RESUMEN
Alzheimer's disease (AD) is the most prevalent cause of dementia in the elderly people. The disease is pathologically characterized by extracellular deposition of beta-amyloid peptide (Aß), cholinergic neurodegeneration and elevation of acetylcholine esterase (AChE) activity in the affected regions. In this study, we investigated the effects of obovatol on memory dysfunction, which was caused by scopolamine. Obovatol (0.2, 0.5 and 1 mg/kg for 7 day) attenuated scopolamine (1 mg/kg, i.p.)-induced amnesia in a dose-dependent manner, as revealed by the Morris water maze test and step-through passive avoidance test. Mechanism studies exhibited that obovatol dose-dependently alleviated scopolamine-induced increase in Aß generation and ß-secretase activity in the cortex and hippocampus. Obovatol also attenuated scopolamine-induced rise in AChE activity in the cortex and hippocampus. Obovatol might rescue scopolamine-mediated impaired learning and memory function by attenuating Aß accumulation and stabilizing cholinergic neurotransmission, which suggests that the natural compound could be a useful agent for the prevention of the development or progression of AD neurodegeneration.
Asunto(s)
Amnesia/prevención & control , Trastornos del Conocimiento/prevención & control , Cognición/efectos de los fármacos , Memoria/efectos de los fármacos , Nootrópicos/farmacología , Éteres Fenílicos/farmacología , Escopolamina , Acetilcolinesterasa/metabolismo , Amnesia/inducido químicamente , Amnesia/enzimología , Amnesia/psicología , Péptidos beta-Amiloides/metabolismo , Animales , Conducta Animal/efectos de los fármacos , Corteza Cerebral/efectos de los fármacos , Corteza Cerebral/enzimología , Trastornos del Conocimiento/inducido químicamente , Trastornos del Conocimiento/enzimología , Trastornos del Conocimiento/psicología , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Proteínas Ligadas a GPI/metabolismo , Hipocampo/efectos de los fármacos , Hipocampo/enzimología , Masculino , Ratones , Ratones Endogámicos ICR , Actividad Motora/efectos de los fármacos , Factores de TiempoRESUMEN
BACKGROUND: Neuroinflammation is important in the pathogenesis and progression of Alzheimer disease (AD). Previously, we demonstrated that lipopolysaccharide (LPS)-induced neuroinflammation caused memory impairments. In the present study, we investigated the possible preventive effects of 4-O-methylhonokiol, a constituent of Magnolia officinalis, on memory deficiency caused by LPS, along with the underlying mechanisms. METHODS: We investigated whether 4-O-methylhonokiol (0.5 and 1 mg/kg in 0.05% ethanol) prevents memory dysfunction and amyloidogenesis on AD model mice by intraperitoneal LPS (250 µg/kg daily 7 times) injection. In addition, LPS-treated cultured astrocytes and microglial BV-2 cells were investigated for anti-neuroinflammatory and anti-amyloidogenic effect of 4-O-methylhonkiol (0.5, 1 and 2 µM). RESULTS: Oral administration of 4-O-methylhonokiol ameliorated LPS-induced memory impairment in a dose-dependent manner. In addition, 4-O-methylhonokiol prevented the LPS-induced expression of inflammatory proteins; inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) as well as activation of astrocytes (expression of glial fibrillary acidic protein; GFAP) in the brain. In in vitro study, we also found that 4-O-methylhonokiol suppressed the expression of iNOS and COX-2 as well as the production of reactive oxygen species, nitric oxide, prostaglandin E2, tumor necrosis factor-α, and interleukin-1ß in the LPS-stimulated cultured astrocytes. 4-O-methylhonokiol also inhibited transcriptional and DNA binding activity of NF-κB via inhibition of IκB degradation as well as p50 and p65 translocation into nucleus of the brain and cultured astrocytes. Consistent with the inhibitory effect on neuroinflammation, 4-O-methylhonokiol inhibited LPS-induced Aß1-42 generation, ß- and γ-secretase activities, and expression of amyloid precursor protein (APP), BACE1 and C99 as well as activation of astrocytes and neuronal cell death in the brain, in cultured astrocytes and in microglial BV-2 cells. CONCLUSION: These results suggest that 4-O-methylhonokiol inhibits LPS-induced amyloidogenesis via anti-inflammatory mechanisms. Thus, 4-O-methylhonokiol can be a useful agent against neuroinflammation-associated development or the progression of AD.
