Neuroprotective and Preventative Effects of Molecular Hydrogen.

One of the beneficial effects of molecular hydrogen (H, hydrogen gas) is neuroprotection and prevention of neurological disorders. It is important and useful if taking H every day can prevent or ameliorate the progression of neurodegenerative disorders, such as Parkinson's disease or Alzheimer's disease, both lacking specific therapeutic drugs. There are several mechanisms of how H protects neuronal damage. Anti-oxidative, anti-inflammatory, and the regulation of the endocrine system via stomach-brain connection seem to play an important role. At the cellular and tissue level, H appears to prevent the production of reactive oxygen species (ROS), and not only hydroxy radical (•OH) but also superoxide. In Parkinson's disease model mice, chronic intake of H causes the release of ghrelin from the stomach. In Alzheimer's disease model mice, sex-different neuroprotection is observed by chronic intake of H. In female mice, declines of estrogen and estrogen receptor-β (ERβ) are prevented by H, upregulating brain-derived neurotrophic factor (BDNF) and its receptor, tyrosine kinase receptor B (TrkB). The question of how drinking H upregulates the release of ghrelin or attenuates the decline of estrogen remains to be investigated and the mechanism of how H modulates endocrine systems and the fundamental question of what or where is the target of H needs to be elucidated for a better understanding of the effects of H.