RESUMO
Fortea et al.'s. (2024) recent data analysis elegantly calls attention to familial late-onset Alzheimer's disease (AD) with APOE4 homozygosity. The article by Grant (2024) reviews the factors associated with AD, particularly the APOE genotype and lifestyle, and the broad implications for prevention, both for individuals with the lifestyles associated with living in resource-rich countries and for those enduring environmental adversity in poverty settings, including high exposure to enteric pathogens and precarious access to healthcare. Grant discusses the issue of APOE genotype and its implications for the benefits of lifestyle modifications. This review highlights that bearing APOE4 could constitute an evolutionary benefit in coping with heavy enteric infections and malnutrition early in life in the critical formative first two years of brain development. However, the critical issue may be that this genotype could be a health concern under shifts in lifestyle and unhealthy diets during aging, leading to severe cognitive impairments and increased risk of AD. This commentary supports the discussions of Grant and the benefits of improving lifestyle for decreasing the risks for AD while providing further understanding and modelling of the early life benefits of APOE4 amidst adversity. This attention to the pathophysiology of AD should help further elucidate these critical, newly appreciated pathogenic pathways for developing approaches to the prevention and management in the context of the APOE genetic variations associated with AD.
Assuntos
Doença de Alzheimer , Apolipoproteína E4 , Desnutrição , Plasticidade Neuronal , Humanos , Doença de Alzheimer/genética , Doença de Alzheimer/prevenção & controle , Apolipoproteína E4/genética , Plasticidade Neuronal/genética , Desnutrição/genética , Desnutrição/complicações , Homozigoto , Estilo de VidaRESUMO
Pannexin-1 (Panx1) hemichannel is a non-selective transmembrane channel that may play important roles in intercellular signaling by allowing the permeation of ions and metabolites, such as ATP. Although recent evidence shows that the Panx1 hemichannel is involved in controlling excitatory synaptic transmission, the role of Panx1 in inhibitory transmission remains unknown. Here, we studied the contribution of Panx1 to the GABAergic synaptic efficacy onto CA1 pyramidal neurons (PyNs) by using patch-clamp recordings and pharmacological approaches in wild-type and Panx1 knock-out (Panx1-KO) mice. We reported that blockage of the Panx1 hemichannel with the mimetic peptide 10Panx1 increases the synaptic level of endocannabinoids (eCB) and the activation of cannabinoid receptors type 1 (CB1Rs), which results in a decrease in hippocampal GABAergic efficacy, shifting excitation/inhibition (E/I) balance toward excitation and facilitating the induction of long-term potentiation. Our finding provides important insight unveiling that Panx1 can strongly influence the overall neuronal excitability and play a key role in shaping synaptic changes affecting the amplitude and direction of plasticity, as well as learning and memory processes.
Assuntos
Hipocampo , Proteínas do Tecido Nervoso , Plasticidade Neuronal , Células Piramidais , Animais , Camundongos , Conexinas/genética , Conexinas/metabolismo , Hipocampo/metabolismo , Potenciação de Longa Duração/fisiologia , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Plasticidade Neuronal/genética , Plasticidade Neuronal/fisiologia , Células Piramidais/metabolismo , Células Piramidais/fisiologia , Transmissão SinápticaRESUMO
The noradrenergic system is implicated in neuropathologies contributing to major disorders of the memory, including post-traumatic stress disorder and Alzheimer's disease. Determining the impact of norepinephrine on cellular function and plasticity is thus essential for making inroads into our understanding of these brain conditions, while expanding our capacity for treating them. Norepinephrine is a neuromodulator within the mammalian central nervous system which plays important roles in cognition and associated synaptic plasticity. Specifically, norepinephrine regulates the formation of memory through the stimulation of ß-ARs, increasing the dynamic range of synaptic modifiability. The mechanisms through which NE influences neural circuit function have been extended to the level of the epigenome. This review focuses on recent insights into how the noradrenergic recruitment of epigenetic modifications, including DNA methylation and post-translational modification of histones, contribute to homo- and heterosynaptic plasticity. These advances will be placed in the context of synaptic changes associated with memory formation and linked to brain disorders and neurotherapeutic applications.