Asunto(s)
Péptidos beta-Amiloides/metabolismo , Antiinflamatorios/uso terapéutico , Compuestos de Bifenilo/uso terapéutico , Inflamación/tratamiento farmacológico , Lignanos/uso terapéutico , Trastornos de la Memoria/tratamiento farmacológico , FN-kappa B/metabolismo , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Análisis de Varianza , Animales , Antiinflamatorios/farmacología , Ácido Aspártico Endopeptidasas/metabolismo , Astrocitos/efectos de los fármacos , Reacción de Prevención/efectos de los fármacos , Compuestos de Bifenilo/farmacología , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Línea Celular Transformada , Ciclooxigenasa 2/metabolismo , Citocinas/metabolismo , Dinoprostona/metabolismo , Modelos Animales de Enfermedad , Ensayo de Cambio de Movilidad Electroforética , Proteína Ácida Fibrilar de la Glía/metabolismo , Etiquetado Corte-Fin in Situ , Inflamación/inducido químicamente , Lignanos/farmacología , Lipopolisacáridos/toxicidad , Masculino , Aprendizaje por Laberinto/efectos de los fármacos , Trastornos de la Memoria/inducido químicamente , Trastornos de la Memoria/patología , Ratones , Ratones Endogámicos ICR , Microglía/efectos de los fármacos , Óxido Nítrico/metabolismo , Fragmentos de Péptidos/metabolismoRESUMEN
Etiology of Alzheimer's disease (AD) is obscure, but neuroinflammation and accumulation of ß-amyloid (Aß) are implicated in pathogenesis of AD. We have shown anti-inflammatory and neurotrophic properties of obovatol, a biphenolic compound isolated from Magnolia obovata. In this study, we examined the effect of obovatol on cognitive deficits in two separate AD models: (i) mice that received intracerebroventricular (i.c.v.) infusion of Aß(1-42) (2.0 µg/mouse) and (ii) Tg2576 mice-expressing mutant human amyloid precursor protein (K670N, M671L). Injection of Aß(1-42) into lateral ventricle caused memory impairments in the Morris water maze and passive avoidance tasks, being associated with neuroinflammation. Aß(1-42) -induced abnormality was significantly attenuated by administration of obovatol. When we analyzed with Tg2576 mice, long-term treatment of obovatol (1 mg/kg/day for 3 months) significantly improved cognitive function. In parallel with the improvement, treatment suppressed astroglial activation, BACE1 expression and NF-κB activity in the transgenic mice. Furthermore, obovatol potently inhibited fibrillation of Aßin vitro in a dose-dependent manner, as determined by Thioflavin T fluorescence and electron microscopic analysis. In conclusion, our data demonstrated that obovatol prevented memory impairments in experimental AD models, which could be attributable to amelioration of neuroinflammation and amyloidogenesis by inhibition of NF-κB signaling pathway and anti-fibrillogenic activity of obovatol.
