Pharmacological evidence for the possible involvement of the NMDA receptor pathway in the anticonvulsant effect of tramadol in mice.

Background: Previous studies have shown controversial results regarding the pro- or anticonvulsant effects of tramadol. Additionally, the underlying mechanism of seizure induction or alleviation by tramadol has not been fully understood. In the current study, the effects of tramadol on pentylenetetrazole (PTZ)-induced seizure and the possible involvement of the N-methyl-D-aspartate (NMDA) pathway were assessed in mice. Methods: Male Naval Medical Research Institute (NMRI) mice were treated with intravenous infusion of PTZ in order to induce clonic seizures and determine seizure threshold. Tramadol was injected intraperitoneally (0.1-150 mg/kg) 30 minutes prior to elicitation of seizures. The possible effects of intraperitoneal injections of NMDA receptor antagonists, ketamine (0.5 mg/kg) and MK-801 (0.5 mg/kg) on the anticonvulsant property of tramadol were investigated subsequently. Results: Tramadol (1-100 mg/kg) increased PTZ-induced seizure threshold in a dose-dependent, time-independent manner, with optimal anticonvulsant effect at a dose of 100 mg/kg. Acute administration of either ketamine (0.5 mg/kg) or MK-801 (0.5 mg/kg) potentiated the anticonvulsant effect of a subeffective dose of tramadol (0.3 mg/kg). Conclusion: These results suggest a possible role of the NMDA pathway in the anticonvulsant effect of tramadol.

Effects of N-methyl-d-aspartate receptor antagonist MK-801 (dizocilpine) on bone homeostasis in mice.

OBJECTIVES: To gain insight into the role of the N-methyl-d-aspartate (NMDA) receptor in bone metabolism by examining the effects of its noncompetitive antagonist, MK-801 (dizocilpine), on bone homeostasis and bone healing in mice. METHODS: MK-801 (2.5 mg/kg) or saline (in control groups) was intravenously administered to healthy mice and mice with bone-defects daily for seven to 14 days. Bone defects were artificially created in femurs using a drill and reamer. Following euthanasia, bones were extracted and processed for microcomputed tomography (µCT) and histological analyses. The effects of MK-801 on osteoclast differentiation by bone marrow macrophages (BMMs) were examined in vitro. mRNA expressionlevels of Grin3b levels were also examined using reverse-transcription polymerase chain reaction (RT-PCR). RESULTS: Bone volume was significantly decreased in mice administered MK-801 for 14 days. Additionally, the number of osteoclasts was reduced, while number of osteoblasts and rate of bone formation were increased in these mice. MK-801 inhibited osteoclast differentiation dose-dependently in vitro. RT-PCR findings suggested expression of Grin3b, a subunit of the NMDA receptor, in BMMs. During the healing process of artificially created defects in femurs, no significant differences were found between the control and MK-801-treated groups, indicating no stimulatory or inhibitory effects by MK-801 administration. CONCLUSIONS: These results indicate that blockade of the NMDA receptor by MK-801 administration affects bone metabolism but not the healing process of artificial bone defects.

Encefalitis anti NMDAR: Reporte de caso con seguimiento a largo plazo Anti-NMDAR / Encephalitis NMDAR: Case report with a long - term follow-up

Resumen La encefalitis autoinmune por anticuerpos antineurales de superficie, abarca un amplio espectro de entidades clínicas. La encefalitis por anticuerpos contra el antígeno de superficie de la porción externa del receptor del N-metil-D-aspartato (RNMDA) es la más frecuente y de mejor caracterización. Se reporta el caso de un adolescente con un cuadro clínico neurosiquiátrico y crisis epilépticas de reciente inicio, que presentó respuesta positiva para anticuerpos anti-RNMDA y respuesta parcial a tratamiento con corticoterapia e inmunoglobulina; en vista de esto, recibió manejo adicional con recambio plasmático seguido por terapia de mantenimiento con ciclos de inmunoglobulina, sin uso de inmunosupresores. Se reportan los resultados del seguimiento a largo plazo.

Summary Autoimmune encephalitis due to surface antineural antibodies covers a wide spectrum of clinical entities. Encephalitis due to antibodies against the surface antigen of the external portion of the N-methyl-D-aspartate receptor (RNMDA) is the most frequent and best characterized. The case of an adolescent with a clinical picture of neurosychiatric disorder and epileptic seizures of recent onset is presented: he had a positive response for anti-RNMDA antibodies, and a partial response to treatment with corticosteroid therapy and immunoglobulin; therefore, he received additional management with plasma exchange followed by maintenance therapy with immunoglobulin cycles, without the use of immunosuppressants. The results of a long-term follow-up are reported.

