Stoichiometry of a Recombinant GABA<sub>A</sub>Receptor

Chang, Yongchang; Wang, Ruoping; Barot, Sonal; Weiss, David S.

doi:10.1523/jneurosci.16-17-05415.1996

Cited by 399 publications

(318 citation statements)

References 57 publications

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“…The most common GABA A R subunit combination found in the brain contains two ␣ subunits, two ␤ subunits, and one ␥ subunit (Im et al, 1995;Chang et al, 1996;Li and De Blas, 1997;Jechlinger et al, 1998;Farrar et al, 1999), although combinations of two ␣, one ␤, and two ␥ subunits also occur in the brain (Backus et al, 1993;Khan et al, 1994aKhan et al, ,b, 1996.…”

Section: Individual Hippocampal Pyramidal Cells and Interneurons In Cmentioning

confidence: 99%

GABAergic Innervation Organizes Synaptic and Extrasynaptic GABA_AReceptor Clustering in Cultured Hippocampal Neurons

2002

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We have studied the effects of GABAergic innervation on the clustering of GABA A receptors (GABA A Rs) in cultured hippocampal neurons. In the absence of GABAergic innervation, pyramidal cells form small (0.36 Ϯ 0.01 m diameter) GABA A R clusters at their surface in the dendrites and soma. When receiving GABAergic innervation from glutamic acid decarboxylase-containing interneurons, pyramidal cells form large (1.62 Ϯ 0.08 m breadth) GABA A R clusters at GABAergic synapses. This is accompanied by a disappearance of the small GABA A R clusters in the local area surrounding each GABAergic synapse. Although the large synaptic GABA A R clusters of any neuron contained all GABA A R subunits and isoforms expressed by that neuron, the small clusters not localized at GABAergic synapses showed significant heterogeneity in subunit and isoform composition. Another difference between large GABAergic and small non-GABAergic GABA A R clusters was that a significant proportion of the latter was juxtaposed to postsynaptic markers of glutamatergic synapses such as PSD-95 and AMPA receptor GluR1 subunit. The densities of both the glutamate receptor-associated and non-associated small GABA A R clusters were decreased in areas surrounding GABAergic synapses. However, no effect on the density or distribution of glutamate receptor clusters was observed. The results suggest that there are local signals generated at GABAergic synapses that induce both assembly of large synaptic GABA A R clusters at the synapse and disappearance of the small GABA A R clusters in the surrounding area. In the absence of GABAergic innervation, weaker GABA A R-clustering signals, generated at glutamatergic synapses, induce the formation of small postsynaptic GABA A R clusters that remain juxtaposed to glutamate receptors at glutamatergic synapses.

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Section: Individual Hippocampal Pyramidal Cells and Interneurons In Cmentioning

confidence: 99%

GABAergic Innervation Organizes Synaptic and Extrasynaptic GABA_AReceptor Clustering in Cultured Hippocampal Neurons

2002

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“…This stoichiometry could be checked (despite the lack of an independent and equivalent e ect of the mutation) by expressing mixtures of wild type and mutant for each of the subunits and counting the di erent components of the dose response curve (Labarca et al, 1995;Chang et al, 1996). This is only possible if each mutation produces a substantial shift in EC 50 , su cient to allow the unequivocal determination of up to three components in the interval of the shift.…”

Section: Stoichiometry Of A3b4a5 Receptorsmentioning

confidence: 99%

Formation of functional α3β4α5 human neuronal nicotinic receptors in Xenopus oocytes: a reporter mutation approach

Groot-Kormelink

Boorman

Sivilotti

2001

British J Pharmacology

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1 The a5 subunit participates to the formation of native neuronal nicotinic receptors, particularly in autonomic ganglia. Like the related b3 subunit, a5 forms functional recombinant receptors if expressed together with a pair of typical a and b subunits, but its e ect on the properties of the resulting aba5 receptor depends on the a and b subunits chosen and on the expression system. We used a reporter mutation approach to test whether a5, like b3, is incorporated as a single copy in human a3b4a5 receptors expressed in oocytes. 2 As previously reported, the main indication of the presence of a5 in a3b4a5 wt was an increase in apparent receptor desensitization (compared with a3b4 receptors). If the a3b4a5 receptor bore a 9'T mutation in the second transmembrane domain of either a3 or b4, a5 incorporation produced a decrease in ACh sensitivity (by 4 fold for a3 LT b4a5 vs a3 LT b4 and by 40 fold for a3b4 LT a5 vs a3b4 LT ). The much greater e ect observed in a3b4 LT a5 receptors accords with the hypothesis that a5 takes the place of a b subunit in the receptor. 3 Introducing a 9'T mutation in a5 had no e ect on the agonist sensitivity of a3b4a5 receptors, but reduced apparent desensitisation, as judged by the sag in the current response to high agonist concentrations. 4 Introducing the 9'T mutation in a3 or b4 in the triplet receptor reduced the EC 50 for ACh by a similar extent (7 and 9 fold, respectively), suggesting that a3b4a5 receptors contain two copies each of a and b and therefore only one copy of a5.

