# A Glutamatergic Medial Prefrontal Cortex–Locus Coeruleus Circuit Drives Intestinal Dysmotility in Diarrhea-Predominant Irritable Bowel Syndrome

## TL;DR

This study identifies a brain circuit linking the medial prefrontal cortex and locus coeruleus that causes gut motility issues in a mouse model of diarrhea-predominant irritable bowel syndrome.

## Contribution

The study reveals a novel glutamatergic mPFC-LC circuit as a driver of intestinal dysmotility in IBS-D.

## Key findings

- Chemogenetic inhibition of mPFC glutamatergic neurons reduces intestinal dysmotility in a mouse model of IBS-D.
- Activation of the mPFC-LC glutamatergic circuit induces intestinal dysmotility in control mice.
- Inhibition of the mPFC-LC circuit ameliorates intestinal dysmotility in neonatally stressed mice.

## Abstract

Diarrhea-predominant irritable bowel syndrome (IBS-D) is a common chronic disorder of gut–brain interaction characterized by intestinal dysmotility. Central sensitization has a proposed role in intestinal dysmotility, yet the precise neural circuits and mechanisms remain poorly understood. In this study, we established a neonatal maternal deprivation plus restraint stress (NMD + RS) mouse model that recapitulates key diarrhea-like phenotypes. Neural activation mapping revealed a significant upregulation of c-Fos expression within the medial prefrontal cortex (mPFC) and locus coeruleus (LC), which was predominantly localized to glutamatergic neurons. Chemogenetic inhibition of mPFC glutamatergic neurons suppressed intestinal dysmotility, whereas the activation of mPFC glutamatergic neurons evoked intestinal dysmotility in control mice. Furthermore, viral tracing revealed direct projections from mPFC neurons to glutamatergic neurons in the LC. Subsequent chemogenetic manipulation of these LC glutamatergic neurons receiving projection from mPFC neurons similarly regulated intestinal motility, demonstrating a functional downstream node. Critically, selective activation of the mPFC-LC glutamatergic circuit significantly induced intestinal dysmotility in CON mice. In contrast, inhibition of the mPFC-LC glutamatergic circuit significantly ameliorated intestinal dysmotility in NMD + RS mice. Our findings proved that the enhanced activity of the mPFC-LC circuit led to intestinal dysmotility in NMD + RS mice, hopefully providing new mechanistic perspectives and a potential neuromodulatory target for clinical management of IBS.