Asunto(s)
Enfermedad de Alzheimer/complicaciones , Compuestos de Bifenilo/uso terapéutico , Trastornos del Conocimiento/tratamiento farmacológico , Trastornos del Conocimiento/etiología , Éteres Fenílicos/uso terapéutico , Enfermedad de Alzheimer/inducido químicamente , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/patología , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Péptidos beta-Amiloides/metabolismo , Péptidos beta-Amiloides/toxicidad , Precursor de Proteína beta-Amiloide/genética , Análisis de Varianza , Animales , Reacción de Prevención/efectos de los fármacos , Compuestos de Bifenilo/química , Trastornos del Conocimiento/genética , Modelos Animales de Enfermedad , Ensayo de Cambio de Movilidad Electroforética , Humanos , Masculino , Aprendizaje por Laberinto/efectos de los fármacos , Ratones , Ratones Endogámicos ICR , Ratones Transgénicos , Mutación/genética , Fragmentos de Péptidos/toxicidad , Éteres Fenílicos/químicaRESUMEN
Neuroinflammation and accumulation of ß-amyloid are critical pathogenic mechanisms of Alzheimer's disease (AD). In the previous study, we have shown that systemic lipopolysaccharide (LPS) caused neuroinflammation with concomitant increase in ß-amyloid and memory impairments in mice. In an attempt to investigate anti-neuroinflammatory properties of obovatol isolated from Magnolia obovata, we administered obovatol (0.2, 0.5 and 1.0 mg/kg/day, p.o.) to animals for 21 days before injection of LPS (0.25 mg/kg, i.p.). We found that obovatol dose-dependently attenuates LPS-induced memory deficit in the Morris water maze and passive avoidance tasks. Consistent with the results of memory tasks, the compound prevented LPS-induced increases in Aß1â42 formation, ß- and γ-secretases activities and levels of amyloid precursor protein, neuronal ß-secretase 1 (BACE1), and C99 (a product of BACE1) in the cortex and hippocampus. The LPS-mediated neuroinflammation as determined by Western blots and immunostainings was significantly ameliorated by the compound. Furthermore, LPS-induced nuclear factor (NF)-κB DNA binding activity was drastically abolished by obovatol as shown by the electrophoretic mobility shift assay. The anti-neuroinflammation and anti-amyloidogenesis by obovatol were replicated in in vitro studies. These results show that obovatol mitigates LPS-induced amyloidogenesis and memory impairment via inhibiting NF-κB signal pathway, suggesting that the compound might be plausible therapeutic intervention for neuroinflammation-related diseases such as AD.
Asunto(s)
Compuestos de Bifenilo/uso terapéutico , Trastornos de la Memoria/tratamiento farmacológico , Memoria/efectos de los fármacos , FN-kappa B/antagonistas & inhibidores , Éteres Fenílicos/uso terapéutico , Animales , Compuestos de Bifenilo/química , Compuestos de Bifenilo/farmacología , Encéfalo/metabolismo , Hipocampo/metabolismo , Lipopolisacáridos/toxicidad , Magnolia/química , Masculino , Trastornos de la Memoria/inducido químicamente , Trastornos de la Memoria/metabolismo , Ratones , Ratones Endogámicos ICR , FN-kappa B/metabolismo , Neuronas/metabolismo , Éteres Fenílicos/química , Éteres Fenílicos/farmacología , Transducción de Señal/efectos de los fármacos , Transducción de Señal/fisiologíaRESUMEN
Accumulations of amyloid-ß (Aß) and oxidative damage are critical pathological mechanisms in the development of Alzheimer's disease (AD). We previously found that 4-O-methylhonokiol, a compound extracted from Magnolia officinalis, improved memory dysfunction in Aß-injected and presenilin 2 mutant mice through the reduction of accumulated Aß. To investigate mechanisms of the reduced Aß accumulation, we examined generation, degradation, efflux and aggregation of Aß in Swedish AßPP AD model (AßPPsw) mice pre-treated with 4-O-methylhonokiol (1.0 mg/kg) for 3 months. 4-O-methylhonokiol treatment recovered memory impairment and prevented neuronal cell death. This memory improving activity was associated with 4-O-methylhonokiol-induced reduction of Aß1-42 accumulation in the brains of AßPPsw mice. According to the reduction of Aß1-42 accumulation, 4-O-methylhonkiol modulated oxidative damage sensitive enzymes. 4-O-methylhonkiol decreased expression and activity of brain beta-site AßPP cleaving enzyme (BACE1), but increased clearance of Aß in the brain through an increase of expressions and activities of Aß degradation enzymes; insulin degrading enzyme and neprilysin. 4-O-methylhonkiol also increased expression of Aß transport molecule, low density lipoprotein receptor-related protein-1 in the brain and liver. 4-O-methylhonkiol decreased carbonyl protein and lipid peroxidation, but increased glutathione levels in the brains of AßPPsw mice suggesting that oxidative damage of protein and lipid is critical in the impairment of those enzyme activities. 4-O-methylhonokiol treatment also prevented neuronal cell death in the AßPPsw mousee brain through inactivation of caspase-3 and BAX. These results suggest that 4-O-methylhonokiol might prevent the development and progression of AD by reducing Aß accumulation through an increase of clearance and decrease of Aß generation via antioxidant mechanisms.
