Abstract
GABAA-receptors, the major synaptic targets for the neutotransmitter GABA, are gated chloride channels. By their allosteric drug-induced modulation they serve as molecular control elements through which the levels of anxiety, vigilance, muscle tension and epileptiform activity can be regulated. Despite their functional prominence, the structural requirements of fully functional GABAA-receptors are still elusive. Expression of cDNAs coding for the α1- and β1-subunits of rat brain yielded GABA-gated chloride channels which were modulated by barbiturates but displayed only agonistic responses to ligands of the benzodiazepine receptor. GABAA-receptors with fully functional benzodiazepine receptor sites were formed when the α1- and α1-subunits were coexpressed with the γ2-subunit of rat brain. These receptors, however, failed to show cooperativity of GABA in gating the channel. In order to determine the subunit repertoire available for receptor assembly in different neuronal populations in vivo, the sites of subunit gene expression were (α1, α2, α3, α5, α6, β1, β2, β3, γ2) mapped by in situ hybridization histochemistry in brain sections. The mRNAs of the α1-, β1- and γ2-subunits were co-localized e.g. in mitral cells of olfactory bulb, pyramidal cells of hippocampus as well as granule cells of dentate gyrus and cerebellum. The lack of colocalization in various other brain areas points to an extensive receptor heterogeneity. The presence of multiple GABAA-receptors in brain may contribute to synaptic plasticity, differential responsiveness of neurons to GABA and to variations in drug profiles.
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References
Gray, J. A. 1982. The Neuropsychology of Anxiety: An Enquiry into the Function of the Septo-Hippocampal System. Oxford University Press, Oxford.
Haefely, W. 1983. Transquillizers. Pages 107–151, in, Psychopharmacology 1, Part 1: Preclinical Psychopharmacology, D. G. Grahame-Smith and P. J. Cowen, (eds.) Elsevier Science Publishing.
Mohler, H., and Okada, T. 1977. Demonstration of benzodiazepine receptors in the central nervous system. Science 198:849–851.
Squires, R. F. and Braestrup, C. 1977. Benzodiazepine receptors in rat brain. Nature 266:732–734.
Haefely, W., Kyburz, E., Gerecke, M. and Mohler, H. (1985). Recent advances in the molecular pharmacology of benzodiazepine receptors and in the structure activity relationships of their agonists and antagonists. Adv. Drug. Res. 14, 165–322.
Haefely, W. 1989. Pharmacology of the allosteric modulation of GABAA receptors by benzodiazepine receptor ligands. Pages 47–70in: E. A. Barnard and E. Costa (eds.) Allosteric Modulation of Amino Acid Receptors: Therapeutic Implications. Raven Pres Ltd., New York.
Costa, E., Alho, H., Favaron, M. and Manev, H. 1989. Pharmacological implications in the allosteric modulation of neurotransmitter amino acid receptors. Pages 3–18,in: E. A. Barnard and E. Costa, (eds.) Allosteric Modulation of Amino Acid Receptors: Therapeutic Implications. Fidia Research Foundation Symposium Series. Raven Press, New York.
Richards, J. G. and Mohler, H. 1984. Benzodiazepine receptors. Neuropharmacology 23:233–242.
Young, W. S. III, and Kuhar, M. J. 1980. Radiohistochemical localization of benzodiazepine receptors in rat brain. J. Pharm. Exp. Ther. 212:337–346.
Mohler, H., Schoch, P., Richards, J. G., Häring, P., Takacs, B., and Stähli, C. 1986. Monoclonal antibodies as probes for studying the structure and location of the GABA receptor/benzodiazepine receptor/chloride channel complex. Pages 285–297,in: R. W. Olsen and J. C. Venter, (eds.) Benzodiazepine/GABA Receptors and Chloride Channels: Structural and Functional Properties, Alan R. Liss, New York.
Richards, J. G., Mohler H. and Haefely, W. 1986. Mapping benzodiazepine receptors in the CNS by radiohistochemistry and immunohistochemistry. Pages 629–677,in P. Panula, H. Päivärinta and S. Soinita, (eds.). Neurology and Neurobiology, Vol. 16, Neurohistochemistry, Modern Methods and Applications, edit. by Alan R. Lis, New York.
Richards, J. G., Schoch, P., Häring, P., Takacs, B. and Mohler, H. 1987. Resolving GABAA/benzodiazepine receptors: Cellular and subcellular localization in the CNS with monoclonal antibodies. J. Neurosci. 7:1866–1886.
