# Peripheral inflammation is accompanied by cerebral hypoperfusion in mice

## TL;DR

This study shows that peripheral inflammation in mice leads to reduced blood flow in the brain, potentially explaining how chronic pain affects brain function.

## Contribution

The first use of laser speckle contrast imaging to show cerebral hypoperfusion caused by peripheral inflammation in mice.

## Key findings

- CFA-induced peripheral inflammation causes dose-dependent cerebral hypoperfusion in mice.
- Laser speckle contrast imaging reveals vascular changes in the parietal-temporal lobes.
- Peripheral inflammation may lead to long-term brain plasticity through vascular mechanisms.

## Abstract

Chronic pain is a disabling condition that is accompanied by neuropsychiatric comorbidities such as anxiety, depression, and cognitive decline. While the peripheral alterations are well-studied, we lack an understanding of how these peripheral changes can result in long-lasting brain alterations and the ensuing behavioral phenotypes. This study aims to quantify changes in cerebral blood perfusion using laser speckle contrast imaging (LSCI) in the murine Complete Freund's adjuvant (CFA) model of unilateral peripheral inflammation.

Twenty four adult male and female C57BL/6 mice were randomly assigned to control (0.05 ml saline) or 1 of 3 experimental groups receiving CFA (0.01 ml, 0.05 ml, and 0.1 ml) on the right hindpaw. Three days after the intraplantar injections, animals were examined for signs of inflammation and subjected to craniotomy and in vivo LSCI of the parietal-temporal lobes.

Unilateral administration of CFA resulted in signs of local inflammation as well as cerebral hypoperfusion in dose-dependent manner.

To our knowledge, this is the first study using laser speckle contrast imaging to examine the effects of CFA-induced peripheral inflammation on cerebral blood perfusion. It serves as a first step in delineating the path by which insult to peripheral tissues can cause long-lasting brain plasticity via vascular mechanisms.