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1.
J Neuroinflammation ; 20(1): 1, 2023 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-36593485

RESUMO

Chronic hyperammonemia, a main contributor to hepatic encephalopathy (HE), leads to neuroinflammation which alters neurotransmission leading to cognitive impairment. There are no specific treatments for the neurological alterations in HE. Extracellular vesicles (EVs) from mesenchymal stem cells (MSCs) reduce neuroinflammation in some pathological conditions. The aims were to assess if treatment of hyperammonemic rats with EVs from MSCs restores cognitive function and analyze the underlying mechanisms. EVs injected in vivo reach the hippocampus and restore performance of hyperammonemic rats in object location, object recognition, short-term memory in the Y-maze and reference memory in the radial maze. Hyperammonemic rats show reduced TGFß levels and membrane expression of TGFß receptors in hippocampus. This leads to microglia activation and reduced Smad7-IkB pathway, which induces NF-κB nuclear translocation in neurons, increasing IL-1ß which alters AMPA and NMDA receptors membrane expression, leading to cognitive impairment. These effects are reversed by TGFß in the EVs from MSCs, which activates TGFß receptors, reducing microglia activation and NF-κB nuclear translocation in neurons by normalizing the Smad7-IkB pathway. This normalizes IL-1ß, AMPA and NMDA receptors membrane expression and, therefore, cognitive function. EVs from MSCs may be useful to improve cognitive function in patients with hyperammonemia and minimal HE.


Assuntos
Vesículas Extracelulares , Hiperamonemia , Células-Tronco Mesenquimais , Ratos , Animais , Ratos Wistar , Inflamação/metabolismo , Doenças Neuroinflamatórias , Receptores de N-Metil-D-Aspartato/metabolismo , Hiperamonemia/terapia , Hiperamonemia/metabolismo , NF-kappa B/metabolismo , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiônico/metabolismo , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiônico/farmacologia , Hipocampo/metabolismo , Cognição , Células-Tronco Mesenquimais/metabolismo , Vesículas Extracelulares/metabolismo , Fator de Crescimento Transformador beta/metabolismo
2.
Sci Rep ; 13(1): 656, 2023 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-36635357

RESUMO

Neurons in the cerebral cortex form excitatory and inhibitory circuits with specific laminar locations. The mechanisms underlying the development of these spatially specific circuits is not fully understood. To test if postsynaptic N-methyl-D-aspartate (NMDA) receptors on excitatory neurons are required for the development of specific circuits to these neurons, we genetically ablated NMDA receptors from a subset of excitatory neurons in the temporal association cortex (TeA) through in utero electroporation and assessed the intracortical circuits connecting to L5 neurons through in vitro whole-cell patch clamp recordings coupled with laser-scanning photostimulation (LSPS). In NMDAR knockout neurons, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor-mediated connections were largely intact. In contrast both LSPS and mini-IPSC recordings revealed that γ-aminobutyric acid type A (GABAA) receptor-mediated connections were impaired in NMDAR knockout neurons. These results suggest that postsynaptic NMDA receptors are important for the development of GABAergic circuits.


Assuntos
Receptores de N-Metil-D-Aspartato , Transmissão Sináptica , Transmissão Sináptica/fisiologia , Neurônios/fisiologia , Córtex Cerebral/fisiologia , Receptores de AMPA , Receptores de GABA-A/genética
3.
Phytomedicine ; 109: 154594, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36610115

RESUMO

BACKGROUND: Over-activation of N-methyl-D-aspartate receptors (NMDARs) is involved in sporadic Alzheimer's disease. Silibinin, a natural flavonoid gained from the seeds of Silybum marianum, exerts neuroprotective effects on sporadic AD models, but its impacts on NMDARs remain unknown. PURPOSE: To study silibinin's regulatory effects on NMDARs pathway in sporadic AD models. METHODS: MTT assay, western blotting, confocal microscopy, flow cytometry, RT-PCR, and siRNA transfection etc. were used for cellular and molecular studies. The direct interactions between silibinin and NMDAR subunits were evaluated by computational molecular docking, drug affinity responsive target stability (DARTS) assay and cellular thermal shift assay (CETSA). Y maze test, novel objects recognition test and Morris water maze test were conducted to examine the learning and memory ability of rats. RESULTS: An in vitro AD model was established by treating HT22 murine hippocampal neurons with streptozotocin (STZ), as evidenced by the amyloid ß (Aß) deposition and hyperphosphorylation of tau proteins. Silibinin shows protection of neurons against STZ-induced cell damage. It is noteworthy that STZ-induced cellular calcium influx is inhibited by silibinin-treatment, indicating the possible modulation of calcium channels. Studies on NMDARs, the most widely distributed calcium channel, by using molecular docking, DARTS and CESTA, reveal that the GluN2B subunit, but not GluN2A, is the potential target of silibinin. Further studies using the pharmacological agonist (NMDA) and the GluN2B-specific inhibitor (Ifenprodil) or siRNA, indicate that the protection by silibinin treatment from STZ-induced cytotoxicity is medicated through interference with GluN2B-containing NMDARs, followed by the upregulation of CaMKIIα/ BDNF/ TrkB signaling pathway and improved levels of synaptic proteins (SYP and PSD-95). The results in vivo using rats intracerebroventricularly injected with STZ (ICV-STZ), a well-established sporadic AD model, confirm that silibinin improves learning and memory ability in association with modulation of the GluN2B/CaMKIIα/ BDNF/TrkB signaling pathway. CONCLUSION: Inhibiting over-activation of GluN2B-containing NMDARs is involved in the neuroprotective effect of silibinin on STZ-induced sporadic AD models.