Adjunctive memantine for opioid use disorder treatment: A systematic review.

Memantine is commonly used for the treatment of moderate-to-severe Alzheimer's disease. Due to its antagonism of the N-methyl-d-aspartate (NMDA) receptor, which has been shown to block rewarding and reinforcing effects of morphine, memantine has been investigated for potential utilization in opioid use disorder (OUD). The objective of this systematic review is to assess the evidence available to determine the safety and efficacy of memantine as treatment for OUD. Pubmed (1946-August 2019) and Embase (1947-August 2019) were queried using the following search terms: opioid-related disorders, opioids, substance withdrawal syndrome, withdrawal syndrome, opiate addiction, opiate, opiate dependence, opiate substitution treatment, managed opioid withdrawal, or drug withdrawal and memantine. After assessing studies appropriate for the objective, one single-blind and five double-blind, placebo-controlled trials were included. Of the included studies, four demonstrated beneficial effects of memantine either as monotherapy or adjunct to methadone or buprenorphine on reducing opioid cravings and methadone dose, increasing retention rates, and improving cognitive performance in patients with OUD. Two studies did not show benefit on patient retention rates with memantine adjunct to naltrexone. Study durations ranged from 3 to 13 weeks, and memantine dosing ranged from 5 to 60 mg/day. Memantine was well tolerated with similar rates of adverse effects between treatment groups. Based on the reviewed literature, memantine appears most beneficial as an adjunctive treatment for OUD when combined with methadone or buprenorphine, but not naltrexone. Larger studies with longer periods of treatment and follow-up are needed to support the use of memantine in the management of OUD.

NMDA receptor modulation of glutamate release in activated neutrophils.

BACKGROUND: Neutrophil depletion improves neurologic outcomes in experimental sepsis/brain injury. We hypothesized that neutrophils may exacerbate neuronal injury through the release of neurotoxic quantities of the neurotransmitter glutamate. METHODS: Real-time glutamate release by primary human neutrophils was determined using enzymatic biosensors. Bacterial and direct protein-kinase C (Phorbol 12-myristate 13-acetate; PMA) activation of neutrophils in human whole blood, isolated neutrophils or human cell lines were compared in the presence/absence of N-Methyl-d-aspartic acid receptor (NMDAR) antagonists. Bacterial and direct activation of neutrophils from wild-type and transgenic murine neutrophils deficient in NMDAR-scaffolding proteins were compared using flow cytometry (phagocytosis, reactive oxygen species (ROS) generation) and real-time respirometry (oxygen consumption). FINDINGS: Both glutamate and the NMDAR co-agonist d-serine are rapidly released by neutrophils in response to bacterial and PMA-induced activation. Pharmacological NMDAR blockade reduced both the autocrine release of glutamate, d-serine and the respiratory burst by activated primary human neutrophils. A highly specific small-molecule inhibitor ZL006 that limits NMDAR-mediated neuronal injury also reduced ROS by activated neutrophils in a murine model of peritonitis, via uncoupling of the NMDAR GluN2B subunit from its' scaffolding protein, postsynaptic density protein-95 (PSD-95). Genetic ablation of PSD-95 reduced ROS production by activated murine neutrophils. Pharmacological blockade of the NMDAR GluN2B subunit reduced primary human neutrophil activation induced by Pseudomonas fluorescens, a glutamate-secreting Gram-negative bacillus closely related to pathogens that cause hospital-acquired infections. INTERPRETATION: These data suggest that release of glutamate by activated neutrophils augments ROS production in an autocrine manner via actions on NMDAR expressed by these cells. FUND: GLA: Academy Medical Sciences/Health Foundation Clinician Scientist. AVG is a Wellcome Trust Senior Research Fellow.

[Autoimmune encephalitis associated to antibodies against the N-methyl-D-aspartate receptor: Report of two cases].

Anti-N-methyl-D-aspartate receptor encephalitis is a neurological syndrome that is more common in young women and is often associated with ovarian teratoma. It is characterized by acute general unspecific symptoms that evolve to neurological deterioration, psychosis and seizures. In its more advanced stage it is associated with abnormal movements and dysautonomia.We report two cases in women of 23 and 12 years of age. Given its low incidence, we present the clinical exercise that led to their diagnoses and the treatment options employed.

