Characterization of the binding of [<sup>3</sup>H]‐CGS 19755: a novel N‐methyl‐<scp>d</scp>‐aspartate antagonist with nanomolar affinity in rat brain

Murphy, Deborah E.; Hutchison, Alan J.; Hurt, Stephen D.; Williams, Michael; Sills, Matthew A.

doi:10.1111/j.1476-5381.1988.tb11723.x

Cited by 168 publications

(49 citation statements)

References 13 publications

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“…In contrast to this finding, the block induced by 0.7 M CGS-19755, a competitive antagonist at the glutamate recognition site of the NMDA receptor (Murphy et al, 1988;Aizenman and Hartnett, 1992), was observed to increase slightly but significantly ( p Ͻ 0.01, ANOVA) with development in a total of 69 additional neurons tested at 13-30 DIV (Fig. 1 D, inset).…”

Section: Changes In Nmda Receptor Subunit Expression In Cultured Cortcontrasting

confidence: 43%

NMDA and Glutamate Evoke Excitotoxicity at Distinct Cellular Locations in Rat Cortical NeuronsIn Vitro

et al. 2000

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The development of cortical neurons in vivo and in vitro is accompanied by alterations in NMDA receptor subunit expression and concomitant modifications in the pharmacological profile of NMDA-activated ionic currents. For example, we observed that with decreasing NR2B/NR2A subunit expression ratio, the block of NMDA receptor-mediated whole-cell responses by the NR2B-selective antagonist haloperidol was also decreased. In mature cultures (Ͼ22 d in vitro), however, NMDA responses obtained from excised nucleated macropatches, which comprised a large portion of the soma, remained strongly antagonized by haloperidol. These results suggest that in more mature neurons NR1/NR2B receptors appear to be preferentially expressed in the cell body. As predicted from the whole-cell recording pharmacological profile, NMDA-induced toxicity was largely unaffected by haloperidol in mature cultures. However, haloperidol effectively blocked glutamate toxicity in the same cultures, suggesting that the neurotoxic actions of this amino acid were mostly due to the activation of somatic NMDA receptors. In experiments in which the potency of glutamate toxicity was increased by the transport inhibitor L-trans-pyrrolidine-2,4-dicarboxylic acid, the neuroprotective effects of haloperidol were significantly diminished. This was likely because of the fact that glutamate, now toxic at much lower concentrations, was able to reach and activate dendritic receptors under these conditions. These results strongly argue that exogenous glutamate and NMDA normally induce excitotoxicity at distinct cellular locations in mature mixed neuronal cultures and that NR1/NR2B receptors remain an important component in the expression of glutamate, but not NMDA-induced excitotoxicity.

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Section: Changes In Nmda Receptor Subunit Expression In Cultured Cortcontrasting

confidence: 43%

NMDA and Glutamate Evoke Excitotoxicity at Distinct Cellular Locations in Rat Cortical NeuronsIn Vitro

et al. 2000

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“…In the present study, 3H-CPP poorly labeled NMDA receptors in regions that contain predominantly NR2B mRNA (e.g., striatum and lateral septum); however, in other studies (Monaghan, Beaton, and Larson, unpublished observations) we have found that the antagonist 3H-CGP39653 binds with low affinity in regions containing NR2B mRNA (e.g., striatum, septum). Taken together, these findings suggest that the high-affinity antagonist binding site (Murphy et al, 1988;Porter et al, 1992;vanAmsterdam et al, 1992;Benke et al, 1993) represents NR2A-containing NMDA receptors while the low-affinity radiolabeled antagonist binding site represents NMDA receptors that contain NR2B subunits.…”

Section: Discussionmentioning

confidence: 84%

The molecular basis of NMDA receptor subtypes: native receptor diversity is predicted by subunit composition

