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1.
Comput Math Methods Med ; 2022: 4997393, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35509858

RESUMO

Objective: To analyze the role of C5a, C5a receptor (CD88), glutamic acid, and N-methyl-D-aspartic acid receptors (NMDAR1 and NMDAR2B) in the onset of neuromyelitis optica (NMO) disease in mice. Method: To select C57BL/6 wild-type (WT) mice and C5a receptor gene knockout (C5aR-/-) mice, use NMO-IgG and hemolytic complement to intervene in spinal cord tissue sections and optic nerves to establish an NMO model in vitro. The experiment was carried out with five groups (control group, WT group, C5aR-/- group, C5a group, and C5a+C5aRA group), with six mice in each group. The differences of American spinal cord injury (ASIA) motor scores were compared among all groups. The expressions of aquaporin (AQP4), glial fibrillary acidic protein (GFAP), NMDAR1, and NMDAR2B in spinal cord and optic nerve tissues were detected. The difference of glutamic acid (Glu) concentrations in culture solutions of the spinal cord and optic nerves was compared. Result: The ASIA motor score of the control group was significantly lower than that of the other four groups. The C5a-/- group was significantly higher than the WT group. The C5a+C5aRA group was significantly higher than the C5a group in terms of ASIA motor score. In the control group, AQP4 and GFAP showed expression loss. The C5aR-/- group's loss rate was significantly higher than that of the WT group. The loss rate of the C5a+C5aRA group was significantly higher than that of the C5a group. In the control group, the protein expressions of NMDAR1 and NMDAR2B were significantly lower than that of the other four groups. The C5aR-/- group was significantly higher than the WT group. The C5a+C5aRA group was significantly higher than the C5a group in protein expression. In the control group, the concentration of Glu in the C5aR-/- group was significantly higher than that in the WT group, and the C5a group was significantly lower than the C5a+C5aRA group. Conclusion: The deletion of the C5a receptor promotes NMDAR activity, which affects the toxic excitatory effect of NMDAR in NMO and regulates the neurotoxic effect of glutamic acid, thus participating in the pathogenesis of NMO.


Assuntos
Neuromielite Óptica , Traumatismos da Medula Espinal , Animais , Modelos Animais de Doenças , Ácido Glutâmico , Humanos , Camundongos , Camundongos Endogâmicos C57BL , N-Metilaspartato , Neuromielite Óptica/genética , Neuromielite Óptica/metabolismo , Receptor da Anafilatoxina C5a/genética
2.
Proc Natl Acad Sci U S A ; 119(19): e2121653119, 2022 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-35507872

RESUMO

SignificanceGlutamate transporters harness ionic gradients present across the membrane for the rapid removal of glutamate from the synaptic space. Normal function of glutamate transporters is required for efficient synaptic transmission and preventing excitotoxicity. Central to the transport mechanism is the coupled binding of Na+ and the substrate. While structural studies have identified the Na+ and the substrate binding sites, the mechanism by which Na+ and substrate binding is coupled is not known. In this study, we developed assays to monitor Na+ binding and to track key conformational changes in GltPh, an archaeal homolog of glutamate transporters. We use these assays along with previously developed assays to describe the specific roles of the Na+ sites in the coupling mechanism.


Assuntos
Sistema X-AG de Transporte de Aminoácidos , Sódio , Sistema X-AG de Transporte de Aminoácidos/química , Sítios de Ligação , Ácido Glutâmico/metabolismo , Íons/metabolismo , Sódio/metabolismo
3.
4.
eNeuro ; 9(3)2022.
Artigo em Inglês | MEDLINE | ID: mdl-35523583

