# Inhaled molecular hydrogen attenuates intense acute exercise-induced hippocampal inflammation in sedentary rats.
> 激しい急性運動による海馬炎症に対する吸入水素ガスの抑制効果：非運動習慣ラットを用いた検討


## Abstract

This study examined whether inhaled molecular hydrogen (2% H2) modulates hippocampal inflammation and oxidative stress in sedentary rats subjected to intense acute treadmill exercise. Animals ran in a sealed chamber while breathing either 2% H2 or a control gas mixture. Hippocampal tissue was collected immediately and 3 hours post-exercise. Exercise elevated TNF-α, IL-6, and IL-10 immediately after the session, with no change in IL-1β. H2 inhalation suppressed the exercise-induced rises in TNF-α and IL-6 while further amplifying the IL-10 response. Oxidative stress markers—SOD activity, TBARS, and NOx—were unaffected by either exercise or H2. All measured parameters returned to baseline levels by 3 hours post-exercise. These findings indicate that H2 exerts anti-inflammatory effects in the hippocampus by downregulating pro-inflammatory cytokines and upregulating anti-inflammatory cytokine production, without altering local oxidative stress status.

### Mechanism

H2 inhalation reduces exercise-induced hippocampal inflammation by suppressing pro-inflammatory cytokines TNF-α and IL-6 while simultaneously enhancing the anti-inflammatory cytokine IL-10, without altering oxidative stress markers such as SOD, TBARS, or NOx.

## Bibliographic

- **Authors**: Nogueira JE, de Deus JL, Amorim MR, Batalhão ME, Leão RM, Carnio EC, et al.
- **Journal**: Neurosci Lett
- **Year**: 2020 (2020-01-10)
- **PMID**: [31715290](https://pubmed.ncbi.nlm.nih.gov/31715290/)
- **DOI**: [10.1016/j.neulet.2019.134577](https://doi.org/10.1016/j.neulet.2019.134577)
- **Study type**: animal study
- **Delivery route**: inhalation
- **Effect reported**: positive
- **H2 concentration**: 2%

## Delivery context

For inhalation applications of molecular hydrogen, the lower flammability limit (LFL) deserves careful handling. The classical 4% figure applies to closed-system mixtures; the practical inhalation-environment threshold is 10%. Even pure-hydrogen output (the UFL 75% paradox) passes through the flammable range at the air–gas boundary. High-concentration (66% / 100%) inhalers are documented in the Japanese Consumer Affairs Agency accident-information database and are not recommended.

## Safety notes

For inhalation applications of molecular hydrogen, the lower flammability limit (LFL) deserves careful handling. The classical 4% figure applies to closed-system mixtures; the practical inhalation-environment threshold is 10%. Even pure-hydrogen output (the UFL 75% paradox) passes through the flammable range at the air–gas boundary. High-concentration (66% / 100%) inhalers are documented in the Japanese Consumer Affairs Agency accident-information database and are not recommended.

See also:
- [Inhalation concentration and LFL / UFL](https://h2-papers.org/en/safety-notes/inhalation-concentration)
- [Consumer Affairs Agency accident cases](https://h2-papers.org/en/safety-notes/accident-cases)
- [LFL / UFL terminology](https://h2-papers.org/en/safety-notes/lfl-ufl-explained)
- [Inhalation safety threshold lineage](https://h2-papers.org/en/safety-notes/lineage)

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> **Cite as**: H2 Papers — PMID 31715290. https://h2-papers.org/en/papers/31715290
> **Source**: PubMed PMID [31715290](https://pubmed.ncbi.nlm.nih.gov/31715290/)