Assuntos
Doença de Alzheimer , Fármacos Neuroprotetores , Ratos , Camundongos , Animais , Doença de Alzheimer/induzido quimicamente , Doença de Alzheimer/tratamento farmacológico , Receptores de N-Metil-D-Aspartato/metabolismo , Peptídeos beta-Amiloides/metabolismo , Silibina/farmacologia , Fármacos Neuroprotetores/farmacologia , Fármacos Neuroprotetores/uso terapêutico , Estreptozocina , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Simulação de Acoplamento Molecular , Modelos Animais de Doenças
4.
Cell Mol Life Sci ; 80(2): 42, 2023 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-36645496

RESUMO

N-methyl-D-aspartate receptors (NMDARs) play vital roles in normal brain functions (i.e., learning, memory, and neuronal development) and various neuropathological conditions, such as epilepsy, autism, Parkinson's disease, Alzheimer's disease, and traumatic brain injury. Endogenous neuroactive steroids such as 24(S)-hydroxycholesterol (24(S)-HC) have been shown to influence NMDAR activity, and positive allosteric modulators (PAMs) derived from 24(S)-hydroxycholesterol scaffold can also enhance NMDAR function. This study describes the structural determinants and mechanism of action for 24(S)-hydroxycholesterol and two novel synthetic analogs (SGE-550 and SGE-301) on NMDAR function. We also show that these agents can mitigate the altered function caused by a set of loss-of-function missense variants in NMDAR GluN subunit-encoding GRIN genes associated with neurological and neuropsychiatric disorders. We anticipate that the evaluation of novel neuroactive steroid NMDAR PAMs may catalyze the development of new treatment strategies for GRIN-related neuropsychiatric conditions.


Assuntos
Doença de Alzheimer , Doenças do Sistema Nervoso , Neuroesteroides , Humanos , Receptores de N-Metil-D-Aspartato/metabolismo , Neuroesteroides/farmacologia , Neuroesteroides/uso terapêutico , Hidroxicolesteróis/farmacologia , Hidroxicolesteróis/uso terapêutico , Doenças do Sistema Nervoso/tratamento farmacológico , Doenças do Sistema Nervoso/genética , Doença de Alzheimer/tratamento farmacológico , Esteroides/farmacologia , Regulação Alostérica/fisiologia
5.
Int J Mol Sci ; 24(2)2023 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-36674542

RESUMO

Schizophrenia (SZ) is a heterogeneous mental disorder, affecting ~1% of the worldwide population. One of the main pathophysiological theories of SZ is the imbalance of excitatory glutamatergic pyramidal neurons and inhibitory GABAergic interneurons, involving N-methyl-D-aspartate receptors (NMDAr). This may lead to local glutamate storms coupled with excessive dendritic pruning and subsequent cellular stress, including nitrosative stress, during a critical period of neurodevelopment, such as adolescence. Nitrosative stress is mediated by nitric oxide (NO), which is released by NO synthases (NOS) and has emerged as a key signaling molecule implicated in SZ. Regarding glutamatergic models of SZ, the administration of NMDAr antagonists has been found to increase NOS levels in the prefrontal cortex (PFC) and ventral hippocampus (HPC). We hypothesized that suboptimal NOS function in adolescence could be a target for early treatments, including clozapine (CLZ) and the novel metabotropic glutamate receptor modulator JNJ-46356479 (JNJ). We analyzed the protein levels of NOS isoforms in adult PFC and HPC of a postnatal ketamine induced murine model of SZ receiving CLZ or JNJ during adolescence by western blot. Endothelial NOS and neuronal NOS increased under ketamine administration in PFC and decreased in CLZ or JNJ treatments. The same trends were found in the HPC in neuronal NOS. In contrast, inducible NOS was increased under JNJ treatment with respect to ketamine induction in the HPC, and the same trends were found in the PFC. Taken together, our findings suggest a misbalance of the NOS system following NMDAr antagonist administration, which was then modulated under early CLZ and JNJ treatments.


