were also modified in HFD-LSR+/+, suggesting that STD-LSR+/- mice demonstrated a predisposition towards a "high-fat"-like profile, which could reflect dysregulation of liver lipid homeostasis. Since similar profiles of genes were affected by either LSR heterozygosity or by high-fat diet, this would suggest that LSR is a key receptor in regulating hepatic lipid homeostasis, and whose downregulation combined with a Western-type diet may increase predisposition to diet-induced obesity.
Assuntos
Dieta Hiperlipídica/efeitos adversos , Homeostase/genética , Metabolismo dos Lipídeos/genética , Fígado/metabolismo , Receptores de Lipoproteínas/genética , Transcriptoma/genética , Animais , Regulação para Baixo/genética , Feminino , Heterozigoto , Insulina/genética , Lipídeos/genética , Camundongos , Obesidade/genética , Aumento de Peso/genéticaRESUMO
BACKGROUND: We aimed to determine the association of clinical and routine cerebrospinal fluid biochemical markers (total protein, IgG index and oligoclonal bands) with disability in multiple sclerosis and whether these biomarkers assessed at diagnosis add prognostic value. METHODS: We followed a cohort of patients included in the Multiple Sclerosis Lorraine Register (eastern France) who had a diagnosis of multiple sclerosis for at least 5 years, as well as biological markers values and MRI findings (Barkhof's criteria). In a Cox regression model, endpoint was time to score of 4 on the Expanded Disability Status Scale (EDSS) (i.e., limited time walking without aid or rest for more than 500 m). RESULTS: For 407 patients included, the median time from multiple sclerosis onset to EDSS score 4 was 4.5 years [2.2-7.2]. Cerebrospinal fluid total protein factor < 500 mg/L was associated with EDSS score 4 on bivariate analysis (hazard ratio 0.66, 95% confidence interval 0.46-0.95, p = 0.02). On multivariate analysis, older age at disease onset (≥50 years) and initial primary progressive course of MS but not biological markers predicted worse prognosis. CONCLUSION: Routine cerebrospinal fluid biological markers at diagnosis were not prognostic factors of multiple sclerosis progression.
Assuntos
Biomarcadores/líquido cefalorraquidiano , Progressão da Doença , Esclerose Múltipla/diagnóstico , Valor Preditivo dos Testes , Sistema de Registros , Adulto , Feminino , Seguimentos , França , Humanos , Masculino , Pessoa de Meia-Idade , Esclerose Múltipla/líquido cefalorraquidiano , Prognóstico , Índice de Gravidade de Doença , Adulto JovemRESUMO
The development of novel therapeutic strategies for Alzheimer's disease (AD) represents one of the biggest unmet medical needs today. Application of neurotrophic factors able to modulate neuronal survival and synaptic connectivity is a promising therapeutic approach for AD. We aimed to determine whether the loco-regional delivery of ciliary neurotrophic factor (CNTF) could prevent amyloid-beta (Abeta) oligomer-induced synaptic damages and associated cognitive impairments that typify AD. To ensure long-term administration of CNTF in the brain, we used recombinant cells secreting CNTF encapsulated in alginate polymers. The implantation of these bioreactors in the brain of Abeta oligomer-infused mice led to a continuous secretion of recombinant CNTF and was associated with the robust improvement of cognitive performances. Most importantly, CNTF led to full recovery of cognitive functions associated with the stabilization of synaptic protein levels in the Tg2576 AD mouse model. In vitro as well as in vivo, CNTF activated a Janus kinase/signal transducer and activator of transcription-mediated survival pathway that prevented synaptic and neuronal degeneration. These preclinical studies suggest that CNTF and/or CNTF receptor-associated pathways may have AD-modifying activity through protection against progressive Abeta-related memory deficits. Our data also encourage additional exploration of ex vivo gene transfer for the prevention and/or treatment of AD.