RESUMO

Excitatory amino acid transporters (EAATs) control visual signal transmission in the retina by rapidly removing glutamate released from photoreceptors and bipolar cells (BCs). Although it has been reported that EAAT2 and EAAT5 are expressed at presynaptic terminals of photoreceptors and some BCs in mammals, the distinct functions of these two glutamate transporters in retinal synaptic transmission, especially at a single synapse, remain elusive. In this study, we found that EAAT2 was expressed in all BC types while coexisting with EAAT5 in rod bipolar (RB) cells and several types of cone BCs from mice of either sex. Our immunohistochemical study, together with a recently published literature (Gehlen et al., 2021), showed that EAAT2 and EAAT5 were both located in RB axon terminals near release sites. Optogenetic, electrophysiological and pharmacological analyses, however, demonstrated that EAAT2 and EAAT5 regulated neurotransmission at RB→AII amacrine cell synapses in significantly different ways: EAAT5 dramatically affected both the peak amplitude and kinetics of postsynaptic responses in AIIs, whereas EAAT2 had either relatively small or opposite effects. By contrast, blockade of EAAT1/GLAST, which was exclusively expressed in Müller cells, showed no obvious effect on AII responses, indicating that glutamate uptake by Müller cells did not influence synaptic transmission from RB terminals. Furthermore, we found that temporal resolution at RB→AII synapses was reduced substantially by blockade of EAAT5 but not EAAT2. Taken together, our work reveals the distinct functions of EAAT2 and EAAT5 in signal transmission at RB ribbon synapses.


Assuntos
Sistema X-AG de Transporte de Aminoácidos , Transportador 2 de Aminoácido Excitatório/metabolismo , Transportador 5 de Aminoácido Excitatório/metabolismo , Células Bipolares da Retina , Sistema X-AG de Transporte de Aminoácidos/metabolismo , Animais , Ácido Glutâmico/metabolismo , Mamíferos/metabolismo , Camundongos , Terminações Pré-Sinápticas/metabolismo , Retina/metabolismo , Células Bipolares da Retina/metabolismo , Transmissão Sináptica/fisiologia
5.
Neuron ; 110(8): 1280-1283, 2022 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-35447097

RESUMO

Neurons can release multiple neurotransmitters. Are they packaged in segregated pools of vesicles or within the same ones? In this issue of Neuron, Kim et al., 2022, examined features of GABA-glutamate co-release at basal ganglia to habenula synapses.


Assuntos
Ácido Glutâmico , Vesículas Sinápticas , Neurônios , Sinapses , Ácido gama-Aminobutírico
6.
In Vitro Cell Dev Biol Anim ; 58(4): 289-294, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35469046

RESUMO

Glutamate neurotoxicity is involved in neurodegenerative diseases, including Alzheimer's and Parkinson's diseases. Excess glutamate causes caspase-independent programmed cell death via oxidative stress and calcium influx. Our previous study showed that calpain-1 localizes to both the cytoplasm and mitochondria, where apoptosis-inducing factor (AIF) is cleaved by calpain-1 and translocates to the nucleus to induce DNA fragmentation. The autoinhibitory region of calpain-1 conjugated with the cell-penetrating peptide HIV1-Tat (namely Tat-µCL) specifically prevents the activity of mitochondrial calpain-1 and attenuates neuronal cell death in animal models of retinitis pigmentosa, as well as glutamate-induced cell death in mouse hippocampal HT22 cells. In the present study, we constructed a lentiviral vector expressing the Tat-µCL peptide and evaluated its protective effect against glutamate-induced cell death in HT22 cells. Lentiviral transduction with Tat-µCL significantly suppressed glutamate-induced nuclear translocation of AIF and DNA fragmentation. The findings of the present study suggest that the stable expression of Tat-µCL may be a potential gene therapy modality for neurodegenerative diseases.


