藻酸双酯钠对培养神经细胞谷氨酸兴奋毒性的保护作用

目的 :观察藻酸双酯钠 (PSS)对培养神经细胞谷氨酸兴奋毒性的保护作用。方法 :体外培养大鼠胚胎皮层神经细胞 ,加入谷氨酸观察谷氨酸对神经细胞的兴奋毒性及PSS的保护作用。结果 :PSS 5 0 ,1 0 0 ,1 5 0mg·L-1能显著减少细胞死亡 ,降低乳酸脱氢酶(LDH)漏出量 ,一氧化氮 (NO)含量及丙二醛 (MDA)生成 ,提高超氧歧化酶 (SOD)活性。结论 :PSS对培养神经细胞谷氨酸兴奋毒性具有显著的保护作用 ,其机制可能与PSS抗脂质过氧化作用有关。     

Meso-dihydroguaiaretic acid and licarin A of Machilus thunbergii protect against glutamate-induced toxicity in primary cultures of a rat cortical cells

1 We previously reported that four lignans isolated from the bark of Machilus thunbergii Sieb. et Zucc. (Lauraceae) protected primary cultures of rat cortical neurons from neurotoxicity induced by glutamate. 2 Among the lignans, meso-dihydroguaiarectic acid (MDGA) and licarin A significantly attenuated glutamate-induced neurotoxicity when added prior to or right after the excitotoxic glutamate challenge. 3 The neuroprotective activities of two lignans appeared to be more effective in protecting neurons against neurotoxicity induced by NMDA than that induced by kainic acid. 4 MDGA and licarin A diminished the calcium influx that routinely accompanies with the glutamate-induced neurotoxicity, and inhibited the subsequent overproduction of cellular nitric oxide and peroxide to the level of control cells. They also preserved cellular activities of antioxidative enzymes such as superoxide dismutase, glutathione peroxidase and glutathione reductase reduced in the glutamate-injured neuronal cells. 5 Thus, our results suggest that MDGA and licarin A significantly protect primary cultured neuronal cells against glutamate-induced oxidative stress, via antioxidative activities.     

Danthron inhibits the neurotoxicity induced by various compounds causing oxidative damages including beta-amyloid (25-35) in primary cortical cultures

Oxidative stress caused by an elevation in reactive oxygen species (ROS) plays an important role in Alzheimer's disease and other neurodegenerative diseases. In this study, we examined the neuroprotective effect of danthron (1,8-dihydroxyanthraquinone) against neurotoxicities induced by beta-amyloid (25-35), excitotoxins, apoptosis, and oxidative stress in primary cortical cultures. Danthron dose-dependently reduced neuronal injury induced by 30 microM beta-amyloid (25-35). Danthron significantly inhibited oxidative injury induced by 100 microM Fe(3+) and decreased membrane lipid peroxidation induced by 100 microM Fe(3+) as measured by thiobarbituric-acid-reactive substance (TBARS). Danthron (0.5-50 microM) ameliorated the effects of buthionine sulfoximine (BSO, 1 mM), which depletes endogenous glutathione by 10-73%. Danthron also dose-dependently inhibited neuronal injury mediated by nitric oxide (NO) radicals, but failed to inhibit injury due to superoxide radicals (O(2-)). These results suggest danthron treatment may, in part, reduce neurotoxicity related to beta-amyloid protein by both dominant inhibitory effects on membrane lipid peroxidation and glutathione deprivation.     

Aristolactam BII of Saururus chinensis attenuates glutamate-induced neurotoxicity in rat cortical cultures probably by inhibiting nitric oxide production

Saurolactam and aristolactam BII, aristolactam-type alkaloids isolated from the aerial part of Saururus chinensis (Lour.) Ball (Saururaceae), showed significant neuroprotective activity against glutamate-induced toxicity in primary cultured rat cortical cells. The action mechanism of aristolactam BII, the more potent neuroprotective compound, was investigated using primary cultures of rat cortical cells as an in vitro system. Aristolactam BII attenuated glutamate-induced neurotoxicity significantly when it was added immediately or up to 9 h after the excitotoxic glutamate challenge. The alkaloid could not protect cultured neuronal cells from neurotoxicity induced by kainic acid or N-methyl- D-aspartate in a pre-treatment paradigm. However, aristolactam BII successfully reduced the overproduction of nitric oxide and the level of cellular peroxide in cultured neurons when it was treated as a post-treatment paradigm. These results may suggest that aristolactam BII exerts its significant neuroprotective effects on glutamate-injured primary cultures of rat cortical cells by directly inhibiting the production of nitric oxide.     