Encefalitis autoinmunitaria asociada a anticuerpos contra el receptor N-metil-D-aspartato: presentación de dos casos / Autoimmune encephalitis associated to antibodies against the N-methyl-D-aspartate receptor: Report of two cases

Resumen La encefalitis asociada a anticuerpos contra receptores N-metil-D-aspartato es un síndrome neurológico que se presenta más comúnmente en mujeres jóvenes y frecuentemente se asocia al teratoma de ovario. Se caracteriza por un cuadro clínico agudo con síntomas generales inespecíficos que evoluciona hacia deterioro neurológico, psicosis y convulsiones; en su etapa más avanzada, se asocia con movimientos anormales y disautonomía. Se reportan dos casos en mujeres de 23 y 12 años. Dada su baja incidencia, se explica el proceso clínico que llevó a su diagnóstico y las opciones de tratamiento empleadas.

Abstract Anti-N-methyl-D-aspartate receptor encephalitis is a neurological syndrome that is more common in young women and is often associated with ovarian teratoma. It is characterized by acute general unspecific symptoms that evolve to neurological deterioration, psychosis and seizures. In its more advanced stage it is associated with abnormal movements and dysautonomia. We report two cases in women of 23 and 12 years of age. Given its low incidence, we present the clinical exercise that led to their diagnoses and the treatment options employed.

Expression of NMDA receptor and microRNA-219 in rats submitted to cerebral ischemia associated with alcoholism / Expressão do receptor de NMDA e do microRNA-129 em ratos submetidos à isquemia cerebral associada ao alcoolismo

ABSTRACT Alcohol consumption aggravates injuries caused by ischemia. Many molecular mechanisms are involved in the pathophysiology of cerebral ischemia, including neurotransmitter expression, which is regulated by microRNAs. Objective: To evaluate the microRNA-219 and NMDA expression in brain tissue and blood of animals subjected to cerebral ischemia associated with alcoholism. Methods: Fifty Wistar rats were divided into groups: control, sham, ischemic, alcoholic, and ischemic plus alcoholic. The expression of microRNA-219 and NMDA were analyzed by real-time PCR. Results: When compared to the control group, the microRNA-219 in brain tissue was less expressed in the ischemic, alcoholic, and ischemic plus alcoholic groups. In the blood, this microRNA had lower expression in alcoholic and ischemic plus alcoholic groups. In the brain tissue the NMDA gene expression was greater in the ischemic, alcoholic, and ischemic plus alcoholic groups. Conclusion: A possible modulation of NMDA by microRNA-219 was observed with an inverse correlation between them.

RESUMO Algumas condições podem agravar os danos causados pelo processo isquêmico, tais como o consumo de álcool, e diversos mecanismos moleculares que estão envolvidos na fisiopatologia da isquemia cerebral, incluindo a expressão de neurotransmissores, e estes podem estar regulados por microRNAs. Objetivo: Avaliar a expressão de NMDA e do microRNA-219 no tecido cerebral e no sangue de animais submetidos à isquemia cerebral associada ao alcoolismo. Métodos: 50 ratos Wistar foram divididos em: controle, sham, isquêmico, alcoólico e isquêmico mais alcoólico. A expressão de microRNA-219 e de NMDA foram analisadas por PCR em tempo real. Resultados: Quando comparado com o grupo controle, o microRNA-219 no tecido cerebral foi menos expresso nos grupos isquêmico, alcoólico e associado. No sangue, este microRNA teve menor expressão no grupo alcoólico e no associado. Em relação à expressão do gene do NMDA, em tecido cerebral foi maior nos grupos isquêmico, alcoólico e no associado. Conclusão: Uma possível modulação de NMDA pelo microRNA-219 foi observada, com uma correlação inversa entre eles.

Neuronal activity patterns in the mediodorsal thalamus and related cognitive circuits are modulated by metabotropic glutamate receptors.