Assuntos
Calpaína , Ácido Glutâmico , Animais , Fator de Indução de Apoptose/genética , Fator de Indução de Apoptose/metabolismo , Calpaína/genética , Calpaína/metabolismo , Morte Celular , Ácido Glutâmico/metabolismo , Ácido Glutâmico/toxicidade , Hipocampo/metabolismo , Camundongos , Estresse Oxidativo , Peptídeos/metabolismo
7.
Nat Neurosci ; 25(5): 607-616, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35484406

RESUMO

Astrocytes are glial cells that interact with neuronal synapses via their distal processes, where they remove glutamate and potassium (K+) from the extracellular space following neuronal activity. Astrocyte clearance of both glutamate and K+ is voltage dependent, but astrocyte membrane potential (Vm) is thought to be largely invariant. As a result, these voltage dependencies have not been considered relevant to astrocyte function. Using genetically encoded voltage indicators to enable the measurement of Vm at peripheral astrocyte processes (PAPs) in mice, we report large, rapid, focal and pathway-specific depolarizations in PAPs during neuronal activity. These activity-dependent astrocyte depolarizations are driven by action potential-mediated presynaptic K+ efflux and electrogenic glutamate transporters. We find that PAP depolarization inhibits astrocyte glutamate clearance during neuronal activity, enhancing neuronal activation by glutamate. This represents a novel class of subcellular astrocyte membrane dynamics and a new form of astrocyte-neuron interaction.


Assuntos
Astrócitos , Neurônios , Animais , Astrócitos/fisiologia , Ácido Glutâmico , Camundongos , Neuroglia , Neurônios/fisiologia , Sinapses/fisiologia
8.
Zhen Ci Yan Jiu ; 47(4): 283-9, 2022 Apr 25.
Artigo em Chinês | MEDLINE | ID: mdl-35486007

RESUMO

OBJECTIVE: To observe the effect of acupuncture at "Yanglingquan" (GB34) and "Baihui" (GV20) on Na+/K+-ATPase, excitatory amino acid transporters (EAATs) and glutamate (Glu) in hippocampus of post-stroke spasticity rats, so as to explore the central mechanism in anti-spasticity. METHODS: In a total of 48 healthy SD rats, 12 rats were randomly selected to be included into sham operation group, and the remaining rats were used to make a middle cerebral artery occlusion (MCAO) model using a suture method. On the 3rd day after modeling, MCAO limb spasticity rats were screened by neurological deficit symptoms and muscle tension scores, and randomly divided into the model, GB34 (Hui-puncture at GB34) and GB34+GV20 (Hui-puncture at GB34 and horizontal insertion at GV20) groups (n=12 rats in each group), and the treatment was lasted for 7 conse-cutive days. The neurological symptoms and muscle tension score were observed with the Zea Longa score and modified Ashworth scale (MAS). The levels of Glu, EAAT1 (GLAST) and EAAT2 (GLT-1) in the ischemic area of cerebral hippocampus were detected by ELISA, the expression of Na+/K+-ATPase α1 (ATP1α1) was detected by Western blot, the expression of ATP1α1 mRNA was detected by real-time PCR, and the expression of GLAST, GLT-1 and ATP1α1 was detected by immunofluorescence. RESULTS: After modeling, Zea Longa score and MAS score were increased (P<0.01), the level of Glu in the ischemic area of cerebral hippocampus was increased (P<0.01), while the expression levels of GLAST, GLT-1, ATP1α1 protein and mRNA were all decreased (P<0.01) in the model group relevant to the sham operation group. After 7 days' treatment, all the increased and decreased levels of the indexes mentioned above were reversed in the two acupuncture groups relevant to the model group (P<0.01, P<0.05), and the effects of acupuncture at GB34+GV20 were obviously superior to that of acupuncture at GB34 (P<0.05, P<0.01). CONCLUSION: Acupuncture can alleviate post-stroke spasticity effectively, which may be related to its effect in up-regulating the expressions of Na+/K+-ATPase and EAATs in hippocampus. The anti-spastic effect of acupuncture at GB34+GV20 is superior to GB34 alone.