Assuntos
Doença de Alzheimer/complicações , Fator Neurotrófico Ciliar/biossíntese , Fator Neurotrófico Ciliar/uso terapêutico , Transtornos da Memória/etiologia , Transtornos da Memória/terapia , Sinapses/efeitos dos fármacos , Doença de Alzheimer/genética , Peptídeos beta-Amiloides/administração & dosagem , Peptídeos beta-Amiloides/metabolismo , Peptídeos beta-Amiloides/farmacologia , Precursor de Proteína beta-Amiloide/genética , Animais , Apoptose/genética , Encéfalo/patologia , Contagem de Células/métodos , Terapia Baseada em Transplante de Células e Tecidos/métodos , Células Cultivadas , Fator Neurotrófico Ciliar/administração & dosagem , Modelos Animais de Doenças , Inibidores Enzimáticos/farmacologia , Ensaio de Imunoadsorção Enzimática/métodos , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/genética , Proteínas de Fluorescência Verde/genética , Humanos , Masculino , Aprendizagem em Labirinto/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Mutação/genética , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Fragmentos de Peptídeos/administração & dosagem , Fragmentos de Peptídeos/farmacologia , Transdução de Sinais/efeitos dos fármacos , Sinapses/metabolismo , Sinaptossomos/metabolismo , Sinaptossomos/patologia , Sinaptossomos/ultraestrutura , Fatores de Tempo , Transfecção/métodosRESUMO
As a hepatic receptor for triglyceride-rich lipoproteins, the lipolysis-stimulated lipoprotein receptor (LSR) may be involved in the dynamics of lipid distribution between the liver and peripheral tissues. Here, we explore the potential role of leptin in regulating LSR. At physiological concentrations (1-10 ng/ml), leptin increased LSR protein and mRNA levels in Hepa1-6 cells through an ERK1/2-dependent and α-amanitin-sensitive pathway. In vivo, leptin treatment of C57BL6/Rj mice (1 µg 2×/d, 8 d) led to a significant increase in hepatic LSR mRNA and protein, decreased liver triglycerides and increased VLDL secretion as compared to controls. LSR(+/-) mice with elevated postprandial lipemia placed on a high-fat (60% kcal) diet exhibited accelerated weight gain and increased fat mass as compared to controls. While plasma leptin levels were increased 3-fold, hepatic leptin receptor protein levels and phosphorylation of ERK1/2 were significantly reduced. Therefore, leptin is an important regulator of LSR protein levels providing the means for the control of hepatic uptake of lipids during the postprandial phase. However, this may no longer be functional in LSR(+/-) mice placed under a chronic dietary fat load, suggesting that this animal model could be useful for the study of molecular mechanisms involved in peripheral leptin resistance.
Assuntos
Leptina/farmacologia , Metabolismo dos Lipídeos/efeitos dos fármacos , Lipólise/efeitos dos fármacos , Fígado/efeitos dos fármacos , Período Pós-Prandial , Receptores de Lipoproteínas/metabolismo , Regulação para Cima/efeitos dos fármacos , Animais , Western Blotting , Peso Corporal/efeitos dos fármacos , Linhagem Celular , Imunofluorescência , Leptina/sangue , Fígado/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Reação em Cadeia da PolimeraseRESUMO
BACKGROUND: The molecular basis of McCune Albright syndrome (MAS) is a recurrent GNAS Postzygotic gain of function sporadic mutation, resulting in a mosaic disease. Most of girls present precocious puberty, caused by the development of recurrent ovarian cysts with autonomous Hyperestrogenic stimulation. After menarche, the majority of patients with ovarian GNAS mutation have menstrual disturbances and infertility. OBJECTIVES: We wanted to focus on the fertility of MAS females and propose an appropriate management, by a detailed case report and an exhaustive review of the literature on fertility and pregnancy in MAS females. RESULTS: We present the case of a 29-year-old MAS female, who had previously undergone a unilateral ovariectomy and was managed by in vitro fertilization (IVF). Eight oocytes with many morphological abnormalities were retrieved. The GNAS mutation was found at a low frequency in follicular cells. The ovarian histopathological examination showed developing follicles of all stages, strongly expressing AMH by immunohistochemistry. In addition, AMH was high (45.5 pmol/L) and the AMH / AFC ratio (5.69 pmol/L per follicle) was much higher than in PCOS and control groups (2.16, and 1.34 respectively). CONCLUSIONS: Ovarian and endometrial involvement can be responsible for infertility in MAS women. IVF and oophorectomy may be useful in management. The genetic characterization of the different tissues may have a prognostic utility. Moreover, we suggest that the AMH could be a marker of the ovarian activity in MAS. Further studies are needed to clarify the potential oocyte abnormalities and the risk of miscarriages in order to guide genetic counseling.
Assuntos
Hormônio Antimülleriano/metabolismo , Fertilização in vitro/métodos , Displasia Fibrosa Poliostótica/complicações , Infertilidade Feminina/terapia , Adulto , Feminino , Displasia Fibrosa Poliostótica/genética , Humanos , Infertilidade Feminina/genética , Ovariectomia/métodosRESUMO
BACKGROUND/OBJECTIVE: The aim of this study was to assess, in routine, the rates with which an amyloid deposition was documented by 18F-florbetaben PET in patients with suspected Alzheimer's disease (AD) but with isolated increases in cerebrospinal fluid (CSF) tau-protein concentrations, and the subsequent impact of these PET results on medical management. METHODS: This prospective study included 34 patients with mild neurocognitive disorders (MND) and suspected AD (73±9 years, 16 women) and with abnormal CSF concentrations in total-tau (T-tau) and/or phosphorylated-tau (P-tau) proteins but normal Aß42 concentration and Aß42/Aß40 ratio. These patients were referred to 8F-florbetaben PET from which the PET-related changes in the confidence for AD diagnosis (low, intermediate, or high) and treatments were reported. RESULTS: The PET examinations were positive for amyloid deposition (brain amyloid plaque load, BAPL score >1) in none of the 9 patients with an increase in only T-tau proteins and in 8 among the 25 (32%) with an increase in P-tau proteins (one BAPL score of 2 and seven BAPL scores of 3). Knowledge of the PET results was associated with subsequent changes in diagnostic confidence in 44% of patients (15/34) and in the intention-to-treat with a cholinesterase inhibitor drug in 18% (6/34). CONCLUSION: In patients with suspected AD and isolated increase in CSF tau protein concentrations, an amyloid deposition is documented by 18F-florbetaben PET in as much as one third of cases when the concentration of P-tau is abnormal, and PET results are associated with significant further changes in medical management.
