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The precise regulation of synaptic integrity is critical for neuronal network connectivity and proper brain function. Essential aspects of the activity and localization of synaptic proteins are regulated by posttranslational modifications. S-palmitoylation is a reversible covalent modification of the cysteine with palmitate. It modulates affinity of the protein for cell membranes and membranous compartments. Intracellular palmitoylation dynamics are regulated by crosstalk with other posttranslational modifications, such as S-nitrosylation. S-nitrosylation is a covalent modification of cysteine thiol by nitric oxide and can modulate protein functions. Therefore, simultaneous identification of endogenous site-specific proteomes of both cysteine modifications under certain biological conditions offers new insights into the regulation of functional pathways. Still unclear, however, are the ways in which this crosstalk is affected in brain pathology, such as stress-related disorders. Using a newly developed mass spectrometry-based approach Palmitoylation And Nitrosylation Interplay Monitoring (PANIMoni), we analyzed the endogenous S-palmitoylation and S-nitrosylation of postsynaptic density proteins at the level of specific single cysteine in a mouse model of chronic stress. Among a total of 813 S-PALM and 620 S-NO cysteine sites that were characterized on 465 and 360 proteins, respectively, we sought to identify those that were differentially affected by stress. Our data show involvement of S-palmitoylation and S-nitrosylation crosstalk in the regulation of 122 proteins including receptors, scaffolding proteins, regulatory proteins and cytoskeletal components. Our results suggest that atypical crosstalk between the S-palmitoylation and S-nitrosylation interplay of proteins involved in synaptic transmission, protein localization and regulation of synaptic plasticity might be one of the main events associated with chronic stress disorder, leading to destabilization in synaptic networks.
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Neurônios/citologia , Óxido Nítrico/metabolismo , Proteômica/métodos , Estresse Fisiológico , Sinapses/metabolismo , Animais , Células Cultivadas , Cromatografia Líquida , Cisteína/metabolismo , Regulação da Expressão Gênica , Lipoilação , Masculino , Camundongos , Plasticidade Neuronal , Neurônios/metabolismo , Processamento de Proteína Pós-Traducional , Transporte Proteico , Espectrometria de Massas em TandemRESUMO
Precise control of dendritic spine density and synapse formation is critical for normal and pathological brain functions. Therefore, signaling pathways influencing dendrite outgrowth and remodeling remain a subject of extensive investigations. Here, we report that prolonged activation of the serotonin 5-HT7 receptor (5-HT7R) with selective agonist LP-211 promotes formation of dendritic spines and facilitates synaptogenesis in postnatal cortical and striatal neurons. Critical role of 5-HT7R in neuronal morphogenesis was confirmed by analysis of neurons isolated from 5-HT7R-deficient mice and by pharmacological inactivation of the receptor. Acute activation of 5-HT7R results in pronounced neurite elongation in postnatal striatal and cortical neurons, thus extending previous data on the morphogenic role of 5-HT7R in embryonic and hippocampal neurons. We also observed decreased number of spines in neurons with either genetically (i.e. 5-HT7R-knock-out) or pharmacologically (i.e. antagonist treatment) blocked 5-HT7R, suggesting that constitutive 5-HT7R activity is critically involved in the spinogenesis. Moreover, cyclin-dependent kinase 5 and small GTPase Cdc42 were identified as important downstream effectors mediating morphogenic effects of 5-HT7R in neurons. Altogether, our data suggest that the 5-HT7R-mediated structural reorganization during the postnatal development might have a crucial role for the development and plasticity of forebrain areas such as cortex and striatum, and thereby can be implicated in regulation of the higher cognitive functions. Read the Editorial Highlight for this article on page 644.
