Activity of 2,3-benzodiazepines at Native Rat and Recombinant Human Glutamate Receptors In Vitro: Stereospecificity and Selectivity Profiles

doi:10.1016/S0028-3908(96)00156-6

Neuropharmacology

Volume 35, Issue 12, December 1996, Pages 1689-1702

https://doi.org/10.1016/S0028-3908(96)00156-6 Get rights and content

Abstract

The activity and selectivity of the glutamate receptor antagonists belonging to the 2,3-benzodiazepine class of compounds have been examined at recombinant human non-NMDA glutamate receptors expressed in HEK293 cells and on native rat NMDA and non-NMDA receptors in vitro. The racemic 2,3-benzodiazepines GYK152466, LY293606 (GYKI53405) and LY300168 (GYKI53655) inhibited AMPA (10 μM)-mediated responses in recombinant human GluR1 receptors expressed in HEK293 cells with approximate ic₅₀ values of 18 μM, 24 μM and 6 μM, respectively and AMPA (10 μM) responses in recombinant human GluR4 expressing HEK293 cells with approximate ic₅₀ values of 22 μM, 28 μM and 5 μM, respectively. GYKI 52466, LY293606 and LY300168 were non-competitive antagonists of AMPA receptor-mediated responses in acutely isolated rat cerebellar Purkinje neurons with approximate ic₅₀ values of 10 μM, 8 μM and 1.5 μM, respectively. The activity of racemic compounds LY293606 and LY300168 was established to reside in the (−) isomer of each compound. At a concentration of 100 μM, GYKI52466, LY293606 and LY300168 produced <30% inhibition of kainate-activated currents evoked in HEK293 cells expressing either human homomeric GluR5 or GluR6 receptors or heteromeric GluR6+KA2 kainate receptors. The activity of the 2,3-benzodiazepines at 100 μM was weak at kainate receptors, but was stereoselective. Similar levels of inhibition were observed for kainate-induced currents in dorsal root ganglion neurons. Intact tissue preparations were also used to examine the stereoselective actions of the 2,3-benzodiazepines. In the cortical wedge preparation, the active isomer of LY300168, LY303070, produced a non-competitive antagonism of AMPA-evoked depolarizations with smaller changes in depolarizations induced by kainate and no effect on NMDA-dependent depolarizations. LY303070 was also effective in preventing 30 μM AMPA-induced depolarizations in isolated spinal cord dorsal roots with an approximate ic₅₀ value of 1 μM. Synaptic transmission in the hemisected spinal cord preparation was stereoselectively antagonized by the active isomers of LY300168 and LY293606. In summary, these results indicate that 2,3-benzodiazepines are potent, selective and stereospecific antagonists of the AMPA subtype of the non-NMDA glutamate receptor. © 1997 Elsevier Science Ltd. All rights reserved.

Section snippets

MATERIALS AND METHODS

All experiments were performed at room temperature (20–22°C).

RESULTS

The 2,3-benzodiazepines used in the present study are shown in Fig. 1.

DISCUSSION

The present studies have investigated the potency, selectivity and stereoselectivity of three 2,3-benzodiazepines which are being used more frequently as selective non-competitive AMPA antagonists. We have used a variety of in vitro preparations including cloned and expressed channels in HEK293 cells and also AMPA, kainate or NMDA receptors in either isolated cells or intact tissue preparations.

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Activity of 2,3-benzodiazepines at Native Rat and Recombinant Human Glutamate Receptors In Vitro: Stereospecificity and Selectivity Profiles

Abstract

Section snippets

MATERIALS AND METHODS

RESULTS

DISCUSSION

Neuron

Neuropharmacology

Neuron

Brain. Res. Devel. Brain Res.

Eur. J. Pharmacol.

Neuron

Neuron

Trends Pharmacol. Sci.

Bioorg. Med. Chem. Lett.

Trends Pharmacol. Sci.

Neuron

The primary afferent depolarizing actions of kainate in the rat

Br. J. Pharmacol.

Pharmacological discrimination of GluR5 and GluR6 kainate receptor subtypes by (3S, 5aR, 6R, 8aR)-6-[2-((1(2) H-tetrazole-5-yl)ethyl]decahydroisoquinoline-3-carboxylic acid

Molec. Pharmacol.

Excitatory amino acid receptors in the vertebrate nervous system

Pharmacol. Rev.

Glutamate in CNS disorders

Drugs New Perspect.

Cyclothiazide acts at a site on the α-amino-3 hydroxy-5-methyl-4-isoxazole propionic receptor complex that does not recognise competitive or non-competitive AMPA receptor antagonists

J. Pharmacol. Exp. Ther.

Non-N-methyl-D-aspartate receptor antagonism by 3-N-substituted 2,3-benzodiazepines; relationship to anti-convulsant activity

J. Pharmacol. Exp. Ther.

Cloning, expression and pharmacological characterization of a human glutamate receptor: hGluR4

Recept. Channels

An improved patch clamp technique for high resolution current recordings from cell and cell free membrane patches

Pflügers Arch.