Assuntos
Clozapina , Ketamina , Esquizofrenia , Humanos , Adulto , Camundongos , Animais , Clozapina/farmacologia , Ketamina/farmacologia , Ketamina/metabolismo , Esquizofrenia/metabolismo , Ácido Glutâmico/metabolismo , Estresse Nitrosativo , Córtex Pré-Frontal/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo
6.
Mol Brain ; 16(1): 12, 2023 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-36670484

RESUMO

The N-methyl-D-aspartate receptors (NRs) in hippocampal CA3 are crucial for the synaptic transmission and plasticity within the CA3 recurrent circuit, which supports the hippocampal functions, such as pattern completion, and reverberatory association of sensory inputs. Previous study showed that synchronous activation of distinct cell populations in CA3, which correspond to distinct events, associated independent events, suggesting that the recurrent circuit expressing NRs in CA3 mediates the artificial association of memory events stored in CA3 ensembles. However, it is still unclear whether CA3 NRs are crucial for the artificial association of memory events stored in the CA3 ensembles. Here we report that the triple transgenic mice (cfos-tTA/KA1-Cre/NR1 flox/flox), which specifically lack NRs in the CA3 cell ensembles, showed impairment in artificial association between two events, which in control mice triggered artificial association. This result indicates that NRs in the hippocampal CA3 are required for the artificial association of memory events stored in the CA3 cell ensembles.


Assuntos
Hipocampo , Receptores de N-Metil-D-Aspartato , Camundongos , Animais , Receptores de N-Metil-D-Aspartato/metabolismo , Hipocampo/metabolismo , Transmissão Sináptica , Camundongos Transgênicos , Região CA3 Hipocampal/metabolismo
7.
Cells ; 12(2)2023 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-36672218

RESUMO

BACKGROUND: The N-methyl-D-aspartate receptor (NMDAR) is a target in current treatments for Alzheimer's disease (AD). The human prion protein (PrPC) has an important role in the pathophysiology of AD. We hypothesized that PrPC modulates NMDA signaling, thus being a process associated with Alzheimer's disease. METHODS: NMDAR signaling was characterized in the absence or presence of PrPC in cAMP level determination, mitogen-activated protein kinase (MAPK) pathway and label-free assays in homologous and heterologous systems. Bioluminescence resonance energy transfer was used to detect the formation of NMDAR-PrPC complexes. AXIS™ Axon Isolation Devices were used to determine axonal transport of Tau and pTau proteins in cortical primary neurons in the absence or presence of PrPC. Finally, proximity ligation assays were used to quantify NMDA-PrPC complex formation in neuronal primary cultures isolated from APPSw/Ind transgenic mice, an Alzheimer's disease model expressing the Indiana and Swedish mutated version of the human amyloid precursor protein (APP). RESULTS: We discovered a direct interaction between the PrPC and the NMDAR and we found a negative modulation of NMDAR-mediated signaling due to the NMDAR-PrPC interaction. In mice primary neurons, we identified NMDA-PrPC complexes where PrPC was capable of blocking NMDAR-mediated effects. In addition, we observed how the presence of PrPC results in increased neurotoxicity and neuronal death. Similarly, in microglial primary cultures, we observed that PrPC caused a blockade of the NMDA receptor link to the MAPK signaling cascade. Interestingly, a significant increase in NMDA-PrPC macromolecular complexes was observed in cortical neurons isolated from the APPSw,Ind transgenic model of AD. CONCLUSIONS: PrPC can interact with the NMDAR, and the interaction results in the alteration of the receptor functionality. NMDAR-PrPC complexes are overexpressed in neurons of APPSw/Ind mouse brain. In addition, PrPC exacerbates axonal transport of Tau and pTau proteins.


Assuntos
Doença de Alzheimer , Camundongos , Humanos , Animais , Doença de Alzheimer/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Proteínas Priônicas/metabolismo , N-Metilaspartato/farmacologia , N-Metilaspartato/metabolismo , Fosforilação , Neurônios/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Camundongos Transgênicos
8.
Nat Commun ; 14(1): 91, 2023 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-36609445

RESUMO

Pleiotropic mechanisms have been implicated in Alzheimer's disease (AD), including transcriptional dysregulation, protein misprocessing and synaptic dysfunction, but how they are mechanistically linked to induce cognitive deficits in AD is unclear. Here we find that the histone methyltransferase Smyd3, which catalyzes histone H3 lysine 4 trimethylation (H3K4me3) to activate gene transcription, is significantly elevated in prefrontal cortex (PFC) of AD patients and P301S Tau mice, a model of tauopathies. A short treatment with the Smyd3 inhibitor, BCI-121, rescues cognitive behavioral deficits, and restores synaptic NMDAR function and expression in PFC pyramidal neurons of P301S Tau mice. Fbxo2, which encodes an E3 ubiquitin ligase controlling the degradation of NMDAR subunits, is identified as a downstream target of Smyd3. Smyd3-induced upregulation of Fbxo2 in P301S Tau mice is linked to the increased NR1 ubiquitination. Fbxo2 knockdown in PFC leads to the recovery of NMDAR function and cognitive behaviors in P301S Tau mice. These data suggest an integrated mechanism and potential therapeutic strategy for AD.