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Córtex Cerebral/citologia , Corpo Estriado/citologia , Espinhas Dendríticas/metabolismo , Neurogênese/genética , Neurônios/citologia , Receptores de Serotonina/metabolismo , Sinapses/genética , Animais , Animais Recém-Nascidos , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Células Cultivadas , Espinhas Dendríticas/efeitos dos fármacos , Diterpenos , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Regulação da Expressão Gênica no Desenvolvimento/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Rede Nervosa/efeitos dos fármacos , Rede Nervosa/fisiologia , Neurogênese/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Piperazinas/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Receptores de Serotonina/genética , Antagonistas da Serotonina/farmacologia , Agonistas do Receptor de Serotonina/farmacologia , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Sinapses/efeitos dos fármacos , Fatores de TempoRESUMO
Nuclear speckles, also known as interchromatin granule clusters (IGCs), are subnuclear domains highly enriched in proteins involved in transcription and mRNA metabolism and, until recently, have been regarded primarily as their storage and modification hubs. However, several recent studies on non-neuronal cell types indicate that nuclear speckles may directly contribute to gene expression as some of the active genes have been shown to associate with these structures. Neuronal activity is one of the key transcriptional regulators and may lead to the rearrangement of some nuclear bodies. Notably, the impact of neuronal activation on IGC/nuclear speckles organization and function remains unexplored. To address this research gap, we examined whether and how neuronal stimulation affects the organization of these bodies in granular neurons from the rat hippocampal formation. Our findings demonstrate that neuronal stimulation induces morphological and proteomic remodelling of the nuclear speckles under both in vitro and in vivo conditions. Importantly, these changes are not associated with cellular stress or cell death but are dependent on transcription and splicing.
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Modifications of properties of the adult sensory cortex by elimination of sensory input (deprivation) serves as a model for studying plasticity in the adult brain. We studied the effects of short- and long-term deprivation (sparing one row of vibrissae) upon the barrel cortex. The response to stimulation (exploration of a new environment) of the spared row was examined with [14C]-2-deoxyglucose autoradiography and c-Fos immunohistochemistry. Both methods found large increases of the functional cortical representation of the spared row of vibrissae, extending into parts of the barrel cortex previously activated by the deprived vibrissae. With both methods, the greatest expansion of spared input was observed in cortical layer IV. In this way, we established a model, which was applied for examining involvement of matrix metalloproteinase 9 (MMP-9), upon experience-dependent cortical plasticity. MMP-9 is an enzyme implicated in plastic modification of the neuronal connections. We found that MMP-9 activity was increased in response to stimulation, and furthermore, MMP-9 knockout mice showed a modest but significant decrease of plasticity in layer IV with 2-DG mapping and in layers II/III with c-Fos mapping. Thus, in adult mouse brain experience-dependent plasticity is in part supported by the activity of MMP-9.
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Mapeamento Encefálico/métodos , Metaloproteinase 9 da Matriz/metabolismo , Plasticidade Neuronal/fisiologia , Córtex Somatossensorial/fisiologia , Animais , Autorradiografia , Desoxiglucose/farmacologia , Imuno-Histoquímica , Metaloproteinase 9 da Matriz/deficiência , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas Proto-Oncogênicas c-fos/metabolismo , Privação Sensorial/fisiologia , Vibrissas/inervaçãoRESUMO
In the search for new options for the pharmacological treatment of major depressive disorder, compounds with a rapid onset of action and high efficacy but lacking a psychotomimetic effect are of particular interest. In the present study, we evaluated the antidepressant potential of NitroSynapsin (NS) at behavioural, structural, and functional levels. NS is a memantine derivative and a dual allosteric N-methyl-d-aspartate receptors (NMDAR) antagonist using targeted delivery by the aminoadamantane of a warhead nitro group to inhibitory redox sites on the NMDAR. In a chronic restraint stress (CRS) mouse model of depression, five doses of NS administered on three consecutive days evoked antidepressant-like activity in the chronically stressed male C57BL/6J mice, reversing CRS-induced behavioural disturbances in sucrose preference and tail suspension tests. CRS-induced changes in morphology and density of dendritic spines in cerebrocortical neurons in the medial prefrontal cortex (mPFC) were also reversed by NS. Moreover, CRS-induced reduction in long-term potentiation (LTP) in the mPFC was found to be prevented by NS based on the electrophysiological recordings. Our study showed that NS restores structural and functional synaptic plasticity and reduces depressive behaviour to the level found in naïve animals. These results preliminarily revealed an antidepressant-like potency of NS.