褪黑素对大脑皮层细胞一氧化氮含量及其神经毒性作用的影响

目的：探讨褪黑素(MT)抗衰老作用与神经细胞NO释放之间的联系。方法：连续给予老年小鼠MT，检测大脑皮层神经细胞NO含量的变化,并用原代培养的大鼠皮层神经元，去血清培养后，观察MT对高钾、谷氨酸（Glu）诱发NO释放及硝普钠（SNP）致神经毒性作用的影响。结果：MT能明显抑制老年小鼠脑内NO含量的增高，并拮抗KCI与Glu诱发的NO释放及SNP引起的神经毒性，对大脑神经元有保护作用。结论：MT抑制大脑皮层NO含量增高，可能是其抗衰老作用的机制之一。     

The neuroprotective effect of a nitric oxide inhibitor in a rat model of focal cerebral ischaemia.

Recent data showed that glutamate toxicity in primary cortical cultures is mediated by nitric oxide. In order to investigate the effect of inhibition of NO synthase on focal cerebral ischaemia in rats, we studied the histological consequences of a middle cerebral artery (MCA) occlusion after post-operative treatment with NG-nitro-L-arginine methyl ester, an inhibitor of nitric oxide synthase. We found a significant reduction of cortical (-43%) and striatal (-25%) necrotic volumes induced by MCA occlusion, indicating that NO synthesis plays an important role in the neurotoxic cascade leading to neuronal damage after focal cerebral ischaemia in rats.     

Neuronal response to radical stress

Glutamate and reactive oxygen species including nitric oxide (NO) and superoxide anion (O2.-) have been postulated to play pivotal roles in the pathogenesis of the neuronal cell loss that is associated with several neurological disease states including Parkinson's disease and amyotrophic lateral sclerosis. In mesencephalic cultures, nondopaminergic neurons but not dopaminergic neurons are susceptible to NO cytotoxicity, although both types of neurons are damaged by glutamate. Methylphenylpyridium ion (MPP+) selectively enhances glutamate and NO cytotoxicity against dopaminergic neurons of mesencephalic cultures. It is suggested that glutathione plays an important role in the expression of NO-mediated glutamate cytotoxicity in dopaminergic neurons. In cultured spinal neurons, glutamate coadministered with the glutamate transporter inhibitor selectively damages motor neurons. Motor neurons are injured by NO, whereas nonmotor neurons are protected by NO through the guanylyl cyclase-cGMP cascade. It is suggested that selective motor neuronal death caused by chronic low-level exposure to glutamate is mediated by the formation of NO in nonmotor neurons. It is possible that neurotoxicity induced by NO and O2.- associated with neurodegenerative disorders is regulated by intracellular defense systems such as glutathione and cGMP.     

神经生长因子对一氧化氮介导的大鼠脑皮质神经元毒性的影响

研究神经生长因子（ＮＧＦ）对一氧化氮（ＮＯ）介导的大鼠脑皮质神经无毒性的影响。方法：用原代培养的大鼠胎鼠脑皮质神经细胞，测定ＮＯ含量及原生型一氧化氮合酶（ｃＮＯＳ）基因表达，并研究ＮＧＦ对细胞缺氧／缺糖损伤的影响。结果：细胞缺氧／缺糖培养 ２４ ｈ后，细胞死亡率明显增高，ＮＯ大量释放。 ＮＧＦ １００ μｇ／Ｌ显著提高细胞生存力，降低ＮＯ释放，但其对硝普钠（ＳＮＰ）３００ μｍｏｌ／Ｌ引起的ＮＯ大量释放及细胞死亡率升高无明显影响。 ＮＧＦ５０、１００ μｇ／Ｌ显著降低细胞缺氧／缺糖引起的 ｃＮＯＳ ｍＲＮＡ的高表达。结论：ＮＯ介导了细胞缺氧／缺糖损伤，ＮＧＦ通过抑制ｃＮＯＳ活性，降低ＮＯ释放来保护神经元免受缺氧／缺糖损伤。     

Nitric oxide-mediated effect of nipradilol, an alpha- and beta-adrenergic blocker, on glutamate neurotoxicity in rat cortical cultures