Mohler, H., Richards, J. G. and Wu, J.-Y. 1981. Autoradiographic localization of benzodiazepine receptors in immunohistochemically identified GABAergic synapses. Proc. Natl. Acad. Sci. USA, 78:1935–1939.
Mohler, H., Malherbe, P., Sequier, J. M., Bannwarth, W., Schoch, P., and Richards, J. G. 1989. Location, structure and sites of synthesis of the GABAA receptor in the central nervous system. Pages 31–46,in: E. A. Barnard and E. Costa, (eds.) Allosteric Modulation of Amino Acid Receptors: Therapeutic Implications. Raven Press, New York.
Mohler, H., Battersby, M. K., and Richards, J. G. 1980. Benzodiazepine receptor protein identified and visualized in brain tissue by a photoaffinity label. Proc. Natl. Acad. Sci. USA, 77:1666–1670.
Sieghart, W. and Karobath, M. 1980. Molecular heterogeneity of benzodiazepine receptors. Nature 286:285–287.
Fuchs, K., Mohler, H., and Sieghart, W. 1988. Various proteins from rat brain specifically and irreversibly labeled by 3H-flunitrazepam are distinct α-subunits of the GABA-benzodiazepine receptor complex. Neurosci. Letters 90:314–319.
Bureau, M. and Olsen, R. W. 1988. γ-Aminobutyric acid/benzodiazepine receptor carries binding sites on both two major peptide subunits. Bioch. Biophys. Res. Comm. 153:1006–1011.
Sigel, E., Stephenson, E. A., Mamalaki, C. and Barnard, E. A. 1983. A γ-aminobutyric acid/benzodiazepine receptor complex of bovine cerebral cortex: Purification and partial characterization. J. Biol. Chem. 258:6965–6971.
Schoch, P., Häring, P., Takacs, B., Stähli, C., and Mohler, H. 1984. A GABA/benzodiazepine receptor from bovine brain: Purification, reconstitution and immunological characterization. J. Recept. Res. 4:189–200.
Sigel, E. and Barnard, E. A. 1984. A γ-aminobutyric acid/benzodiazepine receptor complex from bovine cerebral cortex. J. Biol. Chem., 259:7219–7223.
Mamalaki, C., Stephenson, F. A., and Barnard, E. A. 1987. The GABAA/benzodiazepine receptor is a heterotetramer of homologous α- and β-subunits. EMBO J. 6:561–565.
Sato, T. N. and Neale, J. H. 1987. The type I and type II γ-aminobutyric acid/benzodiazepine receptor: 1. purification and two-dimensional electrophoretic analysis of the receptor from cortex and cerebellum. Biochem. Biophys. Res. Commun. 146:568–574.
Schoch, P., Richards, J. G., Häring, P., Takacs, B., Stähli, C., Staehelin, T., Haefely, W. and Mohler, H. 1985. Co-localization of GABAA receptors and benzodiazepine receptors in the brain shown by monoclonal antibodies. Nature 314:168–171.
Häring, P., Stähli, C., Schoch, P., Takacs, B., Staehelin, T. and Mohler, H. 1985. Monoclonal antibodies revcal structural homogeneity of γ-aminobutyric acid/benzodiazepine receptors in different brain areas. Proc. Natl. Acad. Sci. USA 82:4837–4841.
Barker, J. L. and Owen, D. G. 1986. Electrophysiological pharmacology of GABA and diazepam in cultured CNS neurons. Pages 135–166,in: R. W. Olsen and J. C. Venter, (eds.) Benzodiazepine /GABA Receptors and Chloride Channels: Structural and Functional Properties, Alan R. Liss 1986.
Olsen, R. W. and Venter, J. C. eds. Benzodiazepine/GABA Receptors and Chloride Channels: Structural and Functional Properties. Alan R. Liss, New York, 1986.
Pritchett, D. B., Sontheimer, H., Gorman, C. M., Kettenmann, H., Seeburg, P. H. and Schofield, P. R. 1988. Transient expression shows ligand gating and allosteric potentiation of GABAA-receptor subunits. Science 242:1306–1308.
Mohler, H., Malherbe, P., Draguhn, A., Sigel, E., Séquier, J. M., Persson, E. and Richards, J. G. 1989. GABAA-receptor subunits: functional expression and gene localization. In: GABA and Benzodiazepine Receptor Subtypes, G. Biggio and E. Costa, eds., Raven Press (in press).