Assuntos
Terapia por Acupuntura , Acidente Vascular Cerebral , Pontos de Acupuntura , Terapia por Acupuntura/métodos , Adenosina Trifosfatases , Animais , Ácido Glutâmico , Infarto da Artéria Cerebral Média , Espasticidade Muscular/genética , Espasticidade Muscular/terapia , RNA Mensageiro , Ratos , Ratos Sprague-Dawley , Acidente Vascular Cerebral/complicações , Acidente Vascular Cerebral/genética , Acidente Vascular Cerebral/terapia
9.
Nature ; 605(7908): 172-178, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35444281

RESUMO

Ionotropic glutamate receptors (iGluRs) are tetrameric ligand-gated ion channels that open their pores in response to binding of the agonist glutamate1-3. An ionic current through a single iGluR channel shows up to four discrete conductance levels (O1-O4)4-6. Higher conductance levels have been associated with an increased number of agonist molecules bound to four individual ligand-binding domains (LBDs)6-10. Here we determine structures of a synaptic complex of AMPA-subtype iGluR and the auxiliary subunit γ2 in non-desensitizing conditions with various occupancy of the LBDs by glutamate. We show that glutamate binds to LBDs of subunits B and D only after it is already bound to at least the same number of LBDs that belong to subunits A and C. Our structures combined with single-channel recordings, molecular dynamics simulations and machine-learning analysis suggest that channel opening requires agonist binding to at least two LBDs. Conversely, agonist binding to all four LBDs does not guarantee maximal channel conductance and favours subconductance states O1 and O2, with O3 and O4 being rare and not captured structurally. The lack of subunit independence and low efficiency coupling of glutamate binding to channel opening underlie the gating of synaptic complexes to submaximal conductance levels, which provide a potential for upregulation of synaptic activity.


Assuntos
Receptores de Glutamato , Receptores Ionotrópicos de Glutamato , Ácido Glutâmico/metabolismo , Simulação de Dinâmica Molecular , Domínios Proteicos , Receptores de Glutamato/metabolismo , Receptores Ionotrópicos de Glutamato/metabolismo
10.
Biomolecules ; 12(4)2022 04 18.
Artigo em Inglês | MEDLINE | ID: mdl-35454185

RESUMO

Glutamate is the major excitatory neurotransmitter in the central nervous system and is intricately linked to learning and memory. Its activity depends on the expression of AMPA and NMDA receptors and excitatory amino transporters on neurons and glial cells. Glutamate transporters prevent the excess accumulation of glutamate in synapses, which can lead to aberrant synaptic signaling, excitotoxicity, or cell death. Neuroinflammation can occur acutely after surgical trauma and contributes to the development of perioperative neurocognitive disorders, which are characterized by impairment in multiple cognitive domains. In this review, we aim to examine how glutamate handling and glutamatergic function are affected by neuroinflammation and their contribution to cognitive impairment. We will first summarize the current data regarding glutamate in neurotransmission, its receptors, and their regulation and trafficking. We will then examine the impact of inflammation on glutamate handling and neurotransmission, focusing on changes in glial cells and the effect of cytokines. Finally, we will discuss these changes in the context of perioperative neuroinflammation and the implications they have for perioperative neurocognitive disorders.


Assuntos
Disfunção Cognitiva , Ácido Glutâmico , Disfunção Cognitiva/metabolismo , Ácido Glutâmico/metabolismo , Humanos , Neuroglia/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo
11.
Biochem Biophys Res Commun ; 606: 163-167, 2022 05 28.
Artigo em Inglês | MEDLINE | ID: mdl-35364324

RESUMO

The present work shows that the rate of free respiration of liver mitochondria (in the absence of ATP synthesis (state 4) during the oxidation of succinate is 1.7 times higher than during the oxidation of glutamate with malate. In turn, in the case of oxidation of ferrocyanide with ascorbate, this value is 3.1 times greater than in the case of succinate oxidation. A similar pattern is also observed upon stimulation of free respiration by low concentrations (5 and 10 µM) of the protonophore uncoupler 2,4-dinitrophenol (DNP). It is found that the passive leakage rate of protons in state 4 is the same if the H+/O ratios are 10, 6, and 2 upon the oxidation of glutamate with malate, succinate, and ferrocyanide with ascorbate, respectively. At these values of the H+/O ratio, low concentrations of DNP stimulate passive proton leakage equally during the oxidation of these respiration substrates. In the case of succinate oxidation, bypassing complex III by N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) to the maximum degree, as well as switching this complex completely to idle mode by α,ω-hexadecanedioic acid (HDA) cause a 3-fold stimulation of respiration in state 4. We conclude that at mitochondrial free respiration the values of the H+/2e- ratio for complexes I, III, and IV of the respiratory chain are 4, 4, and 2, respectively. It is assumed that the free respiration of mitochondria is carried out by simple diffusion of protons through the inner membrane, and the rate of this diffusion depends on the total number of protons released by the complexes of the electron transport chain into the intermembrane space.