Assuntos
Doença de Alzheimer/diagnóstico por imagem , Proteínas Amiloidogênicas/metabolismo , Proteínas tau/líquido cefalorraquidiano , Idoso , Doença de Alzheimer/líquido cefalorraquidiano , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Compostos de Anilina , Feminino , Radioisótopos de Flúor , Humanos , Masculino , Neuroimagem , Fragmentos de Peptídeos/metabolismo , Tomografia por Emissão de Pósitrons , Estudos Prospectivos , EstilbenosRESUMO
Alzheimer's disease (AD) is a major public health concern in all countries. Although the precise cause of AD is still unknown, a growing body of evidence supports the notion that soluble amyloid beta-peptide (Abeta) may be the proximate cause of synaptic injuries and neuronal death early in the disease. AD patients display lower levels of docosahexaenoic acid (DHA, C22:6 ; n-3) in plasma and brain tissues as compared to age-matched controls. Furthermore, epidemiological studies suggest that high DHA intake might have protective properties against neurodegenerative diseases. These observations are supported by in vivo studies showing that DHA-rich diets limits the synaptic loss and cognitive defects induced by Abeta peptide. Although the molecular basis of these neuroprotective effects remains unknown, several mechanisms have been proposed such as (i) regulation of the expression of potentially protective genes, (ii) activation of anti-inflammatory pathways, (iii) modulation of functional properties of the synaptic membranes along with changes in their physicochemical and structural features.
Assuntos
Doença de Alzheimer/dietoterapia , Doença de Alzheimer/prevenção & controle , Peptídeos beta-Amiloides/antagonistas & inibidores , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Ácidos Docosa-Hexaenoicos/uso terapêutico , Encefalite/dietoterapia , Fármacos Neuroprotetores/uso terapêutico , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Animais , Encéfalo/fisiopatologia , Ácidos Docosa-Hexaenoicos/metabolismo , Encefalite/metabolismo , Encefalite/fisiopatologia , Alimentos Formulados/normas , Humanos , Metabolismo dos Lipídeos/efeitos dos fármacos , Metabolismo dos Lipídeos/fisiologia , Fármacos Neuroprotetores/metabolismo , Sinapses/efeitos dos fármacos , Sinapses/metabolismoRESUMO
BACKGROUND: Alzheimer's disease (AD) cerebrospinal fluid (CSF) biomarkers have recently been included in the criteria for AD diagnosis. Unfortunately, their wider use in routine and interpretation require more standardization, particularly for the pre-analytical steps. In particular, amyloid-ß (Aß)42 peptide measurement is strongly influenced by the type of collection tube and by repeated freeze/thaw cycles. OBJECTIVE: The objectives of this study were to compare, in clinical setting, the impact of collection tubes and the repetition of freeze/thaw cycles on Aß42 and Aß40 concentrations and consequently determine if the Aß42/Aß40 ratio could resolve the diagnosis difficulties related to these pre-analytical parameters. METHODS: CSF from 35 patients was collected in different polypropylene (PP) and stored at - 80°C after sampling. For CSF collected in the reference tube, three successive freeze-thaw cycles were done. Aß42 and Aß40 concentrations were determined in each condition in order to calculate the Aß42/Aß40 ratio. RESULTS: Our results showed that CSF Aß42 and Aß40 values were significantly different according to the type of collection tube and the number of freeze/thaw cycles. Although the calculation of the Aß42/Aß40 ratio eliminated the effect of PP tube-dependent variation, this was not the case for freeze-thaw cycle-associated variation. CONCLUSION: The use of Aß42/Aß40 ratio rather than Aß42 alone could contribute toward pre-analytical standardization, thus allowing the general use of CSF AD biomarkers in routine practice.