Asunto(s)
Enfermedad de Alzheimer/complicaciones , Péptidos beta-Amiloides/metabolismo , Compuestos de Bifenilo/uso terapéutico , Lignanos/uso terapéutico , Trastornos de la Memoria/tratamiento farmacológico , Trastornos de la Memoria/etiología , Presenilina-2/metabolismo , Enfermedad de Alzheimer/genética , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Precursor de Proteína beta-Amiloide/genética , Análisis de Varianza , Animales , Reacción de Prevención/efectos de los fármacos , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Dicroismo Circular/métodos , Modelos Animales de Enfermedad , Conducta Exploratoria/efectos de los fármacos , Humanos , Peroxidación de Lípido/efectos de los fármacos , Peroxidación de Lípido/genética , Aprendizaje por Laberinto/efectos de los fármacos , Trastornos de la Memoria/patología , Ratones , Ratones Transgénicos , Neprilisina/metabolismo , Presenilina-2/genética , Carbonilación Proteica/efectos de los fármacos , Carbonilación Proteica/genética , Tiempo de Reacción/efectos de los fármacos , Tiempo de Reacción/genéticaRESUMEN
Oxidative stress induced neuronal cell death by accumulation of ß-amyloid (Aß) is a critical pathological mechanism of Alzheimer's disease (AD). Intracerebroventrical infusion of Aß(1-42) (300 pmol/day per mouse) for 14 days induced neuronal cell death and memory impairment, but pre-treatment of 4-O-methylhonokiol (4-O-MH), a novel compound extracted from Magnolia officinalis for 3 weeks (0.2, 0.5 and 1.0 mg/kg) prior to the infusion of Aß(1-42) and during the infusion dose dependently improved Aß(1-42)-induced memory impairment and prevented neuronal cell death. Additionally, 4-O-MH reduced Aß(1-42) infusion-induced oxidative damages of protein and lipid but reduced glutathione levels in the cortex and hippocampus. Aß(1-42) infusion-induced activation of astrocytes and p38 mitogenic activated protein (MAP) kinase was also prevented by 4-O-MH in mice brains. In further study using culture cortical neurons, p38 MAP kinase inhibitor abolished the inhibitory effect of 4-O-MH (10 µM) on the Aß(1-42) (5 µM)-induced reactive oxidative species generation and neuronal cell death. These results suggest that 4-O-MH might prevent the development and progression of AD through the reduction of oxidative stress and neuronal cell death via inactivation of p38 MAP kinase pathway.