Assuntos
Potenciação de Longa Duração , Norepinefrina , Animais , Epigênese Genética , Potenciação de Longa Duração/fisiologia , Mamíferos/metabolismo , Plasticidade Neuronal/genética , Norepinefrina/fisiologia , Receptores Adrenérgicos beta/metabolismo , Sinapses/metabolismoRESUMO
BACKGROUND: Obsessive-compulsive disorder (OCD) is characterized by intrusive thoughts and repetitive actions, that presents the involvement of the cortico-striatal areas. The contribution of environmental risk factors to OCD development suggests that epigenetic mechanisms may contribute to its pathophysiology. DNA methylation changes and gene expression were evaluated in post-mortem brain tissues of the cortical (anterior cingulate gyrus and orbitofrontal cortex) and ventral striatum (nucleus accumbens, caudate nucleus and putamen) areas from eight OCD patients and eight matched controls. RESULTS: There were no differentially methylated CpG (cytosine-phosphate-guanine) sites (DMSs) in any brain area, nevertheless gene modules generated from CpG sites and protein-protein-interaction (PPI) showed enriched gene modules for all brain areas between OCD cases and controls. All brain areas but nucleus accumbens presented a predominantly hypomethylation pattern for the differentially methylated regions (DMRs). Although there were common transcriptional factors that targeted these DMRs, their targeted differentially expressed genes were different among all brain areas. The protein-protein interaction network based on methylation and gene expression data reported that all brain areas were enriched for G-protein signaling pathway, immune response, apoptosis and synapse biological processes but each brain area also presented enrichment of specific signaling pathways. Finally, OCD patients and controls did not present significant DNA methylation age differences. CONCLUSIONS: DNA methylation changes in brain areas involved with OCD, especially those involved with genes related to synaptic plasticity and the immune system could mediate the action of genetic and environmental factors associated with OCD.
Assuntos
Encéfalo/metabolismo , Metilação de DNA , Transtorno Obsessivo-Compulsivo/genética , Idoso , Núcleo Caudado , Ilhas de CpG/genética , Feminino , Giro do Cíngulo , Humanos , Sistema Imunitário/metabolismo , Imunidade/genética , Masculino , Plasticidade Neuronal/genética , Núcleo Accumbens , Córtex Pré-Frontal , PutamenRESUMO
BACKGROUND: Stress increases DNA methylation, primarily a suppressive epigenetic mechanism catalyzed by DNA methyltransferases (DNMT), and decreases the expression of genes involved in neuronal plasticity and mood regulation. Despite chronic antidepressant treatment decreases stress-induced DNA methylation, it is not known whether inhibition of DNMT would convey rapid antidepressant-like effects. AIM: This work tested such a hypothesis and evaluated whether a behavioral effect induced by DNMT inhibitors (DNMTi) corresponds with changes in DNA methylation and transcript levels in genes consistently associated with the neurobiology of depression and synaptic plasticity (BDNF, TrkB, 5-HT1A, NMDA, and AMPA). METHODS: Male Wistar rats received intraperitoneal (i.p.) injection of two pharmacologically different DNMTi (5-AzaD 0.2 and 0.6 mg/kg or RG108 0.6 mg/kg) or vehicle (1 ml/kg), 1 h or 7 days before the learned helplessness test (LH). DNA methylation in target genes and the correspondent transcript levels were measured in the hippocampus (HPC) and prefrontal cortex (PFC) using meDIP-qPCR. In parallel separate groups, the antidepressant-like effect of 5-AzaD and RG108 was investigated in the forced swimming test (FST). The involvement of cortical BDNF-TrkB-mTOR pathways was assessed by intra-ventral medial PFC (vmPFC) injections of rapamycin (mTOR inhibitor), K252a (TrkB receptor antagonist), or vehicle (0.2 µl/side). RESULTS: We found that both 5-AzaD and RG108 acutely and 7 days before the test decreased escape failures in the LH. LH stress increased DNA methylation and decreased transcript levels of BDNF IV and TrkB in the PFC, effects that were not significantly attenuated by RG108 treatment. The systemic administration of 5-AzaD (0.2 mg/kg) and RG108 (0.2 mg/kg) induced an antidepressant-like effect in FST, which was, however, attenuated by TrkB and mTOR inhibition into the vmPFC. CONCLUSION: These findings suggest that acute inhibition of stress-induced DNA methylation promotes rapid and sustained antidepressant effects associated with increased BDNF-TrkB-mTOR signaling in the PFC.