Assuntos
Peptídeos beta-Amiloides/líquido cefalorraquidiano , Fragmentos de Peptídeos/líquido cefalorraquidiano , Manejo de Espécimes/normas , Idoso , Idoso de 80 Anos ou mais , Biomarcadores/líquido cefalorraquidiano , Feminino , Congelamento , Humanos , Masculino , Pessoa de Meia-Idade , Polipropilenos , Manejo de Espécimes/instrumentação , Proteínas tau/líquido cefalorraquidianoRESUMO
Although a major risk factor for Alzheimer's disease (AD), the "aging" parameter is not systematically considered in preclinical validation of anti-AD drugs. To explore how aging affects neuronal reactivity to anti-AD agents, the ciliary neurotrophic factor (CNTF)-associated pathway was chosen as a model. Comparison of the neuroprotective properties of CNTF in 6- and 18-month old mice revealed that CNTF resistance in the older animals is associated with the exclusion of the CNTF-receptor subunits from rafts and their subsequent dispersion to non-raft cortical membrane domains. This age-dependent membrane remodeling prevented both the formation of active CNTF-receptor complexes and the activation of prosurvival STAT3 and ERK1/2 pathways, demonstrating that age-altered membranes impaired the reactivity of potential therapeutic targets. CNTF-receptor distribution and CNTF signaling responses were improved in older mice receiving dietary docosahexaenoic acid, with CNTF-receptor functionality being similar to those of younger mice, pointing toward dietary intervention as a promising adjuvant strategy to maintain functional neuronal membranes, thus allowing the associated receptors to respond appropriately to anti-AD agents.
Assuntos
Envelhecimento/genética , Envelhecimento/fisiologia , Encéfalo/citologia , Membrana Celular/fisiologia , Neurônios/citologia , Nootrópicos/uso terapêutico , Animais , Fator Neurotrófico Ciliar/fisiologia , Gorduras Insaturadas na Dieta , Ácidos Docosa-Hexaenoicos , Sistema de Sinalização das MAP Quinases/fisiologia , Masculino , Microdomínios da Membrana , Camundongos Endogâmicos C57BL , Receptor do Fator Neutrófico Ciliar/fisiologia , Fator de Transcrição STAT3/metabolismo , Transdução de SinaisRESUMO
Recent data have revealed that soluble oligomeric forms of amyloid peptide (Abeta) may be the proximate effectors of the neuronal injury and death occurring in Alzheimer's disease (AD). However, the molecular mechanisms associated with the neuronal cell death induced by the nonfibrillar Abeta remain to be elucidated. In this study, we investigated the role of the cytosolic Ca2+-dependent phospholipase A2 (cPLA2), and its associated metabolic pathway, i.e., the arachidonic acid (AA) cascade, in the apoptotic cell death induced by soluble oligomers of Abeta. The treatment of rat cortical neurons with low concentrations of soluble Abeta(1-40) or Abeta(1-42) peptide resulted in an early calcium-dependent release of AA associated with a transient relocalization of cPLA2. Both cPLA2 antisense oligonucleotides and a selective inhibitor of cPLA2 activity abolished the release of AA from neurons and also protected cells against apoptosis induced by Abeta. Furthermore, inhibitors of the PKC, p38, and MEK/ERK pathways that are involved in cPLA2 phosphorylation and activation reduced Abeta-induced cell death. Finally, we demonstrate that inhibitors of cyclooxygenase-2 reduced the Abeta-induced cell death by 55%. Our studies suggest a novel neuronal response of soluble oligomers of Abeta, which occurs through a cPLA2 signaling cascade and an AA-dependent death pathway. This may prove to be crucial in AD processes and could provide important targets for drug development.
Assuntos
Peptídeos beta-Amiloides/metabolismo , Apoptose/fisiologia , Citosol/enzimologia , Neurônios/enzimologia , Neurônios/fisiologia , Fragmentos de Peptídeos/metabolismo , Fosfolipases A/metabolismo , Animais , Ácido Araquidônico/metabolismo , Células Cultivadas , Córtex Cerebral/citologia , Ciclo-Oxigenase 2 , Humanos , Proteínas de Membrana , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Fosfolipases A2 , Prostaglandina-Endoperóxido Sintases/metabolismo , Ratos , SolubilidadeRESUMO
Oligomeric amyloid-ß (Aß) peptide contributes to impaired synaptic connections and neurodegenerative processes, and as such, represents a primary therapeutic target for Alzheimer's disease (AD)-modifying approaches. However, the lack of efficacy of drugs that inhibit production of Aß demonstrates the need for a better characterization of its toxic effects, both on synaptic and neuronal function. Here, we used conditioned medium obtained from recombinant HEK-AßPP cells expressing the human amyloid-ß protein precursor (Aß-CM), to investigate Aß-induced neurotoxic and synaptotoxic effects. Characterization of Aß-CM revealed that it contained picomolar amounts of cell-secreted Aß in its soluble form. Incubation of primary cortical neurons with Aß-CM led to significant decreases in synaptic protein levels as compared to controls. This effect was no longer observed in neurons incubated with conditioned medium obtained from HEK-AßPP cells grown in presence of the γ-secretase inhibitor, Semagacestat or LY450139 (LY-CM). However, neurotoxic and pro-apoptotic effects of Aß-CM were only partially prevented using LY-CM, which could be explained by other deleterious compounds related to chronic oxidative stress that were released by HEK-AßPP cells. Indeed, full neuroprotection was observed in cells exposed to LY-CM by additional treatment with the antioxidant resveratrol, or with the pluripotent n-3 polyunsaturated fatty acid docosahexaenoic acid. Inhibition of Aß production appeared necessary but insufficient to prevent neurodegenerative effects associated with AD due to other neurotoxic compounds that could exert additional deleterious effects on neuronal function and survival. Therefore, association of various types of protective agents needs to be considered when developing strategies for AD treatment.