Assuntos
Complexo III da Cadeia de Transporte de Elétrons , Mitocôndrias Hepáticas , Transporte de Elétrons , Complexo III da Cadeia de Transporte de Elétrons/metabolismo , Elétrons , Ácido Glutâmico/metabolismo , Mitocôndrias Hepáticas/metabolismo , Consumo de Oxigênio , Prótons , Respiração , Succinatos , Ácido Succínico/metabolismo
12.
Curr Biol ; 32(9): 2011-2021.e3, 2022 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-35385692

RESUMO

Previous studies suggest that the median preoptic nucleus (MnPO) of the hypothalamus plays an important role in regulating the wake-sleep cycle and, in particular, homeostatic sleep drive. However, the precise cellular phenotypes, targets, and central mechanisms by which the MnPO neurons regulate the wake-sleep cycle remain unknown. Both excitatory and inhibitory MnPO neurons innervate brain regions implicated in sleep promotion and maintenance, suggesting that both cell types may participate in sleep control. Using genetically targeted approaches, we investigated the role of the MnPO GABAergic (MnPOVgat) and glutamatergic (MnPOVglut2) neurons in modulating wake-sleep behavior of mice. We found that both neuron populations differentially participate in wake-sleep control, with MnPOVgat neurons being involved in sleep homeostasis and MnPOVglut2 neurons facilitating sleep during allostatic (stressful) challenges.


Assuntos
Ácido Glutâmico , Área Pré-Óptica , Animais , Ácido Glutâmico/metabolismo , Camundongos , Neurônios/fisiologia , Área Pré-Óptica/fisiologia , Sono/fisiologia , Ácido gama-Aminobutírico/metabolismo
13.
Purinergic Signal ; 18(2): 199-204, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35476241

RESUMO

Anxiety involves abnormal glucocorticoid signalling and altered glia-neuron communication in brain regions processing emotional responses. Adenosine A2A receptor (A2AR) blockade ameliorates mood and memory impairments by preventing synaptic dysfunction and astrogliosis. Since the glucocorticoid dexamethasone (DEX) can mimic early life-stress conditions, leading to anxiety-like behaviours, we now tested if A2AR blockade prevents alterations in the morphology and function of astrocytes exposed to DEX. Cultured astrocytes exposed to DEX exhibited an up-regulation of astrocytic markers (GFAP, connexin-43 and glutamine synthetase), as well as of A2AR. Moreover, DEX enhanced ATP and glutamate release and increased basal astrocytic Ca2+ levels. The selective A2AR antagonist SCH58261 prevented DEX-induced alterations in ATP release and basal Ca2+ levels but did not affect DEX-induced alteration of glutamate release and astrocytic markers. These findings suggest that alterations in astrocytes function, which might contribute to abnormal glucocorticoid brain signalling, are controlled by A2AR, and therefore, reinforce the relevance of A2AR as a potential therapeutic target to manage mood disorders.