The mediodorsal thalamus (MD) likely plays an important role in cognition as it receives abundant afferent connections from the amygdala and prefrontal cortex (PFC). Indeed, disturbed activity within the MD is thought to precipitate cognitive deficits associated with schizophrenia. As compounds acting at the Group II metabotropic glutamate (mGlu) receptors (subtypes mGlu2/mGlu3) have efficacy in animal models of schizophrenia, we investigated whether a Group II agonist and an mGlu2 positive allosteric modulator (PAM) could modulate MD activity. Extracellular single-unit recordings were made in vivo from MD neurones in anaesthetised rats. Responses were elicited by electrical stimulation of the PFC and/or amygdala, with Group II compounds locally applied as required. The Group II agonist reduced inhibition evoked in the MD: an effect manifested as an increase in short-latency responses, and a decrease in long-latency burst-firing. This disinhibitory action of the Group II receptors in the MD represents a mechanism of potential therapeutic importance as increased inhibition in the MD has been associated with cognitive deficit-onset. Furthermore, as co-application of the mGlu2 PAM did not potentiate the Group II agonist effects in the MD, we suggest that the Group II disinhibitory effect is majority-mediated via mGlu3. This heterogeneity in Group II receptor thalamic physiology bears consequence, as compounds active exclusively at the mGlu2 subtype are unlikely to perturb maladapted MD firing patterns associated with cognitive deficits, with activity at mGlu3 receptors possibly more appropriate. Indeed, polymorphisms in the mGlu3, but not the mGlu2, gene have been detected in patients with schizophrenia.

Neurociencias y aplicaciones psicoterapéuticas en el renacimiento de la investigación con psicodélicos / Neurosciences and psycotherapeutic applications in the psychedelic research renaissaince

The main scope of this review is to expose the main advances regarding recent research of psychedelic substances in the neurociences and their potential psychotherapeutic applications. Psilocybin, a 5-HT2A receptor agonist has been associated with reduced activity in the Default-Mode Network (commonly activated during introspection and self-reflection), enhanced access to biographical memories, positive emotional attentional bias and a reduction on anxiety and mood symptoms. The administration of 3,4-methylenedioxy-N-methylamphetamine (MDMA) could significantly aid the psychotherapeutic process in patients with Post-Traumatic Stress Disorder by strengthening the therapeutic alliance through the release of oxytocin, as well as facilitating emotional regulation from frontal areas to the amygdala during the recollection of traumatic memories. Furthermore, the administration of ayahuasca (an amazonic beverage containing dimethyltryptamine, which binds with the 5-HT2A receptor) and ketamine (a NMDA receptor agonist) in pilot studies has resulted in reduced problematic use of cocaine, heroine, alcohol and tobacco, as well as reported reduction in craving in addiction. While modern research with substances containing psychedelic properties is still young, initial findings suggest the need of expanding the number of studies in order to further clarify their potential risks, benefits and action mechanisms associated to their administration.

El objetivo de esta revisión consiste en exponer los principales avances en la investigación reciente con sustancias psicodélicas en las neurociencias y sus aplicaciones psioterapéuticas. La acción de la psilocibina, un agonista del receptor 5-HT2A, ha sido asociada a una desactivación en la Default Mode Network (activada durante la introspección y pensamientos auto-referentes), un mayor acceso a la memoria autobiográfica, un sesgo atencional emocionalmente positivo y a reducciones en la sintomatología de trastornos de ansiedad y de ánimo. Se ha planteado que la 3,4-metilendioximetanfetamina (MDMA) podría asistir de forma significativa el proceso terapéutico en casos con Trastorno por Estrés Postraumático al fortalecer la alianza terapéutica y permitir una reelaboración de recuerdos traumáticos con menores conductas de evitación. Sus mecanismos terapéuticos se han asociado a la liberación de oxitocina y a una mayor regulación desde áreas frontales hacia la amígdala. Adicionalmente, la administración de ayahuasca (brebaje de origen amazónico que contiene dimetiltriptamina, la cual actúa sobre el receptor 5-HT2A) y ketamina (agonista de receptores NMDA) en estudios iniciales ha resultado en reducción de uso problemático de cocaína, heroína, alcohol, tabaco como también en el "craving" asociado a su consumo. Si bien la investigación moderna de substancias con propiedades psicodélicas es reciente, resultados iniciales fomentan un mayor número de investigaciones para dilucidar los potenciales riesgos, beneficios y mecanismos de acción asociados a su administración.

Effect of flupirtine on the growth and viability of U373 malignant glioma cells.

