RESUMO
The liver X receptor agonist, GW3965, improves cognition in Alzheimer's disease (AD) mouse models. Here, we determined if short-term GW3965 treatment induces changes in the DNA methylation state of the hippocampus, which are associated with cognitive improvement. Twenty-four-month-old triple-transgenic AD (3xTg-AD) mice were treated with GW3965 (50 mg/kg/day for 6 days). DNA methylation state was examined by modified bisulfite conversion and hybridization on Illumina Infinium Methylation BeadChip 450 k arrays. The Morris water maze was used for behavioral analysis. Our results show in addition to improvement in cognition methylation changes in 39 of 13,715 interrogated probes in treated 3xTg-AD mice compared with untreated 3xTg-AD mice. These changes in methylation probes include 29 gene loci. Importantly, changes in methylation status were mainly from synapse-related genes (SYP, SYN1, and DLG3) and neurogenesis-associated genes (HMGB3 and RBBP7). Thus, our results indicate that liver X receptors (LXR) agonist treatment induces rapid changes in DNA methylation, particularly in loci associated with genes involved in neurogenesis and synaptic function. Our results suggest a new potential mechanism to explain the beneficial effect of GW3965.
Assuntos
Doença de Alzheimer/metabolismo , Benzoatos/farmacologia , Benzilaminas/farmacologia , Metilação de DNA/efeitos dos fármacos , Neurogênese , Receptores Nucleares Órfãos/agonistas , Sinapses/efeitos dos fármacos , Doença de Alzheimer/genética , Animais , Feminino , Proteína HMGB3/genética , Proteína HMGB3/metabolismo , Receptores X do Fígado , Camundongos , Proteínas Qa-SNARE/genética , Proteínas Qa-SNARE/metabolismo , Proteína 7 de Ligação ao Retinoblastoma/genética , Proteína 7 de Ligação ao Retinoblastoma/metabolismo , Sinapses/metabolismo , Sinaptofisina/genética , Sinaptofisina/metabolismoRESUMO
Alzheimer's disease (AD) is the major cause of dementia worldwide. The pharmacological activation of nuclear receptors (Liver X receptors: LXRs or Retinoid X receptors: RXR) has been shown to induce overexpression of the ATP-Binding Cassette A1 (ABCA1) and Apolipoprotein E (ApoE), changes that are associated with improvement in cognition and reduction of amyloid beta pathology in amyloidogenic AD mouse models (i.e. APP, PS1: 2tg-AD). Here we investigated whether treatment with a specific LXR agonist has a measurable impact on the cognitive impairment in an amyloid and Tau AD mouse model (3xTg-AD: 12-months-old; three months treatment). The data suggests that the LXR agonist GW3965 is associated with increased expression of ApoE and ABCA1 in the hippocampus and cerebral cortex without a detectable reduction of the amyloid load. We also report that most cells overexpressing ApoE (86±12%) are neurons localized in the granular cell layer of the hippocampus and entorhinal cortex. In the GW3965 treated 3xTg-AD mice we also observed reduction in astrogliosis and increased number of stem and proliferating cells in the subgranular zone of the dentate gyrus. Additionally, we show that GW3965 rescued hippocampus long term synaptic plasticity, which had been disrupted by oligomeric amyloid beta peptides. The effect of GW3965 on synaptic function was protein synthesis dependent. Our findings identify alternative functional/molecular mechanisms by which LXR agonists may exert their potential benefits as a therapeutic strategy against AD.