et al. 1994

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The relationship between four pharmacologically distinct NMDA receptor subtypes, identified in radioligand binding studies, and the recently identified NMDA receptor subunits (NR1a-g, NR2A-D) has not been determined. In this report, we demonstrate that the anatomical distribution of the four NMDA receptor subtypes strikingly parallels the distribution of mRNA encoding NR2A-D subunits. The distribution of NR2A mRNA was very similar to that of “antagonist-preferring” NMDA receptors [defined by high-affinity 3H-2-carboxypiperazine-4-yl-propyl- 1-phosphonic (3H-CPP) binding sites; correlation coefficient = 0.88]. Agonist-preferring NMDA receptors localized to brain regions expressing both NR2B mRNA and NR1- mRNA (NR1 splice variant lacking insert 1). NR2C mRNA was largely restricted to the cerebellar granule cell layer, a region that displays a unique pharmacological profile. NR2D mRNA localized exclusively to those diencephalic nuclei that have a fourth, distinct pharmacological profile (typified by the midline thalamic nuclei). The pharmacology of native NMDA receptors was compared to that of heteromeric NMDA receptors expressed in Xenopus oocytes (NR1/NR2A, NR1/NR2B, NR1/NR2C). The oocyte-expressed NR1/NR2A receptor displayed a higher affinity for antagonists and a slightly lower affinity for agonists than the NR1/NR2B receptor. These patterns are analogous to those found for radioligand binding to native receptors in the lateral thalamus and medial striatum, respectively. NMDA receptors in the lateral thalamus (with a high density of NR2A subunit mRNA) displayed higher affinity for antagonists and a lower affinity for agonists than did NMDA receptors of the medial striatum (a region rich in NR2B mRNA). Relative to the NR1/NR2A and NR1/NR2B receptors, oocyte-expressed NR1/NR2C receptors had a lower affinity specifically for both D-3-(2- carboxypiperazin-4-yl)-1-propenyl-1-phosphonic acid (D-CPPene) and homoquinolinate (HQ). This pattern was identical to that observed for cerebellar (NR2C-containing) versus forebrain (NR2A- and NR2B- containing) NMDA receptors. Taken together, the data in this report suggest that the four previously identified native NMDA receptor subtypes differ in their NR2 composition. Furthermore, the NR2 subunits significantly contribute to the anatomical and pharmacological diversity of NMDA receptor subtypes.

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“…In addition, the IC50s for both drugs were above the observed K,s for these drugs measured in radioligand binding experiments (Olverman et al, 1984;Murphy et al, 1988). NMDA receptor stimulation might cause activation of a positive feedback loop in which glutamate stimulates the release of endogenous NMDA agonist (presumably, but not necessarily, glutamate), generating a non-linear relationship between receptor occupancy and toxicity .…”

Section: Discussion Glutamine Toxicity In Astrocyte-poor Cultures Ismentioning

confidence: 94%

Accumulation of extracellular glutamate and neuronal death in astrocyte‐poor cortical cultures exposed to glutamine

Rosenberg

1991

Glia

103

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The function of astrocytes in cerebral cortex may be studied by comparing the properties of conventional, astrocyte-rich cultures with astrocyte-poor cultures in which astrocyte proliferation has been stringently suppressed. Exposure of astrocyte-poor, but not astrocyte-rich, cultures to fresh medium containing 2 mM glutamine resulted in the death of most neurons within 24 h. This study was undertaken to understand the basis for the apparent toxicity of glutamine in astrocyte-poor cultures. The toxicity of glutamine was found to be mediated by glutamate, which demonstrated an LD50 as a neurotoxin in astrocyte-poor cultures of 2 microM. Exposure of astrocyte-poor (but not astrocyte-rich) cultures to fresh medium containing glutamine for 17.5-24 h resulted in the accumulation of substantial quantities of glutamate (255 +/- 158 microM; mean +/- standard deviation) coincident with the death of neurons in the cultures. Exposure of astrocyte-poor cultures to glutamate in the absence of glutamine did not result in the accumulation of extracellular glutamate. Both the neuronal death and the extracellular glutamate accumulation in astrocyte-poor cultures exposed to glutamine could be blocked by N-methyl-D-aspartate (NMDA) antagonists. These observations suggest that astrocytes as well as glutamine may play an important role in the pathogenesis of glutamate neurotoxicity in the central nervous system.

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Characterization of the binding of [³H]‐CGS 19755: a novel N‐methyl‐d‐aspartate antagonist with nanomolar affinity in rat brain

Cited by 168 publications

References 13 publications

NMDA and Glutamate Evoke Excitotoxicity at Distinct Cellular Locations in Rat Cortical NeuronsIn Vitro

NMDA and Glutamate Evoke Excitotoxicity at Distinct Cellular Locations in Rat Cortical NeuronsIn Vitro

The molecular basis of NMDA receptor subtypes: native receptor diversity is predicted by subunit composition

Accumulation of extracellular glutamate and neuronal death in astrocyte‐poor cortical cultures exposed to glutamine

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Characterization of the binding of [3H]‐CGS 19755: a novel N‐methyl‐d‐aspartate antagonist with nanomolar affinity in rat brain

Cited by 168 publications

References 13 publications

NMDA and Glutamate Evoke Excitotoxicity at Distinct Cellular Locations in Rat Cortical NeuronsIn Vitro

NMDA and Glutamate Evoke Excitotoxicity at Distinct Cellular Locations in Rat Cortical NeuronsIn Vitro

The molecular basis of NMDA receptor subtypes: native receptor diversity is predicted by subunit composition

Accumulation of extracellular glutamate and neuronal death in astrocyte‐poor cortical cultures exposed to glutamine

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Characterization of the binding of [³H]‐CGS 19755: a novel N‐methyl‐d‐aspartate antagonist with nanomolar affinity in rat brain