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Depressão , Transtorno Depressivo Maior , Camundongos , Animais , Masculino , Depressão/tratamento farmacológico , Córtex Pré-Frontal , Camundongos Endogâmicos C57BL , Plasticidade Neuronal/fisiologia , Antidepressivos/farmacologia , Antidepressivos/uso terapêutico , Modelos Animais de Doenças , Receptores de N-Metil-D-Aspartato/metabolismoRESUMO
BACKGROUND: Quantitative analysis of changes in dendritic spine morphology has become an interesting issue in contemporary neuroscience. However, the diversity in dendritic spine population might seriously influence the result of measurements in which their morphology is studied. The detection of differences in spine morphology between control and test group is often compromised by the number of dendritic spines taken for analysis. In order to estimate the impact of dendritic spine diversity we performed Monte Carlo simulations examining various experimental setups and statistical approaches. The confocal images of dendritic spines from hippocampal dissociated cultures have been used to create a set of variables exploited as the simulation resources. RESULTS: The tabulated results of simulations given in this article, provide the number of dendritic spines required for the detection of hidden morphological differences between control and test groups in terms of spine head-width, length and area. It turns out that this is the head-width among these three variables, where the changes are most easily detected. Simulation of changes occurring in a subpopulation of spines reveal the strong dependence of detectability on the statistical approach applied. The analysis based on comparison of percentage of spines in subclasses is less sensitive than the direct comparison of relevant variables describing spines morphology. CONCLUSIONS: We evaluated the sampling aspect and effect of systematic morphological variation on detecting the differences in spine morphology. The results provided here may serve as a guideline in selecting the number of samples to be studied in a planned experiment. Our simulations might be a step towards the development of a standardized method of quantitative comparison of dendritic spines morphology, in which different sources of errors are considered.
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Espinhas Dendríticas/ultraestrutura , Animais , Hipocampo/citologia , Microscopia Confocal , Método de Monte Carlo , Ratos , Ratos WistarRESUMO
The complexity of the depressive symptoms observed in humans makes modeling depressive behavior in rodents challenging. Here, we present a highly reproducible protocol to generate mouse models that mimic several aspects of depression, namely anhedonia and loss of motivation. We describe acclimatization of animals and baseline determination, followed by the chronic unpredictable stress (CUS) protocol to induce anhedonic and resilient behaviors. The protocol can generate anhedonic and resilient mice at roughly equal frequencies, providing a reliable model for translational research. For complete details on the use and execution of this protocol, please refer to Baczynska et al. (2022), Bijata et al. (2022), and Krzystyniak et al. (2019).
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Anedonia , Estresse Psicológico , Animais , Modelos Animais de Doenças , Testes de Função Cardíaca , Humanos , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Dystroglycan (DG) is a cell membrane protein that binds to the extracellular matrix in various mammalian tissues. The function of DG has been well defined in embryonic development as well as in the proper migration of differentiated neuroblasts in the central nervous system (CNS). Although DG is known to be a target for matrix metalloproteinase-9 (MMP-9), cleaved in response to enhanced synaptic activity, the role of DG in the structural remodeling of dendritic spines is still unknown. Here, we report for the first time that the deletion of DG in rat hippocampal cell cultures causes pronounced changes in the density and morphology of dendritic spines. Furthermore, we noted a decrease in laminin, one of the major extracellular partners of DG. We have also observed that the lack of DG evokes alterations in the morphological complexity of astrocytes accompanied by a decrease in the level of aquaporin 4 (AQP4), a protein located within astrocyte endfeet surrounding neuronal dendrites and synapses. Regardless of all of these changes, we did not observe any effect of DG silencing on either excitatory or inhibitory synaptic transmission. Likewise, the knockdown of DG had no effect on Psd-95 protein expression. Our results indicate that DG is involved in dendritic spine remodeling that is not functionally reflected. This may suggest the existence of unknown mechanisms that maintain proper synaptic signaling despite impaired structure of dendritic spines. Presumably, astrocytes are involved in these processes.
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Espinhas Dendríticas/metabolismo , Distroglicanas/metabolismo , Hipocampo/metabolismo , Plasticidade Neuronal/genética , Transdução de Sinais/genética , Animais , Animais Recém-Nascidos , Aquaporina 4/metabolismo , Astrócitos/metabolismo , Adesão Celular/genética , Células Cultivadas , Proteína 4 Homóloga a Disks-Large/metabolismo , Distroglicanas/genética , Técnicas de Silenciamento de Genes/métodos , Laminina/metabolismo , Metaloproteinase 9 da Matriz/metabolismo , Ratos , Ratos Wistar , Sinapses/metabolismo , TransfecçãoRESUMO
Three-dimensional segmentation and analysis of dendritic spine morphology involve two major challenges: 1) how to segment individual spines from the dendrites and 2) how to quantitatively assess the morphology of individual spines. To address these two issues, we developed software called 3dSpAn (3-dimensional Spine Analysis), based on implementing a previously published method, 3D multi-scale opening algorithm in shared intensity space. 3dSpAn consists of four modules: a) Preprocessing and Region of Interest (ROI) selection, b) Intensity thresholding and seed selection, c) Multi-scale segmentation, and d) Quantitative morphological feature extraction. In this article, we present the results of segmentation and morphological analysis for different observation methods and conditions, including in vitro and ex vivo imaging with confocal microscopy, and in vivo observations using high-resolution two-photon microscopy. In particular, we focus on software usage, the influence of adjustable parameters on the obtained results, user reproducibility, accuracy analysis, and also include a qualitative comparison with a commercial benchmark. 3dSpAn software is freely available for non-commercial use at www.3dSpAn.org .
