RESUMO
Major depressive disorder (MDD) has demonstrated its negative impact on various aspects of the lives of those affected. Although several therapies have been developed over the years, it remains a challenge for mental health professionals. Thus, understanding the pathophysiology of MDD is necessary to improve existing treatment options or seek new therapeutic alternatives. Clinical and preclinical studies in animal models of depression have shown the involvement of synaptic plasticity in both the development of MDD and the response to available drugs. However, synaptic plasticity involves a cascade of events, including the action of presynaptic proteins such as synaptophysin and synapsins and postsynaptic proteins such as postsynaptic density-95 (PSD-95). Additionally, several factors can negatively impact the process of spinogenesis/neurogenesis, which are related to many outcomes, including MDD. Thus, this narrative review aims to deepen the understanding of the involvement of synaptic formations and their components in the pathophysiology and treatment of MDD.
Assuntos
Transtorno Depressivo Maior , Plasticidade Neuronal , Humanos , Transtorno Depressivo Maior/metabolismo , Transtorno Depressivo Maior/tratamento farmacológico , Transtorno Depressivo Maior/fisiopatologia , Animais , Plasticidade Neuronal/fisiologia , Plasticidade Neuronal/efeitos dos fármacos , Sinapses/metabolismo , Sinapses/efeitos dos fármacosRESUMO
INTRODUCTION: Impaired brain protein synthesis, synaptic plasticity, and memory are major hallmarks of Alzheimer's disease (AD). The ketamine metabolite (2R,6R)-hydroxynorketamine (HNK) has been shown to modulate protein synthesis, but its effects on memory in AD models remain elusive. METHODS: We investigated the effects of HNK on hippocampal protein synthesis, long-term potentiation (LTP), and memory in AD mouse models. RESULTS: HNK activated extracellular signal-regulated kinase 1/2 (ERK1/2), mechanistic target of rapamycin (mTOR), and p70S6 kinase 1 (S6K1)/ribosomal protein S6 signaling pathways. Treatment with HNK rescued hippocampal LTP and memory deficits in amyloid-ß oligomers (AßO)-infused mice in an ERK1/2-dependent manner. Treatment with HNK further corrected aberrant transcription, LTP and memory in aged APP/PS1 mice. DISCUSSION: Our findings demonstrate that HNK induces signaling and transcriptional responses that correct synaptic and memory deficits in AD mice. These results raise the prospect that HNK could serve as a therapeutic approach in AD. HIGHLIGHTS: The ketamine metabolite HNK activates hippocampal ERK/mTOR/S6 signaling pathways. HNK corrects hippocampal synaptic and memory defects in two mouse models of AD. Rescue of synaptic and memory impairments by HNK depends on ERK signaling. HNK corrects aberrant transcriptional signatures in APP/PS1 mice.
Assuntos
Doença de Alzheimer , Modelos Animais de Doenças , Hipocampo , Ketamina , Camundongos Transgênicos , Plasticidade Neuronal , Animais , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/metabolismo , Ketamina/análogos & derivados , Ketamina/farmacologia , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Plasticidade Neuronal/efeitos dos fármacos , Camundongos , Potenciação de Longa Duração/efeitos dos fármacos , Peptídeos beta-Amiloides/metabolismo , Biossíntese de Proteínas/efeitos dos fármacos , Serina-Treonina Quinases TOR/metabolismo , RNA Mensageiro/metabolismo , Memória/efeitos dos fármacos , Masculino , Transtornos da Memória/tratamento farmacológico , Camundongos Endogâmicos C57BL , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Presenilina-1/genética , HumanosRESUMO
