# Astrocytic Connexin43 Channels Are Essential for Breathing Pattern Stabilization in the preBötzinger Complex

## TL;DR

This study shows that astrocytic connexin43 channels in the preBötzinger complex are crucial for stabilizing breathing patterns through ATP release and neuron activation.

## Contribution

The study identifies a novel astrocyte-to-neuron signaling pathway involving Cx43 hemichannels and P2Y1 receptors in respiratory regulation.

## Key findings

- Cx43 hemichannels in preBötC astrocytes are the predominant connexin subtype and essential for breathing pattern stabilization.
- Blocking Cx43 channels increases breathing frequency and activates preBötCSST neurons via ATP release and P2Y1 receptor activation.
- Genetic knockdown of astrocytic Cx43 leads to high-frequency breathing and increased respiratory motor output.

## Abstract

Astrocytes within the preBötzinger complex (preBötC) critically regulate respiratory rhythmogenesis and pattern formation. However, the molecular mechanisms underlying their contributions remain poorly understood. This study aims to investigate whether connexin 43 (Cx43) channels, a prominent subtype of connexin proteins expressed in preBötC astrocytes, are essential for stabilizing breathing patterns.

We employed a multidisciplinary approach, integrating whole‐body plethysmography, in vivo fiber photometry, phrenic nerve discharge (PND) recordings, photostimulation, RNAscope fluorescence in situ hybridization, and RNA sequencing to elucidate the functional role of Cx43 channels in respiratory regulation.

Elevated activation levels of preBötC astrocytes were synchronized with specific respiratory events, including sighs and transiently augmented breathing. RNA‐sequencing analysis demonstrated that Gja1 (encoding Cx43) was identified as the predominant connexin transcript in preBötC astrocytes. Photostimulation of preBötC astrocytes significantly increased PND frequency in anesthetized mice, an effect replicated by pharmacological blockade of Cx43 hemichannels. Conditional knockdown of astrocytic Gja1 in the preBötC considerably increased resting breathing frequency and minute ventilation. Blockade of Cx43 hemichannels enhanced astrocytic activation and induced ATP accumulation around somatostatin‐expressing preBötC neurons (preBötCSST). Furthermore, Cx43 hemichannel blockade activated preBötCSST neurons, an effect mediated by P2Y1 but not P2X receptors.

We identify an astrocyte‐to‐neuron signaling cascade involving Cx43 hemichannel‐dependent ATP release, P2Y1 receptor activation on preBötCSST neurons, and subsequent modulation of respiratory motor output. These findings establish Cx43 hemichannels as critical molecular determinants for stabilizing breathing patterns.

Both pharmacological blockade and genetic knockdown of astrocytic connexin43 channels in the preBötzinger complex induce a high‐frequency breathing pattern, thereby enhancing respiratory motor output. This effect is mediated by astrocytic activation and subsequent ATP release, which activates P2Y1 receptors on somatostatin‐expressing preBötzinger complex neurons.