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Espinhas Dendríticas , Imageamento Tridimensional , Imageamento Tridimensional/métodos , Microscopia Confocal/métodos , Reprodutibilidade dos Testes , SoftwareRESUMO
Clinical and preclinical studies show evidence that chronic stress or nutritional deficits in dietary zinc (Zn) intake may be risk factors for developing major depressive disorder (MDD). Furthermore, there may be possible links between low serum Zn levels and development of treatment-resistant depression. In the present work, we combined chronic restraint stress (CRS) and a low-zinc diet (ZnD) in mice and carried out a set of behavioral and biochemical studies. The mice were treated with four different antidepressant compounds, namely, ketamine, Ro 25-6981 (Ro), hyperforin and lanicemine (Hyp + Lan), and imipramine (IMI). We show that CRS or ZnD alone or a combination of CRS and ZnD (CRS + ZnD) induces anhedonia observed in the sucrose preference test (SPT). The behavioral effects of CRS were restored by ketamine or IMI. However, only Hyp + Lan restored the deficits in behavioral phenotype in mice subjected to CRS + ZnD. We also showed that the antidepressant-like effects observed in Hyp + Lan-treated CRS + ZnD mice were associated with changes in the morphology of the dendritic spines (restored physiological level) in the hippocampus (Hp). Finally, we studied the metabolism of ketamine and its brain absorption in CRS and CRS + ZnD mice. Our results suggest that CRS + ZnD does not alter the metabolism of ketamine to (2R,6R;2S,6S)-HNK; however, CRS + ZnD can induce altered bioavailability and distribution of ketamine in the Hp and frontal cortex (FC) in CRS + ZnD animals compared to the control and CRS groups.
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Major depressive disorder is a complex disease resulting from aberrant synaptic plasticity that may be caused by abnormal serotonergic signaling. Using a combination of behavioral, biochemical, and imaging methods, we analyze 5-HT7R/MMP-9 signaling and dendritic spine plasticity in the hippocampus in mice treated with the selective 5-HT7R agonist (LP-211) and in a model of chronic unpredictable stress (CUS)-induced depressive-like behavior. We show that acute 5-HT7R activation induces depressive-like behavior in mice in an MMP-9-dependent manner and that post mortem brain samples from human individuals with depression reveal increased MMP-9 enzymatic activity in the hippocampus. Both pharmacological activation of 5-HT7R and modulation of its downstream effectors as a result of CUS lead to dendritic spine elongation and decreased spine density in this region. Overall, the 5-HT7R/MMP-9 pathway is specifically activated in the CA1 subregion of the hippocampus during chronic stress and is crucial for inducing depressive-like behavior.
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Região CA1 Hipocampal , Transtorno Depressivo Maior , Animais , Região CA1 Hipocampal/metabolismo , Transtorno Depressivo Maior/metabolismo , Metaloproteinase 9 da Matriz/metabolismo , Camundongos , Receptores de Serotonina/metabolismoRESUMO
Accurate tRNA processing is crucial for human mitochondrial genome expression, but the mechanisms of mt-tRNA cleavage and the key enzymes involved in this process are poorly characterized. At least two activities are required for proper mt-tRNA maturation: RNase P cleaving precursor molecules at the 5' end and tRNase Z at the 3' end. In human mitochondria only RNase P has been identified so far. Using RT-PCR and northern blot analyses we found that silencing of the human ELAC2 gene results in impaired 3' end of mt-tRNAs. We demonstrate this for several mitochondrial tRNAs, encoded on both mtDNA strands, including tRNA (Val) , tRNA (Lys) , tRNA (Arg) , tRNA (Gly) , tRNA (Leu(UUR)) and tRNA (Glu) . The silencing of the MRPP1 gene that encodes a subunit of mtRNase P resulted in inhibition of both 5' and 3' processing. We also demonstrate the double mitochondrial/nuclear localization of the ELAC2 protein using immunofluorescence. Our results indicate that ELAC2 functions as a tRNase Z in human mitochondria and suggest that mt-tRNase Z preferentially cleaves molecules already processed by the proteinaceous mtRNase P.