Assuntos
Peptídeos beta-Amiloides/farmacologia , Neurônios/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Alanina/análogos & derivados , Alanina/farmacologia , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Análise de Variância , Animais , Azepinas/farmacologia , Caspase 3/metabolismo , Células Cultivadas , Córtex Cerebral/citologia , Meios de Cultivo Condicionados/farmacologia , Embrião de Mamíferos , Proteína Glial Fibrilar Ácida/metabolismo , Humanos , Estresse Oxidativo/efeitos dos fármacos , Estresse Oxidativo/genética , Fosfopiruvato Hidratase/metabolismo , Ratos , Transdução de Sinais/efeitos dos fármacos , TransfecçãoRESUMO
Lipids are the fundamental structural components of biological membranes. For a long time considered as simple barriers segregating aqueous compartments, membranes are now viewed as dynamic interfaces providing a molecular environment favorable to the activity of membrane-associated proteins. Interestingly, variations in membrane lipid composition, whether quantitative or qualitative, play a crucial role in regulation of membrane protein functionalities. Indeed, a variety of alterations in brain lipid composition have been associated with the processes of normal and pathological aging. Although not establishing a direct cause-and-effect relationship between these complex modifications in cerebral membranes and the process of cognitive decline, evidence shows that alterations in membrane lipid composition affect important physicochemical properties notably impacting the lateral organization of membranes, and thus microdomains. It has been suggested that preservation of microdomain functionality may represent an effective strategy for preventing or decelerating neuronal dysfunction and cerebral vulnerability, processes that are both aggravated by aging. The working hypothesis developed in this review proposes that preservation of membrane organization, for example, through nutritional supplementation of docosahexaenoic acid, could prevent disturbances in and preserve effective cerebral function.
Assuntos
Envelhecimento , Encéfalo/metabolismo , Lipídeos de Membrana/metabolismo , Microdomínios da Membrana/metabolismo , Proteínas de Membrana/metabolismo , Doença de Alzheimer/metabolismo , Doença de Alzheimer/prevenção & controle , Encéfalo/efeitos dos fármacos , Ácidos Docosa-Hexaenoicos/administração & dosagem , Ácidos Docosa-Hexaenoicos/metabolismo , Humanos , Microdomínios da Membrana/química , Microdomínios da Membrana/efeitos dos fármacos , Modelos Biológicos , Fármacos Neuroprotetores/administração & dosagem , Fármacos Neuroprotetores/metabolismoRESUMO
In order to approach the astroglial implication of addictive and neurotoxic processes associated with psychostimulant drug abuse, the effects of amphetamine or cocaine (1-100 microM) on redox status, AP-1 transcription factor and pro-enkephalin, an AP-1 target gene, were investigated in the human astrocyte-like U373 MG cells. We demonstrated an early increase in the generation of radical oxygen species and in the formation of 4-hydroxynonenal-adducts reflecting the pro-oxidant action of both substances. After 1 h or 96 h of treatment, Fos and Jun protein levels were altered and the DNA-binding activity of AP-1 was increased in response to both substances. Using supershift experiments, we observed that the composition of AP-1 dimer differed according to the substance and the duration of treatment. FRA-2 protein represented the main component of the chronic amphetamine- or cocaine-activated complexes, which suggests its relevance in the long-term effects of psychostimulant drugs. Concomitantly, the pro-enkephalin gene was differently regulated by either 6 h or 96 h of treatment. Because astrocytes interact extensively with the neurons in the brain, our data led us to conclude that oxidation-regulated AP-1 target genes may represent one of the molecular mechanisms underlying neuronal adaptation associated with psychostimulant dependence.