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the accumulation of amyloid-ß, leading to N-methyl-D-aspartate (NMDA) receptor-dependent synaptic depression, spine elimination, and memory deficits. Glycine transporter type 1 (GlyT1) modulates glutamatergic neurotransmission via NMDA receptors (NMDAR), presenting a potential alternative therapeutic approach for AD. This study investigates the neuroprotective potential of GlyT1 inhibition in an amyloid-ß-induced AD mouse model. C57BL/6 mice were treated with N-[3-([1,1-Biphenyl]-4-yloxy)-3-(4-fluorophenyl)propyl]-N-methylglycine (NFPS), a GlyT1 inhibitor, 24 h prior to intrahippocampal injection of amyloid-ß. NFPS pretreatment prevented amyloid-ß-induced cognitive deficits in short-term and long-term memory, evidenced by novel object recognition and spatial memory tasks. Moreover, NFPS pretreatment curbed microglial activation, astrocytic reactivity, and subsequent neuronal damage from amyloid-ß injection. An extensive label-free quantitative UPLC-MSE proteomic analysis was performed on the hippocampi of mice treated with NFPS. In proteomics, KEGG enrichment analysis revealed increased in dopaminergic synapse, purine-containing compound biosynthetic process and long-term potentiation, and a reduction in Glucose catabolic process and glycolytic process pathways. The western blot analysis confirmed that NFPS treatment elevated BDNF levels, correlating with enhanced TRKB phosphorylation and mTOR activation. Moreover, NFPS treatment reduced the GluN2B expression after 6 h, which was associated with an increase on CaMKIV and CREB phosphorylation. Collectively, these findings demonstrate that GlyT1 inhibition by NFPS activates diverse neuroprotective pathways, enhancing long-term potentiation signaling and countering amyloid-ß-induced hippocampal damage.
Assuntos
Doença de Alzheimer , Peptídeos beta-Amiloides , Proteínas da Membrana Plasmática de Transporte de Glicina , Hipocampo , Camundongos Endogâmicos C57BL , Fármacos Neuroprotetores , Animais , Doença de Alzheimer/metabolismo , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/induzido quimicamente , Doença de Alzheimer/prevenção & controle , Peptídeos beta-Amiloides/metabolismo , Masculino , Fármacos Neuroprotetores/farmacologia , Fármacos Neuroprotetores/uso terapêutico , Camundongos , Hipocampo/metabolismo , Hipocampo/efeitos dos fármacos , Proteínas da Membrana Plasmática de Transporte de Glicina/antagonistas & inibidores , Proteínas da Membrana Plasmática de Transporte de Glicina/metabolismo , Modelos Animais de Doenças , Sarcosina/análogos & derivados , Sarcosina/farmacologia , Sarcosina/uso terapêutico , Neuroproteção/efeitos dos fármacos , Neuroproteção/fisiologiaRESUMO
The central amygdaloid nucleus (CeA) has an ancient phylogenetic development and functions relevant for animal survival. Local cells receive intrinsic amygdaloidal information that codes emotional stimuli of fear, integrate them, and send cortical and subcortical output projections that prompt rapid visceral and social behavior responses. We aimed to describe the morphology of the neurons that compose the human CeA (N = 8 adult men). Cells within CeA coronal borders were identified using the thionine staining and were further analyzed using the "single-section" Golgi method followed by open-source software procedures for two-dimensional and three-dimensional image reconstructions. Our results evidenced varied neuronal cell body features, number and thickness of primary shafts, dendritic branching patterns, and density and shape of dendritic spines. Based on these criteria, we propose the existence of 12 morphologically different spiny neurons in the human CeA and discuss the variability in the dendritic architecture within cellular types, including likely interneurons. Some dendritic shafts were long and straight, displayed few collaterals, and had planar radiation within the coronal neuropil volume. Most of the sampled neurons showed a few to moderate density of small stubby/wide spines. Long spines (thin and mushroom) were observed occasionally. These novel data address the synaptic processing and plasticity in the human CeA. Our morphological description can be combined with further transcriptomic, immunohistochemical, and electrophysiological/connectional approaches. It serves also to investigate how neurons are altered in neurological and psychiatric disorders with hindered emotional perception, in anxiety, following atrophy in schizophrenia, and along different stages of Alzheimer's disease.
