# Hydrogen sulfide as a potent predator-derived kairomone mediating fear-related responses in mice

## TL;DR

Hydrogen sulfide, a toxic gas, acts as a warning signal for mice to detect nearby predators, triggering fear responses through specific neurons.

## Contribution

This study identifies hydrogen sulfide as a predator-derived kairomone detected by mouse olfactory neurons.

## Key findings

- Hydrogen sulfide activates Grueneberg ganglion neurons via CNGA3 channels, triggering fear-related behaviors.
- GG neurons are biologically relevant for detecting H2S, linking it to predator-prey dynamics.
- H2S serves as a kairomone signaling danger from predator secretions.

## Abstract

Olfaction plays a critical role in survival across species, notably in threat detection. Volatile olfactory molecules signaling the presence of a danger in the environment share a specific chemical signature, particularly sulfur-containing moieties detected by the mouse olfactory Grueneberg ganglion (GG) neurons. Our study focuses on one of the most toxic air pollutant, hydrogen sulfide (H2S). We reveal here a novel facet of H2S which acts as a danger signal, a kairomone alerting the prey for the presence of nearby predators as H2S can originate from meat-eater secretions. H2S activates the cyclic nucleotide-gated channels (CNGA3) present on the sensory cilia of GG neurons. This direct channel opening lets calcium into the cells ensuring neuronal activation and signal transmission to specific brain regions associated with stress and fear-related behaviors. Moreover, using GG-axotomized mice, we demonstrate the biological relevance of GG neurons to detect H2S. These results give new insights into predator-prey dynamics and danger communication which is fundamental for the survival of the species.

Detection of hydrogen sulfide by the neurons of the olfactory Grueneberg ganglion sheds light on a new kairomonal role for this toxic gas in predator-prey dynamics and danger communication