Pharmacological characterization of a GluR6 kainate receptor in cultured hippocampal neurons.
We have examined the pharmacology of kainate receptors in cultured hippocampal neurons (6-8 days in vitro (DIV)) from embryonic rats (E17). Cultured neurons were pre-treated with concanavalin A to remove kainate receptor desensitization and whole-cell voltage clamp electrophysiology employed to record inward currents in response to glutamatergic agonists and antagonists. N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid (AMPA) receptor responses were blocked using MK801 (3 microM) and the 2,3-benzodiazepine, LY300168 (GYKI53655, 50 microM), respectively. Inward currents were recorded in hippocampal neurons upon application of kainate and the 2S,4R isomer of 4-methyl glutamic acid (SYM2081) with EC50 values of 3.4 +/- 0.4 microM and 1.6 +/- 0.5 microM, respectively (n = 6 cells). The GluR5 selective agonists, LY339434 (100 microM) and (RS)-2-amino-3-(3-hydroxy-5-tert-butyl-4-isoxazolyl) propionic acid (ATPA) (100 microM), did not evoke detectable inward currents in any cell responding to kainate. LY293558 and the selective GluR5 antagonist, LY382884, had weak antagonist effects on responses evoked by either kainate or (2S,4R)-4-methyl glutamate (IC50 > 300 microM). The quinoxalinedione, 2,3-dihyro-6-nitro-7-sulfamoyl-benzo(f)quinoxaline (NBQX), blocked both kainate and (2S,4R)-4-methyl glutamate-activated currents at much lower concentrations (IC50 approximately 10 microM). These results provide pharmacological evidence that ion channels comprised of GluR6 kainate receptor subunits mediate kainate receptor responses in hippocampal neurons cultured 6-8 DIV.
Bleakman
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Eli Lilly and Company, Lilly Neuroscience, Lilly Research Laboratories, Lilly Corporate Center, Indianapolis, IN 46285-0510, USA. bleakman_david@lilly.com
Ogden
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AM
Ornstein
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Hoo
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D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D015870:Gene Expression; D005971:Glutamates / Q000494:pharmacology; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D007546:Isoquinolines / Q000378:metabolism / Q000494:pharmacology; D007608:Kainic Acid / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D018408:Patch-Clamp Techniques; D011810:Quinoxalines / Q000378:metabolism / Q000494:pharmacology; D011869:Radioligand Assay; D018091:Receptors, AMPA / Q000187:drug effects / Q000378:metabolism; D018092:Kainic Acid Receptors / Q000187:drug effects* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013777:Tetrazoles / Q000378:metabolism / Q000494:pharmacology; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology; D000097806:GluK2 Kainate Receptor
D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D005971:Glutamates; D007546:Isoquinolines; D007608:Kainic Acid; D011810:Quinoxalines; D018091:Receptors, AMPA; D018092:Kainic Acid Receptors; D011993:Recombinant Fusion Proteins; D013777:Tetrazoles; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D000097806:GluK2 Kainate Receptor; C062865:2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline; C046105:4-methylglutamic acid; C082309:tezampanel