H₂ Papers

日本語 ・View as Markdown

Hydrogen restores central tryptophan and metabolite levels and maintains mitochondrial homeostasis to protect rats from chronic mild unpredictable stress damage.

水素吸入が慢性軽度予測不能ストレスラットにおけるトリプトファン代謝および脳内ミトコンドリア恒常性に与える影響

animal study inhalation positive 2–4%

Abstract

Forty Sprague-Dawley rats were randomly assigned to control, CUMS model, hydrogen inhalation, or positive drug groups. Following four weeks of stress modeling, 2–4% hydrogen gas was administered by inhalation. Behavioral tests, biochemical assays, and immunohistochemical analyses revealed that hydrogen inhalation reduced depressive-like behaviors and attenuated hippocampal neuronal injury in CUMS-exposed animals. Levels of monoamine neurotransmitters, tryptophan and its metabolites, inflammatory cytokines, and oxidative stress markers were restored toward control values. Additionally, mitochondrial homeostasis was preserved, accompanied by upregulation of PGC-1α, PINK1, and Parkin expression, suggesting activation of mitochondrial biogenesis and mitophagy pathways.

Mechanism

Hydrogen upregulates PGC-1α, PINK1, and Parkin to promote mitochondrial biogenesis and mitophagy, while simultaneously reducing oxidative stress and neuroinflammation, thereby protecting hippocampal neurons in CUMS-exposed rats.

Bibliographic

Authors
Li J, Hao G, Yan Y, Li M, Li G, Lu Z, et al.
Journal
Neurochem Int
Year
2025
PMID
39653185
DOI
10.1016/j.neuint.2024.105914

Tags

Disease:cognitive decline (111) depression / anxiety (34) Delivery:inhalation delivery (196) Mechanism:autophagy (32) anti-inflammatory (743) mitochondrial function (226) 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.

See also:

Other papers on the same disease / condition