GABAA receptor subtype selectivity of the proconvulsant rodenticide TETS

Pressly, Brandon; Nguyen, Hai M.; Wulff, Heike

doi:10.1007/s00204-017-2089-4

Cited by 12 publications

(35 citation statements)

References 44 publications

(70 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…c Suggested structure of the hydrolysis product based on high-resolution mass spectrometry. d Total picrotoxinin plasma, liver and brain concentrations in mice; n = 6-9 mice per time point; shown mean ± SD values in nM concentrations, which would block roughly 10-20% of GABA A current based on picrotoxinin's IC 50 in electrophysiological experiments (Pressly et al 2018), were, however, sufficient to induce seizures, since 75% of the 42 mice in our study exhibited seizures (score 3-5 on the Racine scale) and 25% died during the experiments. Death typically occurred between 20 and 30 min after picrotoxinin administration and brain concentrations in these animals were found to be 376 ± 120 nM (n = 10).…”

Section: Picrotoxinin Is Rapidly Metabolized In Vivomentioning

confidence: 99%

“…To determine whether the TETS detected by the ELISA is pharmacodynamically active, we pooled serum from several mice that had been sacrificed on day 2 (n = 5) or day 14 (n = 7), cleaned it up as described for the ELISA assay and then reconstituted with Ringers solution. This solution was then perfused onto L929 cells that were transiently transfected with α 2 β 3 γ 2 GABA A receptors, the receptor combination that is most sensitive to TETS inhibition (Pressly et al 2018). As shown in Fig.…”

Section: Tets Remains Pharmacodynamically Active In Vivo For 14 Daysmentioning

confidence: 99%

“…Today, picrotoxin or its active component picrotoxinin, are mostly used as pharmacological tools to inhibit γ-aminobutyric acid type A (GABA A ) receptor-mediated chloride currents (Ffrench-Constant et al 1993;Olsen 2015). While picrotoxinin shows little subtype selectivity and inhibits most recombinantly expressed GABA A receptors with an IC 50 of roughly 4 μM in wholecell patch-clamp experiments, TETS inhibits α 2 β 3 γ 2 (IC 50 480 nM) and α 6 β 3 γ 2 (IC 50 400 nM) receptors 7-10-fold more potently than most other GABA A receptors (Pressly et al 2018). Since α 2 β 3 γ 2 receptors make up 15-20% of the GABA A receptors in the mammalian brain (Fritschy and Mohler 1995;Pirker et al 2000; Rudolph and Knoflach 2011), we previously proposed that α 2 β 3 γ 2 is probably the most important GABA A receptor for the seizure-inducing activity of TETS (Pressly et al 2018).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Comparison of the toxicokinetics of the convulsants picrotoxinin and tetramethylenedisulfotetramine (TETS) in mice

et al. 2020

Self Cite

View full text Add to dashboard Cite

Acute intoxication with picrotoxin or the rodenticide tetramethylenedisulfotetramine (TETS) can cause seizures that rapidly progress to status epilepticus and death. Both compounds inhibit γ-aminobutyric acid type-A (GABA A) receptors with similar potency. However, TETS is approximately 100 × more lethal than picrotoxin. Here, we directly compared the toxicokinetics of the two compounds following intraperitoneal administration in mice. Using LC/MS analysis we found that picrotoxinin, the active component of picrotoxin, hydrolyses quickly into picrotoxic acid, has a short in vivo half-life, and is moderately brain penetrant (brain/plasma ratio 0.3). TETS, in contrast, is not metabolized by liver microsomes and persists in the body following intoxication. Using both GC/MS and a TETS-selective immunoassay we found that mice administered TETS at the LD 50 of 0.2 mg/kg in the presence of rescue medications exhibited serum levels that remained constant around 1.6 μM for 48 h before falling slowly over the next 10 days. TETS showed a similar persistence in tissues. Whole-cell patch-clamp demonstrated that brain and serum extracts prepared from mice at 2 and 14 days after TETS administration significantly blocked heterologously expressed α 2 β 3 γ 2 GABA A-receptors confirming that TETS remains pharmacodynamically active in vivo. This observed persistence may contribute to the long-lasting and recurrent seizures observed following human exposures. We suggest that countermeasures to neutralize TETS or accelerate its elimination should be explored for this highly dangerous threat agent.

show abstract

Section: Picrotoxinin Is Rapidly Metabolized In Vivomentioning

confidence: 99%

Section: Tets Remains Pharmacodynamically Active In Vivo For 14 Daysmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Comparison of the toxicokinetics of the convulsants picrotoxinin and tetramethylenedisulfotetramine (TETS) in mice

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…Normally, this binding is selective and irreversible. Very recently, α 2 β 3 γ 2 was shown to be the most important GABA A receptor for the seizure-inducing activity of TETS [ 15 ]. The regulation of chloride in the neuron is therefore disrupted [ 16 ].…”

Section: Toxicokinetics and Toxicodynamicsmentioning

confidence: 99%

Tetramethylenedisulfotetramine: A Health Risk Compound and a Potential Chemical Warfare Agent

