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Different screening methods are being developed to generate adeno-associated viral vectors (AAV) with the ability to bypass the blood-brain barrier (BBB) upon intravenous administration. Recently, the AAV9P31 stood out as the most efficient version among a library of peptide-displaying capsids selected in C57BL/6 mice using RNA-driven biopanning. In this work we have characterized in detail its biodistribution in different mouse strains (C57BL/6 and Balb/c), as well as in Sprague Dawley rats and non-human primates (Macaca fascicularis). Using GFP and NanoLuc reporter genes, we confirmed homogeneous infection and transgene expression across the CNS of mice injected intravenously with AAV9P31. A more restricted pattern was observed upon either intracerebroventricular or intraparenchymal injection. Following intravenous delivery, region- and cell-specific differential patterns of transduction were observed in the mouse brain, including a preferential transduction of astrocytes and neurons in the cerebral cortex and striatum, whereas neurons were the only transduced cell type in subcortical locations across the hippocampus, thalamus, hypothalamus, mesencephalon, brainstem and cerebellum. Furthermore, transduced microglial cells were never found in any CNS location. Peripheral organs transduced upon intravenous administration included lung, liver, peritoneum, heart and skeletal muscle. However, a comparable performance of AAV9P31 to bypass the BBB in rats and macaques was not observed, although a more limited neuronal transduction was found in the brainstem of rats upon intravenous delivery. Finally, intracerebroventricular delivery in macaques resulted in neuronal transduction in cortical, subcortical structures and cerebellum following a patchy pattern. In conclusion, the widespread CNS transduction obtained in mice upon intravenous delivery of AAV9P31 represents a powerful tool for modeling a wide variety of neurological disorders as well as an appealing choice for the evaluation of gene therapy-based therapeutics.
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The cell cycle consists of successive events that lead to the generation of new cells. The cell cycle is regulated by different cyclins, cyclin-dependent kinases (CDKs) and their inhibitors, such as p27Kip1. At the nuclear level, p27Kip1 has the ability to control the evolution of different phases of the cell cycle and oppose cell cycle progression by binding to CDKs. In the cytoplasm, diverse functions have been described for p27Kip1, including microtubule remodeling, axonal transport and phagocytosis. In Alzheimer's disease (AD), alterations to cycle events and a purported increase in neurogenesis have been described in the early disease process before significant pathological changes could be detected. However, most neurons cannot progress to complete their cell division and undergo apoptotic cell death. Increased levels of both the p27Kip1 levels and phosphorylation status have been described in AD. Increased levels of Aß42, tau hyperphosphorylation or even altered insulin signals could lead to alterations in p27Kip1 post-transcriptional modifications, causing a disbalance between the levels and functions of p27Kip1 in the cytoplasm and nucleus, thus inducing an aberrant cell cycle re-entry and alteration of extra cell cycle functions. Further studies are needed to completely understand the role of p27Kip1 in AD and the therapeutic opportunities associated with the modulation of this target.
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Doença de Alzheimer/patologia , Ciclo Celular , Inibidor de Quinase Dependente de Ciclina p27/química , Inibidor de Quinase Dependente de Ciclina p27/metabolismo , Processamento de Proteína Pós-Traducional , Doença de Alzheimer/metabolismo , Animais , HumanosRESUMO
Understanding the mechanisms involved in cognitive resilience in Alzheimer's disease (AD) represents a promising strategy to identify novel treatments for dementia in AD. Previous findings from our group revealed that the study of aged-Tg2576 cognitive resilient individuals is a suitable tool for this purpose. In the present study, we performed a transcriptomic analysis using the prefrontal cortex of demented and resilient Tg2576 transgenic AD mice. We have been able to hypothesize that pathways involved in inflammation, amyloid degradation, memory function, and neurotransmission may be playing a role on cognitive resilience in AD. Intriguingly, the results obtained in this study are suggestive of a reduction of the influx of peripheral immune cells into the brain on cognitive resilient subjects. Indeed, CD4 mRNA expression is significantly reduced on Tg2576 mice with cognitive resilience. For further validation of this result, we analyzed CD4 expression in human AD samples, including temporal cortex and peripheral blood mononuclear cells (PBMC). Interestingly, we have found a negative correlation between CD4 mRNA levels in the periphery and the score in the Mini-Mental State Exam of AD patients. These findings highlight the importance of understanding the role of the immune system on the development of neurodegenerative diseases and points out to the infiltration of CD4+ cells in the brain as a key player of cognitive dysfunction in AD.