Asunto(s)
Péptidos beta-Amiloides/efectos adversos , Apoptosis , Compuestos de Bifenilo/farmacología , Lignanos/farmacología , Trastornos de la Memoria/tratamiento farmacológico , Estrés Oxidativo , Fragmentos de Péptidos/efectos adversos , Proteínas Quinasas p38 Activadas por Mitógenos/antagonistas & inhibidores , Enfermedad de Alzheimer/fisiopatología , Análisis de Varianza , Animales , Astrocitos/efectos de los fármacos , Astrocitos/metabolismo , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Modelos Animales de Enfermedad , Hipocampo/efectos de los fármacos , Hipocampo/patología , Peroxidación de Lípido , Magnolia/química , Masculino , Trastornos de la Memoria/inducido químicamente , Trastornos de la Memoria/fisiopatología , Ratones , Ratones Endogámicos ICR , Neuronas/citología , Neuronas/metabolismo , Carbonilación Proteica , Especies Reactivas de Oxígeno/análisisRESUMEN
Presenilin 2 (PS2) mutation increases Aß generation and neuronal cell death in the brains of Alzheimer disease (AD) patients. In a previous study, we showed that increased oxidative damage and activation of extracellular signal-regulated kinase (ERK) were associated with Aß generation and neuronal cell death in neuronal cells expressing mutant PS2. In this study, we show that oral treatment with 4-O-methylhonokiol, a novel compound isolated from Magnolia officinalis, for 3 months (1.0mg/kg) prevented PS2 mutation-induced memory impairment and neuronal cell death accompanied by a reduction in Aß(1-42) accumulation. We also found that 4-O-methylhonokiol inhibited PS2 mutation-induced activation of ERK and ß-secretase, and oxidative protein and lipid damage, but recovered glutathione levels in the cortex and hippocampus of PS2 mutant mice. Additionally, 4-O-methylhonokiol prevented PS2 mutation-induced activation of astrocytes as well as production of TNF-α, IL-1ß, reactive oxygen species (ROS), and nitric oxide (NO) in neurons. Generation of TNF-α, IL-1ß, ROS, and NO and ERK activation in cultured astrocytes treated with lipopolysaccharide (1µg/ml) were also prevented by 4-O-methylhonokiol in a dose-dependent manner. These results suggest that the improving effects of 4-O-methylhonokiol on memory function may be associated with a suppression of the activation of ERK and astrocytes as well as a reduction in oxidative damage. Thus, 4-O-methylhonokiol may be useful in the prevention and treatment of AD.
Asunto(s)
Apoptosis/efectos de los fármacos , Astrocitos/efectos de los fármacos , Compuestos de Bifenilo/farmacología , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Lignanos/farmacología , Trastornos de la Memoria/prevención & control , Presenilina-2/genética , Animales , Antiinflamatorios/farmacología , Apoptosis/genética , Astrocitos/metabolismo , Astrocitos/patología , Regulación hacia Abajo/efectos de los fármacos , Evaluación Preclínica de Medicamentos , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Trastornos de la Memoria/genética , Trastornos de la Memoria/patología , Ratones , Ratones Mutantes , Ratones Transgénicos , Modelos Biológicos , Estrés Oxidativo/efectos de los fármacos , Estrés Oxidativo/genéticaRESUMEN
Previously, we found that obovatol, a lignan compound isolated from Magnolia officinalis, has anti-cancer, anti-inflammatory, and anxiolytic effects. Recent studies showed that honokiol, magnolol, and 4-O-methylhonokiol, lignin compounds isolated from the Magnolia family have neurotrophic activity. In this study, we examined whether or not obovatol also exhibits neurite-promoting effects on rat embryonic neuronal cells. Obovatol increased neurite outgrowth in a concentration-dependent manner. Consistent with the neurite outgrowth effect, the expression of neurite differentiation markers also increased in response to obovatol. We also found that obovatol increased levels of NGF and BDNF released into the culture medium. In addition, the combination of low concentrations of obovatol (1 and 2 µM) with NGF (50 ng/ml) or with BDNF (10 ng/ml) greatly enhanced neurite outgrowth. Subsequently, we found that obovatol increased phosphorylation of ERK. However, the neurite outgrowth, and NGF and BDNF release induced by obovatol were prevented by an ERK-specific inhibitor. These results suggest that obovatol promotes neurite outgrowth due to the increased release of neurotrophic factors via activation of the ERK pathway.