OBJECTIVE: Flupirtine is a non-opioid analgesic without antipyretic or antiphlogistic properties but with favorable tolerability in humans. This analgesic also exhibits neuroprotective activities. Furthermore, flupirtine antagonizes glutamate- and NMDA-induced intracellular levels of Ca(2+) and counteracts the effects of focal cerebral ischemia. Although flupirtine has been used to relieve pain caused by different diseases and clinical procedures, information on the safety and efficacy of flupirtine is limited. The present study was conducted to investigate the neuroprotective effects of flupirtine on U373 malignant glioma (MG) cell lines. METHODS: Cell viability and cell cycle analysis was performed by MTT assay and flow cytometry, respectively. RESULTS: Variations in the growth of U373 MG cells in 5 mM N-methyl-D-aspartate (NMDA), 1 mM flupirtine, and combined treatment indicated the antagonistic effects of NMDA and flupirtine on MG cell lines. The variation in the percentage of gated cell population in different cell cycle phases showed significant variations after 48 h of treatment. CONCLUSION: Flupirtine has neuroprotective effect of on U373 MG cells, which limits its use in the pain management of brain tumors. This property warrants further studies using animal models and large-scale clinical trials.

What should you know about limbic encephalitis? / O que deve saber sobre encefalites auto-imunes?

Autoimmune encephalitis is an inflammatory disorder characterized by a subacute impairment of short-term memory, psychiatric features and seizures. It is often associated with a variety of other neurological symptoms, and its differential diagnosis is wide, leading to challenges in its recognition. It used to be regarded as a rare disease, usually paraneoplastic and with poor prognosis. However, with the recent recognition of membrane-surface directed antibodies, it is now known that in a substantial proportion of cases there is no association with any malignancy and there is a good prognosis if treated. Hence, early recognition and prompt initiation of immunotherapies are of great importance.

A encefalite autoimune é uma doença inflamatória caracterizada por envolvimento subagudo da memória de curto prazo, presença de sintomas psicóticos e crises epilépticas. Dada a diversidade de sintomas na apresentação, o diagnóstico diferencial é um verdadeiro desafio. Anteriormente, era considerada uma doença rara, de etiologia paraneoplásica e com mau prognóstico. No entanto, com a recente descoberta dos anticorpos dirigidos à superfície da membrana, é atualmente reconhecido que uma grande parte dos casos não tem uma neoplasia subjacente e apresenta um ótimo prognóstico. Assim, o diagnóstico e tratamento imunoterápico precoces são de extrema importância.

Effects of N-methyl-D-aspartate on the cochlear potentials / 第二军医大学学报

Objective: To investigate the effect of N methyl D aspartate(NMDA) on cochlear potentials and to find out the possible neurotoxic effect of NMDA on cochlea function in guinea pigs. Methods: After basal compound action potentials (CAP) and cochlear microphonics (CM) were recorded by round window electrode, animals ( n =5) were treated with Hanks applied to the round window membrane (RWM) for 20 min as control. Then 100 ?mol/L NMDA was applied to the RWM for another 20 min. Results: Hanks produced no obvious changes in CAP threshold, CAP N1 and CM latency and amplitude. CAP thresholds at all frequencies of tone burst were significantly elevated by application of NMDA, threshold shifts ranged from 13 27 dB. NMDA significantly reduced the CAP N1 amplitudes at all intensities of stimulations. CAP amplitudes were suppressed by 50% 75%. NMDA also significantly increased the CAP latency, the latency of CAP evoked by 6 kHz tone burst at intensity of -90 dB(output attenuation) was (1.9?0.06) ms after Hanks treatment and (2.76?0.21) ms after NMDA treatment ( P

Effects of lidocaine on the proliferation of PC12 cells inhibited by NMDA / 中华麻醉学杂志

Objective It has been shown that adult brain is still capable of neurogenesis which can beinhibited by activation of NMDA receptor.Since lidocaine can inhibit NMDA-mediated excitatoryueurotransmission,we aimed to investigate the interaction between lidocaine and NMDA on the proliferation ofpheochromocytoma cells which are used as a model for central neuronal cells.Methods The PC 12 ceils culturedin vitro were divided into 6 groups:(1)control group,cultured in normal DMEM complete nutrient liquidmedium;(2)NMDA group,cultured in DMEM containing 400 ?mol?L~(-1) NMDA;(3)-(6)lidocaine group,cultured in DMEM medium containing 400 ?mol L~(-1) NMDA and 10,10~2,10~3 or 10~4 ?mol?L~(-1) lidocaine.After 5day incubation,the cell cycle progression was analysed using a flow cytometer.The percentage of cells in S-phase(S-phase fraction,SPF)was determined and proliferation activity(cells in S+G_2 phase/cells in M-phase)wascalculated.Results NMDA 400 ?mol?L~(-1) significantly decreased the SPF of PC12 cells in group 2 compared tocontrol group,and proliferation activity(S+G_2 phase/M-phase)was also significantly reduced(P0.05).The SPF of PC12 cell ingroup 3 and 6(10 and 10~4 ?mol?L~(-1) lidocaine)was also significantly higher than that in NMDA group butsignificantly lower than that in control group.Conclusion NMDA inhibits proliferation of PC12 cells whilelidocaine can antagonize the inhibitory effect of NMDA and promotes proliferation and differentiation of centralneuronal cells.

