# The impact of nicotine on the olfactory memory and its relationship with TRPA1

## TL;DR

Nicotine improves mouse olfactory memory and protects brain cells through a receptor called TRPA1.

## Contribution

This study shows that nicotine's effect on olfactory memory depends on TRPA1 activation.

## Key findings

- Oral nicotine treatment improves olfactory memory in mice.
- Nicotine reduces neuronal apoptosis in the piriform cortex.
- TRPA1 knockout abolishes nicotine’s beneficial effect.

## Abstract

Olfactory disorders are related to cognitive decline, yet effective treatments remain limited. Cigarette smoke impairs olfaction, but one of its components, nicotine, can protect nerve cells in the central nervous system. Transient receptor potential ankyrin 1 (TRPA1) is expressed in central olfactory tract conduction and can be activated by nicotine. We therefore investigated whether nicotine influences olfaction through TRPA1. After inducing olfactory damage with methimazole, one of the following agents was then administered for 42 days to wild-type (WT) and TRPA1 knockout (TRPA1 KO) mice: phosphate-buffered saline, cigarette smoke extract, or nicotine. Olfactory behavioral testing and histological analyses were performed. In WT mice, intraoral nicotine improved olfactory memory and reduced neuronal apoptosis in the piriform cortex (PC). In TRPA1 KO mice, however, these effects of nicotine were abolished. Nicotine improved olfaction through TRPA1 in central olfactory tract conduction. Nicotine may thus represent a potential therapeutic strategy for olfactory impairment.

•Oral nicotine treatment improves olfactory memory in mice•Nicotine reduces neuronal apoptosis in the piriform cortex•TRPA1 knockout abolishes nicotine’s beneficial effect•Nicotine’s neuroprotective action in the piriform cortex is TRPA1-dependent

Oral nicotine treatment improves olfactory memory in mice

Nicotine reduces neuronal apoptosis in the piriform cortex

TRPA1 knockout abolishes nicotine’s beneficial effect

Nicotine’s neuroprotective action in the piriform cortex is TRPA1-dependent

Biological sciences; Neuroscience; Cell biology