GABA-induced uncoupling of GABA/benzodiazepine site interactions is mediated by increased GABAA receptor internalization and associated with a change in subunit composition

Gutiérrez, María Laura; Ferreri, María Celeste; Gravielle, Marı́a Clara

doi:10.1016/j.neuroscience.2013.10.077

Cited by 19 publications

(13 citation statements)

References 38 publications

(38 reference statements)

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“…GABA‐induced uncoupling is accompanied by a subunit‐selective decrease in the mRNA levels of the GABA A receptor (Gravielle et al, ). Our recent results suggest that the receptor uncoupling is associated with a reduction in the percentage of α3‐contaning GABA A receptors (Gutiérrez et al, ). On the other hand, it has been shown that PKA and PKC activations differentially regulate the transcription of the GABA A receptor α1 subunit in neocortical neurons (Hu et al, ).…”

Section: Discussionmentioning

confidence: 90%

“…However, the mRNA levels of some receptor subunits (α2, α4, α5, γ1, and γ2) do not change (Gravielle et al, ). We recently demonstrated that the GABA‐induced uncoupling is associated with a decrease in the proportion of GABA A receptors containing α3 subunits (Gutiérrez et al, ), a receptor subtype that exhibits the highest coupling strength between the GABA and benzodiazepine sites (Puia et al, ; Wafford et al, ; Smith et al, ).…”

Section: Resultsmentioning

confidence: 99%

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GABA‐induced uncoupling of GABA/benzodiazepine site interactions is associated with increased phosphorylation of the GABA_A receptor

Gutiérrez

Ferreri

Farb

et al. 2014

J of Neuroscience Research

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The use-dependent regulation of the GABAA receptor occurs under physiological, pathological, and pharmacological conditions. Tolerance induced by prolonged administration of benzodiazepines is associated with changes in GABAA receptor function. Chronic exposure of neurons to GABA for 48 hr induces a downregulation of the GABAA receptor number and an uncoupling of the GABA/benzodiazepine site interactions. A single brief exposure ((t1/2) = 3 min) of rat neocortical neurons to the neurotransmitter initiates a process that results in uncoupling hours later (t(1/2) = 12 hr) without alterations in the number of GABAA receptors and provides a paradigm to study the uncoupling mechanism selectively. Here we report that uncoupling induced by a brief GABAA receptor activation is blocked by the coincubation with inhibitors of protein kinases A and C, indicating that the uncoupling is mediated by the activation of a phosphorylation cascade. GABA-induced uncoupling is accompanied by subunit-selective changes in the GABAA receptor mRNA levels. However, the GABA-induced downregulation of the α3 subunit mRNA level is not altered by the kinase inhibitors, suggesting that the uncoupling is the result of a posttranscriptional regulatory process. GABA exposure also produces an increase in the serine phosphorylation on the GABAA receptor γ2 subunit. Taken together, our results suggest that the GABA-induced uncoupling is mediated by a posttranscriptional mechanism involving an increase in the phosphorylation of GABAA receptors. The uncoupling of the GABAA receptor may represent a compensatory mechanism to control GABAergic neurotransmission under conditions in which receptors are persistently activated.

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Section: Discussionmentioning

confidence: 90%

Section: Resultsmentioning

confidence: 99%

GABA‐induced uncoupling of GABA/benzodiazepine site interactions is associated with increased phosphorylation of the GABA_A receptor

Gutiérrez

Ferreri

Farb

et al. 2014

J of Neuroscience Research

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“…This potentiating effect of BZD is lost after prolonged or high dose acute exposure (Tietz et al, 1989;Holt et al, 1999), characterized first by a loss of sedative/hypnotic activity followed by the anticonvulsant properties behaviorally (Lister and Nutt, 1986;Wong et al, 1986;File et al, 1988;Bateson, 2002). The induction of BZD tolerance occurs in part due to the uncoupling of allosteric actions between GABA and BZD (Gallager et al, 1984;Marley and Gallager, 1989), a process that appears to rely on GABA A R receptor internalization (Ali and Olsen, 2001;Gutierrez et al, 2014). We have previously shown that 24 h BZD treatment leads to decreased surface and total levels of the α 2 subunit in cultured hippocampal neurons that was dependent on lysosomal-mediated degradation (Jacob et al, 2012); however, the process by which the α 2 subunit is selectively targeted to lysosomes is still unknown.…”

Section: Introductionmentioning

confidence: 99%

Diazepam Accelerates GABAAR Synaptic Exchange and Alters Intracellular Trafficking

