# Discovery of a Novel and Potent Kir4.1 Inhibitor as a Safe and Rapid‐Onset Antidepressant Agent in Mice

## TL;DR

Researchers discovered a new compound, JX3212, that rapidly and safely reduces depression-like behaviors in mice by inhibiting the Kir4.1 potassium channel.

## Contribution

The study introduces JX3212, a novel and potent Kir4.1 inhibitor with rapid antidepressant effects and good safety margins in preclinical models.

## Key findings

- JX3212 shows strong in vitro inhibitory activity against Kir4.1 with good selectivity and brain penetration.
- A single dose of JX3212 rapidly reduces depression-like behaviors in mice within one hour.
- JX3212 has better safety margins than ketamine and imipramine in behavioral tests.

## Abstract

Major depressive disorder is a serious psychiatric disorder for which novel and fast‐acting antidepressants are required. Targeted inhibition of the astrocytic inwardly rectifying potassium channel 4.1 (Kir4.1) in the lateral habenula could rapidly alleviate depression‐like behaviors. A previous study identified Kir4.1 as a promising target for achieving rapid‐onset antidepressant effects. The aim of this study is to identify novel Kir4.1 inhibitors with good druggability through structural modification of the lead compound EHop‐016, resulting in fifty derivatives. Among these, JX3212 exhibits the most potent in vitro inhibitory activity against Kir4.1, with acceptable selectivity and excellent brain exposure. Notably, a single administration of JX3212 results in rapid‐onset antidepressant effects within 1 h in multiple rodent models of depression, with comparable efficacy to (S)‐ketamine; this inhibitor‐like effect is abolished in mice with tamoxifen‐induced conditional Kir4.1 knockout in astrocytes. Additionally, JX3212 demonstrates superior safety margins compared to both (S)‐ketamine and the conventional antidepressant imipramine in murine behavioral assays. In summary, JX3212 functions as a selective Kir4.1 inhibitor with favorable druggability and stable antidepressant efficacy in preclinical models. This pharmacological profile supports the further development of JX3212 as a promising therapeutic candidate for major depressive disorder.

The preferred derivative JX3212 demonstrates strong inhibitory activity against Kir4.1 with favorable druggability and shows significant antidepressant efficacy in vivo.