# The effect of hydrogen gas on a mouse bilateral common carotid artery occlusion.
> マウス両側総頸動脈閉塞モデルにおける水素ガス吸入の効果


## Abstract

Male C57BL/6J mice underwent transient bilateral common carotid artery occlusion (BCCAO) using a nontraumatic aneurysm clip and were assigned to sham, BCCAO, or BCCAO plus 1.3% hydrogen gas inhalation groups. Cerebral blood flow in both cortical hemispheres was monitored continuously via laser Doppler perfusion imaging, and vital signs were recorded throughout. At 24 hours post-ischemia, oxidative stress was quantified by 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels, neuronal damage in the hippocampal CA1 region was histologically assessed, and brain water content was measured. Hydrogen gas administration did not alter vital signs or cerebral blood flow. Nevertheless, 8-OHdG expression was reduced, hippocampal CA1 neuronal injury was diminished, and brain edema was attenuated in hydrogen-treated animals, suggesting a neuroprotective role for hydrogen gas in this ischemia model.

### Mechanism

Hydrogen gas is proposed to selectively scavenge hydroxyl radicals, thereby reducing oxidative DNA damage (8-OHdG), attenuating hippocampal CA1 neuronal injury, and limiting cerebral edema following bilateral carotid occlusion.

## Bibliographic

- **Authors**: Nagatani K, Takeuchi S, Kobayashi H, Otani N, Wada K, Fujita M, et al.
- **Journal**: Acta Neurochir Suppl
- **Year**: 2013
- **PMID**: [23564105](https://pubmed.ncbi.nlm.nih.gov/23564105/)
- **DOI**: [10.1007/978-3-7091-1434-6_10](https://doi.org/10.1007/978-3-7091-1434-6_10)
- **Study type**: animal study
- **Delivery route**: inhalation
- **Effect reported**: positive
- **H2 concentration**: 1.3%

## 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 23564105. https://h2-papers.org/en/papers/23564105
> **Source**: PubMed PMID [23564105](https://pubmed.ncbi.nlm.nih.gov/23564105/)