Assuntos
Doença de Alzheimer/metabolismo , Doença de Alzheimer/fisiopatologia , Receptores Nucleares Órfãos/metabolismo , Transportador 1 de Cassete de Ligação de ATP/metabolismo , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/metabolismo , Animais , Apolipoproteínas E/metabolismo , Benzoatos/farmacologia , Benzoatos/uso terapêutico , Benzilaminas/farmacologia , Benzilaminas/uso terapêutico , Biomarcadores/metabolismo , Proliferação de Células/efeitos dos fármacos , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Córtex Cerebral/patologia , Transtornos Cognitivos/complicações , Transtornos Cognitivos/tratamento farmacológico , Transtornos Cognitivos/metabolismo , Transtornos Cognitivos/fisiopatologia , Proteínas de Ligação a DNA , Giro Denteado/efeitos dos fármacos , Giro Denteado/metabolismo , Giro Denteado/patologia , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Feminino , Imunofluorescência , Gliose/complicações , Gliose/patologia , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Hipocampo/patologia , Receptores X do Fígado , Potenciação de Longa Duração/efeitos dos fármacos , Masculino , Camundongos Transgênicos , Proteínas do Tecido Nervoso/metabolismo , Nestina/metabolismo , Células-Tronco Neurais/efeitos dos fármacos , Células-Tronco Neurais/metabolismo , Proteínas Nucleares/metabolismo , Receptores Nucleares Órfãos/agonistas , Biossíntese de Proteínas/efeitos dos fármacos , Regulação para Cima/efeitos dos fármacos , Proteínas tau/metabolismoRESUMO
Black bean (Phaseolus vulgaris L.) seed coats are a rich source of natural compounds with potential beneficial effects on human health. Beans exert hypolipidaemic activity; however, this effect has not been attributed to any particular component, and the underlying mechanisms of action and protein targets remain unknown. The aim of the present study was to identify and quantify primary saponins and flavonoids extracted from black bean seed coats, and to study their effects on lipid metabolism in primary rat hepatocytes and C57BL/6 mice. The methanol extract of black bean seed coats, characterised by a HPLC system with a UV-visible detector and an evaporative light-scattering detector and HPLC-time-of-flight/MS, contained quercetin 3-O-glucoside and soyasaponin Af as the primary flavonoid and saponin, respectively. The extract significantly reduced the expression of SREBP1c, FAS and HMGCR, and stimulated the expression of the reverse cholesterol transporters ABCG5/ABCG8 and CYP7A1 in the liver. In addition, there was an increase in the expression of hepatic PPAR-α. Consequently, there was a decrease in hepatic lipid depots and a significant increase in bile acid secretion. Furthermore, the ingestion of this extract modulated the proportion of lipids that was used as a substrate for energy generation. Thus, the results suggest that the extract of black bean seed coats may decrease hepatic lipogenesis and stimulate cholesterol excretion, in part, via bile acid synthesis.
Assuntos
Colagogos e Coleréticos/uso terapêutico , Suplementos Nutricionais , Flavonoides/uso terapêutico , Lipotrópicos/uso terapêutico , Phaseolus/química , Saponinas/uso terapêutico , Sementes/química , Animais , Ácidos e Sais Biliares/metabolismo , Células Cultivadas , Colagogos e Coleréticos/química , Colagogos e Coleréticos/isolamento & purificação , Colagogos e Coleréticos/metabolismo , Colesterol/metabolismo , Flavonoides/química , Flavonoides/isolamento & purificação , Flavonoides/metabolismo , Regulação da Expressão Gênica , Hepatócitos/citologia , Hepatócitos/enzimologia , Hepatócitos/metabolismo , Metabolismo dos Lipídeos , Lipotrópicos/química , Lipotrópicos/isolamento & purificação , Lipotrópicos/metabolismo , Receptores X do Fígado , Masculino , México , Camundongos , Camundongos Endogâmicos C57BL , Receptores Nucleares Órfãos/agonistas , Receptores Nucleares Órfãos/genética , Receptores Nucleares Órfãos/metabolismo , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/metabolismo , Extratos Vegetais/uso terapêutico , Distribuição Aleatória , Ratos , Saponinas/química , Saponinas/isolamento & purificação , Saponinas/metabolismoRESUMO
BACKGROUND: Advanced glycation end products (AGE) alter lipid metabolism and reduce the macrophage expression of ABCA-1 and ABCG-1 which impairs the reverse cholesterol transport, a system that drives cholesterol from arterial wall macrophages to the liver, allowing its excretion into the bile and feces. Oxysterols favors lipid homeostasis in macrophages and drive the reverse cholesterol transport, although the accumulation of 7-ketocholesterol, 7alpha- hydroxycholesterol and 7beta- hydroxycholesterol is related to atherogenesis and cell death. We evaluated the effect of glycolaldehyde treatment (GAD; oxoaldehyde that induces a fast formation of intracellular AGE) in macrophages overloaded with oxidized LDL and incubated with HDL alone or HDL plus LXR agonist (T0901317) in: 1) the intracellular content of oxysterols and total sterols and 2) the contents of ABCA-1 and ABCG-1. METHODS: Total cholesterol and oxysterol subspecies were determined by gas chromatography/mass spectrometry and HDL receptors content by immunoblot. RESULTS: In control macrophages (C), incubation with HDL or HDL + T0901317 reduced the intracellular content of total sterols (total cholesterol + oxysterols), cholesterol and 7-ketocholesterol, which was not observed in GAD macrophages. In all experimental conditions no changes were found in the intracellular content of other oxysterol subspecies comparing C and GAD macrophages. GAD macrophages presented a 45% reduction in ABCA-1 protein level as compared to C cells, even after the addition of HDL or HDL + T0901317. The content of ABCG-1 was 36.6% reduced in GAD macrophages in the presence of HDL as compared to C macrophages. CONCLUSION: In macrophages overloaded with oxidized LDL, glycolaldehyde treatment reduces the HDL-mediated cholesterol and 7-ketocholesterol efflux which is ascribed to the reduction in ABCA-1 and ABCG-1 protein level. This may contribute to atherosclerosis in diabetes mellitus.