Katafuchi, Toshihiko, Kondo, Tetsuya, Take, Sachiko et al. · Annals of the New York Academy of Sciences · 2006 · DOI
This study investigated how the brain's immune system might cause fatigue by looking at what happens when rats are exposed to a viral-like trigger. Researchers found that certain immune molecules in the brain (interferons) increased while a key fatigue-related brain chemical (serotonin) decreased. When they gave the rats a medication that boosted serotonin activity, the fatigue improved, suggesting that low serotonin in a specific brain region may play a role in fatigue.
This mechanistic study provides preliminary evidence that brain cytokines and serotonin dysregulation—not just peripheral muscle fatigue—may underlie ME/CFS fatigue. If these findings translate to humans, they could explain why ME/CFS involves cognitive and mood symptoms alongside physical exhaustion, and might identify new therapeutic targets for treating central fatigue.
This study does not prove that these mechanisms cause human ME/CFS fatigue; it demonstrates association in an acute rat model triggered by a synthetic viral mimic. The poly I:C model induces short-term immune activation rather than chronic illness, so findings may not directly apply to the persistent, post-exertional nature of ME/CFS. Causality cannot be confirmed without additional intervention studies and human validation.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Katafuchi, Toshihiko, Kondo, Tetsuya, Take, Sachiko, & Yoshimura, Megumu (2006). Brain cytokines and the 5-HT system during poly I:C-induced fatigue.. Annals of the New York Academy of Sciences. https://doi.org/10.1196/annals.1366.020
BibTeX
@article{mecfsatlas-katafuchi-2006-brain-cytokines,
author = {Katafuchi, Toshihiko and Kondo, Tetsuya and Take, Sachiko and Yoshimura, Megumu},
title = {Brain cytokines and the 5-HT system during poly I:C-induced fatigue.},
journal = {Annals of the New York Academy of Sciences},
year = {2006},
doi = {10.1196/annals.1366.020},
note = {PubMed: 17192569},
url = {https://www.mecfsatlas.com/evidence/katafuchi-2006-brain-cytokines},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/katafuchi-2006-brain-cytokines
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