Sponsor
NIH grants R01 AA025024 and R01 AA028680.
Published In
European Journal of Pain
Document Type
Article
Publication Date
11-2023
Subjects
Hyperalgesia -- chemically induced
Abstract
Background
Social interactions with subjects experiencing pain can increase nociceptive sensitivity in observers, even without direct physical contact. In previous experiments, extended indirect exposure to soiled bedding from mice with alcohol withdrawal-related hyperalgesia enhanced nociception in their conspecifics. This finding suggested that olfactory cues could be sufficient for nociceptive hypersensitivity in otherwise untreated animals (also known as “bystanders”).
Aim
The current study addressed this possibility using an inflammation-based hyperalgesia model and long- and short-term exposure paradigms in C57BL/6J mice.
Materials & Method
Adult male and female mice received intraplantar injection of complete Freund's adjuvant (CFA) and were used as stimulus animals to otherwise naïve same-sex bystander mice (BS). Another group of untreated mice (OLF) was simultaneously exposed to the bedding of the stimulus mice.
Results
In the long-term, 15-day exposure paradigm, the presence of CFA mice or their bedding resulted in reduced von Frey threshold but not Hargreaves paw withdrawal latency in BS or OLF mice. In the short-term paradigm, 1-hr interaction with CFA conspecifics or 1-hr exposure to their bedding induced mechanical hypersensitivity in BS and OLF mice lasting for 3 hrs. Chemical ablation of the main olfactory epithelium prevented bedding-induced and stimulus mice-induced mechanical hypersensitivity. Gas chromatography-mass spectrometry (GC-MS) analysis of the volatile compounds in the bedding of experimental mice revealed that CFA-treated mice released an increased number of compounds indicative of disease states.
Rights
Copyright (c) 2023 The Authors
This work is licensed under a Creative Commons Attribution 4.0 International License.
Locate the Document
DOI
10.1002/ejp.2201
Persistent Identifier
https://archives.pdx.edu/ds/psu/40981
Citation Details
Zhang, Y., Luo, W., Heinricher, M. M., & Ryabinin, A. E. (2023). CFA‐treated mice induce hyperalgesia in healthy mice via an olfactory mechanism. European Journal of Pain.