RESUMEN
Amyloid-ß peptide (Aß) has been shown to cause synaptic dysfunction and can render neurons vulnerable to excitotoxicity and oxidative stress. Na,K-ATPase plays an important role to maintain cell ionic equilibrium and it can be modulated by N-methyl-D-aspartate (NMDA)-nitric oxide (NO)-cyclic GMP pathway. Disruption of NO synthase (NOS) activity and reactive oxygen species (ROS) production could lead to changes in Na,K-ATPase isoforms' activities that may be detrimental to the cells. Our aim was to evaluate the signaling pathways of Aß in relation to NMDA-NOS-cyclic GMP versus oxidative stress on α1-/α2,3-Na,K-ATPase activities in rat hippocampal slices. Aß1-40 induced a concentration-dependent increase of NOS activity and increased cyclic guanosine monophosphate (cGMP), TBARS (thiobarbituric acid reactive substances), and 3-Nitrotyrosine (3-NT)-modified protein levels in rat hippocampal slices. The increase in NOS activity and cyclic GMP levels induced by Aß1-40 was completely blocked by MK-801 (inhibitor of NMDA receptor) and L-NAME (inhibitor of NOS) pre-treatment but changes in TBARS levels were only partially blocked by both compounds. The Aß treatment also decreased Na,K-ATPase activity which was reverted by N-nitro-L-arginine methyl ester hydrochloride (L-NAME) but not by MK-801 pre-treatment. The decrease in enzyme activity induced by Aß was isoform-specific since only α1-Na,K-ATPase was affected. These findings suggest that the activation of NMDA-NOS signaling cascade linked to α2,3-Na,K-ATPase activity may mediate an adaptive, neuroprotective response to Aß in rat hippocampus.
Asunto(s)
Hipocampo , Estrés Oxidativo , Animales , GMP Cíclico , Maleato de Dizocilpina , N-Metilaspartato , NG-Nitroarginina Metil Éster/farmacología , Óxido Nítrico , Péptidos , Ratas , ATPasa Intercambiadora de Sodio-Potasio , Sustancias Reactivas al Ácido TiobarbitúricoRESUMEN
Phosphatase and tensin homolog (PTEN) is an important protein with key modulatory functions in cell growth and survival. PTEN is crucial during embryogenesis and plays a key role in the central nervous system (CNS), where it directly modulates neuronal development and synaptic plasticity. Loss of PTEN signaling function is associated with cognitive deficits and synaptic plasticity impairment. Accordingly, Pten mutations have a strong link with autism spectrum disorder. In this study, neuronal Pten haploinsufficient male mice were subjected to a long-term environmental intervention - intermittent fasting (IF) - and then evaluated for alterations in exploratory, anxiety and learning and memory behaviors. Although no significant effects on spatial memory were observed, mutant mice showed impaired contextual fear memory in the passive avoidance test - an outcome that was effectively rescued by IF. In this study, we demonstrated that IF modulation, in addition to its rescue of the memory deficit, was also required to uncover behavioral phenotypes otherwise hidden in this neuronal Pten haploinsufficiency model.
Asunto(s)
Disfunción Cognitiva/terapia , Ayuno , Haploinsuficiencia , Fosfohidrolasa PTEN/deficiencia , Animales , Trastornos de Ansiedad/terapia , Conducta Animal , Discapacidades para el Aprendizaje/terapia , Masculino , Trastornos de la Memoria/terapia , RatonesRESUMEN
Na,K-ATPase, an ion pump, has been shown to interact with other proteins in signaling complexes in cardiac myocytes, renal and glial cells, and several other cell types. Our previous in vivo studies indicated that intrahippocampal administration of ouabain (OUA), an inhibitor of Na,K-ATPase, induces NFκB activation, leading to an increase in mRNA levels of target genes of this transcription factor in the rat hippocampus. The present work investigated whether OUA can regulate NF-κB in primary cultured rat cerebellar cells. Cells were treated with different concentrations of OUA (1, 10 or 100 µM) for different periods of time (1, 2 and 4 h). OUA induced a time- and concentration-dependent activation of NFκB (peak of activation: 10 µM, 2 h), involving both p50/p65 and p50/p50 NFκB dimers. OUA (10 µM, 2 h) induced upregulation of tumor necrosis factor α (Tnf-α), interleukin-1ß (Il-1ß), and brain derived neurotrophic factor (Bdnf) mRNA levels. Both NFκB activation and gene expression activation induced by OUA (10 µM) were abolished when cells were pre-treated for 20 min with MK-801 (N-Methyl-D-Aspartate (NMDA) receptor antagonist), manumycin A (farnesyltransferase inhibitor), PP-1(Src-family tyrosine kinase inhibitor) and PD98059 (mitogen-activated protein kinase (MAPK) inhibitor). OUA (10 µM) alone or in the presence of MK-801, PP-1, PD98059 did not cause cell death or DNA fragmentation. These findings suggest that OUA activates NFκB by NMDA-Src-Ras-like protein through MAPK pathways in cultured cerebellar cells. This pathway may mediate an adaptive response in the central nervous system.