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Doença de Alzheimer/metabolismo , Antígenos CD4/genética , Córtex Cerebral/metabolismo , Cognição , Inflamação , Leucócitos Mononucleares/metabolismo , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/genética , Doença de Alzheimer/imunologia , Doença de Alzheimer/fisiopatologia , Animais , Córtex Cerebral/fisiologia , Feminino , Perfilação da Expressão Gênica , Regulação da Expressão Gênica , Humanos , Masculino , Camundongos , Camundongos Transgênicos , Pessoa de Meia-Idade , Córtex Pré-Frontal/metabolismo , Lobo Temporal/metabolismoRESUMO
Despite the well-accepted role of the two main neuropathological markers (ß-amyloid and tau) in the progression of Alzheimer's disease, the interaction and specific contribution of each of them is not fully elucidated. To address this question, in the present study, an adeno-associated virus (AAV9) carrying the mutant P301L form of human tau, was injected into the dorsal hippocampi of APP/PS1 transgenic mice or wild type mice (WT). Three months after injections, memory tasks, biochemical and immunohistochemical analysis were performed. We found that the overexpression of hTauP301L accelerates memory deficits in APP/PS1 mice, but it did not affect memory function of WT mice. Likewise, biochemical assays showed that only in the case of APP/PS1-hTauP301L injected mice, an important accumulation of tau was observed in the insoluble urea fraction. Similarly, electron microscopy images revealed that numerous clusters of tau immunoparticles appear at the dendrites of APP/PS1 injected mice and not in WT animals, suggesting that the presence of amyloid is necessary to induce tau aggregation. Interestingly, these tau immunoparticles accumulate in dendritic mitochondria in the APP/PS1 mice, whereas most of mitochondria in WT injected mice remain free of tau immunoparticles. Taken together, it seems that amyloid induces tau aggregation and accumulation in the dendritic mitochondria and subsequently may alter synapse function, thus, contributing to accelerate cognitive decline in APP/PS1 mice.
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Doença de Alzheimer/complicações , Peptídeos beta-Amiloides/efeitos adversos , Transtornos Cognitivos/patologia , Modelos Animais de Doenças , Mitocôndrias/patologia , Proteínas tau/metabolismo , Precursor de Proteína beta-Amiloide/fisiologia , Animais , Transtornos Cognitivos/etiologia , Transtornos Cognitivos/metabolismo , Feminino , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Mitocôndrias/metabolismo , Fosforilação , Presenilina-1/fisiologia , Sinapses , Proteínas tau/genéticaRESUMO
We report that, in the rat, administering insulin-like growth factor II (IGF-II, also known as IGF2) significantly enhances memory retention and prevents forgetting. Inhibitory avoidance learning leads to an increase in hippocampal expression of IGF-II, which requires the transcription factor CCAAT enhancer binding protein ß and is essential for memory consolidation. Furthermore, injections of recombinant IGF-II into the hippocampus after either training or memory retrieval significantly enhance memory retention and prevent forgetting. To be effective, IGF-II needs to be administered within a sensitive period of memory consolidation. IGF-II-dependent memory enhancement requires IGF-II receptors, new protein synthesis, the function of activity-regulated cytoskeletal-associated protein and glycogen-synthase kinase 3 (GSK3). Moreover, it correlates with a significant activation of synaptic GSK3ß and increased expression of GluR1 (also known as GRIA1) α-amino-3-hydroxy-5-methyl-4-isoxasolepropionic acid receptor subunits. In hippocampal slices, IGF-II promotes IGF-II receptor-dependent, persistent long-term potentiation after weak synaptic stimulation. Thus, IGF-II may represent a novel target for cognitive enhancement therapies.