Assuntos
Núcleo Central da Amígdala , Masculino , Adulto , Animais , Humanos , Filogenia , Espinhas Dendríticas/fisiologia , Neurônios/fisiologia , InterneurôniosRESUMO
SUMMARY: We evaluated the role and mechanism of acteoside in the regulation of memory impairment induced by chronic unpredictable mild stress (CUMS). CUMS was used to induce depression in rats and the successful establishment of CUMS model were verified by forced swimming test and sucrose preference test. The Y-maze test and novel object recognition test assessed memory functions. The structural changes in the cortex and hippocampus were observed by hematoxylin and eosin (HE) staining. Immunofluorescence staining and western blotting determined the protein levels. Y-maze test and novel object recognition test showed that there was memory performance impairment in rats of CUMS group, which was improved by the acteoside treatment. HE staining showed that CUMS exposure damaged the structure in the cortex and hippocampus, while the acteoside treatment alleviated the structural changes. Compared with the control group, the levels of BNDF and CREB in the cortex and hippocampus of the CUMS group were significantly decreased. Acteoside significantly reversed the expressions of these proteins in CUMS rats. Meanwhile, compared with the control group, the levels of p-mTOR and p- P70S6K in the cortex and hippocampus of the CUMS group were significantly increased, and these changes were significantly reversed by acteoside. Nevertheless, the effect of acteoside on mTOR signaling was markedly blocked by rapamycin, a specific inhibitor of mTOR signaling. Acteoside can attenuate memory impairment and ameliorate neuronal damage and synaptic plasticity in depression rats probably via inhibiting the mTOR signaling pathway. Acteoside may serve as a novel reagent for the prevention of depression.
Evaluamos el papel y el mecanismo del acteoside en la regulación del deterioro de la memoria inducido por estrés leve crónico impredecible (ELCI). Se utilizó ELCI para inducir depresión en ratas y el establecimiento exitoso del modelo ELCI se verificó mediante una prueba de natación forzada y una prueba de preferencia de sacarosa. La prueba del laberinto en Y y la prueba de reconocimiento de objetos novedosos evaluaron las funciones de la memoria. Los cambios estructurales en la corteza y el hipocampo se observaron mediante tinción con hematoxilina y eosina (HE). La tinción por inmunofluorescencia y la transferencia Western determinaron los niveles de proteína. La prueba del laberinto en Y y la prueba de reconocimiento de objetos novedosos mostraron que había un deterioro del rendimiento de la memoria en ratas del grupo ELCI, que mejoró con el tratamiento con acteósidos. La tinción con HE mostró que la exposición a ELCI dañó la estructura de la corteza y el hipocampo, mientras que el tratamiento con actósidos alivió los cambios estructurales. En comparación con el grupo de control, los niveles de BNDF y CREB en la corteza y el hipocampo del grupo ELCI disminuyeron significativamente. Acteoside revirtió significativamente las expresiones de estas proteínas en ratas ELCI. Mientras tanto, en comparación con el grupo control, los niveles de p-mTOR y p-P70S6K en la corteza y el hipocampo del grupo ELCI aumentaron significativamente, y estos cambios fueron revertidos significativamente ELCI por el acteoside. Sin embargo, el efecto del acteoside sobre la señalización de mTOR fue notablemente bloqueado por la rapamicina, un inhibidor específico de la señalización de mTOR. El acteoside puede atenuar el deterioro de la memoria y mejorar el daño neuronal y la plasticidad sináptica en ratas con depresión, probablemente mediante la inhibición de la vía de señalización mTOR. Acteoside puede servir como un reactivo novedoso para la prevención de la depresión.