Assuntos
Doença de Alzheimer , Tauopatias , Animais , Camundongos , Doença de Alzheimer/complicações , Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Cognição , Modelos Animais de Doenças , Histona Metiltransferases , Histona-Lisina N-Metiltransferase/genética , Camundongos Transgênicos , Proteínas tau/metabolismo , Tauopatias/genética , Receptores de N-Metil-D-Aspartato/metabolismo
9.
Neuropharmacology ; 225: 109378, 2023 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-36539011

RESUMO

Ketamine, functioning as a channel blocker of the excitatory glutamate-gated N-methyl-d-aspartate (NMDA) receptors, displays compelling fast-acting and sustained antidepressant effects for treatment-resistant depression. Over the past decades, clinical and preclinical studies have implied that the pathology of depression is associated with dysfunction of glutamatergic transmission. In particular, the discovery of antidepressant agents modulating NMDA receptor function has prompted breakthroughs for depression treatment compared with conventional antidepressants targeting the monoaminergic system. In this review, we first summarized the signalling pathway of the ketamine-mediated antidepressant effects, based on the glutamate hypothesis of depression. Second, we reviewed the hypotheses of the synaptic mechanism and network of ketamine antidepressant effects within different brain areas and distinct subcellular localizations, including NMDA receptor antagonism on GABAergic interneurons, extrasynaptic and synaptic NMDA receptor-mediated antagonism, and ketamine blocking bursting activities in the lateral habenula. Third, we reviewed the different roles of NMDA receptor subunits in ketamine-mediated cognitive and psychiatric behaviours in genetically-manipulated rodent models. Finally, we summarized the structural basis of NMDA receptor channel blockers and discussed NMDA receptor modulators that have been reported to exert potential antidepressant effects in animal models or in clinical trials. Integrating the cutting-edge technologies of cryo-EM and artificial intelligence-based drug design (AIDD), we expect that the next generation of first-in-class rapid antidepressants targeting NMDA receptors would be an emerging direction for depression therapeutics. This article is part of the Special Issue on 'Ketamine and its Metabolites'.


Assuntos
Depressão , Ketamina , Animais , Depressão/tratamento farmacológico , Receptores de N-Metil-D-Aspartato/metabolismo , Ketamina/farmacologia , Ketamina/uso terapêutico , Ketamina/metabolismo , Inteligência Artificial , Antidepressivos/farmacologia , Antidepressivos/uso terapêutico , Antidepressivos/metabolismo , Ácido Glutâmico/metabolismo
10.
Brain Res Bull ; 193: 84-94, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36539101

RESUMO

Auditory steady-state responses (ASSRs) are recurrent neural activities entrained to regular cyclic auditory stimulation. ASSRs are altered in individuals with schizophrenia, and may be related to hypofunction of the N-methyl-D-aspartate (NMDA) glutamate receptor. Noncompetitive NMDA receptor antagonists, including ketamine, have been used in ASSR studies of rodent models of schizophrenia. Although animal studies using non-human primates are required to complement rodent studies, the effects of ketamine on ASSRs are unknown in intact awake non-human primates. In this study, after administration of vehicle or ketamine, click trains at 20-83.3 Hz were presented to elicit ASSRs during recording of electroencephalograms in intact, awake macaque monkeys. The results indicated that ASSRs quantified by event-related spectral perturbation and inter-trial coherence were maximal at 83.3 Hz after vehicle administration, and that ketamine reduced ASSRs at 58.8 and 83.3 Hz, but not at 20 and 40 Hz. The present results demonstrated a reduction of ASSRs by the NMDA receptor antagonist at optimal frequencies with maximal responses in intact, awake macaques, comparable to ASSR reduction in patients with schizophrenia. These findings suggest that ASSR can be used as a neurophysiological biomarker of the disturbance of gamma-oscillatory neural circuits in this ketamine model of schizophrenia using intact, awake macaques. Thus, this model with ASSRs would be useful in the investigation of human brain pathophysiology as well as in preclinical translational research.