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Hipocampo/metabolismo , Fator de Crescimento Insulin-Like II/metabolismo , Memória/fisiologia , Animais , Proteína beta Intensificadora de Ligação a CCAAT/metabolismo , Regulação da Expressão Gênica , Hipocampo/efeitos dos fármacos , Fator de Crescimento Insulin-Like II/farmacologia , Potenciação de Longa Duração/fisiologia , Masculino , Memória/efeitos dos fármacos , Ratos , Ratos Long-Evans , Fatores de TempoRESUMO
Sildenafil (Viagra) is a selective inhibitor of phosphodiesterase type 5 (PDE5), which degrades cyclic guanosine monophosphate to the linear nucleotide. Sildenafil is acutely used in erectile dysfunction and chronically in pulmonary hypertension. Evidence in the last decade shows that sildenafil may have potential as a therapeutic option for Alzheimer's disease or other neurodegenerative disorders. The purpose of this work was to explore whether sildenafil crosses the blood-brain barrier. Pharmacokinetic properties of sildenafil in rodents were investigated using (11) C-radiolabeling followed by in vivo positron emission tomography (PET) and ex vivo tissue dissection and gamma counting. PET results in rats suggest penetration into the central nervous system. Ex vivo data in perfused animals suggest that trapping of [(11) C]sildenafil within the cerebral vascular endothelium limits accumulation in the central nervous system parenchyma. Peroral sildenafil administration to Macaca fascicularis and subsequent chemical analysis of plasma and cerebrospinal fluid (CSF) using liquid chromatography coupled with tandem mass spectrometry showed that drug content in the CSF was high enough to achieve PDE5 inhibition, which was also demonstrated by the significant increases in CSF cyclic guanosine monophosphate levels. Central actions of sildenafil include both relaxation of the cerebral vasculature and inhibition of PDE5 in neurons and glia. This central action of sildenafil may underlie its efficacy in neuroprotection models, and may justify the continued search for a PDE5 ligand suitable for PET imaging. Sildenafil interacts with phosphodiesterase type 5 (PDE5) expressed in the endothelium and/or smooth muscle cells of brain vessels and also crosses the blood-brain barrier to interact with PDE5 expressed in brain cells. At therapeutic doses, the concentration of sildenafil in the cerebrospinal fluid (CSF) is high enough to inhibit PDE5 in the neural cells (neurons and glia). In turn, the concentration of cGMP likely increases in parenchymal cells and, as shown in this report, in the CSF. Read the Editorial Highlight for this article on page 220. Cover Image for this issue: doi: 10.1111/jnc.13302.
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GMP Cíclico/líquido cefalorraquidiano , Inibidores da Fosfodiesterase 5/farmacocinética , Citrato de Sildenafila/farmacocinética , Animais , Encéfalo/diagnóstico por imagem , Encéfalo/efeitos dos fármacos , Cromatografia Líquida , GMP Cíclico/sangue , Rim/diagnóstico por imagem , Rim/efeitos dos fármacos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Macaca fascicularis , Masculino , Tomografia por Emissão de Pósitrons , Ratos , Ratos Sprague-Dawley , Espectrometria de Massas em Tandem , Testículo/efeitos dos fármacos , Testículo/metabolismo , Fatores de Tempo , Distribuição Tecidual/efeitos dos fármacos , Tomógrafos ComputadorizadosRESUMO
AIMS: Levels of the cyclic nucleotides guanosine 3', 5'-monophosphate (cGMP) or adenosine 3', 5'-monophosphate (cAMP) that play important roles in memory processes are not characterized in Alzheimer's disease (AD). The aim of this study was to analyse the levels of these nucleotides in cerebrospinal fluid (CSF) samples from patients diagnosed with clinical and prodromal stages of AD and study the expression level of the enzymes that hydrolyzed them [phosphodiesterases (PDEs)] in the brain of AD patients vs. METHODS: For cGMP and cAMP CSF analysis, the cohort (n = 79) included cognitively normal participants (subjective cognitive impairment), individuals with stable mild cognitive impairment or AD converters (sMCI and cMCI), and mild AD patients. A high throughput liquid chromatography-tandem mass spectrometry method was used. Interactions between CSF cGMP or cAMP with mini-mental state examination (MMSE) score, CSF Aß(1-42) and CSF p-tau were analysed. For PDE4, 5, 9 and 10 expression analysis, brains of AD patients vs. controls (n = 7 and n = 8) were used. RESULTS: cGMP, and not cAMP levels, were significantly lower in the CSF of patients diagnosed with mild AD when compared with nondemented controls. CSF levels of cGMP showed a significant association with MMSE-diagnosed clinical dementia and with CSF biomarker Aß42 in AD patients. Significant increase in PDE5 expression was detected in temporal cortex of AD patients compared with that of age-matched healthy control subjects. No changes in the expression of others PDEs were detected. CONCLUSIONS: These results support the potential involvement of cGMP in the pathological and clinical development of AD. The cGMP reduction in early stages of AD might participate in the aggravation of amyloid pathology and cognitive decline.