Assuntos
Anfetamina/farmacologia , Astrócitos/efeitos dos fármacos , Fármacos do Sistema Nervoso Central/farmacologia , Cocaína/farmacologia , Encefalinas/metabolismo , Precursores de Proteínas/metabolismo , Fator de Transcrição AP-1/metabolismo , Sistema X-AG de Transporte de Aminoácidos/genética , Sistema X-AG de Transporte de Aminoácidos/metabolismo , Análise de Variância , Western Blotting/métodos , Linhagem Celular , Proteínas de Ligação a DNA/metabolismo , Relação Dose-Resposta a Droga , Esquema de Medicação , Ensaio de Desvio de Mobilidade Eletroforética/métodos , Encefalinas/genética , Transportador 2 de Aminoácido Excitatório/genética , Transportador 2 de Aminoácido Excitatório/metabolismo , Fluoresceínas , Antígeno 2 Relacionado a Fos , Regulação da Expressão Gênica/efeitos dos fármacos , Proteína Glial Fibrilar Ácida/metabolismo , Humanos , Oxirredução/efeitos dos fármacos , Precursores de Proteínas/genética , Proteínas Proto-Oncogênicas c-fos/metabolismo , Proteínas Proto-Oncogênicas c-jun/metabolismo , RNA Mensageiro/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodos , Sais de Tetrazólio , Tiazóis , Fatores de Tempo , Fatores de Transcrição/metabolismoRESUMO
Alzheimer's disease (AD) is a neurodegenerative disease that has been linked to changes in cholesterol metabolism. Neuronal cholesterol content significantly influences the pro-apoptotic effect of amyloid-ß peptide42 (Aß42), which plays a key role in AD development. We previously reported that aged mice with reduced expression of the lipolysis stimulated lipoprotein receptor (LSR+/-), demonstrate membrane cholesterol accumulation and decreased intracellular lipid droplets in several brain regions, suggesting a potential role of LSR in brain cholesterol distribution. We questioned if these changes rendered the LSR+/- mouse more susceptible to Aß42-induced cognitive and biochemical changes. Results revealed that intracerebroventricular injection of oligomeric Aß42 in male 15-month old LSR+/+ and LSR+/- mice led to impairment in learning and long-term memory and decreased cortical cholesterol content of both groups; these effects were significantly amplified in the Aß42-injected LSR+/- group. Total latency of the Morris test was significantly and negatively correlated with cortical cholesterol content of the LSR+/- mice, but not of controls. Significantly lower cortical PSD95 and SNAP-25 levels were detected in Aß42-injected LSR+/- mice as compared to Aß42-injected LSR+/+ mice. In addition, 24S-hydroxy cholesterol metabolite levels were significantly higher in the cortex of LSR+/- mice. Taken together, these results suggest that changes in cortex cholesterol regulation as a result of the LSR+/- genotype were linked to increased susceptibility to amyloid stress, and we would therefore propose the aged LSR+/- mouse as a new model for understanding the link between modified cholesterol regulation as a risk factor for AD.
Assuntos
Peptídeos beta-Amiloides/farmacologia , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Colesterol/metabolismo , Fragmentos de Peptídeos/farmacologia , Receptores de Lipoproteínas/deficiência , Análise de Variância , Animais , Proteína 4 Homóloga a Disks-Large , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/genética , Guanilato Quinases/metabolismo , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Hidroxicolesteróis/metabolismo , Aprendizagem em Labirinto/efeitos dos fármacos , Aprendizagem em Labirinto/fisiologia , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , RNA Mensageiro , Receptores de Lipoproteínas/genética , Análise de Regressão , Proteína 25 Associada a Sinaptossoma/metabolismoRESUMO
Oxidative stress has been demonstrated in Alzheimer's disease (AD) brain and may affect glutamate transport (GT), thereby leading to excitotoxic neuronal death. Since oxidative stress markers have been shown also in peripheral tissues, we investigated possible GT alterations in fibroblast cultures obtained from 18 patients with AD and 15 control patients and analyzed the effects of the lipoperoxidation product 4-hydroxynonenal (4-HNE) and antioxidants. Basal GT was decreased by 60% in fibroblasts from patients with AD versus control patients. Exposure to HNE did not affect GT in control patients, but it reduced GT by 50% in patients with AD, without any concomitant change in cell viability; conversely, HNE exposure induced a larger increase in ROS intracellular levels in AD than in control fibroblasts. Glutathione and N-acetylcysteine completely blocked 4-HNE effects and also increased basal uptake in AD cells. Moreover, inhibition of glutathione synthesis in control fibroblasts by pretreatment with buthionine sulfoximine resulted in GT reduction (40%) and an increase in ROS levels after exposure to 4-HNE. Nevertheless, since there are no differences between GSH basal level in controls and patients with AD, the alteration of other antioxidant systems cannot be excluded. Our study supports the hypothesis of a systemic impairment of GT in AD, possibly linked to oxidative stress and to reduced antioxidant defenses, which may be partially reversed by antioxidant treatment. Therefore, we suggest fibroblast cultures as a tool for exploring pathogenetic mechanisms and possible therapeutic strategies in patients with AD.