Dunn, S. M. J., Martin, C. R., Agey, M. W. and Miyazahi, R. 1989. Functional reconstitution of the bovine brain GABAA receptor from solubilized components. Biochemistry 28:2545–2551.
Dunn, S. M. J., Shelman, R. A. and Agey, M. W. 1989. Fluorescence measurements of anion transport by the GABAA receptor in reconstituted membrane preparations. Biochemistry 28:2551–2557.
Parker, I., Gundersen, B. and Miledi, R. 1986. Action of pentobarbital on rat brain receptors expressed in Xenopus oocytes. J. Neurosci. 6:2290–2297.
Smart, T. G., Houamed, K., von Renterghem, C. and Constanti, A. 1987. mRNA directed synthesis and insertion of functional amino acid receptors in Xenopus laevis cocytes. Biochem. Soc. Trans. 15:117–122.
Sigel, E. and Baur, R. 1988. Allosteric modulation by benzodiazepine receptor ligands of the GABAA receptor channei expressed in Xenopus oocytes. J. Neurosci. 8:289–295.
Schofield, P. R., Darlison, M. G., Fujita, N., Burt, D. R., Stephenson, F. A., Rodriguez, H., Rhee, L. M., Ramachandran, V. R., Glencorse, T., Seeburg, P. H. and Barnard, E. A. 1987. Sequence and functional expression of the GABAA-receptor shows a ligand-gated receptor super-family. Nature 328:221–227.
Levitan, E. S., Blair, L. A. C., Dionne, V. E. and Barnard, E. A. 1988. Biophysical and pharmacological properties of cloned GABAA receptor subunits expressed in Xenopus oocytes. Neuron 1:779–781.
Levitan, E. S., Schofield, P. R., Burt, D. R., Rhee, L. M., Wisden, W., Kohler, M., Fujita, N., Rodriguez, H. F., Stephenson, S., Darlison, M. G., Barnard, E. A. and Seeburg, P. H. 1988. Structural and functional basis for GABAA receptor heterogeneity. Nature 335:76–79.
Malherbe, P. Draguhn, A., Multhaup, G., Beyreuther, K. and Mohler, H. 1989. GABAA-receptor expressed from rat brain α-and β-subunit cDNAs displays potentiation by benzodiazepine receptor ligands. (submitted).
Hunkeler, W., Mohler, H., Pieri, L., Polc, P., Bonetti, E. P., Cumin, R., Schaffner, R. and Haefely, W. 1981. Selective antagonists of benzodiazepines. Nature 290:514–516.
Haefely, W. 1988. The preclinical pharmacology of flumazenil. Eur. J. Anaesthesiol. Suppl. 2:25–36.
Braestrup, C., Schmiechen, R., Nielsen, M. and Petersen, E. N. 1982. Interaction of convulsive ligands with benzodiazepine receptor. Science 216:1241–1243.
Dascal, N. 1987. The use of Xenopus oocytes for the study of ion channels. CRC Critical Reviews in Biochemistry 22:317–386.
Pritchett, D. B., Sontheimer, H., Shivers, B. D., Ymer, S., Kettenmann, H., Schofield, P. R. and Seeburg, P. H. 1989. Importance of a novel GABAA receptor subunit for benzodiazepine pharmacology. Nature 338:582–585.
Malherbe, P., Sigel, E., Baur, R., Persohn, E., Richards, J. G., and Mohler, H. Functional characteristics and sites of gene expression of the α1, β1, γ2-isoform of the rat GABAA-receptor (submitted).
Sakmann, B., Hamill, O. P., and Bormann, J. 1983. Patchclamp measurements of elementary chloride currents activated by the putative inhibitory transmitter GABA and glycine in mammalian spinal cord neurons. J. Neural Transmission, Suppl. 18:83–95.
Bormann, J. and Clapham, D. E. 1985. γ-Aminobutyric acid receptor channels in adrenal chromaffin cells: A patch-clamp study. Proc. Natl. Acad. Sci. USA 82:2168–2172.
Bormann, J., Hamill, O. P. and Sakmann, B. 1987. Mechanism of anion permeation through channels gated by glycine and γ-aminobutyric acid in mouse cultured spinal neurones. J. Physiol. (London) 385:243–286.