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Doença de Alzheimer/líquido cefalorraquidiano , GMP Cíclico/líquido cefalorraquidiano , Idoso , Doença de Alzheimer/enzimologia , Doença de Alzheimer/patologia , Encéfalo/enzimologia , Encéfalo/patologia , Disfunção Cognitiva/líquido cefalorraquidiano , Disfunção Cognitiva/enzimologia , Disfunção Cognitiva/patologia , AMP Cíclico/líquido cefalorraquidiano , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Diester Fosfórico HidrolasesRESUMO
Phosphodiesterase type 5 inhibitors (PDE5-Is) have recently emerged as a potential therapeutic strategy for neuroinflammatory, neurodegenerative, and memory loss diseases. Mechanistically, PDE5-Is produce an anti-inflammatory and neuroprotection effect by increasing expression of nitric oxide synthases and accumulation of cGMP and activating protein kinase G (PKG), the signaling pathway of which is thought to play an important role in the development of several neurodiseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). The aim of this paper was to review present knowledge of the signaling pathways that underlie the use of PDE5-Is in neuroinflammation, neurogenesis, learning, and memory.
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Cognição/efeitos dos fármacos , Degeneração Neural/tratamento farmacológico , Neuroimunomodulação/efeitos dos fármacos , Inibidores da Fosfodiesterase 5/farmacologia , Animais , Barreira Hematoencefálica/efeitos dos fármacos , Cognição/fisiologia , Humanos , Camundongos , Degeneração Neural/fisiopatologia , Neurogênese/efeitos dos fármacos , Neurogênese/fisiologia , Neuroglia/efeitos dos fármacos , Neuroimunomodulação/fisiologia , Fármacos Neuroprotetores/farmacologia , Nucleotídeos Cíclicos/metabolismo , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologiaRESUMO
JOURNAL/nrgr/04.03/01300535-202409000-00040/figure1/v/2024-01-16T170235Z/r/image-tiff Plaques of amyloid-ß (Aß) and neurofibrillary tangles are the main pathological characteristics of Alzheimer's disease (AD). However, some older adult people with AD pathological hallmarks can retain cognitive function. Unraveling the factors that lead to this cognitive resilience to AD offers promising prospects for identifying new therapeutic targets. Our hypothesis focuses on the contribution of resilience to changes in excitatory synapses at the structural and molecular levels, which may underlie healthy cognitive performance in aged AD animals. Utilizing the Morris Water Maze test, we selected resilient (asymptomatic) and cognitively impaired aged Tg2576 mice. While the enzyme-linked immunosorbent assay showed similar levels of Aß42 in both experimental groups, western blot analysis revealed differences in tau pathology in the pre-synaptic supernatant fraction. To further investigate the density of synapses in the hippocampus of 16-18 month-old Tg2576 mice, we employed stereological and electron microscopic methods. Our findings indicated a decrease in the density of excitatory synapses in the stratum radiatum of the hippocampal CA1 in cognitively impaired Tg2576 mice compared with age-matched resilient Tg2576 and non-transgenic controls. Intriguingly, through quantitative immunoelectron microscopy in the hippocampus of impaired and resilient Tg2576 transgenic AD mice, we uncovered differences in the subcellular localization of glutamate receptors. Specifically, the density of GluA1, GluA2/3, and mGlu5 in spines and dendritic shafts of CA1 pyramidal cells in impaired Tg2576 mice was significantly reduced compared with age-matched resilient Tg2576 and non-transgenic controls. Notably, the density of GluA2/3 in resilient Tg2576 mice was significantly increased in spines but not in dendritic shafts compared with impaired Tg2576 and non-transgenic mice. These subcellular findings strongly support the hypothesis that dendritic spine plasticity and synaptic machinery in the hippocampus play crucial roles in the mechanisms of cognitive resilience in Tg2576 mice.