Assuntos
Ketamina , Esquizofrenia , Animais , Humanos , Esquizofrenia/tratamento farmacológico , Ketamina/farmacologia , Potenciais Evocados Auditivos/fisiologia , Vigília , Receptores de N-Metil-D-Aspartato , Estimulação Acústica/métodos , Eletroencefalografia/métodos , Primatas
11.
J Alzheimers Dis ; 91(2): 877-893, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36502323

RESUMO

BACKGROUND: Alzheimer's disease (AD) is the most common form of neurodegenerative dementia among the elderly. Excitotoxicity has been implicated as playing a dominant role in AD, especially related to the hyperactivation of excitatory neurons. Death-associated protein kinase 1 (DAPK1) is a calcium/calmodulin-dependent kinase and involved in the pathogenesis of AD, but the roles and mechanisms of DAPK1 in excitotoxicity in AD are still uncertain. OBJECTIVE: We mainly explored the underlying mechanisms of DAPK1 involved in the excitotoxicity of AD and its clinical relevance. METHODS: Differentiated SH-SY5Y human neuroblastoma cells, PS1 V97 L transgenic mice, and human plasma samples were used. Protein expression was assayed by immunoblotting, and intracellular calcium and neuronal damage were analyzed by flow cytometry. Plasma DAPK1 was measured by ELISA. RESULTS: We found that DAPK1 was activated after amyloid-ß oligomers (AßOs) exposure in differentiated SH-SY5Y cells. Besides, we found the phosphorylation of GluN2B subunit at Ser1303 was increased, which contributing to excitotoxicity and Ca2+ overload in SH-SY5Y cells. Inhibiting DAPK1 activity, knockdown of DAPK1 expression, and antagonizing GluN2B subunits could effectively prevent AßOs-induced activation of GluN2B subunit, Ca2+ overload, and neuronal apoptosis. Additionally, we found that DAPK1 was elevated in the brain of AD transgenic mouse and in the plasma of AD patients. CONCLUSION: Our finding will help to understand the mechanism of DAPK1 in the excitotoxicity in AD and provide a reference for the diagnosis and therapy of AD.


Assuntos
Doença de Alzheimer , Neuroblastoma , Camundongos , Animais , Humanos , Idoso , Doença de Alzheimer/genética , Proteínas Quinases Associadas com Morte Celular/genética , Cálcio/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Camundongos Transgênicos , Peptídeos beta-Amiloides/metabolismo
12.
Epilepsy Res ; 189: 107065, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36516565

RESUMO

Language dysfunction is a common and serious comorbidity of epilepsy, especially in individuals with epilepsy aphasia spectrum syndromes. Childhood epilepsy with centrotemporal spikes is on the mild end of the spectrum, while epileptic encephalopathy with continuous spike-and-wave during sleep syndrome is on the severe end. Traditional antiseizure medicines and immunotherapy are currently used to treat severely affected patients, but the results are usually disappointing. The discovery that GRIN2A is the primary monogenic etiology of these diseases has opened the door to precision treatments. The GRIN2A gene encodes GluN2A protein, which constitutes a subunit of the NMDA receptor (NMDAR). The GRIN2A pathogenic variants cause gain or loss of function of NMDAR; the former can be treated with uncompetitive NMDAR antagonists, such as memantine, while the latter with NMDAR co-agonist serine. Hyper-precision therapies with various other effective agents are likely to be developed shortly to target the diverse functional effects of different variants. Precision treatments for GRIN2A-related disorders will benefit those who suffer from the condition and pave the way for new therapeutic approaches to a variety of other NMDAR-linked neurodegenerative and psychiatric diseases (schizophrenia, Parkinson's disease, Alzheimer's disease, and so on). Furthermore, more research into GRIN2A-related disorders will help us better understand the neuroinflammatory and neuroimmunological basis of epilepsy, as well as the pathological and physiological network activation mechanisms that cause sleep activation of central-temporal spikes and language impairment.


Assuntos
Afasia , Epilepsia , Síndromes Epilépticas , Síndrome de Landau-Kleffner , Humanos , Criança , Síndrome de Landau-Kleffner/genética , Mutação , Epilepsia/tratamento farmacológico , Epilepsia/genética , Distúrbios da Fala , Receptores de N-Metil-D-Aspartato/genética , Receptores de N-Metil-D-Aspartato/metabolismo
13.
Neuropharmacology ; 222: 109297, 2023 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-36341805

RESUMO

N-methyl-D-aspartate receptors (NMDARs) play an essential role in excitatory neurotransmission in the mammalian brain, and their physiological importance is underscored by the large number of pathogenic mutations that have been identified in the receptor's GluN subunits and associated with a wide range of diseases and disorders. Here, we characterized the functional and pharmacological effects of the pathogenic N650K variant in the GluN1 subunit, which is associated with developmental delay and seizures. Our microscopy experiments showed that when expressed in HEK293 cells (from ATCC®), the GluN1-N650K subunit increases the surface expression of both GluN1/GluN2A and GluN1/GluN2B receptors, but not GluN1/GluN3A receptors, consistent with increased surface expression of the GluN1-N650K subunit expressed in hippocampal neurons (from embryonic day 18 of Wistar rats of both sexes). Using electrophysiology, we found that the GluN1-N650K variant increases the potency of GluN1/GluN2A receptors to both glutamate and glycine but decreases the receptor's conductance and open probability. In addition, the GluN1-N650K subunit does not form functional GluN1/GluN2B receptors but does form fully functional GluN1/GluN3A receptors. Moreover, in the presence of extracellular Mg2+, GluN1-N650K/GluN2A receptors have a similar and increased response to ketamine and memantine, respectively, while the effect of both drugs had markedly slower onset and offset compared to wild-type GluN1/GluN2A receptors. Finally, we found that expressing the GluN1-N650K subunit in hippocampal neurons reduces excitotoxicity, and memantine shows promising neuroprotective effects in neurons expressing either wild-type GluN1 or the GluN1-N650K subunit. This study provides the functional and pharmacological characterization of NMDARs containing the GluN1-N650K variant.