Nipradilol (3,4-dihydro-8-(2-hydroxy-3-isopropylamino)propoxy-3-nitroxy-2H-1-benzopyran) is used clinically as an anti-glaucoma ophthalmic solution in Japan, and was recently reported to suppress N-methyl-d-aspartate-induced retinal damage in rats. Here we investigated cytotoxic and cytoprotective actions of nipradilol on primary cultures of rat cortical neurons. Treatment of cortical cultures with a high concentration (500 microM) of nipradilol significantly reduced cell viability, increased lactate dehydrogenase (LDH) release and nitrite concentration in culture medium, whereas desnitro-nipradilol (3,4-dihydro-8-(2-hydroxy-3-isopropylamino)propoxy-3-hydroxy-2H-1-benzopyran) had no significant effects. Nipradilol-induced neuronal damage was inhibited by S-hexylglutathione, a glutathione S-transferase inhibitor, and FeTPPS (5,10,15,20-tetrakis(4-sulfonatophenyl)prophyrinato iron (III) chloride), a peroxynitrite decomposition catalyst. On the other hand, relatively low concentrations (10-100 microM) of nipradilol but not desnitro-nipradilol prevented neuronal cell death induced by 24 h application of 100 microM glutamate. Importantly, neuroprotective concentration (100 microM) of nipradilol suppressed glutamate-induced elevation of intracellular Ca2+ concentrations, but had no effect on intracellular cyclic GMP levels. Hence, nipradilol can protect cultured cortical neurons against glutamate neurotoxicity via cyclic GMP-independent mechanisms, and nitric oxide (NO) released from the nitoroxy moiety of nipradilol may mediate neuroprotective effect through the modulation of NMDA receptor function.     

Mechanisms of neuroprotective effects of therapeutic acetylcholinesterase inhibitors used in treatment of Alzheimer's disease

Donepezil, galanthamine, and tacrine are therapeutic acetylcholinesterase (AChE) inhibitors used for the treatment of Alzheimer's disease. The aim of this paper is to review recent findings on their neuroprotective properties and the mechanisms of neuroprotection against glutamate neurotoxicity in rat cortical neurons. First, the hallmark of neurotoxicity induced by two different glutamate treatment conditions was examined, revealing that acute glutamate treatment (1 mM, 10 min) induces necrotic neuronal death and that moderate glutamate treatment (100 microM, 24 hr) induces apoptotic neuronal death. Next, we showed that therapeutic AChE inhibitors protect cortical neurons from glutamate neurotoxicity in a time- and concentration-dependent manner. We examined the mechanism of this neuroprotective effect and found that the neuroprotective effects against both acute and moderate glutamate treatments are mediated through nicotinic acetylcholine receptors (nAChRs), or more specifically, the effects of donepezil and galanthamine are mediated through alpha4- and alpha7-nAChR. We also showed that donepezil and galanthamine protect cortical neurons against acute glutamate treatment-induced neurotoxicity at steps before, and that tacrine protects at steps after, nitric oxide radical formation. On the other hand, the neuroprotective effects of donepezil and galanthamine, but not of tacrine, against neurotoxicity induced by moderate glutamate treatment were mediated through the phosphatidylinositol 3-kinase-Akt pathway. These findings unveiled the hitherto unknown neuroprotective effects of therapeutic AChE inhibitors and provided valuable insights into its neuroprotective mechanisms. They may very likely form the basis for a novel treatment strategy against Alzheimer's disease.     

15-Methoxypinusolidic acid from Biota orientalis attenuates glutamate-induced neurotoxicity in primary cultured rat cortical cells.

15-Methoxypinusolidic acid (15-MPA), a pinusolide derivative isolated from Biota orientalis (Cupressaceae) leaves prevented glutamate-induced excitotoxicity in primary cultured rat cortical cells in vitro. 15-MPA had more selectivity in protecting neurons against N-methyl-D-aspartate (NMDA)-induced neurotoxicity than that induced by kainic acid (KA). The glutamate-induced increase of intracellular calcium ([Ca2+]i) in cortical cells was effectively reduced by 15-MPA. Moreover, 15-MPA could successfully reduce the subsequent overproduction of nitric oxide (NO) and the level of cellular peroxide, and inhibit glutathione (GSH) depletion and lipid peroxidation induced by glutamate in our cultures. Collectively, these results suggested that 15-MPA attenuated glutamate-induced excitotoxicity via stabilization of [Ca2+]i homeostasis and suppression of oxidative stress possibly through the actions on the NMDA receptors.     