Assuntos
Adenosina , Astrócitos , Adenosina/farmacologia , Trifosfato de Adenosina , Dexametasona/farmacologia , Glucocorticoides , Ácido Glutâmico , Receptor A2A de Adenosina
14.
Biomacromolecules ; 23(5): 1864-1872, 2022 05 09.
Artigo em Inglês | MEDLINE | ID: mdl-35394759

RESUMO

Glutamate, the main excitatory neurotransmitter in the central nervous system, plays an essential role in several cognitive activities such as memorizing and learning. Excessive glutamate release and disturbance of glutamate homeostasis participates in multiple neuronal pathologies including cerebral ischemia (inadequate blood supply), traumatic brain injury (e.g., from a fall or an accident), multiple sclerosis, epilepsy, migraine, fetal hypoxia, or Alzheimer's disease. Attenuating excitotoxicity by, for example, targeting glutamate receptors has proved to be beneficial in animal models but has largely failed in clinical trials because of toxic side effects. New therapeutic concepts have been explored to reduce the excitotoxic effect caused by the excessive glutamate release by using or stimulating glutamate-depleting enzymes in the bloodstream. These enzymes indirectly act upon the brain by depleting glutamate in the bloodstream, which is believed to siphon it out of the brain. Recent studies have shown that bioconjugate approaches applied to such enzymes exacerbate this therapeutic effect but raise additional questions for future research. This Perspective provides an overview of lessons learned by our group when exploring bioconjugate approaches for combatting glutamate excitotoxicity as an illustration of how research on therapeutic bioconjugates is evolving.


Assuntos
Ácido Glutâmico , Receptores de Glutamato , Animais , Encéfalo/metabolismo , Sistema Nervoso Central/metabolismo , Neurônios/metabolismo , Receptores de Glutamato/metabolismo
15.
Neuroscience ; 491: 156-165, 2022 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-35405302

RESUMO

Orexin and melanin-concentrating hormone (MCH) neurons constitute the energy balance circuitry that coordinates the fasting response. Orexin neurons mediate food foraging at the expense of energy storage, while MCH neurons promote energy storage by reducing energy expenditure and increasing food intake. It is unknown if these cell groups undergo plastic changes as hunger and metabolic changes escalate over time during fasting. To address this, we performed in vitro electrophysiological recording on orexin and MCH neurons in the lateral hypothalamus and perifornical area from rats fasted for 12 or 24 h or fed ad-libitum. Orexin neurons showed a transient decrease in presynaptic glutamate release at 12 h. This turned to an increase at 24 h of fasting, while membrane potential depolarized and AMPA receptor conductance increased. In contrast, MCH neurons were transiently depolarized at 12 h fasting along with increased presynaptic glutamate release. These changes reversed at 24 h, while the number of AMPA receptors decreased. Our results indicate that MCH neurons are preferentially activated during the early phase of fasting (12 h), which would protect against weight loss. With a longer fast, orexin neurons become activated, which would promote arousal and exploratory activity required for foraging behaviors. This alternating activation of these cell groups may reflect a dynamic balance of energy conservation and foraging behaviors to optimize energy balance during ongoing fasting.


Assuntos
Jejum , Hormônios Hipotalâmicos , Animais , Ácido Glutâmico/metabolismo , Hormônios Hipotalâmicos/metabolismo , Hipotálamo/metabolismo , Melaninas/metabolismo , Neurônios/metabolismo , Orexinas/metabolismo , Hormônios Hipofisários/metabolismo , Ratos
16.
Cell Rep ; 39(1): 110642, 2022 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-35385725

RESUMO

Mutation or disruption of the Shank/ProSAP family of genes is a high risk factor for autism spectrum disorders (ASDs) and intellectual disability. N-methyl-D-aspartate glutamate receptor (NMDAR) dysfunction contributes to the development of autism-like behaviors. However, the molecular mechanism of Shank-mediated NMDAR modulation is still not clear. Here, we show that the scaffold protein plenty of SH3s (POSH) directly interacts with two other scaffold proteins, PSD95 and SHANK2/3, at excitatory synapses. In POSH conditional knockout (cKO) mice, normal synaptic clustering of NMDAR/PSD-95/SHANK complex is disrupted, accompanied by abnormal dendritic spine development and glutamatergic transmission in hippocampal neurons. POSH cKO mice display profound autism-like behaviors, including impairments in social interactions, social communication, repetitive behaviors, and deficits in learning and memory. Thus, POSH clusters at the postsynaptic density (PSD) with PSD-95 and SHANK2/3 and plays important roles in the signaling mechanisms of the NMDAR/PSD-95/POSH/SHANK complex as well as in spine development and brain function.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Ácido Aspártico , Proteínas do Citoesqueleto , Ácido Glutâmico , Receptores de N-Metil-D-Aspartato , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Animais , Ácido Aspártico/metabolismo , Proteínas do Citoesqueleto/metabolismo , Proteína 4 Homóloga a Disks-Large/metabolismo , Ácido Glutâmico/metabolismo , Camundongos , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Sinapses/metabolismo , Transmissão Sináptica
17.
Development ; 149(9)2022 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-35394012