Assuntos
Memantina , Receptores de N-Metil-D-Aspartato , Humanos , Ratos , Feminino , Masculino , Animais , Ratos Wistar , Receptores de N-Metil-D-Aspartato/genética , Memantina/farmacologia , Células HEK293 , Ácido Glutâmico , Mamíferos
14.
Behav Brain Res ; 438: 114169, 2023 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-36273648

RESUMO

Mitragynine, an indole alkaloid from the plant Mitragyna speciosa (Kratom), has been reported to modify hippocampal synaptic transmission. However, the role of glutamatergic neurotransmission modulating synaptic plasticity in mitragynine-induced synaptic changes is still unknown. Here, we determined the role of AMPA- and NMDA glutamate receptors in mitragynine-induced synaptic plasticity in the hippocampus. Male Sprague Dawley rats received either vehicle or mitragynine (10 mg/kg), with or without the AMPA receptor antagonist, NBQX (3 mg/kg), or the NMDA receptor antagonist, MK-801 (0.2 mg/kg). Field excitatory postsynaptic potentials (fEPSP) during baseline, paired-pulse facilitation (PPF) and long-term potentiation (LTP) were recorded in-vivo in the hippocampal CA1 area of anaesthetised rats. Basal synaptic transmission and LTP were significantly impaired after mitragynine, NBQX, and MK-801 alone, without an effect on PPF. Combined effects suggest a weak functional AMPA- as well as NMDA receptor antagonist action of mitragynine.


Assuntos
Maleato de Dizocilpina , Receptores de AMPA , Receptores de N-Metil-D-Aspartato , Animais , Ratos , Maleato de Dizocilpina/farmacologia , Hipocampo/metabolismo , Potenciação de Longa Duração , Plasticidade Neuronal , Ratos Sprague-Dawley , Receptores de N-Metil-D-Aspartato/metabolismo , Transmissão Sináptica , Receptores de AMPA/metabolismo
15.
Biochem Biophys Res Commun ; 641: 186-191, 2023 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-36535077

RESUMO

Activation of N-methyl-d-aspartate receptors (NMDARs) requires binding of a co-agonist in addition to l-glutamate. d-serine binds to the co-agonist site on GluN1 subunits of NMDARs and modulates glutamatergic neurotransmission. While loss of GluN1 subunits in mice results in neonatal death due to respiratory failure, animals that lack a d-serine synthetic enzyme, serine racemase (SR), show grossly normal growth. However, SR-independent origins of d-serine in the brain remain unclarified. In the present study, we investigated the origin of brain d-serine in mice. Loss of SR significantly reduced d-serine in the cerebral cortex, but a portion of d-serine remained in both neonates and adults. Although d-serine was also produced by intestinal bacteria, germ-free experiments did not influence d-serine levels in the cerebral cortex. In addition, treatment of SR-knockout mice with antibiotics showed a significant reduction of intestinal d-serine, but no reduction in the brain. On the other hand, restriction of dietary intake reduced systemic circulation of d-serine and resulted in a slight decrease of d-serine in the cerebral cortex, but did not account for brain d-serine found in the SR-knockout mice. Therefore, our findings show that endogenous d-serine of non-SR origin exists in the brain. Such previously unrecognized, SR-independent, endogenous d-serine may contribute baseline activity of NMDARs, especially in developing brain, which has minimal SR expression.