Delayed increase of Ca2+ influx elicited by glutamate: role in neuronal death

The mechanism of delayed neurotoxicity, triggered by glutamate, was studied in 7-8-day-old primary cultures of rat cerebellar granule cells. Treatment of cultures for 15 min with 50 microM glutamate in Mg2+ -free medium, followed by removal of the excitoxin, resulted in neuronal death, which started to appear 2-3 hr after the termination of glutamate treatment. The number of dead neurons increased gradually in the next few hours and 80-85% of neurons were found dead 24 hr later. Antagonists of N-methyl-D-aspartate-sensitive glutamate receptors (phencyclidine) or 1.2 mM MgCl2, but not the antagonist of N-methyl-D-asparatate-insensitive glutamate receptors (6-cyano-7-nitroquinoxaline-2,3-dione), abolished the neurotoxic effect of kainate. Development of glutamate-induced neuronal death depends strongly on Ca2+. Removal of extracellular Ca2+ (with 1mM ethyleneglycol-bis-(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid) immediately after the termination of glutamate exposure and before the appearance of the early signs of neuronal death (post-glutamate period) dramatically reduced neuronal degeneration. Neurotoxic concentrations of glutamate induced sustained increase of 45Ca2+ uptake in the post-glutamate period. The delayed increase of 45Ca2+ uptake, as well as the delayed neurotoxicity, were not affected by post-glutamate treatment with phencyclidine, dibenzocyclohepteneimine; DL-2-amino-5-phosphonovalerate, or MgCl2 or with voltage-dependent Ca2+ channel blockers (nitrendipine, verapamil, diltiazem). Neurotoxic concentrations of glutamate also induced a delayed sustained increase of [3H]phorbol-12,13-dibutyrate binding, reflecting an increased translocation of protein kinase C (PKC) from cytosol to the cell membrane during the post-glutamate period. Pretreatment of neurons with the ganglioside GT1b (trisialosylgangliotetraglycosylceramide), followed by removal of free GT1b from the incubation medium, prevented PKC translocation, the sustained increase of 45Ca2+ uptake in the post-glutamate period, and the delayed neuronal death. We suggest that the sustained activation and translocation of PKC primed by glutamate receptor stimulation may be the triggering event causing the protracted increase of neuronal Ca2+ influx. This influx is insensitive to voltage-dependent Ca2+ channel blockers and glutamate receptor antagonists. It appears that this delayed increase of Ca2+ influx may be important in causing neuronal death.     

(-)-S·R-蝙蝠葛苏林碱对谷氨酸引起的大鼠大脑皮质神经元损伤的保护作用

用细胞培养方法,在原代培养的大鼠皮质神经细胞上,观察了(-)-S·R-蝙蝠葛苏林碱对谷氨酸引起的神经元损伤的保护作用。以Fura-2/AM为Ca²⁺的荧光指示剂,用AR-CM-MIC阳离子测定系统观察(-)-S·R-蝙蝠葛苏林碱对谷氨酸诱发大鼠脑皮质神经细胞内Ca²⁺升高的影响。结果表明(-)-S·R-蝙蝠葛苏林碱能剂量依赖性地抑制谷氨酸的神经毒作用,对谷氨酸诱发的神经细胞内游离Ca²⁺升高有明显的抑制作用。提示蝙蝠葛苏林碱对缺血性脑损伤有保护作用。     

L—焦谷氨酸对抗从氨酸钠诱发的大鼠皮层神经元损伤

目的：在大鼠皮层神经元研究Ｌ－吡咯烷酮羧酸（Ｌ－ＰＧＡ）对谷氨酸钠（Ｇｌｕ）诱发神经毒性的拮抗作用。方法：原代培养的皮层神经元取自１６ｄ龄的胎鼠,与Ｇｌｕ作用３０分钟,２４后测定神经元的存活及增益昌质中亚硝酸盐的浓度;以Ｆｕｒａ ２－ＡＭｏ ｘｌｅｑｍｗ 〖Ｃａ＾２＋〗;荧光探针,,ＡＲ－ＣＭ－ＭＩＣ阳离子测定系统测定〖Ｃａ＾２＋〗ｉ。结果：Ｌ－ＰＧＡ１０－８０βｍｏｌ．Ｌ＾－１浓度依赖地抑制Ｇ     

Ca2+-mediated neuronal death in rat brain neuronal cultures by veratridine: protection by flunarizine