RESUMO

Both mRNA-binding Fragile X mental retardation protein (FMRP; Fmr1) and mRNA-binding Staufen regulate synaptic bouton formation and glutamate receptor (GluR) levels at the Drosophila neuromuscular junction (NMJ) glutamatergic synapse. Here, we tested whether these RNA-binding proteins act jointly in a common mechanism. We found that both dfmr1 and staufen mutants, and trans-heterozygous double mutants, displayed increased synaptic bouton formation and GluRIIA accumulation. With cell-targeted RNA interference, we showed a downstream Staufen role within postsynaptic muscle. With immunoprecipitation, we showed that FMRP binds staufen mRNA to stabilize postsynaptic transcripts. Staufen is known to target actin-binding, GluRIIA anchor Coracle, and we confirmed that Staufen binds to coracle mRNA. We found that FMRP and Staufen act sequentially to co-regulate postsynaptic Coracle expression, and showed that Coracle, in turn, controls GluRIIA levels and synaptic bouton development. Consistently, we found that dfmr1, staufen and coracle mutants elevate neurotransmission strength. We also identified that FMRP, Staufen and Coracle all suppress pMad activation, providing a trans-synaptic signaling linkage between postsynaptic GluRIIA levels and presynaptic bouton development. This work supports an FMRP-Staufen-Coracle-GluRIIA-pMad pathway regulating structural and functional synapse development.


Assuntos
Proteínas de Drosophila , Ácido Glutâmico , Animais , Drosophila , Proteínas de Drosophila/genética , Proteína do X Frágil de Retardo Mental/genética , Terminações Pré-Sinápticas , RNA Mensageiro/genética , Receptores de Glutamato/genética , Sinapses
18.
Artigo em Inglês | MEDLINE | ID: mdl-35428008

RESUMO

Adolescent depression is a significant public health problem, with the major depressive disorder having been the leading risk factor for suicide and death amongst children and adolescents. For treating depression, antidepressants are used with minimal clinical evidence data and uncertain efficacy in children. L-theanine has anti-depression and other physiological functions. However, few reports are available on the pharmacokinetics of L-theanine, especially in children and adolescents. In this study, a rapid and sensitive hydrophilic interaction liquid chromatography-tandem mass spectrometry method was established and validated for the quantification of L-theanine in juvenile rat plasma and tissues. Chromatographic separation was conducted via an Agilent ZORBAX HILIC plus column in gradient elution mode. L-theanine and [2H5]-L-glutamic acid (internal standard) were determined under the multi-reaction monitoring mode transitions of m/z 175.0 â†’ 157.9 and m/z 153.0 â†’ 88.2 in positive ionisation mode, respectively, and completed methodology verification. In addition, 10 and 35 mg kg-1 of L-theanine were given by intragastric administration to determine the brain and plasma pharmacokinetic characteristics in healthy and chronic unpredictable mild stress rats, respectively. The distribution of tissues and the limbic system were measured at the same time. The results showed that juvenile and diseased rats have higher absorption than adult rats, and age, dosage and health status could affect the process of L-theanine in vivo. L-theanine also has a high degree of tissue distribution. This study lays a foundation for the clinical treatment of depression in children and adolescents.