Assuntos
Receptores de N-Metil-D-Aspartato , Serina , Camundongos , Animais , Serina/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Encéfalo/metabolismo , Racemases e Epimerases/genética , Racemases e Epimerases/metabolismo , Camundongos Knockout , Mamíferos/metabolismo
16.
Neurobiol Learn Mem ; 197: 107709, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36503101

RESUMO

The present study investigated whether N-methyl-d-aspartate (NMDA) receptors in the dorsolateral striatum (DLS) mediate consolidation and retrieval of habit memory. Adult male Long-Evans rats were trained in a response learning version of a water plus-maze task in which rats were reinforced to make a habitual and consistent body-turn response at the maze choice point in order to mount a hidden escape platform. Prior research indicates that acquisition, consolidation, and retrieval in this task requires DLS function. The present study consisted of two experiments. In Experiment 1, rats received intra-DLS post-training injections of the NMDA receptor antagonist 2-amino-5- phosphonopentanoic acid (AP5; 2 µg/side) to examine the role of NMDA receptors in consolidation of habit memory. In Experiment 2, different groups of rats received a single pre-retrieval injection of AP5 in the DLS (AP5; 2 µg/side) during the last day of maze training to examine the potential role of NMDA receptors in retrieval of habit memory. Results indicated that post-training intra-DLS AP5 injections impaired memory consolidation. However, administration of AP5 at the same dose that impaired consolidation had no effect on memory retrieval. The findings are consistent with previous research indicating a role for NMDA receptors in the DLS in memory consolidation, and suggest that NMDA-dependent synaptic activity in the DLS may not be a critical component of habit memory retrieval.


Assuntos
N-Metilaspartato , Receptores de N-Metil-D-Aspartato , Ratos , Masculino , Animais , Receptores de N-Metil-D-Aspartato/fisiologia , Ratos Long-Evans , N-Metilaspartato/farmacologia , Memória/fisiologia , Hábitos , 2-Amino-5-fosfonovalerato/farmacologia
17.
Neuropharmacology ; 225: 109374, 2023 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-36516891

RESUMO

Depression is a complex and highly heterogeneous disorder which diagnosis is based on an exceedingly variable set of clinical symptoms. Current treatments focus almost exclusively on the manipulation of monoamine neurotransmitter systems, but despite considerable efforts, these remain inadequate for a significant proportion of those afflicted by the disorder. The emergence of racemic (R, S)-ketamine as a fast-acting antidepressant has provided an exciting new path for the study of major depressive disorder (MDD) and the search for better therapeutics for its treatment. Previous work suggested that ketamine's mechanism of action is primarily mediated via blockaded of N-methyl-d-aspartate (NMDA) receptors, however, this is an area of active research and clinical and preclinical evidence now indicate that ketamine acts on multiple systems. The last couple of decades have cemented the mesolimbic dopamine reward pathway's involvement in the pathogenesis of MDD and related mood disorders. Exposure to negative stress dysregulates dopamine neuronal activity disrupting reward and motivational processes resulting in anhedonia (lack of pleasure), a hallmark symptom of depression. Although the mechanism(s) underlying ketamine's antidepressant activity continue to be elucidated, current evidence indicate that its therapeutic effects are mediated, at least in part, via long-lasting synaptic changes and subsequent molecular adaptations in brain regions within the mesolimbic dopamine system. Notwithstanding, ketamine is a drug of abuse, and this liability may pose limitations for long term use as an antidepressant. This review outlines the current knowledge of ketamine's actions within the mesolimbic dopamine system and its abuse potential. This article is part of the Special Issue on 'Ketamine and its Metabolites'.


Assuntos
Transtorno Depressivo Maior , Ketamina , Humanos , Ketamina/farmacologia , Ketamina/uso terapêutico , Ketamina/metabolismo , Transtorno Depressivo Maior/tratamento farmacológico , Dopamina , Antidepressivos/farmacologia , Antidepressivos/uso terapêutico , Antidepressivos/metabolismo , Encéfalo/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo
18.
Neuropharmacology ; 225: 109377, 2023 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-36528117

RESUMO

Stress coping strategies represent critical responses to environmental challenges, and active coping has been linked to stress resilience in humans. Understanding the neuroadaptations that support these strategies may provide insights into adaptive and maladaptive stress responses. NMDA receptors (NMDARs) play key roles in neuroadaptation, and NMDARs have been specifically implicated in stress responsiveness. Constitutive knockout mice have been used to implicate the GluN2D NMDAR subunit in regulation of stress-sensitive and affective behavior, but the brain regions in which GluN2D expression changes drive these effects remain unknown. Here we report that following an acute restraint stressor, GluN2D subunit expression is specifically decreased in the bed nucleus of the stria terminalis (BNST), a key region involved in stress processing, in male but not female mice, with no differences found in the thalamus or ventral hippocampus in either sex. Rodents engage in active struggling events during restraint stress that may represent active coping strategies to stress. Thus, we assessed active coping bouts during acute and chronic restraint stress sessions in GluN2D knockout mice. During the first restraint session, GluN2D knockout mice exhibited a pronounced decrease in struggling bouts during restraint stress relative to wild-type littermates, consistent with a role of GluN2D in active coping responses to stress. Repeated, daily restraint sessions revealed a sex-specific role of GluN2D expression on certain aspects of active coping behaviors, with male GluN2D KO mice exhibiting a decrease in total coping bouts measured across five sessions. However, BNST-specific knockdown of GluN2D in male mice did not alter active coping bouts, suggesting either a multi-synaptic role of GluN2D and/or a developmental role of GluN2D in this behavior. Altogether, these data are consistent with a growing literature suggesting that exploration of GluN2D control of stress circuit actions may lead to a novel therapeutic target to consider for stress-related mood disorders.