Assuntos
Animais , Ratos , Depressão/tratamento farmacológico , Polifenóis/administração & dosagem , Glucosídeos/administração & dosagem , Transtornos da Memória/tratamento farmacológico , Estresse Psicológico/complicações , Western Blotting , Imunofluorescência , Ratos Sprague-Dawley , Aprendizagem em Labirinto , Reconhecimento Psicológico/efeitos dos fármacos , Modelos Animais de Doenças , Serina-Treonina Quinases TOR/antagonistas & inibidores , Polifenóis/uso terapêutico , Escala de Avaliação Comportamental , Inibidores de MTOR , Glucosídeos/uso terapêutico , Plasticidade Neuronal/efeitos dos fármacos , NeurôniosRESUMO
Type 2 diabetes mellitus (T2DM) has been shown to affect a series of cognitive processes including memory, increasing the risk for dementia, particularly Alzheimer's disease (AD). Although increasing evidence has supported that both diseases share common features, the pathophysiological mechanisms connecting these two disorders remain to be fully elucidated. Herein, we used Drosophila melanogaster fed on a high-sugar diet (HSD) to mimic T2DM, and investigate its effects on memory as well as identify potential molecular players associated with the memory deficits induced by HSD. Flies hatched from and reared on HSD for 7 days had a substantial decrease in short-term memory (STM). The screening for memory-related genes using transcriptome data revealed that HSD altered the expression of 33% of memory genes in relation to the control. Among the differentially expressed genes (DEGs) with a fold change (FC) higher than two, we found five genes, related to synapse and memory trace formation, that could be considered strong candidates to underlie the STM deficits in HSD flies: Abl tyrosine kinase (Abl), bruchpilot (Brp), minibrain (Mnb), shaker (Sh), and gilgamesh (Gish). We also analyzed genes from the dopamine system, one of the most relevant signaling pathways for olfactory memory. Interestingly, the flies fed on HSD presented a decreased expression of the Tyrosine hydroxylase (Ple) and Dopa decarboxylase (Ddc) genes, signals of a possible dopamine deficiency. In this work, we present promising biomarkers to investigate molecular networks shared between T2DM and AD.
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Doença de Alzheimer , Diabetes Mellitus Tipo 2 , Animais , Drosophila melanogaster/metabolismo , Dopamina/metabolismo , Transtornos da Memória/genética , Dieta , Açúcares/metabolismo , Açúcares/farmacologiaRESUMO
Dendritic spines are cellular specializations that greatly increase the connectivity of neurons and modulate the "weight" of most postsynaptic excitatory potentials. Spines are found in very diverse animal species providing neural networks with a high integrative and computational possibility and plasticity, enabling the perception of sensorial stimuli and the elaboration of a myriad of behavioral displays, including emotional processing, memory, and learning. Humans have trillions of spines in the cerebral cortex, and these spines in a continuum of shapes and sizes can integrate the features that differ our brain from other species. In this chapter, we describe (1) the discovery of these small neuronal protrusions and the search for the biological meaning of dendritic spines; (2) the heterogeneity of shapes and sizes of spines, whose structure and composition are associated with the fine-tuning of synaptic processing in each nervous area, as well as the findings that support the role of dendritic spines in increasing the wiring of neural circuits and their functions; and (3) within the intraspine microenvironment, the integration and activation of signaling biochemical pathways, the compartmentalization of molecules or their spreading outside the spine, and the biophysical properties that can affect parent dendrites. We also provide (4) examples of plasticity involving dendritic spines and neural circuits relevant to species survival and comment on (5) current research advancements and challenges in this exciting research field.
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Encéfalo , Espinhas Dendríticas , Animais , Humanos , Córtex Cerebral , Emoções , AprendizagemRESUMO
Glia comprise a heterogeneous group of cells involved in the structure and function of the central and peripheral nervous system. Glial cells are found from invertebrates to humans with morphological specializations related to the neural circuits in which they are embedded. Glial cells modulate neuronal functions, brain wiring and myelination, and information processing. For example, astrocytes send processes to the synaptic cleft, actively participate in the metabolism of neurotransmitters, and release gliotransmitters, whose multiple effects depend on the targeting cells. Human astrocytes are larger and more complex than their mice and rats counterparts. Astrocytes and microglia participate in the development and plasticity of neural circuits by modulating dendritic spines. Spines enhance neuronal connectivity, integrate most postsynaptic excitatory potentials, and balance the strength of each input. Not all central synapses are engulfed by astrocytic processes. When that relationship occurs, a different pattern for thin and large spines reflects an activity-dependent remodeling of motile astrocytic processes around presynaptic and postsynaptic elements. Microglia are equally relevant for synaptic processing, and both glial cells modulate the switch of neuroendocrine secretion and behavioral display needed for reproduction. In this chapter, we provide an overview of the structure, function, and plasticity of glial cells and relate them to synaptic maturation and modulation, also involving neurotrophic factors. Together, neurons and glia coordinate synaptic transmission in both normal and abnormal conditions. Neglected over decades, this exciting research field can unravel the complexity of species-specific neural cytoarchitecture as well as the dynamic region-specific functional interactions between diverse neurons and glial subtypes.