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Addicts repeatedly relapse to drug seeking even after years of abstinence, and this behavior is frequently induced by the recall of memories of the rewarding effects of the drug. Established memories, including those induced by drugs of abuse, can become transiently fragile if reactivated, and during this labile phase, known as reconsolidation, can be persistently disrupted. Here we show that, in rats, a morphine-induced place preference (mCPP) memory is linked to context-dependent withdrawal as disrupting the reconsolidation of the memory leads to a significant reduction of withdrawal evoked in the same context. Moreover, the hippocampus plays a critical role in linking the place preference memory with the context-conditioned withdrawal, as disrupting hippocampal protein synthesis and cAMP-dependent-protein kinase A after the reactivation of mCPP significantly weakens the withdrawal. Hence, targeting memories induced by drugs may represent an important strategy for attenuating context-conditioned withdrawal and therefore subsequent relapse in opiate addicts.
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Transtornos da Memória/fisiopatologia , Dependência de Morfina/fisiopatologia , Motivação/fisiologia , Síndrome de Abstinência a Substâncias/fisiopatologia , Animais , Aprendizagem da Esquiva/efeitos dos fármacos , Aprendizagem da Esquiva/fisiologia , Condicionamento Psicológico/fisiologia , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Cicloeximida/administração & dosagem , Hipocampo/efeitos dos fármacos , Hipocampo/enzimologia , Hipocampo/fisiopatologia , Masculino , Memória/efeitos dos fármacos , Memória/fisiologia , Transtornos da Memória/psicologia , Morfina/administração & dosagem , Dependência de Morfina/psicologia , Motivação/efeitos dos fármacos , Entorpecentes/administração & dosagem , Inibidores da Síntese de Proteínas/farmacologia , Ratos , Ratos Long-Evans , Comportamento Espacial/efeitos dos fármacos , Comportamento Espacial/fisiologia , Síndrome de Abstinência a Substâncias/psicologiaRESUMO
A complex network of interactions exists between the olfactory, immune and central nervous systems. In this work we intend to investigate this connection through the use of an immunostimulatory odorant like menthol, analyzing its impact on the immune system and the cognitive capacity in healthy and Alzheimer's Disease Mouse Models. We first found that repeated short exposures to menthol odor enhanced the immune response against ovalbumin immunization. Menthol inhalation also improved the cognitive capacity of immunocompetent mice but not in immunodeficient NSG mice, which exhibited very poor fear-conditioning. This improvement was associated with a downregulation of IL-1ß and IL-6 mRNA in the brain´s prefrontal cortex, and it was impaired by anosmia induction with methimazole. Exposure to menthol for 6 months (1 week per month) prevented the cognitive impairment observed in the APP/PS1 mouse model of Alzheimer. Besides, this improvement was also observed by the depletion or inhibition of T regulatory cells. Treg depletion also improved the cognitive capacity of the APPNL-G-F/NL-G-F Alzheimer´s mouse model. In all cases, the improvement in learning capacity was associated with a downregulation of IL-1ß mRNA. Blockade of the IL-1 receptor with anakinra resulted in a significant increase in cognitive capacity in healthy mice as well as in the APP/PS1 model of Alzheimer´s disease. These data suggest an association between the immunomodulatory capacity of smells and their impact on the cognitive functions of the animals, highlighting the potential of odors and immune modulators as therapeutic agents for CNS-related diseases.
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Doença de Alzheimer , Camundongos , Animais , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/genética , Mentol/uso terapêutico , Precursor de Proteína beta-Amiloide/genética , Linfócitos T Reguladores , Camundongos Transgênicos , Cognição , ImunidadeRESUMO
Alzheimer's disease (AD) and ageing are associated with impaired learning and memory, and recent findings point toward modulating chromatin remodeling through histone acetylation as a promising therapeutic strategy. Here we report that systemic administration of the HDAC inhibitor 4-phenylbutyrate (PBA) reinstated fear learning in the Tg2576 mouse model of AD. Tg2576 mice develop age-dependent amyloid pathology and cognitive decline that closely mimics disease progression in humans. Memory reinstatement by PBA was observed independently of the disease stage: both in 6-month-old Tg2576 mice, at the onset of the first symptoms, but also in aged, 12- to 16-month-old mice, when amyloid plaque deposition and major synaptic loss has occurred. Reversal of learning deficits was associated to a PBA-induced clearance of intraneuronal Aß accumulation, which was accompanied by mitigation of endoplasmic reticulum (ER) stress, and to restoration of dendritic spine densities of hippocampal CA1 pyramidal neurons to control levels. Furthermore, the expression of plasticity-related proteins such as the NMDA receptor subunit NR2B and the synaptic scaffold SAP102 was significantly increased by PBA. Our data suggest that the beneficial effects of PBA in memory are mediated both via its chemical chaperone-like activity and via the transcriptional activation of a cluster of proteins required for the induction of synaptic plasticity and structural remodeling.