Assuntos
Doença de Alzheimer/metabolismo , Fibroblastos/metabolismo , Ácido Glutâmico/metabolismo , Estresse Oxidativo , Acetilcisteína/química , Trifosfato de Adenosina/química , Idoso , Idoso de 80 Anos ou mais , Aldeídos/farmacologia , Animais , Antioxidantes/farmacologia , Estudos de Casos e Controles , Cromatografia Líquida de Alta Pressão , Relação Dose-Resposta a Droga , Fibroblastos/patologia , Radicais Livres , Ácido Glutâmico/química , Glutationa/química , Glutationa/metabolismo , Humanos , L-Lactato Desidrogenase/metabolismo , Peroxidação de Lipídeos , Pessoa de Meia-Idade , Espécies Reativas de Oxigênio/metabolismo , Sais de Tetrazólio/farmacologia , Tiazóis/farmacologia , Fatores de TempoRESUMO
BACKGROUND: Cerebrospinal fluid (CSF) biomarkers have recently been included in the criteria for the diagnosis of Alzheimer's disease (AD). Since interpretation of CSF profile requires the combination of three parameters, biological data are not always conclusive and isolated elevation of phosphorylated tau (P-tau) or reduction of amyloid-ß (Aß)42 alone can be observed. In these cases, Aß42/Aß40 ratio could be more relevant than Aß42 absolute values by considering inter-individual variations in the total amyloid load. OBJECTIVE: The objective of this study was to assess the use of Aß42/Aß40 ratio to improve the accuracy of biological conclusions in the diagnosis of patients with ambiguous CSF Aß42 or tau results. METHODS: Among 386 lumbar punctures analyzed in the lab in 2 years, 122 showed ambiguous biological data that were completed by CSF Aß40 quantification and Aß42/Aß40 ratio calculation. A biological conclusion was then made using 0.05 as the Aß42/Aß40 ratio cut-off. RESULTS: Our results showed that one-third of the biological profiles of patients with atypical dementia were ambiguous. The addition of Aß42/Aß40 ratio increased the proportion of interpretable biological profiles from 69% to 87%, without changing the conclusion when usual biomarkers (Aß42 and P-tau) were concordant. CONCLUSION: Our results support the use of the Aß42/Aß40 ratio in addition to the usual CSF AD biomarkers for patients with ambiguous biological profiles. This method could be specifically directed to this population in order to improve the level of certainty for clinical routine practice.
Assuntos
Doença de Alzheimer/líquido cefalorraquidiano , Doença de Alzheimer/diagnóstico , Peptídeos beta-Amiloides/líquido cefalorraquidiano , Fragmentos de Peptídeos/líquido cefalorraquidiano , Proteínas tau/líquido cefalorraquidiano , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores/líquido cefalorraquidiano , Disfunção Cognitiva/líquido cefalorraquidiano , Disfunção Cognitiva/diagnóstico , Demência/líquido cefalorraquidiano , Demência/diagnóstico , Diagnóstico Diferencial , Feminino , Humanos , Doença por Corpos de Lewy/líquido cefalorraquidiano , Doença por Corpos de Lewy/diagnóstico , Masculino , Pessoa de Meia-Idade , Fosforilação , Punção Espinal , Adulto JovemRESUMO
Soluble beta-amyloid (Aß) oligomers are considered to putatively play a critical role in the early synapse loss and cognitive impairment observed in Alzheimer's disease. We previously demonstrated that Aß oligomers activate cytosolic phospholipase A(2) (cPLA(2)), which specifically releases arachidonic acid from membrane phospholipids. We here observed that cPLA(2) gene inactivation prevented the alterations of cognitive abilities and the reduction of hippocampal synaptic markers levels noticed upon a single intracerebroventricular injection of Aß oligomers in wild type mice. We further demonstrated that the Aß oligomer-induced sphingomyelinase activation was suppressed and that phosphorylation of Akt/protein kinase B (PKB) was preserved in neuronal cells isolated from cPLA(2)(-/-) mice. Interestingly, expression of the Aß precursor protein (APP) was reduced in hippocampus homogenates and neuronal cells from cPLA(2)(-/-) mice, but the relationship with the resistance of these mice to the Aß oligomer toxicity requires further investigation. These results therefore show that cPLA(2) plays a key role in the Aß oligomer-associated neurodegeneration, and as such represents a potential therapeutic target for the treatment of Alzheimer's disease.