Neuronal cell degeneration was studied in vitro in primary rat brain neuronal cultures grown in serum-free, chemically defined, CDM R12 medium, by measuring lactate dehydrogenase (LDH) released in the culture medium. A Ca2+-dependent neuronal cell degeneration was observed after prolonged and transient exposure 30 microM veratridine. The release of LDH occurred gradually and could be completely prevented by 2 mM ethylene glycol bis (beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid, 0.1 microM tetrodotoxin, and 1 microM flunarizine. Flunarizine was without effect on neuronal cell loss induced by 1 mM glutamate, 1 mM kainic acid, and 5 mM KCN. The lack of effect on neurotoxicity induced by 1 mM glutamate differentiates flunarizine from N-methyl-D-aspartate antagonists such as MK-801. The latter protected at nanomolar concentrations against glutamate-induced neuronal cell death but had a maximal effect only at 0.1 mM on the veratridine-induced released LDH. It is suggested that, besides the excitatory amino acid receptor pathway, prolonged opening of the veratridine-sensitive Na+ channel can be neurotoxic. The latter can be prevented by flunarizine. The role of Na+ channel blockers as therapeutic agents in cerebral ischemia is discussed.     

Serofendic acid prevents acute glutamate neurotoxicity in cultured cortical neurons

We have previously reported that a novel neuroprotective substance named serofendic acid was purified and isolated from ether extract of fetal calf serum. In the present study, we investigated the effect of serofendic acid on acute neurotoxicity induced by L-glutamate (Glu) using primary cultures of rat cortical neurons. Exposure of cortical cultures to Glu for 1 h caused a marked decrease in cell viability, as determined by trypan blue exclusion. This acute Glu neurotoxicity was prevented by N-methyl-D-aspartate (NMDA) receptor antagonists, extracellular Ca(2+) removal, nitric oxide (NO) synthase inhibitor and NO scavenger. Serofendic acid prevented acute Glu neurotoxicity in a concentration-dependent manner. Acute neurotoxicity was induced by ionomycin, a Ca(2+) ionophore, and S-nitroso-L-cysteine, an NO donor. Serofendic acid also prevented both ionomycin- and S-nitroso-L-cysteine-induced neurotoxicity. Moreover, the protective effect of serofendic acid on acute Glu neurotoxicity was not affected by cycloheximide, a protein synthesis inhibitor, and actinomycin D, an RNA synthesis inhibitor. These results indicate that serofendic acid protects cultured cortical neurons from acute Glu neurotoxicity by reducing the cytotoxic action of NO and de novo protein synthesis is not required for this neuroprotection.     

Amiloride blocks glutamate-operated cationic channels and protects neurons in culture from glutamate-induced death

The diuretic amiloride has been suggested as a specific inhibitor of T-type neuronal Ca²⁺ channels. The effects of amiloride on glutamate receptor-gated cationic channels and glutamate-induced, Ca²⁺-dependent neuronal death were investigated in primary neuronal cultures from neonatal rats. In primary cultures of cerebellar granule neurons of the rat, receiving 50 μM glutamate for 15 min, at 22°C, in the absence of Mg²⁺, about 80% of neurons were killed in about 24 hr. Exposure of neurons to such a pulse of glutamate, in the presence of various concentrations of amiloride, resulted in a dose-dependent protection from neurotoxicity (EC₅₀ 300 μM, complete protection 1 mM). In voltage-clamped cortical and cerebellar neurons of neonatal rats in primary culture, 100 μM amiloride diminished (by about 25%) glutamate- and/or NMDA-evoked cationic currents, recorded in the whole-cell mode. About 80% of the NMDA- (20 μM) stimulated current was inhibited by 700 μM amiloride. The inhibitory effect of amiloride was not voltage-dependent. In outside-out membrane patches, excised from granule cells and held at −50 mV, 100 μM amiloride changed the NMDA-elicited single channel activity into a fast flickering between the open and closed states. The noise analysis of the data revealed that, although resembling the Mg²⁺-induced flickering, the amiloride-induced channel block was more similar to the effects described for the action of local anaesthetics on the nicotinic cholinergic channel. The pharmacological relevance of this action of amiloride requires further characterization; the data point out the necessity of a cautious use of amiloride in studying neuronal function.     