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Doença de Alzheimer/tratamento farmacológico , Espinhas Dendríticas/efeitos dos fármacos , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Inibidores de Histona Desacetilases/administração & dosagem , Transtornos da Memória/tratamento farmacológico , Memória/efeitos dos fármacos , Fenilbutiratos/administração & dosagem , Fatores Etários , Doença de Alzheimer/psicologia , Peptídeos beta-Amiloides/metabolismo , Animais , Região CA1 Hipocampal/metabolismo , Região CA1 Hipocampal/patologia , Espinhas Dendríticas/patologia , Modelos Animais de Doenças , Medo/efeitos dos fármacos , Guanilato Quinases/metabolismo , Humanos , Proteínas de Membrana/metabolismo , Transtornos da Memória/psicologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Placa Amiloide/tratamento farmacológico , Células Piramidais/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Transmissão Sináptica/efeitos dos fármacosRESUMO
Docosahexaenoic acid (DHA), the most abundant polyunsaturated fatty acid in the brain, is essential for successful aging. In fact, epidemiological studies have demonstrated that increased intake of DHA might lower the risk for developing Alzheimer's disease (AD). These observations are supported by studies in animal models showing that DHA reduces synaptic pathology and memory deficits. Different mechanisms to explain these beneficial effects have been proposed; however, the molecular pathways involved are still unknown. In this study, to unravel the main underlying molecular mechanisms activated upon DHA treatment, the effect of a high dose of DHA on cognitive function and AD pathology was analyzed in aged Tg2576 mice and their wild-type littermates. Transcriptomic analysis of mice hippocampi using RNA sequencing was subsequently performed. Our results revealed that, through an amyloid-independent mechanism, DHA enhanced memory function and increased synapse formation only in the Tg2576 mice. Likewise, the IPA analysis demonstrated that essential neuronal functions related to synaptogenesis, neuritogenesis, the branching of neurites, the density of dendritic spines and the outgrowth of axons were upregulated upon-DHA treatment in Tg2576 mice. Our results suggest that memory function in APP mice is influenced by DHA intake; therefore, a high dose of daily DHA should be tested as a dietary supplement for AD dementia prevention.
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In this study we tested whether phosphodiesterase 5 (PDE5) inhibitors, sildenafil and vardenafil, would afford protection against 3-nitropropionic acid (3NP), which produces striatal lesions that closely mimic some of the neuropathological features of Huntington's Disease (HD). The neurotoxin was given over 5 days by constant systemic infusion using osmotic minipumps. Animals treated with PDE5 inhibitors (sildenafil or vardenafil) showed improved neurologic scores, reduced the loss of striatal DARPP-32 protein levels and lesion volumes, and decreased calpain activation produced by 3NP. This protective effect was independent of changes in 3NP-induced succinate dehydrogenase inhibition. Furthermore, striatal p-CREB levels along with the expression of BDNF were significantly increased in sildenafil-treated rats. In summary, PDE5 inhibitors protected against 3NP-induced striatal degeneration by reducing calpain activation and by promoting survival pathways. These data encourage further evaluation of PDE5 inhibitors in transgenic mouse models of HD.