Assuntos
Receptores de N-Metil-D-Aspartato , Núcleos Septais , Animais , Feminino , Masculino , Camundongos , Adaptação Psicológica , Encéfalo/metabolismo , Hipocampo/metabolismo , Camundongos Knockout , Receptores de N-Metil-D-Aspartato/metabolismo , Restrição Física , Núcleos Septais/metabolismo , Estresse Psicológico
19.
Neuropharmacology ; 225: 109386, 2023 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-36549374

RESUMO

Cannabis preparations could be an effective reconsolidation-based treatment for post-traumatic stress disorder. However, the effects of Δ9-tetrahydrocannabinol (THC) in fear memory labilization, a critical condition for retrieval-induced reconsolidation, are undetermined. We sought to investigate the effect of a conventional and an ultra-low dose of THC in memory labilization of adult male Wistar rats submitted to contextual fear conditioning. Pretreatment with THC 0.002, but not THC 0.3 mg/kg, i. p., before memory retrieval, did not change memory expression during the retrieval but impaired reconsolidation. No treatment changed freezing expression in an unpaired context. Before retrieval, THC 0.3, but not THC 0.002, decreased GluN2A-NMDA expression and the GluN2A/GluN2B ratio in the dorsal hippocampus (DH) 24 h later. No changes were observed immediately after retrieval. Pretreatment with THC 0.3 abolished the reconsolidation-impairing effect of anisomycin injected into the DH, suggesting an impairment in memory labilization. This effect was associated with an increased freezing expression in the unpaired context and was not observed with the THC ultra-low dose. The GluN2B-NMDA antagonism increased fear generalization in the anisomycin-treated group but restored its reconsolidation-impairing effect and reduced fear generalization when animals were pretreated with THC 0.3. GluN2A-NMDA antagonism or inhibition of the ubiquitin-proteasome system in the DH did not interfere with the effects of THC 0.3. Our findings indicate that THC causes a bidirectional effect on fear memory labilization that depends on hippocampal GluN2B-NMDA receptors' involvement in fear memory generalization.


Assuntos
Dronabinol , Receptores de N-Metil-D-Aspartato , Ratos , Animais , Masculino , Receptores de N-Metil-D-Aspartato/metabolismo , Ratos Wistar , Dronabinol/farmacologia , N-Metilaspartato/farmacologia , Anisomicina/farmacologia , Medo , Hipocampo
20.
Neurosci Lett ; 795: 137031, 2023 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-36574811

RESUMO

Anti-N-methyl-d-aspartate receptor (anti-NMDAR) encephalitis is an autoimmune epilepsy associated with memory deficits. Research has demonstrated that anti-NMDAR inhibit long-term potentiation, and, at the same time, lead to disinhibition in the form of epileptiform afterpotentials in the potentiated state. While both effects may give rise to the key symptoms of the disease, the molecular basis of being simultaneously inhibitory and disinhibitory is difficult to explain. Here, we explored a possible involvement of the GluN2B subunit. To this aim, we injected cerebrospinal fluid from anti-NMDAR encephalitis patients into the rat hippocampus and prepared brain slices for in vitro field potential recordings. Associational-commissural-fiber-CA3 synapses from anti-NMDAR-treated animals showed increased field potential amplitudes with concomitantly enhanced paired-pulse ratios as compared to control tissue. GluN2B inhibition by Ro25-6981 mimicked these effects in controls but had no effect in anti-NMDAR tissues indicating a presynaptic and occluding effect of anti-NMDAR. We then induced potentiation of associational-commissural-fiber-CA3 synapses, and confirmed that slices from anti-NMDAR-treated animals showed reduced potentiation and pronounced epileptiform afterpotentials. Intriguingly, both effects were absent when Ro25-6981 was added in vitro before inducing potentiation. These results indicate that GluN2B-containing NMDARs, partially expressed presynaptically, show differential sensitivity to anti-NMDAR, and that altered GluN2B function is particularly apparent in the potentiated state rather than under baseline conditions. Since GluN2B inhibition rescued the effects of anti-NMDAR in the potentiated state, this opens the possibility that at least a subgroup of patients could benefit from a GluN2B antagonist.


Assuntos
Encefalite Antirreceptor de N-Metil-D-Aspartato , Ratos , Animais , Encefalite Antirreceptor de N-Metil-D-Aspartato/complicações , Encefalite Antirreceptor de N-Metil-D-Aspartato/tratamento farmacológico , Hipocampo/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Sinapses/fisiologia , Potenciação de Longa Duração/fisiologia
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