Voltage-Dependent Inhibition of Glycine Receptor Channels by Niflumic Acid

Maleeva, Galyna; Peiretti, Franck; Zhorov, Boris S.; Bregestovski, Pìotr

doi:10.3389/fnmol.2017.00125

Cited by 14 publications

(28 citation statements)

References 81 publications

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“…The voltage dependence of the inhibitory action of Azo‐NZ1 suggested that the compound might act as an open channel blocker of GABA A receptors (Maleeva, Peiretti, Zhorov, & Bregestovski, ). To test this hypothesis, we compared the action of Azo‐NZ1 at different concentrations of the agonist.…”

Section: Resultsmentioning

confidence: 99%

“…The 2′ residue of the TM2 domain (see Figure a) is a key region that determines the action of several pore blockers of Cys‐loop receptors, including cyanotriphenylborate (Rundström et al, ), picrotoxin (Lynch, Rajendra, Barry, & Schofield, ; Zhorov & Bregestovski, ), niflumic acid (Maleeva, Peiretti, Zhorov, & Bregestovski, ), and cyclothiazide (Xie, Song, Ripps, & Qian, ). The Azo‐NZ1 construct contains two features that are essential to impart sensitivity to the photochrome: (a) the negative charge of the sulphonate group (mimicking that of the chloride ion) and (b) the distance between this sulphonate group and the carbonyl group of the benzodiazepine core (see Figure S2).…”

Section: Discussionmentioning

confidence: 99%

“…The experiments were carried out on cultured CHO cells (CHO‐K1, ATCC Cat# CCL‐61, ) obtained from the American Type Tissue Culture Collection (ATCC, Molsheim, France) that were maintained in culture conditions as previously described (Maleeva, Peiretti, Zhorov, & Bregestovski, ; Mukhtarov et al, ). For electrophysiological analysis, cells were transfected with cDNAs of several Cys‐loop receptors.…”

Section: Methodsmentioning

confidence: 99%

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A photoswitchable GABA receptor channel blocker

Maleeva

Wutz

Rustler

et al. 2019

British J Pharmacology

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Background and Purpose Anion‐selective Cys‐loop receptors (GABA and glycine receptors) provide the main inhibitory drive in the CNS. Both types of receptor operate via chloride‐selective ion channels, though with different kinetics, pharmacological profiles, and localization. Disequilibrium in their function leads to a variety of disorders, which are often treated with allosteric modulators. The few available GABA and glycine receptor channel blockers effectively suppress inhibitory currents in neurons, but their systemic administration is highly toxic. With the aim of developing an efficient light‐controllable modulator of GABA receptors, we constructed azobenzene‐nitrazepam (Azo‐NZ1), which is composed of a nitrazepam moiety merged to an azobenzene photoisomerizable group. Experimental Approach The experiments were carried out on cultured cells expressing Cys‐loop receptors of known subunit composition and in brain slices using patch‐clamp. Site‐directed mutagenesis and molecular modelling approaches were applied to evaluate the mechanism of action of Azo‐NZ1. Key Results At visible light, being in trans‐configuration, Azo‐NZ1 blocked heteromeric α1/β2/γ2 GABAA receptors, ρ2 GABAA (GABAC), and α2 glycine receptors, whereas switching the compound into cis‐state by UV illumination restored the activity. Azo‐NZ1 successfully photomodulated GABAergic currents recorded from dentate gyrus neurons. We demonstrated that in trans‐configuration, Azo‐NZ1 blocks the Cl‐selective ion pore of GABA receptors interacting mainly with the 2′ level of the TM2 region. Conclusions and Implications Azo‐NZ1 is a soluble light‐driven Cl‐channel blocker, which allows photo‐modulation of the activity induced by anion‐selective Cys‐loop receptors. Azo‐NZ1 is able to control GABAergic postsynaptic currents and provides new opportunities to study inhibitory neurotransmission using patterned illumination.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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A photoswitchable GABA receptor channel blocker

Maleeva

Wutz

Rustler

et al. 2019

British J Pharmacology

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“…This drug and its derivatives are widely used in clinics for the relief of chronic and acute pain conditions [56]. Niflumic acid is also known as an inhibitor of several anion channels, including Ca ++ -activated [57-59] and swelling-activated [12] Cl - channels, and was reported to variably affect different membrane ion transport systems, such as anion exchangers [28, 60], the glycine [61], GABA(A) [62] and N-methyl-D-aspartate [63] receptors and T-type calcium channels [64]. The findings presented here show that 0.01-1 mM niflumic acid, despite being more potent on the swelling-activated Cl - current, also significantly blocked the K + current (Table 2 and Fig.…”

Section: Discussionmentioning

confidence: 99%

A Potassium-Selective Current Affected by Micromolar Concentrations of Anion Transport Inhibitors