Asunto(s)
Compuestos de Bifenilo/farmacología , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Factores de Crecimiento Nervioso/metabolismo , Neuritas/efectos de los fármacos , Neuronas/efectos de los fármacos , Neuronas/metabolismo , Éteres Fenílicos/farmacología , Animales , Antígenos de Diferenciación/metabolismo , Factor Neurotrófico Derivado del Encéfalo/metabolismo , Factor Neurotrófico Derivado del Encéfalo/farmacología , Células Cultivadas , Corteza Cerebral , Descubrimiento de Drogas , Embrión de Mamíferos , Factor de Crecimiento Nervioso/metabolismo , Factor de Crecimiento Nervioso/farmacología , Neuritas/ultraestructura , Enfermedades Neurodegenerativas/tratamiento farmacológico , Neurogénesis/efectos de los fármacos , Neuronas/ultraestructura , Concentración Osmolar , Inhibidores de Proteínas Quinasas/farmacología , Ratas , Ratas Sprague-DawleyRESUMEN
Amyloid beta (Abeta)-induced neurotoxicity is a major pathological mechanism of Alzheimer disease (AD). In this study, we investigated the inhibitory effect of l-theanine, a component of green tea (Camellia sinensis), on Abeta(1-42)-induced neuronal cell death and memory impairment. Oral treatment of l-theanine (2 and 4 mg/kg) for 5 weeks in the drinking water of mice, followed by injection of Abeta(1-42) (2 microg/mouse, icv), significantly attenuated Abeta(1-42)-induced memory impairment. Furthermore, l-theanine reduced Abeta(1-42) levels and the accompanying Abeta(1-42)-induced neuronal cell death in the cortex and hippocampus of the brain. Moreover, l-theanine inhibited Abeta(1-42)-induced extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase as well as the activity of nuclear factor kappaB (NF-kappaB). l-Theanine also significantly reduced oxidative protein and lipid damage and the elevation of glutathione levels in the brain. These data suggest that the positive effects of l-theanine on memory may be mediated by suppression of ERK/p38 and NF-kappaB as well as the reduction of macromolecular oxidative damage. Thus, l-theanine may be useful in the prevention and treatment of AD.
Asunto(s)
Enfermedad de Alzheimer/tratamiento farmacológico , Péptidos beta-Amiloides/metabolismo , Glutamatos/metabolismo , Glutamatos/farmacología , Neuronas/efectos de los fármacos , Enfermedad de Alzheimer/fisiopatología , Péptidos beta-Amiloides/química , Animales , Apoptosis/efectos de los fármacos , Camellia sinensis , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Glutamatos/química , Glutatión/biosíntesis , Peroxidación de Lípido , Masculino , Trastornos de la Memoria/tratamiento farmacológico , Ratones , Ratones Endogámicos ICR , FN-kappa B/metabolismo , Neuronas/metabolismo , Neuronas/patología , Estrés Oxidativo/efectos de los fármacos , Fragmentos de Péptidos/metabolismo , Fragmentos de Péptidos/farmacología , Transducción de Señal/efectos de los fármacos , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismoRESUMEN
Compounds isolated from Magnolia officinalis such as magnolol, honokiol and obovatol exhibit several pharmacological effects on CNS including depressant, anxiolytic and anticonvulsant effects, as well as neuroprotective effects against chemical and heat damages. Recently, honokiol was found to have a neurotrophic effect in fetal rat cortical neurons. In the present study, we show that 4-O-methylhonokiol, a novel compound from Magnolia officinalis, promotes neurite outgrowth in a concentration- dependent manner in rat embryonic neuronal cells. In parallel with the neurite outgrowth activity, the expression of neurite outgrowth marker proteins is also increased by treatment with 4-O-methylhonokiol. We also found that 4-O-methylhonokiol promotes the release of NGF and BDNF into cell culture medium. In addition, lower concentration of 4-O-methylhonokiol (1 and 2 lM) further enhanced neurite outgrowth and expression of neurite outgrowth marker proteins in the presence of NGF (50 ng/ml) or BDNF (10 ng/ml). Subsequently, we found that 4-O-methylhonokiol activates ERK in a concentration- dependent manner. However, the neurite outgrowth activity and the NGF and BDNF release induced by 4-O-methylhonokiol are suppressed by an ERK-specific inhibitor. These results suggest that 4-O-methylhonokiol has the ability to induce neurite outgrowth via the increase of neurotrophic factor levels through ERK activation.