Lorenz-Guertin

Bambino

Das

et al. 2019

Preprint

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Despite 50+ years of clinical use as anxiolytics, anti-convulsants, and sedative/hypnotic agents, the mechanisms underlying benzodiazepine (BZD) tolerance are poorly understood. BZDs potentiate the actions of gamma-aminobutyric acid (GABA), the primary inhibitory neurotransmitter in the adult brain, through positive allosteric modulation of γ2 subunit containing GABA type A receptors (GABA A Rs). Here we define key molecular events impacting γ2 GABA A R and the inhibitory synapse gephyrin scaffold following initial sustained BZD exposure in vitro and in vivo. Using immunofluorescence and biochemical experiments, we found that cultured cortical neurons treated with the classical BZD, diazepam (DZP), presented no substantial change in surface or synaptic levels of γ2-GABA A Rs. In contrast, both γ2 and the postsynaptic scaffolding protein gephyrin showed diminished total protein levels following a single DZP treatment in vitro and in mouse cortical tissue. We further identified DZP treatment enhanced phosphorylation of gephyrin Ser270 and increased generation of gephyrin cleavage products. Selective immunoprecipitation of γ2 from cultured neurons revealed enhanced ubiquitination of this subunit following DZP exposure. To assess novel trafficking responses induced by DZP, we employed a γ2 subunit containing an N terminal fluorogen-activating peptide (FAP) and pH-sensitive green fluorescent protein (γ2 pH FAP). Live-imaging experiments using γ2 pH FAP GABA A R expressing neurons identified enhanced lysosomal targeting of surface GABA A Rs and increased overall accumulation in vesicular compartments in response to DZP. Using fluorescence resonance energy transfer (FRET) measurements between α2 and γ2 subunits within a GABA A R in neurons, we identified reductions in synaptic clusters of this subpopulation of surface BZD sensitive receptor. Moreover, we found DZP simultaneously enhanced synaptic exchange of both γ2-GABA A Rs and gephyrin using fluorescence recovery after photobleaching (FRAP) techniques. Finally we provide the first proteomic analysis of the BZD sensitive GABA A R interactome in DZP vs. vehicle treated mice. Collectively, our results indicate DZP exposure elicits down-regulation of gephyrin scaffolding and BZD sensitive GABA A R synaptic availability via multiple dynamic trafficking processes.

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“…Neuronal activity regulates the surface number and/or function of GABA A receptors. Several lines of evidence suggest that chronic exposure to GABA may induce the GABA A receptor endocytosis (Gutiérrez et al, 2014). In the present study, we found out that 5 days/week exercise may have more presynaptic GABA release than 3 days/week exercise group, so this might be one of the mechanisms underlying the less surface number of GABA A receptors observed in the high frequency exercise group.…”

Section: Discussionmentioning

confidence: 99%

The Frequency-Dependent Aerobic Exercise Effects of Hypothalamic GABAergic Expression and Cardiovascular Functions in Aged Rats

Zhao

Cai

et al. 2017

Front. Aging Neurosci.

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A decline in cardiovascular modulation is a feature of the normal aging process and associated with cardiovascular diseases (CVDs) such as hypertension and stroke. Exercise training is known to promote cardiovascular adaptation in young animals and positive effects on motor and cognitive capabilities, as well as on brain plasticity for all ages in mice. Here, we examine the question of whether aerobic exercise interventions may impact the GABAergic neurons of the paraventricular nucleus (PVN) in aged rats which have been observed to have a decline in cardiovascular integration function. In the present study, young (2 months) and old (24 months) male Wistar rats were divided into young control (YC), old sedentary, old low frequency exercise (20 m/min, 60 min/day, 3 days/week, 12 weeks) and old high frequency exercise (20 m/min, 60 min/day, 5 days/week, 12 weeks). Exercise training indexes were obtained, including resting heart rate (HR), blood pressure (BP), plasma norepinephrine (NE), and heart weight (HW)-to-body weight (BW) ratios. The brain was removed and processed according to the immunofluorescence staining and western blot used to analyze the GABAergic terminal density, the proteins of GAD67, GABAA receptor and gephyrin in the PVN. There were significant changes in aged rats compared with those in the YC. Twelve weeks aerobic exercise training has volume-dependent ameliorated effects on cardiovascular parameters, autonomic nervous activities and GABAergic system functions. These data suggest that the density of GABAergic declines in the PVN is associated with imbalance in autonomic nervous activities in normal aging. Additionally, aerobic exercise can rescue aging-related an overactivity of the sympathetic nervous system and induces modifications the resting BP and HR to lower values via improving the GABAergic system in the PVN.

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GABA-induced uncoupling of GABA/benzodiazepine site interactions is mediated by increased GABAA receptor internalization and associated with a change in subunit composition

Cited by 19 publications

References 38 publications

GABA‐induced uncoupling of GABA/benzodiazepine site interactions is associated with increased phosphorylation of the GABA_A receptor

GABA‐induced uncoupling of GABA/benzodiazepine site interactions is associated with increased phosphorylation of the GABA_A receptor

Diazepam Accelerates GABAAR Synaptic Exchange and Alters Intracellular Trafficking

The Frequency-Dependent Aerobic Exercise Effects of Hypothalamic GABAergic Expression and Cardiovascular Functions in Aged Rats

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GABA-induced uncoupling of GABA/benzodiazepine site interactions is mediated by increased GABAA receptor internalization and associated with a change in subunit composition

Cited by 19 publications

References 38 publications

GABA‐induced uncoupling of GABA/benzodiazepine site interactions is associated with increased phosphorylation of the GABAA receptor

GABA‐induced uncoupling of GABA/benzodiazepine site interactions is associated with increased phosphorylation of the GABAA receptor

Diazepam Accelerates GABAAR Synaptic Exchange and Alters Intracellular Trafficking

The Frequency-Dependent Aerobic Exercise Effects of Hypothalamic GABAergic Expression and Cardiovascular Functions in Aged Rats

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Product

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GABA‐induced uncoupling of GABA/benzodiazepine site interactions is associated with increased phosphorylation of the GABA_A receptor

GABA‐induced uncoupling of GABA/benzodiazepine site interactions is associated with increased phosphorylation of the GABA_A receptor