# Deletion of TRPA1 Ion Channel Modulates the Central Stress Responses in a Mouse Model of Posttraumatic Stress Disorder

## TL;DR

Deleting the TRPA1 ion channel in mice changes brain responses to stress in a PTSD model, affecting noradrenergic activity and glial activation.

## Contribution

Shows TRPA1 modulates PTSD-related stress adaptation in LC and PVN, independent of α2-adrenoceptors.

## Key findings

- TRPA1 deletion increased tyrosine hydroxylase levels in the locus coeruleus.
- TRPA1 deletion reduced astrocyte activation in the paraventricular nucleus.
- Clonidine effects on PTSD behaviors were not influenced by TRPA1 deletion.

## Abstract

What are the main findings?
Genetic deletion of Trpa1 exaggerated TH level in the LC and reduced astrogliosis in PVN in a foot shock-induced mouse model of PTSD.Genetic deletion of Trpa1 did not influence the effects of clonidine treatment on PTSD-related behavior.

Genetic deletion of Trpa1 exaggerated TH level in the LC and reduced astrogliosis in PVN in a foot shock-induced mouse model of PTSD.

Genetic deletion of Trpa1 did not influence the effects of clonidine treatment on PTSD-related behavior.

What are the implications of the main findings?
TRPA1 ion channel may support stress adaptation in PTSD through LC and PVN.This effect is not α2-adrenoceptor-mediated.

TRPA1 ion channel may support stress adaptation in PTSD through LC and PVN.

This effect is not α2-adrenoceptor-mediated.

Background: Posttraumatic stress disorder (PTSD) is a mental illness in which central stress-regulating regions, including locus coeruleus (LC) and paraventricular nucleus of hypothalamus (PVN), play key roles. Clonidine, a central sympatholytic drug, can inhibit LC activity and reduce PTSD-related symptoms, suggesting noradrenergic involvement. Glia-driven immune mechanisms may link LC activity to PVN responses. Since TRPA1 ion channel is implicated in both neuroinflammation and stress adaptation, we aimed to determine whether its presence modulates the function of brain structures contributing to PTSD-related alteration in central stress adaptation. Methods: Foot shock PTSD model was applied to Trpa1 wild-type (WT) and knockout (KO) mice, and outcomes were assessed four weeks later. Immunohistochemistry was used to evaluate tyrosine hydroxylase (TH) levels in the LC and glial activation in the PVN. Behavioral effects of clonidine and circulating corticosterone levels were also examined. Results: Stress increased LC/TH immunoreactivity and PVN glial activation. Trpa1 deletion exaggerated LC/TH responses but reduced PVN astrocyte activation. Clonidine increased freezing and decreased jumping (a hyperarousal marker). KO mice showed enhanced jumping and did not respond to clonidine. Corticosterone levels remained unchanged. Conclusions: TRPA1 may support stress adaptation in PTSD by regulating LC noradrenergic output and PVN neuroinflammation, independently of α2-adrenergic signaling.