Schizandrin protects primary cultures of rat cortical cells from glutamate-induced excitotoxicity

The neuroprotective effect of schizandrin on the glutamate (Glu)-induced neuronal excitotoxicity and its potential mechanisms were investigated using primary cultures of rat cortical cells. After exposure of primary cultures of rat cortical cells to 10 microM Glu for 24 h, cortical cell cultures exhibited remarkable apoptotic death. Pretreatment of the cortical cell cultures with schizandrin (10, 100 microM) for 2 h significantly protected cortical neurons against Glu-induced excitotoxicity. The neuroprotective activity of schizandrin was the most potent at the concentration of 100 microM. Schizandrin reduced apoptotic characteristics by DAPI staining in Glu-injured cortical cell cultures. In addition, schizandrin diminished the intracellular Ca2+ influx, inhibited the subsequent overproduction of nitric oxide (NO), reactive oxygen species (ROS), and cytochrome c, and preserved the mitochondrial membrane potential. Furthermore, schizandrin also increased the cellular level of glutathione (GSH) and inhibited the membrane lipid peroxidation malondialdehyde (MDA). As indicated by Western blotting, schizandrin attenuated the protein level changes of procaspase-9, caspase-9, and caspase-3 and cleaved poly(ADP-ribose) polymerase (PARP). Taken together, these results suggest that schizandrin protected primary cultures of rat cortical cells against Glu-induced apoptosis through a mitochondria-mediated pathway and oxidative stress.     

Prevention of glutamate neurotoxicity in cultured neurons by 3,4-dihydro-6-hydroxy-7-methoxy-2,2-dimethyl-1(2H)-benzopyran (CR-6), a scavenger of nitric oxide.

Glutamate neurotoxicity in cerebellar neurons in culture is mediated by excessive production of nitric oxide (NO). We anticipated that 3,4-dihydro-6-hydroxy-7-methoxy-2,2-dimethyl-1(2H)-benzopyran (CR-6) could act as a scavenger of NO since it contains a position (C-5) highly activated towards nitration reaction. The aim of this work was to assess whether CR-6 acts as an NO scavenger and prevents glutamate neurotoxicity in cultures of cerebellar neurons. It was shown that CR-6 reduced, in a dose-dependent manner, glutamate-induced formation of cGMP (EC50 approximately 15 microM) and prevented glutamate neurotoxicity. The protection was approximately 50% at 3-10 microM and nearly complete at 100 microM. CR-6 did not prevent glutamate-induced activation of NO synthase, but interfered with the glutamate-NO-cGMP pathway at a later step. CR-6 reduced the formation of cGMP induced by S-nitroso-N-acetylpenicillamine (SNAP), an NO-generating agent, indicating that CR-6 acts as a scavenger of NO in cultured neurons. This was further supported by experiments showing that in neurons treated with CR-6 and glutamate, the 5-nitro derivative of CR-6 was formed, as determined by GC-MS analyses. Moreover, in vitro incubation of CR-6 with SNAP also produced the 5-nitroderivative, thus confirming that CR-6 directly reacts with NO. The results reported indicate that CR-6 acts as an NO scavenger in neurons and prevents glutamate neurotoxicity.     

E-p-methoxycinnamic acid protects cultured neuronal cells against neurotoxicity induced by glutamate

1. We previously reported that four new phenylpropanoid glycosides and six known cinnamate derivatives isolated from roots of Scrophularia buergeriana Miquel (Scrophulariaceae) protected cultured cortical neurons from neurotoxicity induced by glutamate. Here, we have investigated the structure-activity relationships in the phenylpropanoids using our primary culture system. 2. The alpha,beta-unsaturated ester moiety and the para-methoxy group in the phenylpropanoids appeared to play a vital role in neuroprotective activity. This suggested that E-p-methoxycinnamic acid (E-p-MCA) might be a crucial component for their neuroprotective activity within the phenylpropanoid compounds. E-p-MCA significantly attenuated glutamate-induced neurotoxicity when added prior to an excitotoxic glutamate challenge. 3. The neuroprotective activity of E-p-MCA appeared to be more effective in protecting neurons against neurotoxicity induced by NMDA than from that induced by kainic acid. E-p-MCA inhibited the binding of [propyl-2,3-(3)H]-CGP39653 and [2-(3)H]-glycine to their respective binding sites on rat cortical membranes. However, even high concentrations of E-p-MCA failed to inhibit completely [propyl-2,3-(3)H]-CGP39653 and [2-(3)H]-glycine binding. 4. Indeed, E-p-MCA diminished the calcium influx that routinely accompanies glutamate-induced neurotoxicity, and inhibited the subsequent overproduction of nitric oxide and cellular peroxide in glutamate-injured neurons. 5. Thus, our results suggest that E-p-MCA exerts significant protective effects against neurodegeneration induced by glutamate in primary cultures of cortical neurons by an action suggestive of partial glutamatergic antagonism.