Assuntos
Peptídeos beta-Amiloides/toxicidade , Transtornos da Memória/enzimologia , Transtornos da Memória/genética , Doenças Neurodegenerativas/enzimologia , Fragmentos de Peptídeos/toxicidade , Fosfolipases A2 Citosólicas/fisiologia , Animais , Células Cultivadas , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Aprendizagem em Labirinto/fisiologia , Transtornos da Memória/induzido quimicamente , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Knockout , Doenças Neurodegenerativas/induzido quimicamenteRESUMO
In the absence of efficient diagnostic and therapeutic tools, Alzheimer's disease (AD) is a major public health concern due to longer life expectancy in the Western countries. Although the precise cause of AD is still unknown, soluble beta-amyloid (Abeta) oligomers are considered the proximate effectors of the synaptic injury and neuronal death occurring in the early stages of AD. Abeta oligomers may directly interact with the synaptic membrane, leading to impairment of synaptic functions and subsequent signalling pathways triggering neurodegeneration. Therefore, membrane structure and lipid status should be considered determinant factors in Abeta-oligomer-induced synaptic and cell injuries, and therefore AD progression. Numerous epidemiological studies have highlighted close relationships between AD incidence and dietary patterns. Among the nutritional factors involved, lipids significantly influence AD pathogenesis. It is likely that maintenance of adequate membrane lipid content could prevent the production of Abeta peptide as well as its deleterious effects upon its interaction with synaptic membrane, thereby protecting neurons from Abeta-induced neurodegeneration. As major constituents of neuronal lipids, n-3 polyunsaturated fatty acids are of particular interest in the prevention of AD valuable diet ingredients whose neuroprotective properties could be essential for designing preventive nutrition-based strategies. In this review, we discuss the functional relevance of neuronal membrane features with respect to susceptibility to Abeta oligomers and AD pathogenesis, as well as the prospective capacities of lipids to prevent or to delay the disease.
Assuntos
Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Metabolismo dos Lipídeos/fisiologia , Doença de Alzheimer/patologia , Doença de Alzheimer/fisiopatologia , Animais , Apoptose/fisiologia , Ácidos Graxos Ômega-3/metabolismo , Humanos , Microdomínios da Membrana/metabolismo , Modelos Biológicos , Transdução de Sinais/fisiologiaRESUMO
N-terminal-truncated forms of amyloid-beta (A beta) peptide have been recently suggested to play a pivotal role early in Alzheimer's disease (AD). Among them, A beta 3(pE)-42 peptide, starting with pyroglutamyl at residue Glu-3, is considered as the predominant A beta species in AD plaques and pre-amyloid lesions. Its abundance is reported to be directly proportional to the severity of the clinical phenotype. The present study investigates the effects of soluble oligomeric A beta 3(pE)-42 after intracerebroventricular injection on mice learning ability and the molecular mechanisms of its in vitro neurotoxicity. Mice injected with soluble A beta 3(pE)-42 or A beta(l-42) displayed impaired spatial working memory and delayed memory acquisition in Y-maze and Morris water maze tests, while those injected with soluble A beta(42-1) showed no effect. These cognitive alterations were associated with free radical overproduction in the hippocampus and olfactory bulbs, but not in the cerebral cortex or cerebellum. In vitro, A beta 3(pE)-42 oligomers induced a redox-sensitive neuronal apoptosis involving caspase activation and an arachidonic acid-dependent pro-inflammatory pathway. These data suggest that A beta 3(pE)-42 could mediate the neurodegenerative process and subsequent cognitive alteration occurring in preclinical AD stages.
Assuntos
Peptídeos beta-Amiloides/administração & dosagem , Aprendizagem em Labirinto/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Neurônios/patologia , Fragmentos de Peptídeos/administração & dosagem , Animais , Apoptose/efeitos dos fármacos , Células Cultivadas , Relação Dose-Resposta a Droga , Masculino , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Recent data have revealed that soluble oligomeric amyloid-beta peptide (Abeta) may be the proximate effectors of neuronal injuries and death in Alzheimer's disease (AD) by unknown mechanisms. Consistently, we recently demonstrated the critical role of a redox-sensitive cytosolic calcium-dependent phospholipase A2 (cPLA2)-arachidonic acid (AA) pathway in Abeta oligomer-induced cell death. According to the involvement of oxidative stress and polyunsaturated fatty acids like AA in the regulation of sphingomyelinase (SMase) activity, the present study underlines the role of SMases in soluble Abeta-induced apoptosis. Soluble Abeta oligomers induced the activation of both neutral and acidic SMases, as demonstrated by the direct measurement of their enzymatic activities, by the inhibitory effects of both specific neutral and acidic SMase inhibitors, and by gene knockdown using antisense oligonucleotides. Furthermore, soluble Abeta-mediated activation of SMases and subsequent cell death were found to be inhibited by antioxidant molecules and a cPLA2-specific inhibitor or antisense oligonucleotide. We also demonstrate that sphingosine-1-phosphate is a potent neuroprotective factor against soluble Abeta oligomer-induced cell death and apoptosis by inhibiting soluble Abeta-induced activation of acidic sphingomyelinase. These results suggest that Abeta oligomers induce neuronal death by activating neutral and acidic SMases in a redox-sensitive cPLA2-AA pathway.