Asunto(s)
Cerebelo/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , FN-kappa B/metabolismo , Ouabaína/farmacología , Receptores de N-Metil-D-Aspartato/agonistas , Transducción de Señal/efectos de los fármacos , Animales , Factor Neurotrófico Derivado del Encéfalo/metabolismo , Cerebelo/metabolismo , Maleato de Dizocilpina/farmacología , Relación Dosis-Respuesta a Droga , Antagonistas de Aminoácidos Excitadores/farmacología , Flavonoides/farmacología , Regulación de la Expresión Génica/efectos de los fármacos , Interleucina-1beta , Ouabaína/antagonistas & inhibidores , Polienos/farmacología , Alcamidas Poliinsaturadas/farmacología , Cultivo Primario de Células , Pirazoles/farmacología , Pirimidinas/farmacología , Ratas , Receptores de N-Metil-D-Aspartato/antagonistas & inhibidores , Factores de Tiempo , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
A decline in cognitive ability is a typical feature of the normal aging process, and of neurodegenerative disorders such as Alzheimer's, Parkinson's and Huntington's diseases. Although their etiologies differ, all of these disorders involve local activation of innate immune pathways and associated inflammatory cytokines. However, clinical trials of anti-inflammatory agents in neurodegenerative disorders have been disappointing, and it is therefore necessary to better understand the complex roles of the inflammatory process in neurological dysfunction. The dietary phytochemical curcumin can exert anti-inflammatory, antioxidant and neuroprotective actions. Here we provide evidence that curcumin ameliorates cognitive deficits associated with activation of the innate immune response by mechanisms requiring functional tumor necrosis factor α receptor 2 (TNFR2) signaling. In vivo, the ability of curcumin to counteract hippocampus-dependent spatial memory deficits, to stimulate neuroprotective mechanisms such as upregulation of BDNF, to decrease glutaminase levels, and to modulate N-methyl-D-aspartate receptor levels was absent in mice lacking functional TNFRs. Curcumin treatment protected cultured neurons against glutamate-induced excitotoxicity by a mechanism requiring TNFR2 activation. Our results suggest the possibility that therapeutic approaches against cognitive decline designed to selectively enhance TNFR2 signaling are likely to be more beneficial than the use of anti-inflammatory drugs per se.