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Mitocôndrias/genética , Proteínas de Neoplasias/metabolismo , Processamento de Terminações 3' de RNA/genética , RNA de Transferência/genética , RNA/metabolismo , Linhagem Celular Tumoral , Núcleo Celular/enzimologia , Núcleo Celular/genética , Núcleo Celular/metabolismo , Endorribonucleases/metabolismo , Células HEK293 , Células HeLa , Humanos , Mitocôndrias/enzimologia , Mitocôndrias/metabolismo , Proteínas de Neoplasias/genética , RNA/genética , Interferência de RNA , RNA Mitocondrial , RNA Interferente Pequeno , RNA de Transferência/metabolismo , Ribonuclease P/metabolismoRESUMO
The extracellular matrix (ECM) has been identified as a critical factor affecting synaptic function. It forms a functional scaffold that provides both the structural support and the reservoir of signaling molecules necessary for communication between cellular constituents of the central nervous system (CNS). Among numerous ECM components and modifiers that play a role in the physiological and pathological synaptic plasticity, matrix metalloproteinase 9 (MMP-9) has recently emerged as a key molecule. MMP-9 may contribute to the dynamic remodeling of structural and functional plasticity by cleaving ECM components and cell adhesion molecules. Notably, MMP-9 signaling was shown to be indispensable for long-term memory formation that requires synaptic remodeling. The core regulators of the dynamic reorganization of the actin cytoskeleton and cell adhesion are the Rho family of GTPases. These proteins have been implicated in the control of a wide range of cellular processes occurring in brain physiology and pathology. Here, we discuss the contribution of Rho GTPases to MMP-9-dependent signaling pathways in the brain. We also describe how the regulation of Rho GTPases by post-translational modifications (PTMs) can influence these processes.
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Encéfalo/metabolismo , Metaloproteinase 9 da Matriz/metabolismo , Plasticidade Neuronal , Proteínas rho de Ligação ao GTP/metabolismo , Actinas/metabolismo , Animais , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Antígeno CD56/metabolismo , Adesão Celular , Moléculas de Adesão Celular/metabolismo , Moléculas de Adesão Celular Neuronais/metabolismo , Sistema Nervoso Central/metabolismo , Distroglicanas/metabolismo , Matriz Extracelular/metabolismo , Humanos , Receptores de Hialuronatos/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Camundongos , Proteínas do Tecido Nervoso/metabolismo , Processamento de Proteína Pós-Traducional , Receptor EphB2/metabolismo , Transdução de Sinais , Sinapses/metabolismoRESUMO
BACKGROUND AND PURPOSE: The therapeutic effects of fluoxetine are believed to be due to increasing neuronal plasticity and reversing some learning deficits. Nevertheless, a growing amount of evidence shows adverse effects of this drug on cognition and some forms of neuronal plasticity. EXPERIMENTAL APPROACH: To study the effects of chronic fluoxetine treatment, we combine an automated assessment of motivation and learning in mice with an investigation of neuronal plasticity in the central amygdala and basolateral amygdala. We use immunohistochemistry to visualize neuronal types and perineuronal nets, along with DI staining to assess dendritic spine morphology. Gel zymography is used to test fluoxetine's impact on matrix metalloproteinase-9, an enzyme involved in synaptic plasticity. KEY RESULTS: We show that chronic fluoxetine treatment in non-stressed mice increases perineuronal nets-dependent plasticity in the basolateral amygdala, while impairing MMP-9-dependent plasticity in the central amygdala. Further, we illustrate how the latter contributes to anhedonia and deficits of reward learning. Behavioural impairments are accompanied by alterations in morphology of dendritic spines in the central amygdala towards an immature state, most likely reflecting animals' inability to adapt. We strengthen the link between the adverse effects of fluoxetine and its influence on MMP-9 by showing that behaviour of MMP-9 knockout animals remains unaffected by the drug. CONCLUSION AND IMPLICATIONS: Chronic fluoxetine treatment differentially affects various forms of neuronal plasticity, possibly explaining its opposing effects on brain and behaviour. These findings are of immediate clinical relevance since reported side effects of fluoxetine pose a potential threat to patients.
