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Hydrogen gas ameliorates oxidative stress in early brain injury after subarachnoid hemorrhage in rats.

クモ膜下出血後の早期脳損傷におけるラットへの水素ガス吸入による酸化ストレス軽減効果

animal study inhalation positive 2.9%

Abstract

This controlled animal study examined the effects of hydrogen gas inhalation on early brain injury in a rat subarachnoid hemorrhage (SAH) model induced by endovascular perforation. A total of 137 adult male Sprague-Dawley rats (280–350 g) received 2.9% H2 gas for 2 hours post-perforation. At 24 hours, H2 inhalation significantly reduced brain edema, attenuated blood-brain barrier disruption, decreased apoptosis, and improved neurological function. Oxidative damage markers—malondialdehyde (lipid), nitrotyrosine (protein), and 8-hydroxyguanosine (DNA)—were all reduced at 24 hours. However, these beneficial effects were not sustained at 72 hours. The findings indicate that the neuroprotective action of H2 in early SAH-related brain injury is primarily mediated through its antioxidative properties.

Mechanism

H2 gas scavenges reactive oxygen species, reducing oxidative damage to lipids (malondialdehyde), proteins (nitrotyrosine), and DNA (8-hydroxyguanosine), thereby suppressing apoptosis and preserving blood-brain barrier integrity to confer neuroprotection after SAH.

Bibliographic

Authors
Zhan Y, Chen C, Suzuki H, Hu Q, Zhi X, Zhang JH
Journal
Crit Care Med
Year
2012
PMID
22336722
DOI
10.1097/CCM.0b013e31823da96d
PMC
PMC4373315

Tags

Delivery:inhalation delivery (196) Mechanism:apoptosis regulation (280) hydroxyl radical scavenging (352) anti-inflammatory (743) lipid peroxidation (238) oxidative stress (899) reactive oxygen species (774)

Delivery context

In air, molecular hydrogen is reported to be combustible across approximately **4% (LFL, lower flammability limit) to 75% (UFL, upper flammability limit)**. Among high-concentration hydrogen inhalers, 66% output sits inside this range, and even pure-hydrogen (100%) output forms a 4–75% concentration-gradient layer at the device–air boundary (the UFL 75% paradox). Engineering principle would therefore call for operation below LFL (the classical 4%); that figure, however, was measured under closed, pre-mixed, static conditions. For the open, dynamic inhalation environment, the empirical value reported in the literature is **10%**, which is the figure referenced in practice as the operating ceiling. The 66% / 100% output devices are recorded in the Japanese Consumer Affairs Agency accident-information database, and from these considerations are not recommended.

→ Evidence by delivery route

Safety notes

In air, molecular hydrogen is reported to be combustible across approximately **4% (LFL, lower flammability limit) to 75% (UFL, upper flammability limit)**. Among high-concentration hydrogen inhalers, 66% output sits inside this range, and even pure-hydrogen (100%) output forms a 4–75% concentration-gradient layer at the device–air boundary (the UFL 75% paradox). Engineering principle would therefore call for operation below LFL (the classical 4%); that figure, however, was measured under closed, pre-mixed, static conditions. For the open, dynamic inhalation environment, the empirical value reported in the literature is **10%**, which is the figure referenced in practice as the operating ceiling. The 66% / 100% output devices are recorded in the Japanese Consumer Affairs Agency accident-information database, and from these considerations are not recommended.

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