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“…The vast majority of GABA A receptors are associations of two a subunits, two b subunits, and a single g subunit, which form a central ion channel, and approximately 80% of all GABA A receptors contain a BZ-binding site located at the interface of the g 2 subunit and the respective a subunit (a 1 , a 2 , a 3 or a 5 ) (Chang et al, 1996;Sigel and Buhr, 1997). It has been postulated that the four BZ site-building a subunits, with their distinct patterns of anatomical distribution in the brain, participate differently in the various effects of BZs.…”

Section: Introductionmentioning

confidence: 99%

Are GABAA Receptors Containing α5 Subunits Contributing to the Sedative Properties of Benzodiazepine Site Agonists?

Savić

Huang

Furtmüller

et al. 2007

Neuropsychopharmacol

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Classical benzodiazepines (BZs) exert anxiolytic, sedative, hypnotic, muscle relaxant, anticonvulsive, and amnesic effects through potentiation of neurotransmission at GABA A receptors containing a 1 , a 2 , a 3 or a 5 subunits. Genetic studies suggest that modulation at the a 1 subunit contributes to much of the adverse effects of BZs, most notably sedation, ataxia, and amnesia. Hence, BZ site ligands functionally inactive at GABA A receptors containing the a 1 subunit are considered to be promising leads for novel, anxioselective anxiolytics devoid of sedative properties. In pursuing this approach, we used two-electrode voltage clamp experiments in Xenopus oocytes expressing recombinant GABA A receptor subtypes to investigate functional selectivity of three newly synthesized BZ site ligands and also compared their in vivo behavioral profiles. The compounds were functionally selective for a 2 -, a 3 -, and a 5 -containing subtypes of GABA A receptors (SH-053-S-CH3 and SH-053-S-CH3-2 0 F) or essentially selective for a 5 subtypes (SH-053-R-CH3). Possible influences on behavioral measures were tested in the elevated plus maze, spontaneous locomotor activity, and rotarod test, which are considered primarily predictive of the anxiolytic, sedative, and ataxic influence of BZs, respectively. The results confirmed the substantially diminished ataxic potential of BZ site agonists devoid of a 1 subunit-mediated effects, with preserved anti-anxiety effects at 30 mg/kg of SH-053-S-CH3 and SH-053-S-CH3-2 0 F. However, all three ligands, dosed at 30 mg/kg, decreased spontaneous locomotor activity, suggesting that sedation may be partly dependent on activity mediated by a 5 -containing GABA A receptors. Hence, it could be of importance to avoid substantial agonist activity at a 5 receptors by candidate anxioselective anxiolytics, if clinical sedation is to be avoided.

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Stoichiometry of a Recombinant GABA_AReceptor

Cited by 399 publications

References 57 publications

GABAergic Innervation Organizes Synaptic and Extrasynaptic GABA_AReceptor Clustering in Cultured Hippocampal Neurons

GABAergic Innervation Organizes Synaptic and Extrasynaptic GABA_AReceptor Clustering in Cultured Hippocampal Neurons

Formation of functional α3β4α5 human neuronal nicotinic receptors in Xenopus oocytes: a reporter mutation approach

Are GABAA Receptors Containing α5 Subunits Contributing to the Sedative Properties of Benzodiazepine Site Agonists?

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Stoichiometry of a Recombinant GABAAReceptor

Cited by 399 publications

References 57 publications

GABAergic Innervation Organizes Synaptic and Extrasynaptic GABAAReceptor Clustering in Cultured Hippocampal Neurons

GABAergic Innervation Organizes Synaptic and Extrasynaptic GABAAReceptor Clustering in Cultured Hippocampal Neurons

Formation of functional α3β4α5 human neuronal nicotinic receptors in Xenopus oocytes: a reporter mutation approach

Are GABAA Receptors Containing α5 Subunits Contributing to the Sedative Properties of Benzodiazepine Site Agonists?

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Stoichiometry of a Recombinant GABA_AReceptor

GABAergic Innervation Organizes Synaptic and Extrasynaptic GABA_AReceptor Clustering in Cultured Hippocampal Neurons

GABAergic Innervation Organizes Synaptic and Extrasynaptic GABA_AReceptor Clustering in Cultured Hippocampal Neurons