Activity of 2,3-benzodiazepines at native rat and recombinant human glutamate receptors in vitro: stereospecificity and selectivity profiles.
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 GYKI52466, LY293606 (GYKI53405) and LY300168 (GYKI53655) inhibited AMPA (10 microM)-mediated responses in recombinant human GluR1 receptors expressed in HEK293 cells with approximate IC50 values of 18 microM, 24 microM and 6 microM, respectively and AMPA (10 microM) responses in recombinant human GluR4 expressing HEK293 cells with approximate IC50 values of 22 microM, 28 microM and 5 microM, 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 microM, 8 microM and 1.5 microM, respectively. The activity of racemic compounds LY293606 and LY300168 was established to reside in the (-) isomer of each compound. At a concentration of 100 microM, 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 microM 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 microM AMPA-induced depolarizations in isolated spinal cord dorsal roots with an approximate IC50 value of 1 microM. 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.
Bleakman
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Eli Lilly and Co., Lilly Research Centre, Windlesham, Surrey, U.K. bleakman_david@lilly.com
Ballyk
B A
BA
Schoepp
D D
DD
Palmer
A J
AJ
Bath
C P
CP
Sharpe
E F
EF
Woolley
M L
ML
Bufton
H R
HR
Kamboj
R K
RK
Tarnawa
I
I
Lodge
D
D
D000818:Animals; D014151:Anti-Anxiety Agents; D001569:Benzodiazepines / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D001581:Benzothiadiazines / Q000494:pharmacology; D002460:Cell Line; D002531:Cerebellum / Q000502:physiology; D002540:Cerebral Cortex / Q000187:drug effects / Q000502:physiology; D018691:Excitatory Amino Acid Antagonists / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D005727:Ganglia, Spinal / Q000502:physiology; D006801:Humans; D007668:Kidney; D008564:Membrane Potentials / Q000187:drug effects; D015394:Molecular Structure; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D011689:Purkinje Cells / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000096:biosynthesis / Q000187:drug effects / Q000502:physiology*; D011994:Recombinant Proteins / Q000187:drug effects / Q000378:metabolism; D013116:Spinal Cord / Q000502:physiology; D013329:Structure-Activity Relationship; D014162:Transfection; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology
D014151:Anti-Anxiety Agents; D001569:Benzodiazepines; D001581:Benzothiadiazines; D018691:Excitatory Amino Acid Antagonists; D018091:Receptors, AMPA; D011994:Recombinant Proteins; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; C061950:GYKI 52466; C079692:GYKI 53655; C085266:talampanel; C004639:cyclothiazide