Protective effect of midazolam against injury to PC12 cells induced by N-methyl-D-aspartate / 中华麻醉学杂志

Objective To evaluate the protective effect of midazolam (MID) on PC 12 cells against injury induced by N-methyl-D-aspartate (NMDA) -Methods The differentiated PC12 cell strain was isolated and cultured in DMEM full nutrient liquid medium and incubated in CO2 incubator at 37℃ and 5 % CO2 for 3-4 days. The experiment consisted of 3 groups : (1) control group; (2) NMDA group and (3) MID treatment group. In NMDA group NMDA 300 ?mol?L-1 was added to DMEM liquid medium. MID group was further divided into five subgroups according to different concentrations of midazolam (MID) added to DMEM liquid medium in addition to NMDA 300 ?mol?L-1 :MID Ⅰ -Ⅴ subgroups (midazolam 0.33, 1, 3, 10, 30?mol?L-1 ). The PC 12 cells were then cultured for another few hours. Cellular viability was assessed by lactic dehydrogenase (LDH) assay and MTT assay. Meanwhile the [Ca2+ ] was measured by Fura-2/AM fluorescence and nitric oxide synthase (NOS) activity was measured with ultraviolet spectrophotometer. Results Exposure to NMDA 300 ?mol?L-1 for 4 h resulted in increase in release of LDH from PC 12 cells and decrease in optical density (OD570nm) absorbed by living cells, indicating that NMDA induced injury to PC12 cells. The presence of midazolam 0.33, 1, 3, 10 ?mol?L-1 ( MID subgroup I -IV ) decreased LDH release and increased OD570nm value. Exposure to NMDA 300 ?mol?L-1 for 4h also resulted in increase in intracellular Ca2+ concentration ([Ca2+ ];) and NOS activity in PC 12 cells. Midazolam 3 and 30?mol?L-1 significantly decreased [Ca2+ ]; and NOS activity as compared with NMDA group.Conclusion Midazolam can attenuate the NMDA-induced injury to PC12 cells, decrease the Ca2+ overloading and NOS activity in PC 12 cells. The inhibitory effects of midazolam on [Ca2+ ]; overloading and NOS activity may be involved in the mechanism of its protective action.

The Vulnerability of the Neonatal Rodent Brain to Glutamate and Aspartate.

Microhistochemical analyses of the circumventricular organs of the four-day-old mouse or rat brain show very high levels of these amino acids after an excitotoxic subcutaneous dose. Nearby regions protected by the blood-brain barrier do not.

Effect of midazolam on amino acid levels in cultured PC12 cells challenged by N-methyl-D-aspartate / 解放军医学杂志

Objective To observe the effect of midazolam (MID) on amino acid levels in cultured PC12 cells challenged by N-methyl-D-aspartate (NMDA), and to explore the possible protective action of midazolam which is an anesthetic. Methods Cultured PC12 cells were divided into control group, NMDA group, and MID group. In NMDA group, PC12 cells were challenged by 300?mol/L NMDA in vitro. In MID group, 3?mol/L or 30?mol/L of MID was added to the challenged PC12 cell culture, thus forming two subgroups. After being treated with NMDA 300?mol/L for 4 hours, the PC12 cells were collected, rinsed, levigated and centrifuged (12 000r/min for 20min, at 4℃), then the supernatant liquid was collected. The levels of amino acids were determined with high performance liquid chromatograpy (HPLC). Results After exposing to NMDA 300?mol/L for 4 hours, the level of glutamate released from PC12 cells rose significantly, whereas the level of glutamine, aparatate and glycine remained unchanged. In the presence of MID 3?mol/L and 30?mol/L for 4 hours, the level of glutamate was lowered significantly (P