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Núcleo Central da Amígdala , Fluoxetina , Animais , Fluoxetina/farmacologia , Humanos , Camundongos , Motivação , Plasticidade Neuronal , RecompensaRESUMO
Tauopathies comprise a heterogeneous family of neurodegenerative diseases characterized by pathological accumulation of hyperphosphorylated Tau protein. Pathological changes in serotonergic signaling have been associated with tauopathy etiology, but the underlying mechanisms remain poorly understood. Here, we studied the role of the serotonin receptor 7 (5-HT7R), in a mouse model of tauopathy induced by overexpressing the human Tau[R406W] mutant associated with inherited forms of frontotemporal dementia. We showed that the constitutive 5-HT7R activity is required for Tau hyperphosphorylation and formation of highly bundled Tau structures (HBTS) through G-protein-independent, CDK5-dependent mechanism. We also showed that 5-HT7R physically interacts with CDK5. At the systemic level, 5-HT7R-mediated CDK5 activation induces HBTS leading to neuronal death, reduced long-term potentiation (LTP), and impaired memory in mice. Specific blockade of constitutive 5-HT7R activity in neurons that overexpressed Tau[R406W] prevents Tau hyperphosphorylation, aggregation, and neurotoxicity. Moreover, 5-HT7R knockdown in the prefrontal cortex fully abrogates Tau[R406W]-induced LTP deficits and memory impairments. Thus, 5-HT7R/CDK5 signaling emerged as a new, promising target for tauopathy treatments.
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Transtornos da Memória , Animais , Modelos Animais de Doenças , Potenciação de Longa Duração , Camundongos , Receptores de Serotonina/genética , Tauopatias , Proteínas tauRESUMO
The neuromuscular junctions (NMJs) connect muscle fibers with motor neurons and enable the coordinated contraction of skeletal muscles. The dystrophin-associated glycoprotein complex (DGC) is an essential component of the postsynaptic machinery of the NMJ and is important for the maintenance of NMJ structural integrity. To identify novel proteins that are important for NMJ organization, we performed a mass spectrometry-based screen for interactors of α-dystrobrevin 1 (aDB1), one of the components of the DGC. The guanidine nucleotide exchange factor (GEF) Arhgef5 was found to be one of the aDB1 binding partners that is recruited to Tyr-713 in a phospho-dependent manner. We show here that Arhgef5 localizes to the NMJ and that its genetic depletion in the muscle causes the fragmentation of the synapses in conditional knockout mice. Arhgef5 loss in vivo is associated with a reduction in the levels of active GTP-bound RhoA and Cdc42 GTPases, highlighting the importance of actin dynamics regulation for the maintenance of NMJ integrity.
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Activity-dependent remodeling of excitatory connections underpins memory formation in the brain. Serotonin receptors are known to contribute to such remodeling, yet the underlying molecular machinery remains poorly understood. Here, we employ high-resolution time-lapse FRET imaging in neuroblastoma cells and neuronal dendrites to establish that activation of serotonin receptor 5-HT4 (5-HT4R) rapidly triggers spatially-restricted RhoA activity and G13-mediated phosphorylation of cofilin, thus locally boosting the filamentous actin fraction. In neuroblastoma cells, this leads to cell rounding and neurite retraction. In hippocampal neurons in situ, 5-HT4R-mediated RhoA activation triggers maturation of dendritic spines. This is paralleled by RhoA-dependent, transient alterations in cell excitability, as reflected by increased spontaneous synaptic activity, apparent shunting of evoked synaptic responses, and enhanced long-term potentiation of excitatory transmission. The 5-HT4R/G13/RhoA signaling thus emerges as a previously unrecognized molecular pathway underpinning use-dependent functional remodeling of excitatory synaptic connections.