Assuntos
Antidepressivos/farmacologia , DNA (Citosina-5-)-Metiltransferases/antagonistas & inibidores , Metilação de DNA/genética , Regulação da Expressão Gênica , Plasticidade Neuronal/genética , Córtex Pré-Frontal/fisiologia , Animais , Comportamento Animal , Fator Neurotrófico Derivado do Encéfalo/genética , Fator Neurotrófico Derivado do Encéfalo/metabolismo , DNA (Citosina-5-)-Metiltransferases/metabolismo , Metilação de DNA/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Desamparo Aprendido , Masculino , Plasticidade Neuronal/efeitos dos fármacos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos Wistar , Receptor trkB/genética , Receptor trkB/metabolismo , Transdução de Sinais/efeitos dos fármacos , Estresse Psicológico/metabolismo , Serina-Treonina Quinases TOR/metabolismoRESUMO
Cannabinoid receptor type 1 (CB1R) modulates synaptic activity and is widely distributed in brain areas such as the hippocampus, cerebellum, cerebral cortex, and striatum, among others. CB1R is involved in processes such as memory, learning, motor coordination, and mood. Genetic deletion of CB1R causes behavioral alterations. In this work, we evaluated neuronal morphology and synaptic structure in the hippocampus of adult male CB1R knockout mice (CB1R-/- ). Morphological changes in the CB1R-/- hippocampus evidenced a decrease in the expression of cytoskeletal proteins neurofilaments 160 KDa, neurofilaments 200 KDa, and microtubule-associated protein 2. CA1 neurons showed decreased arborization and changes in synaptic structure such as lower thickness of postsynaptic density and a reduction in synaptophysin levels. Results obtained in the present work provide evidence of the participation of CB1R in the establishment of neuronal structure and networks that could have an important role in neuronal plasticity. In addition, these changes observed in CB1R-/- could be correlated with behavioral alterations reported.
Assuntos
Hipocampo/anatomia & histologia , Neurônios/ultraestrutura , Receptor CB1 de Canabinoide/genética , Sinapses/ultraestrutura , Animais , Proteínas do Citoesqueleto/genética , Proteínas do Citoesqueleto/metabolismo , Feminino , Hipocampo/ultraestrutura , Imuno-Histoquímica , Masculino , Camundongos , Camundongos Knockout , Proteínas Associadas aos Microtúbulos/genética , Proteínas Associadas aos Microtúbulos/metabolismo , Rede Nervosa/anatomia & histologia , Rede Nervosa/ultraestrutura , Proteínas de Neurofilamentos/genética , Proteínas de Neurofilamentos/metabolismo , Plasticidade Neuronal/genética , Plasticidade Neuronal/fisiologiaRESUMO
Background: Data from the Global Burden of Disease Study 2016 recently estimated that after opioid and cannabis use disorders, cocaine use disorders were among the most common, with around 5.8 million cases around the world. Several genome-wide expression studies (GWES) for cocaine misuse have been carried out in brain tissues from patients and controls and in mouse and rat models.Objectives: In the current work, we used a convergent functional genomics approach to identify novel candidate genes and pathways for cocaine misuse.Methods: We carried out meta-analyses for available GWES for cocaine misuse in humans and mouse and rat models (three, four, and two GWES, respectively). Multiple lines of evidence (GWES, genome-wide association and epigenomic data) were integrated to prioritize top candidate genes, and a functional enrichment analysis was carried out.Results: Several top candidate genes supported by multiple lines of genomic evidence, and with known roles in brain plasticity, were identified: APP, GRIN2A, GRIN2B, KCNA2, MAP4, PCDH10, PPP3CA, SNCB, and SV2C. An enrichment of genes regulated by the AP1 transcription factor was found.Conclusion: This is the first meta-analysis of GWES for cocaine misuse in humans and mouse and rat models. The analysis of convergence of multiple lines of genome-wide evidence identified novel candidate genes and pathways for cocaine misuse, which are of basic and clinical importance.
Assuntos
Transtornos Relacionados ao Uso de Cocaína/genética , Estudos de Associação Genética/métodos , Genômica/métodos , Plasticidade Neuronal/efeitos dos fármacos , Plasticidade Neuronal/genética , Animais , Humanos , Camundongos , Modelos Animais , Modelos Biológicos , Ratos , Fatores de Transcrição/genéticaRESUMO
Maternal physical activity induces brain functional changes and neuroplasticity, leading to an improvement of cognitive functions, such as learning and memory in the offspring. This study investigated the effects of voluntary maternal physical activity on the gene expression of the neurotrophic factors (NTFs): BDNF, NTF4, NTRK2, IGF-1 and IGF-1r in the different areas of mother's brain, placenta and foetus brain of rats. Female Wistar rats (n = 15) were individually housed in voluntary physical activity cages, containing a running wheel, for 4 weeks (period of adaptation) before gestation. Rats were classified as inactive (I, n = 6); active (A, n = 4) and very active (VA, n = 5) according to daily distance spontaneously travelled. During gestation, the dams continued to have access to the running wheel. At the 20th day of gestation, gene expression of NTFs was analysed in different areas of mother's brain (cerebellum, hypothalamus, hippocampus and cortex), placenta and the offspring's brain. NTFs gene expression was evaluated using quantitative PCR. Very active mothers showed upregulation of IGF-1 mRNA in the cerebellum (36.8%) and NTF4 mRNA expression in the placenta (24.3%). In the cortex, there was a tendency of up-regulation of NTRK2 mRNA (p = 0.06) in the A and VA groups when compared to I group. There were no noticeable changes in the gene expression of NTFs in the offspring's brain. Our findings suggest the existence of a developmental plasticity induced by maternal physical activity in specific areas of the brain and placenta representing the first investment for offspring during development.
