Molecular hydrogen increases resilience to stress in mice.
水素ガス吸入がマウスのストレス耐性に与える影響：うつ・不安様行動および神経内分泌応答の検討
Abstract
Failure to adapt to stress can precipitate depressive and anxiety disorders. This animal study examined whether repeated inhalation of a hydrogen-oxygen mixed gas (67% H2 : 33% O2 by volume) could modify stress-related behavioral and neuroendocrine responses in mice. Across multiple behavioral assays—tail suspension, forced swimming, novelty-suppressed feeding, and open-field tests—hydrogen-oxygen inhalation significantly reduced both acute and chronic mild stress (CMS)-induced depressive- and anxiety-like behaviors. ELISA measurements revealed that the gas mixture prevented CMS-associated rises in serum corticosterone, adrenocorticotropic hormone, interleukin-6, and tumor necrosis factor-α. Notably, hydrogen exposure during adolescence produced lasting improvements in stress resilience that persisted into early adulthood. The authors propose that suppression of hypothalamic-pituitary-adrenal axis hyperactivation and attenuation of inflammatory signaling underlie these effects.
Mechanism
Hydrogen gas is proposed to enhance stress resilience by suppressing hypothalamic-pituitary-adrenal axis hyperactivation and reducing pro-inflammatory cytokine levels (IL-6 and TNF-α), thereby dampening both neuroendocrine and inflammatory responses to stress.
Bibliographic
- Authors
- Gao Q, Song H, Wang X, Liang Y, Xi YJ, Gao Y, et al.
- Journal
- Sci Rep
- Year
- 2017 (2017-08-29)
- PMID
- 28852144
- DOI
- 10.1038/s41598-017-10362-6
- PMC
- PMC5575246
Tags
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.
Safety notes
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