Krnjevic, K. Desensitization of GABA receptors, In: GABA-and Benzodiazepine Receptors. E. Costa, ed., Raven Press, New York, pp. 111–120 (1981).
Schofield, P. R., Pritchett, D. B., Sontheimer, H., Kettenmann, H. and Seeburg, P. H. 1989. Sequence and expression of human GABAA receptor α1- and β1-subunits. FEBS Lett. 244:361–364.
Barnard, E. A., Darlison, M. G. and Seeburg, P. 1987. Molecular biology of the GABAA-receptor: the receptor/channel superfamily. TINS 10:502–509.
Stelzer, A., Kay, A. R. and Wong, R. K. S. 1988. GABAA receptor function in hippocampal cells is maintained by phosphorylation factors. Science 241:339–341.
Eichinger, A. and Sieghart, W. 1986. Postnatal development of proteins associated with different benzodiazepine receptors. J. Neurochem. 46:173–180.
Hebebrand, J., Friedl, W., Unverzagt, B. and Propping, P. 1986. Benzodiazepine receptor subunits in avian brain. J. Neurochem. 47:790–793.
Sieghart, W., Mayer, A., and Drexler, G. 1988. Propertics of [3H]flunitrazepam binding to different benzodiazepine binding proteins. Eur. J. Pharmacol. 88:291–299.
Sweetman, P. M. and Tallmann, J. F. 1986. Regional difference in brain benzodiazepine receptor carbohydrates. J. Pharm. Exp. Ther. 29:299–306.
Braestrup, C. and Nielsen, M. J. 1981. [3H]Propyl β-carboline-3-carboxylate as a selective radioligand for the BZ1 benzodiazepine receptor subclass. Neurochem. 37:333–341.
Cash, D. J. and Subbaro, K. 1987. Channel opening of γ-aminobutyric acid receptor from rat brain: Molecular mechanisms of the receptor responses. Biochemistry 26:7562–7570.
Lippa, A. S., Garrett, K. M., Tabakoff, B., Beer, B., Wennogle, L. P. and Meyerson, L. R. 1985. Heterogeneity of brain benzodiazepine receptors: Effects of physiological conditions. Brain Res. Bull. 14:189–195.
Guidotti, A., Alho, H., Berkovich, A., Cox, D. H., Ferrarese, C., Slobodansky, E., Santi, M. R. and Wambebe, D.. DBI processing: allosteric modulation at different GABA/Benzodiazepine receptor subtypes. In: Allosteric Modulation of Amino Acid Receptors: Therapeutic Implications. E. A. Barnard and E. Costa eds. Raven Press, New York, pp. 109–123 (1989).
Malherbe, P. et al. (in preparation).
Sequier, J. M., Richards, J. G., Malherbe, P., Price, G. W., Matthews, S. and Mohler, H. 1988. Mapping of brain areas containing RNA homologous to cDNAS encoding the α-and β-subunits of the rat GABAA γ-aminobutyrate receptor. Proc. Natl. Acad. Sci. USA, 85:7815–7819.
Richards et al. (in preparation).
Sigel, E. and Baur, R. 1988. Activation of protein kinase C differentially modulates neuronal Na+, Ca2+, and γ-aminobutyrate type A channels. Proc. Natl. Acad. Sci. USA 85:6192–6196.
Malherbe, P., Sigel, E., Baur, R., Persohn, E., Richards, J. G. and Mohler, H. 1990. Functional expression and sites of gene transcription of a novel α-subunit of the BABAA-receptor in rat brain. FEBS Lett. (in press).
Richards, J. G., Schoch, P., Häring, P., Takacs, B. and Mohler, H. 1988. Strategies for raising antibodies against benzodiazepine receptors, Pages 159–190,In Van Leeuwen, F.W., Buijs, R.M., Pool, C.W. and Pach, O. (eds.), Molecular Neuroanatomy, Elsevier Publishers.
Ewert, M., Shivers, B.D., Lüddens, H., Mohler, H. and Seeburg, H.P. 1990. Subunit selectivity and epitope characterization of monoclonal antibodies directed against the GABAA/Benzodiazepine receptor (submitted).
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Mohler, H., Malherbe, P., Draguhn, A. et al. GABA A -receptors: Structural requirements and sites of gene expression in mammalian brain. Neurochem Res 15, 199–207 (1990). https://doi.org/10.1007/BF00972210
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DOI: https://doi.org/10.1007/BF00972210