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Actinas/metabolismo , Espinhas Dendríticas/fisiologia , Receptores 5-HT4 de Serotonina/fisiologia , Sinapses/fisiologia , Proteína rhoA de Ligação ao GTP/fisiologia , Citoesqueleto de Actina/metabolismo , Citoesqueleto de Actina/fisiologia , Animais , Animais Recém-Nascidos , Células Cultivadas , Feminino , Potenciação de Longa Duração , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neurônios/metabolismo , Ratos , Ratos Sprague-Dawley , Receptores 5-HT4 de Serotonina/genética , Transdução de Sinais/genética , Transmissão Sináptica/fisiologiaRESUMO
Depression is currently among the top five leading causes of the global burden of disease. Chronic unpredictable mild stress (CUMS) is currently the most commonly used, reliable, and effective rodent model of depression. However, for unclear reasons, this protocol is often difficult to reproduce in different laboratories. We performed a meta-analysis of studies that used the CUMS paradigm to evaluate depressive-like behavior in rodents. We sought to identify strain-dependent susceptibility to stress based on the development of one of the main end points of the model, "anhedonia." The meta-analysis indicated that the CUMS protocol is a robust animal model of depression and is strongly associated with anhedonic behavior in rodents. However, high heterogeneity was found in the single subgroup analysis, which was attributable to modification of the CUMS and sucrose preference protocols. This may explain difficulties in reproducing stress protocols by different research groups.
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Antidepressivos/uso terapêutico , Comportamento Animal/efeitos dos fármacos , Depressão/tratamento farmacológico , Transtorno Depressivo/tratamento farmacológico , Animais , Modelos Animais de Doenças , Humanos , Estresse Psicológico/complicações , Estresse Psicológico/tratamento farmacológicoRESUMO
The 5-HT7 receptor has recently gained much attention due to its involvement in multiple physiological functions and diseases. The insufficient quality of the available molecular probes prompted design of fluorinated 3-(1-alkyl-1H-imidazol-5-yl)-1H-indoles as a new generation of selective 5-HT7 receptor agonists. A potent and drug-like agonist, 3-(1-ethyl-1H-imidazol-5-yl)-5-iodo-4-fluoro-1H-indole (AGH-192, 35, Ki 5-HT7Râ¯=â¯4â¯nM), was identified by optimizing the halogen bond formation with Ser5.42 as the supposed partner. The compound was characterized by excellent water solubility, high selectivity over related CNS targets, high metabolic stability, oral bioavailability and low cytotoxicity. Rapid absorption into the blood, medium half-life and a high peak concentration in the brain Cmaxâ¯=â¯1069â¯ng/g were found after i.p. (2.5â¯mg/kg) administration in mice. AGH-192 may thus serve as the long-sought tool compound in the study of 5-HT7 receptor function, as well as a potential analgesic, indicated by the antinociceptive effect observed in a mouse model of neuropathic pain.
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Imidazóis/química , Imidazóis/farmacocinética , Indóis/química , Indóis/farmacocinética , Neuralgia/tratamento farmacológico , Agonistas do Receptor de Serotonina/química , Agonistas do Receptor de Serotonina/farmacocinética , Administração Oral , Analgésicos/administração & dosagem , Analgésicos/química , Analgésicos/farmacocinética , Analgésicos/farmacologia , Animais , Células HEK293 , Halogenação , Humanos , Imidazóis/administração & dosagem , Imidazóis/uso terapêutico , Indóis/administração & dosagem , Indóis/uso terapêutico , Masculino , Camundongos , Modelos Moleculares , Neuralgia/metabolismo , Receptores de Serotonina/metabolismo , Agonistas do Receptor de Serotonina/administração & dosagem , Agonistas do Receptor de Serotonina/uso terapêuticoRESUMO
The serotonergic system and in particular serotonin 1A receptor (5-HT1AR) are implicated in major depressive disorder (MDD). Here we demonstrated that 5-HT1AR is palmitoylated in human and rodent brains, and identified ZDHHC21 as a major palmitoyl acyltransferase, whose depletion reduced palmitoylation and consequently signaling functions of 5-HT1AR. Two rodent models for depression-like behavior show reduced brain ZDHHC21 expression and attenuated 5-HT1AR palmitoylation. Moreover, selective knock-down of ZDHHC21 in the murine forebrain induced depression-like behavior. We also identified the microRNA miR-30e as a negative regulator of Zdhhc21 expression. Through analysis of the post-mortem brain samples in individuals with MDD that died by suicide we find that miR-30e expression is increased, while ZDHHC21 expression, as well as palmitoylation of 5-HT1AR, are reduced within the prefrontal cortex. Our study suggests that downregulation of 5-HT1AR palmitoylation is a mechanism involved in depression, making the restoration of 5-HT1AR palmitoylation a promising clinical strategy for the treatment of MDD.