Asunto(s)
Trastornos del Conocimiento/tratamiento farmacológico , Trastornos del Conocimiento/metabolismo , Curcumina/uso terapéutico , Lipopolisacáridos/toxicidad , Receptores Tipo II del Factor de Necrosis Tumoral/metabolismo , Transducción de Señal/fisiología , Animales , Células Cultivadas , Trastornos del Conocimiento/inducido químicamente , Curcumina/farmacología , Masculino , Aprendizaje por Laberinto/efectos de los fármacos , Aprendizaje por Laberinto/fisiología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Transducción de Señal/efectos de los fármacos , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
Wnt proteins are involved in tissue development and their signaling pathways play an important role during embryogenesis. Wnt signaling can promote cell survival, which is beneficial for neurons, but could also lead to tumor development in different tissues. The present study investigated the effects of a Wnt protein on the susceptibility of a neural tumor cell line (PC12 cells) to the cytotoxic compounds ferrous sulfate (10 mM), staurosporine (100 and 500 nM), 3-nitropropionic acid (5 mM), and amyloid β-peptide (Aβ25-35; 50 µM). Cells (1 x 10(6) cells/mL) were treated with the Wnt-3a recombinant peptide (200 ng/mL) for 24 h before exposure to toxic insults. The Wnt-3a protein partially protected PC12 cells, with a 6-15 percent increase in cell viability in the presence of toxic agents, similar to the effect measured using the MTT and lactate dehydrogenase cell viability assays. The Wnt-3a protein increased protein expression of β-catenin by 52 percent compared to control. These findings suggest that Wnt signaling can protect neural cells against apoptosis induced by toxic agents, which are relevant to the pathogenesis of Alzheimer’s and Huntington’s diseases.
Asunto(s)
Animales , Ratas , Apoptosis/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Transducción de Señal/efectos de los fármacos , /efectos de los fármacos , Péptidos beta-Amiloides/farmacología , Apoptosis/fisiología , Diferenciación Celular , Proliferación Celular , Compuestos Ferrosos/farmacología , Nitrocompuestos/farmacología , Estrés Oxidativo/fisiología , Propionatos/farmacología , Transducción de Señal/fisiología , Estaurosporina/farmacología , /fisiologíaRESUMEN
It has been shown that ouabain (OUA) can activate the Na,K-ATPase complex and mediate intracellular signaling in the central nervous system (CNS). Inflammatory stimulus increases glutamatergic transmission, especially at N-methyl-D-aspartate (NMDA) receptors, which are usually coupled to the activation of nitric oxide synthase (NOS). Nuclear factor-κB (NF-κB) activation modulates the expression of genes involved in development, plasticity, and inflammation. The present work investigated the effects of OUA on NF-κB binding activity in rat hippocampus and the influence of this OUA-Na,K-ATPase signaling cascade in NMDA-mediated NF-κB activation. The findings presented here are the first report indicating that intrahippocampal administration of OUA, in a concentration that did not alter Na,K-ATPase or NOS activity, induced an activation of NF-κB, leading to increases in brain-derived neurotrophic factor (Bdnf), inducible NOS (iNos), tumor necrosis factor-α (Tnf-α), and B-cell leukemia/lymphoma 2 (Bcl2) mRNA levels. This response was not linked to any significant signs of neurodegeneration as showed via Fluoro-Jade B and Nissl stain. Intrahippocampal administration of NMDA induced NF-κB activation and increased NOS and α(2/3) -Na,K-ATPase activities. NMDA treatment further increased OUA-induced NF-κB activation, which was partially blocked by MK-801, an antagonist of NMDA receptor. These results suggest that OUA-induced NF-κB activation is at least in part dependent on Na,K-ATPase modulatory action of NMDA receptor in hippocampus. The interaction of these signaling pathways could be associated with biological mechanisms that may underlie the basal homeostatic state linked to the inflammatory signaling cascade in the brain.