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Fator Neurotrófico Derivado do Encéfalo/metabolismo , Calpaína/metabolismo , Corpo Estriado/efeitos dos fármacos , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Síndromes Neurotóxicas/tratamento farmacológico , Nitrocompostos/farmacologia , Piperazinas/farmacologia , Propionatos/farmacologia , Sulfonas/farmacologia , Análise de Variância , Animais , Western Blotting , Corpo Estriado/metabolismo , Corpo Estriado/patologia , Fosfoproteína 32 Regulada por cAMP e Dopamina/metabolismo , Masculino , Atividade Motora/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Neurônios/patologia , Síndromes Neurotóxicas/metabolismo , Síndromes Neurotóxicas/patologia , Neurotoxinas/farmacologia , Inibidores de Fosfodiesterase/farmacologia , Purinas/farmacologia , Ratos , Ratos Endogâmicos Lew , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Citrato de Sildenafila , Succinato Desidrogenase/metabolismoRESUMO
The amyloid precursor protein (APP) undergoes sequential cleavages to generate various polypeptides, including the amyloid beta (1-42) peptide (Abeta[1-42]), which is believed to play a major role in amyloid plaque formation in Alzheimer's disease (AD). Here we provide evidence that, in contrast with its pathological role when accumulated, endogenous Abeta in normal hippocampi mediates learning and memory formation. Furthermore, hippocampal injection of picomolar concentrations of exogenous Abeta(1-42) enhances memory consolidation. Correlative data suggest that Abeta peptides may exert their function via nicotinic acethylcoline receptors. Hence, Abeta peptides, including Abeta(1-42), play an important physiological role in hippocampal memory formation.
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Peptídeos beta-Amiloides/metabolismo , Hipocampo/metabolismo , Memória/fisiologia , Fragmentos de Peptídeos/metabolismo , Animais , Comportamento Animal/fisiologia , Ratos , Ratos Long-EvansRESUMO
The brain depends on glucose as a source of energy. This implies the presence of glucose transporters, being GLUT1 and GLUT3 the most relevant. Expression of GLUT12 is found in mouse and human brain at low levels. We previously demonstrated GLUT12 upregulation in the frontal cortex of aged subjects that was even higher in aged Alzheimer's disease (AD) patients. However, the cause and the mechanism through which this increase occurs are still unknown. Here, we aimed to investigate whether the upregulation of GLUT12 in AD is related with aging or Aß deposition in comparison with GLUT1, GLUT3, and GLUT4. In the frontal cortex of two amyloidogenic mouse models (Tg2576 and APP/PS1) GLUT12 levels were increased. Contrary, expression of GLUT1 and GLUT3 were decreased, while GLUT4 did not change. In aged mice and the senescence-accelerated model SAMP8, GLUT12 and GLUT4 were upregulated in comparison with young animals. GLUT1 and GLUT3 did not show significant changes with age. The effect of ß-amyloid (Aß) deposition was also evaluated in Aß peptide i.c.v. injected mice. In the hippocampus, GLUT12 expression increased whereas GLUT4 was not modified. Consistent with the results in the amyloidogenic models, GLUT3 and GLUT1 were downregulated. In summary, Aß increases GLUT12 protein expression in the brain pointing out a central role of the transporter in AD pathology and opening new perspectives for the treatment of this neurodegenerative disease.
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Doença de Alzheimer/metabolismo , Encéfalo/metabolismo , Proteínas Facilitadoras de Transporte de Glucose/metabolismo , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/administração & dosagem , Animais , Encéfalo/patologia , Córtex Cerebral/metabolismo , Córtex Cerebral/patologia , Modelos Animais de Doenças , Injeções Intraventriculares , Camundongos Endogâmicos C57BL , Camundongos TransgênicosRESUMO
Clinical studies revealed that some aged-individuals accumulate a significant number of histopathological Alzheimer´s disease (AD) lesions in their brain, yet without developing any signs of dementia. Animal models of AD represent suitable tools to identify genes that might promote cognitive resilience and hence, this study first set out to identify cognitively resilient individuals in the aged-Tg2576 mouse model. A transcriptomic analysis of these mice identified PLA2G4E as a gene that might confer resistance to dementia. Indeed, a significant decrease in PLA2G4E is evident in the brain of late-stage AD patients, whereas no such changes are observed in early stage patients with AD neuropathological lesions but no signs of dementia. We demonstrated that adeno-associated viral vector-mediated overexpression of PLA2G4E in hippocampal neurons completely restored cognitive deficits in elderly APP/PS1 mice, without affecting the amyloid or tau pathology. These PLA2G4E overexpressing APP/PS1 mice developed significantly more dendritic spines than sham-injected mice, coinciding with the cognitive improvement observed. Hence, these results support the idea that a loss of PLA2G4E might play a key role in the onset of dementia in AD, highlighting the potential of PLA2G4E overexpression as a novel therapeutic strategy to manage AD and other disorders that course with memory deficits.