Patočka

França

et al. 2018

Toxics

View full text Add to dashboard Cite

Tetramethylenedisulfotetramine (TETS, tetramine) is a toxic organic compound that is used as an effective rodenticide. However, this neurotoxin is not only toxic to rodents, it also causes poisoning in humans. Due to its high level of toxicity for humans, the use of TETS as a rodenticide has been banned and its production has been discontinued. Despite this, human poisoning by this substance is unfortunately still very common. The largest number of poisonings are reported in China, but in the United States, dozens of poisonings still happen annually. TETS is one of the most hazardous pesticides and also a possible chemical warfare agent with no known antidote. In this article, we aim to summarize the biochemical and toxicological data of TETS and hope to cast some light on the toxicological risk to human health.

show abstract

“…However, it was not known whether TETS displayed any subtype selectivity and where exactly it was binding. To address the first question, our group recently tested the potency of TETS on the major synaptic and extrasynaptic GABA A receptors associated with convulsant activity using whole-cell patch clamp and reported that TETS is most active on α 2 β 3 γ 2L and α 6 β 3 γ 2L GABA A receptors ( Pressly et al, 2018 ). Based on the observation that α 2 β 3 γ 2 receptors make up 15%–20% of the GABA A receptors in the mammalian central nervous system, we suggested that this receptor combination probably constitutes the most important GABA A receptor target for the seizure-inducing activity of TETS ( Pressly et al, 2018 ).…”

Section: Introductionmentioning

confidence: 99%

Identification of the Functional Binding Site for the Convulsant Tetramethylenedisulfotetramine in the Pore of the α₂β₃γ₂ GABA_A Receptor

et al. 2020

Self Cite

View full text Add to dashboard Cite

Tetramethylenedisulfotetramine (TETS) is a so-called “caged” convulsant that is responsible for thousands of accidental and malicious poisonings. Similar to the widely used GABA receptor type A (GABA A ) antagonist picrotoxinin, TETS has been proposed to bind to the noncompetitive antagonist (NCA) site in the pore of the receptor channel. However, the TETS binding site has never been experimentally mapped, and we here set out to gain atomistic level insights into how TETS inhibits the human α 2 β 3 γ 2 GABA A receptor. Using the Rosetta molecular modeling suite, we generated three homology models of the α 2 β 3 γ 2 receptor in the open, desensitized, and closed/resting state. Three different ligand-docking algorithms (RosettaLigand, Glide, and Swissdock) identified two possible TETS binding sites in the channel pore. Using a combination of site-directed mutagenesis, electrophysiology, and modeling to probe both sites, we demonstrate that TETS binds at the T6′ ring in the closed/resting-state model, in which it shows perfect space complementarity and forms hydrogen bonds or makes hydrophobic interactions with all five pore-lining threonine residues of the pentameric receptor. Mutating T6′ in either the α 2 or β 3 subunit reduces the IC 50 of TETS by ∼700-fold in whole-cell patch-clamp experiments. TETS is thus interacting at the NCA site in the pore of the GABA A receptor at a location that is overlapping but not identical to the picrotoxinin binding site. SIGNIFICANCE STATEMENT Our study identifies the binding site of the highly toxic convulsant tetramethylenedisulfotetramine (TETS), which is classified as a threat agent by the World Health Organization. Using a combination of homology protein modeling, ligand docking, site-directed mutagenesis, and electrophysiology, we show that TETS is binding in the pore of the α 2 β 3 γ 2 GABA receptor type A receptor at the so-called T6′ ring, wherein five threonine residues line the permeation pathway of the pentameric receptor channel.

show abstract

GABAA receptor subtype selectivity of the proconvulsant rodenticide TETS

Cited by 12 publications

References 44 publications

Comparison of the toxicokinetics of the convulsants picrotoxinin and tetramethylenedisulfotetramine (TETS) in mice

Comparison of the toxicokinetics of the convulsants picrotoxinin and tetramethylenedisulfotetramine (TETS) in mice

Tetramethylenedisulfotetramine: A Health Risk Compound and a Potential Chemical Warfare Agent

Identification of the Functional Binding Site for the Convulsant Tetramethylenedisulfotetramine in the Pore of the α₂β₃γ₂ GABA_A Receptor

Contact Info

Product

Resources

About

GABAA receptor subtype selectivity of the proconvulsant rodenticide TETS

Cited by 12 publications

References 44 publications

Comparison of the toxicokinetics of the convulsants picrotoxinin and tetramethylenedisulfotetramine (TETS) in mice

Comparison of the toxicokinetics of the convulsants picrotoxinin and tetramethylenedisulfotetramine (TETS) in mice

Tetramethylenedisulfotetramine: A Health Risk Compound and a Potential Chemical Warfare Agent

Identification of the Functional Binding Site for the Convulsant Tetramethylenedisulfotetramine in the Pore of the α2β3γ2 GABAA Receptor

Contact Info

Product

Resources

About

Identification of the Functional Binding Site for the Convulsant Tetramethylenedisulfotetramine in the Pore of the α₂β₃γ₂ GABA_A Receptor