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Espinhas Dendríticas , Neuroglia , Animais , Humanos , Camundongos , Ratos , Astrócitos , Microglia , NeurôniosRESUMO
Dendritic spine features in human neurons follow the up-to-date knowledge presented in the previous chapters of this book. Human dendrites are notable for their heterogeneity in branching patterns and spatial distribution. These data relate to circuits and specialized functions. Spines enhance neuronal connectivity, modulate and integrate synaptic inputs, and provide additional plastic functions to microcircuits and large-scale networks. Spines present a continuum of shapes and sizes, whose number and distribution along the dendritic length are diverse in neurons and different areas. Indeed, human neurons vary from aspiny or "relatively aspiny" cells to neurons covered with a high density of intermingled pleomorphic spines on very long dendrites. In this chapter, we discuss the phylogenetic and ontogenetic development of human spines and describe the heterogeneous features of human spiny neurons along the spinal cord, brainstem, cerebellum, thalamus, basal ganglia, amygdala, hippocampal regions, and neocortical areas. Three-dimensional reconstructions of Golgi-impregnated dendritic spines and data from fluorescence microscopy are reviewed with ultrastructural findings to address the complex possibilities for synaptic processing and integration in humans. Pathological changes are also presented, for example, in Alzheimer's disease and schizophrenia. Basic morphological data can be linked to current techniques, and perspectives in this research field include the characterization of spines in human neurons with specific transcriptome features, molecular classification of cellular diversity, and electrophysiological identification of coexisting subpopulations of cells. These data would enlighten how cellular attributes determine neuron type-specific connectivity and brain wiring for our diverse aptitudes and behavior.
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Doença de Alzheimer , Espinhas Dendríticas , Humanos , Tonsila do Cerebelo , Neurônios , FilogeniaRESUMO
INTRODUCTION: The use of electrotherapy has been presented as a great resource for the professional physiotherapist in the most diverse pathologies. Stroke is a neurological condition responsible for sequelae such as hemiplegia that directly impair the quality of life of patients. OBJECTIVE: This study aimed to review the literature on the effects of electrotherapeutic resources on motor function and neuroplasticity in individuals with post-stroke sequelae. MATERIALS AND METHODS: 2427 articles were found in databases according to search criteria for each base according to the included descriptors (EndNote Web). After exclusion of duplicate articles, automatically and manually, Phase 1 was performed - reading of titles and abstracts of 1626 articles according to eligibility criteria by two blinded reviewers using the programme Rayyan QCRI (Qatar Computing Research Institute), conflicts were resolved in consensus between the two reviewers. Thus, 13 articles were selected for Phase 2-13 articles were selected for reading in full, leaving 8 articles in this review. To assess the quality of bias of the selected studies, the PEDro Scale was used. RESULTS: In the assessment of neuroplasticity, statistically significant results were found in two studies (p < 0.05). However, the effects of electrostimulation stood out significantly in the motor function of these individuals (p < 0.05). It can be considered with neuroplasticity, since improved functionality can be related to electrostimulation-induced neuroplasticity. Conclusions Electrostimulation is able to promote neuroplasticity and increase motor function, generating positive effects in the treatment of individuals with post-stroke sequelae.