Assuntos
Doença de Alzheimer/genética , Doença de Alzheimer/terapia , Espinhas Dendríticas , Terapia Genética , Fosfolipases A2 do Grupo IV/fisiologia , Fosfolipases A2 do Grupo IV/uso terapêutico , Hipocampo , Memória Espacial , Animais , Comportamento Animal/fisiologia , Modelos Animais de Doenças , Feminino , Regulação da Expressão Gênica/genética , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos TransgênicosRESUMO
A hexanucleotide GGGGCC expansion in intron 1 of chromosome 9 open reading frame 72 (C9orf72) gene is the most frequent cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). The corresponding repeat-containing sense and antisense transcripts cause a gain of toxicity through the accumulation of RNA foci in the nucleus and deposition of dipeptide-repeat (DPR) proteins in the cytoplasm of the affected cells. We have previously reported on the potential of engineered artificial anti-C9orf72-targeting miRNAs (miC) targeting C9orf72 to reduce the gain of toxicity caused by the repeat-containing transcripts. In the current study, we tested the silencing efficacy of adeno-associated virus (AAV)5-miC in human-derived induced pluripotent stem cell (iPSC) neurons and in an ALS mouse model. We demonstrated that AAV5-miC transduces different types of neuronal cells and can reduce the accumulation of repeat-containing C9orf72 transcripts. Additionally, we demonstrated silencing of C9orf72 in both the nucleus and cytoplasm, which has an added value for the treatment of ALS and/or FTD patients. A proof of concept in an ALS mouse model demonstrated the significant reduction in repeat-containing C9orf72 transcripts and RNA foci after treatment. Taken together, these findings support the feasibility of a gene therapy for ALS and FTD based on the reduction in toxicity caused by the repeat-containing C9orf72 transcripts.
RESUMO
The discouraging results with therapies for Alzheimer's disease (AD) in clinical trials, highlights the urgent need to adopt new approaches. Like other complex diseases, it is becoming clear that AD therapies should focus on the simultaneous modulation of several targets implicated in the disease. Recently, using reference compounds and the first-in class CM-414, we demonstrated that the simultaneous inhibition of histone deacetylases [class I histone deacetylases (HDACs) and HDAC6] and phosphodiesterase 5 (PDE5) has a synergistic therapeutic effect in AD models. To identify the best inhibitory balance of HDAC isoforms and PDEs that provides a safe and efficient therapy to combat AD, we tested the compound CM-695 in the Tg2576 mouse model of this disease. CM-695 selectively inhibits HDAC6 over class I HDAC isoforms, which largely overcomes the toxicity associated with HDAC class 1 inhibition. Furthermore, CM-695 inhibits PDE9, which is expressed strongly in the brain and has been proposed as a therapeutic target for AD. Chronic treatment of aged Tg2576 mice with CM-695 ameliorates memory impairment and diminishes brain Aß, although its therapeutic effect was no longer apparent 4 weeks after the treatment was interrupted. An increase in the presence of 78-KDa glucose regulated protein (GRP78) and heat shock protein 70 (Hsp70) chaperones may underlie the therapeutic effect of CM-695. In summary, chronic treatment with CM-695 appears to reverse the AD phenotype in a safe and effective manner. Taking into account that AD is a multifactorial disorder, the multimodal action of these compounds and the different events they affect may open new avenues to combat AD.
RESUMO
Here, we present a series of dual-target phosphodiesterase 9 (PDE9) and histone deacetylase (HDAC) inhibitors devised as pharmacological tool compounds for assessing the implications of these two targets in Alzheimer's disease (AD). These novel inhibitors were designed taking into account the key pharmacophoric features of known selective PDE9 inhibitors as well as privileged chemical structures, bearing zinc binding groups (hydroxamic acids and ortho-amino anilides) that hit HDAC targets. These substituents were selected according to rational criteria and previous knowledge from our group to explore diverse HDAC selectivity profiles (pan-HDAC, HDAC6 selective, and class I selective) that were confirmed in biochemical screens. Their functional response in inducing acetylation of histone and tubulin and phosphorylation of cAMP response element binding (CREB) was measured as a requisite for further progression into complete in vitro absorption, distribution, metabolism and excretion (ADME) and in vivo brain penetration profiling. Compound 31b, a selective HDAC6 inhibitor with acceptable brain permeability, was chosen for assessing in vivo efficacy of these first-in-class inhibitors, as well as studying their mode of action (MoA).