Assuntos
Transtorno Depressivo Maior , Espectrometria de Massas em Tandem , Adolescente , Animais , Cromatografia Líquida de Alta Pressão/métodos , Glutamatos , Ácido Glutâmico , Humanos , Ratos , Ratos Sprague-Dawley , Reprodutibilidade dos Testes , Espectrometria de Massas em Tandem/métodos
19.
Sci Rep ; 12(1): 6921, 2022 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-35484312

RESUMO

Glutamate is implicated in migraine pathogenesis including central sensitization and pain transmission. Altered plasma glutamate levels has been noted in migraine. Chronic migraine (CM) presented a higher degree of central sensitization and pain transmission than episodic migraine (EM). However, no study has evaluated plasma glutamate levels separately in EM and CM. This study aimed to assess plasma glutamate levels in EM and CM compared to controls. An enzyme-linked immunosorbent assay was used to assess plasma glutamate levels in females with EM (n = 98) and CM (n = 92) as well as controls (n = 50). Plasma glutamate levels in participants with EM (median and interquartile range, 49.73 [40.82-66.12] µmol/L, p < 0.001) and CM (58.70 [44.64-72.46] µmol/L, p < 0.001) were significantly higher than those in controls (38.79 [29.50-53.60] µmol/L). Glutamate levels were not significantly different between participants with EM and CM (p = 0.075). There was no significant association of plasma glutamate levels with headache frequency (exponential and 95% confidence interval, 1.285 [0.941-1.755]) and intensity (mild, 59.95 [59.95-59.95] µmol/L vs. moderate, 52.76 [40.83-106.89] µmol/L vs. severe, 55.16 [42.34-68.03] µmol/L, p = 0.472). The plasma glutamate level is a potential indicator for EM and CM.


Assuntos
Ácido Glutâmico , Transtornos de Enxaqueca , Sensibilização do Sistema Nervoso Central , Feminino , Cefaleia , Humanos , Dor
20.
Neurobiol Dis ; 168: 105716, 2022 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-35367629

RESUMO

The distinction between glial painful and protective pathways is unclear and the possibility to finely modulate the system is lacking. Focusing on painful neuropathies, we studied the role of interleukin 1α (IL-1α), an alarmin belonging to the larger family of damage-associated molecular patterns endogenously secreted to restore homeostasis. The treatment of rat primary neurons with increasing doses of the neurotoxic anticancer drug oxaliplatin (0.3-100µM, 48 h) induced the release of IL-1α. The knockdown of the alarmin in neurons leads to their higher mortality when co-cultured with astrocytes. This toxicity was related to increased extracellular ATP and decreased release of transforming growth factor ß1, mostly produced by astrocytes. In a rat model of neuropathy induced by oxaliplatin, the intrathecal treatment with IL-1α was able to reduce mechanical and thermal hypersensitivity both after acute injection (100 ng and 300 ng) and continuous infusion (100 and 300 ng/die-1). Ex vivo analysis on spinal purified astrocyte processes (gliosomes) and nerve terminals (synaptosomes) revealed the property of IL-1α to reduce the endogenous glutamate release induced by oxaliplatin. This protective effect paralleled with an increased number of GFAP-positive cells in the spinal cord, suggesting the ability of IL-1α to evoke a positive, conservative astrocyte phenotype. Endogenous IL-1α induced protective signals in the cross-talk between neurons and astrocytes. Exogenously administered in rats, IL-1α prevented neuropathic pain in the presence of spinal glutamate decrease and astrocyte activation.


Assuntos
Antineoplásicos , Neuralgia , Alarminas/efeitos adversos , Alarminas/metabolismo , Animais , Antineoplásicos/efeitos adversos , Astrócitos/metabolismo , Ácido Glutâmico/metabolismo , Hiperalgesia/metabolismo , Interleucina-1alfa/efeitos adversos , Interleucina-1alfa/metabolismo , Neuralgia/metabolismo , Neurônios/metabolismo , Oxaliplatina/toxicidade , Ratos , Ratos Sprague-Dawley , Medula Espinal/metabolismo
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