Assuntos
Encéfalo/metabolismo , Desenvolvimento Fetal/fisiologia , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Condicionamento Físico Animal/fisiologia , Placenta/metabolismo , Animais , Encéfalo/citologia , Encéfalo/embriologia , Feminino , Fator de Crescimento Insulin-Like I/genética , Masculino , Modelos Animais , Plasticidade Neuronal/genética , Gravidez , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Receptor trkB/genéticaRESUMO
N-methyl-D-aspartate receptors (NMDARs) that contain the NR2A and NR2B subunits play a critical role in neuronal plasticity and dendritogenesis. Gain-and-loss-of function studies indicate that NR2B, but not NR2A, promotes dendritic branching. Accumulating evidence indicates that stimulation of NMDARs activates NADPH oxidase (NOX2), thereby generating superoxide. However, the molecular underpinnings of this process are not understood. RasGRF1, a guanine nucleotide exchange factor, is key for several forms of neuronal plasticity and interacts directly with the tail of NR2B. We investigated whether the NR2B-NMDAR/RasGRF1 pathway regulates the activity of NOX2 and whether superoxide production is required for dendritogenesis. We measured superoxide production in developing primary cultures of hippocampal neurons from 3 to 25 days in vitro (DIV) with the probe dihydroethidium (dHE). We found the highest dHE levels at early and intermediate developmental stages (3-15 DIV), when the NR2B-NMDAR expression is abundant. During these early/intermediate developmental stages, but not in mature neurons (>15 DIV), NMDAR activity is required for superoxide production. We also found that disrupting the NR2B-RasGRF1 interaction led to reduced dHE fluorescence intensity and moreover inhibited dendritic branching in hippocampal neurons. Together, our data indicate that superoxide production is induced by the NR2B-NMDARs/RasGRF1/NOX2 pathway and promotes dendritogenesis.
Assuntos
NADPH Oxidase 2/genética , Neurogênese/genética , Receptores de N-Metil-D-Aspartato/genética , ras-GRF1/genética , Animais , Dendritos/metabolismo , Células Dendríticas/metabolismo , Regulação da Expressão Gênica no Desenvolvimento/genética , Hipocampo/crescimento & desenvolvimento , Hipocampo/metabolismo , Plasticidade Neuronal/genética , Neurônios/metabolismo , Ratos , Transdução de Sinais/genética , Superóxidos/metabolismoRESUMO
Traumatic brain injury (TBI) is a leading cause of disability worldwide, triggering chronic neurodegeneration underlying cognitive and mood disorder still without therapeutic prospects. Based on our previous observations that guanosine (GUO) attenuates short-term neurochemical alterations caused by TBI, this study investigated the effects of chronical GUO treatment in behavioral, molecular, and morphological disturbances 21 days after trauma. Rats subject to TBI displayed mood (anxiety-like) and memory dysfunction. This was accompanied by a decreased expression of both synaptic (synaptophysin) and plasticity proteins (BDNF and CREB), a loss of cresyl violet-stained neurons, and increased astrogliosis and microgliosis in the hippocampus. Notably, chronic GUO treatment (7.5 mg/kg i.p. daily starting 1 h after TBI) prevented all these TBI-induced long-term behavioral, neurochemical, and morphological modifications. This neuroprotective effect of GUO was abrogated in the presence of the adenosine A1 receptor antagonist DPCPX (1 mg/kg) but unaltered by the adenosine A2A receptor antagonist SCH58261 (0.05 mg/kg). These findings show that a chronic GUO treatment prevents the long-term mood and memory dysfunction triggered by TBI, which involves adenosinergic receptors.