Asunto(s)
Inhibidores Enzimáticos/farmacología , Regulación Enzimológica de la Expresión Génica/efectos de los fármacos , Hipocampo/efectos de los fármacos , FN-kappa B/metabolismo , Ouabaína/farmacología , Receptores de N-Metil-D-Aspartato/metabolismo , Análisis de Varianza , Animales , Factor Neurotrófico Derivado del Encéfalo/genética , Factor Neurotrófico Derivado del Encéfalo/metabolismo , Muerte Celular/efectos de los fármacos , Maleato de Dizocilpina/farmacología , Relación Dosis-Respuesta a Droga , Interacciones Farmacológicas , Ensayo de Cambio de Movilidad Electroforética/métodos , Activación Enzimática/efectos de los fármacos , Antagonistas de Aminoácidos Excitadores/farmacología , Hipocampo/citología , Masculino , N-Metilaspartato/farmacología , Neuronas/citología , Neuronas/efectos de los fármacos , Óxido Nítrico Sintasa de Tipo II/genética , Óxido Nítrico Sintasa de Tipo II/metabolismo , Oligonucleótidos/farmacología , Proteínas Proto-Oncogénicas c-bcl-2/genética , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , ARN Mensajero/metabolismo , Ratas , Ratas Wistar , ATPasa Intercambiadora de Sodio-Potasio/metabolismo , Factores de Tiempo , Factor de Necrosis Tumoral alfa/genética , Factor de Necrosis Tumoral alfa/metabolismo , Proteína X Asociada a bcl-2/genética , Proteína X Asociada a bcl-2/metabolismoRESUMEN
Wnt proteins are involved in tissue development and their signaling pathways play an important role during embryogenesis. Wnt signaling can promote cell survival, which is beneficial for neurons, but could also lead to tumor development in different tissues. The present study investigated the effects of a Wnt protein on the susceptibility of a neural tumor cell line (PC12 cells) to the cytotoxic compounds ferrous sulfate (10 mM), staurosporine (100 and 500 nM), 3-nitropropionic acid (5 mM), and amyloid ß-peptide (Aß25-35; 50 µM). Cells (1 x 10(6) cells/mL) were treated with the Wnt-3a recombinant peptide (200 ng/mL) for 24 h before exposure to toxic insults. The Wnt-3a protein partially protected PC12 cells, with a 6-15% increase in cell viability in the presence of toxic agents, similar to the effect measured using the MTT and lactate dehydrogenase cell viability assays. The Wnt-3a protein increased protein expression of ß-catenin by 52% compared to control. These findings suggest that Wnt signaling can protect neural cells against apoptosis induced by toxic agents, which are relevant to the pathogenesis of Alzheimer's and Huntington's diseases.
Asunto(s)
Apoptosis/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Transducción de Señal/efectos de los fármacos , Proteína Wnt3A/efectos de los fármacos , Péptidos beta-Amiloides/farmacología , Animales , Apoptosis/fisiología , Diferenciación Celular , Proliferación Celular , Compuestos Ferrosos/farmacología , Nitrocompuestos/farmacología , Estrés Oxidativo/fisiología , Células PC12 , Propionatos/farmacología , Ratas , Transducción de Señal/fisiología , Estaurosporina/farmacología , Proteína Wnt3A/fisiologíaRESUMEN
Amyloid beta-peptide (A beta) likely causes functional alterations in neurons well prior to their death. Nuclear factor-kappaB (NF-kappaB), a transcription factor that is known to play important roles in cell survival and apoptosis, has been shown to be modulated by A beta in neurons and glia, but the mechanism is unknown. Because A beta has also been shown to enhance activation of N-methyl-D-aspartate (NMDA) receptors, we investigated the role of NMDA receptor-mediated intracellular signaling pathways in A beta-induced NF-kappaB activation in primary cultured rat cerebellar cells. Cells were treated with different concentrations of A beta1-40 (1 or 2 microM) for different periods (6, 12, or 24 hr). MK-801 (NMDA antagonist), manumycin A and FTase inhibitor 1 (farnesyltransferase inhibitors), PP1 (Src-family tyrosine kinase inhibitor), PD98059 [mitogen-activated protein kinase (MAPK) inhibitor], and LY294002 [phosphatidylinositol 3-kinase (PI3-k) inhibitor] were added 20 min before A beta treatment of the cells. A beta induced a time- and concentration-dependent activation of NF-kappaB (1 microM, 12 hr); both p50/p65 and p50/p50 NF-kappaB dimers were involved. This activation was abolished by MK-801 and attenuated by manumycin A, FTase inhibitor 1, PP1, PD98059, and LY294002. A beta at 1 microM increased the expression of inhibitory protein I kappaB, brain-derived neurotrophic factor, inducible nitric oxide synthase, tumor necrosis factor-alpha, and interleukin-1 beta as shown by RT-PCR assays. Collectively, these findings suggest that A beta activates NF-kappaB by an NMDA-Src-Ras-like protein through MAPK and PI3-k pathways in cultured cerebellar cells. This pathway may mediate an adaptive, neuroprotective response to A beta.