Costa

Civello

Bernardinelli

et al. 2018

Cell Physiol Biochem

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Background/Aims: In the human genome, more than 400 genes encode ion channels, which are ubiquitously expressed and often coexist and participate in almost all physiological processes. Therefore, ion channel blockers represent fundamental tools in discriminating the contribution of individual channel types to a physiological phenomenon. However, unspecific effects of these compounds may represent a confounding factor. Three commonly used chloride channel inhibitors, i.e. 4,4′-diisothiocyano-2,2′-stilbene-disulfonic acid (DIDS), 5-nitro-2-[(3-phenylpropyl) amino]benzoic acid (NPPB) and the anti-inflammatory drug niflumic acid were tested to identify the lowest concentration effective on Cl^- channels and ineffective on K⁺ channels. Methods: The activity of the above mentioned compounds was tested by whole cell patch-clamp on the swelling-activated Cl^- current ICl,swell and on the endogenous voltage-dependent, outwardly rectifying K⁺ selective current in human kidney cell lines (HEK 293/HEK 293 Phoenix). Results: Micromolar (1-10 µM) concentrations of DIDS and NPPB could not discriminate between the Cl^- and K⁺ selective currents. Specifically, 1 µM DIDS only affected the K⁺ current and 10 µM NPPB equally affected the Cl^- and K⁺ currents. Only relatively high (0.1-1 mM) concentrations of DIDS and prolonged (5 minutes) exposure to 0.1-1 mM NPPB preferentially suppressed the Cl^- current. Niflumic acid preferentially inhibited the Cl^- current, but also significantly affected the K⁺ current. The endogenous voltage-dependent, outwardly rectifying K⁺ selective current in HEK 293/HEK 293 Phoenix cells was shown to arise from the Kv 3.1 channel, which is extensively expressed in brain and is involved in neurological diseases. Conclusion: The results of the present study underscore that sensitivity of a given physiological phenomenon to the Cl^- channel inhibitors NPPB, DIDS and niflumic acid may actually arise from an inhibition of Cl^- channels but can also result from an inhibition of voltage-dependent K⁺ channels, including the Kv 3.1 channel. The use of niflumic acid as anti-inflammatory drug in patients with concomitant Kv 3.1 dysfunction may result contraindicated.

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“…A recent study has demonstrated that NFA, a member of the fenamate class of non-steroidal anti-inflammatory drugs, is an efficient blocker of GlyRs with a subunit specificity of action ( Maleeva et al, 2017 ). At heterologous expression of the different GlyR subunits it has been shown that a blocking potency of NFA was about one order higher for alpha2 GlyRs than for the receptors formed by alpha1 subunits.…”

Section: Introductionmentioning

confidence: 99%

Developmental Changes in the Inhibition of Glycinergic Synaptic Currents by Niflumic Acid in Hypoglossal Motoneurons

Petukhova

Ponomareva

Mukhamedyarov

et al. 2018

Front. Mol. Neurosci.

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Mammalian brainstem hypoglossal motoneurones (HMs) receive powerful synaptic glycinergic inputs and are involved in a variety of motor functions, including respiration, chewing, sucking, swallowing, and phonation. During the early postnatal development, subunit composition of chloride-permeable glycine receptors (GlyRs) changes leading to a decrease of “fetal” alpha2 and elevation of “adult” alpha1 GlyR subunits. It has been recently demonstrated that niflumic acid (NFA), a member of the fenamate class of non-steroidal anti-inflammatory drugs, is an efficient subunits-specific blocker of GlyRs. At a heterologous expression of different GlyR subunits it has been shown that blocking potency of NFA is more than one order higher for alpha2 GlyRs than for receptors formed by alpha1 subunit. To reveal the action of NFA on the synaptic activity we analyzed here the effects of NFA on the glycinergic inhibitory post-synaptic currents in the HMs from mouse brainstem slices. In the whole-cell patch clamp configuration, the amplitude and the frequency of glycinergic synaptic currents from two age groups have been analyzed: “neonate” (P2–P4) and “juvenile” (P7–P12). Addition of NFA in the presence of antagonists of glutamate and GABA receptors caused a decrease in the mean amplitude and frequency of synaptic events. The degree of the inhibition induced by NFA decreased with the postnatal development, being higher on the motoneurons from “neonate” brainstem slices in comparison with the “juvenile” age group. Analysis of the pair-pulse facilitation suggests the post-synaptic origin of NFA action. These observations provide evidence on the developmental changes in the inhibition by NFA of glycinergic synaptic transmission, which reflects increase in the alpha1 and decrease in the alpha2 GlyR subunits expression in synapses to hypoglossal motoneurons during the early stages of postnatal life.

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Voltage-Dependent Inhibition of Glycine Receptor Channels by Niflumic Acid

Cited by 14 publications

References 81 publications

A photoswitchable GABA receptor channel blocker

A photoswitchable GABA receptor channel blocker

A Potassium-Selective Current Affected by Micromolar Concentrations of Anion Transport Inhibitors

Developmental Changes in the Inhibition of Glycinergic Synaptic Currents by Niflumic Acid in Hypoglossal Motoneurons

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