What question did this study set out to answer?

To identify and develop negative allosteric modulators that selectively target δ-GABA receptors for therapeutic use.

February 5, 2026

Exploring the DS2 Scaffold for GABA A Receptor Modulation: Progress toward the Development of a GABA A δ-Subunit Preferring Negative Allosteric Modulator

Key Points

To identify and develop negative allosteric modulators that selectively target δ-GABA receptors for therapeutic use.
Synthesis of DS2 analogues by modifying initial compound structure.
Biological assays to evaluate pharmacological profiles of the new compounds.
Assessment of GABA currents in recombinant receptors with specific mutations.
Compound 1e displayed negative allosteric modulation and δ-GABA receptor selectivity.
1e demonstrated reduced GABA currents in receptors with gain-of-function mutations relevant to neurological conditions.
1e was also found to be brain-permeable, enhancing its potential as a therapeutic agent.

Abstract

Extrasynaptic δ-containing γ-aminobutyric acid type A receptors (GABAARs) are potential drug targets in the treatment of several neurological disorders with altered tonic inhibition. Only a few compounds exhibit δ-GABAAR selectivity, among which the imidazo1,2-apyridine compound DS2 constitutes a valuable tool compound. Guided by the recently identified molecular determinants responsible for the positive allosteric modulation by DS2 in the TMD α(+)β(-) interface of the α4β1δ GABAAR, a series of DS2 analogues were synthesized. Replacement of a thienyl moiety with an N-methylated pyrrolyl ring (1e) converted the pharmacological profile from positive to negative allosteric modulation. Compound 1e exhibited no activity at selected γ2-containing GABAAR subtypes, indicating δ-GABAAR selectivity. The ability of 1e to reduce the GABA currents of recombinant receptors carrying α4- and δ-subunit gain-of-function mutations found in patients with neurodevelopmental disorders and epilepsy, as well as being brain-permeable, identifies 1e as a lead compound for reducing pathophysiologically excessive tonic inhibition.

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