H-induced transient upregulation of phospholipids with suppression of energy metabolism.

Molecular hydrogen (H) is an antioxidant and anti-inflammatory agent; however, the molecular mechanisms underlying its biological effects are largely unknown. Similar to other gaseous molecules such as inhalation anesthetics, H is more soluble in lipids than in water. A recent study demonstrated that H reduces radical polymerization-induced cellular damage by suppressing fatty acid peroxidation and membrane permeability. Thus, we sought to examine the effects of short exposure to H on lipid composition and associated physiological changes in SH-SY5Y neuroblastoma cells. We analyzed cells by liquid chromatography-high-resolution mass spectrometry to define changes in lipid components. Lipid class analysis of cells exposed to H for 1 hour revealed transient increases in glycerophospholipids including phosphatidylethanolamine, phosphatidylinositol, and cardiolipin. Metabolomic analysis also showed that H exposure for 1 hour transiently suppressed overall energy metabolism accompanied by a decrease in glutathione. We further observed alterations to endosomal morphology by staining with specific antibodies. Endosomal transport of cholera toxin B to recycling endosomes localized around the Golgi body was delayed in H-exposed cells. We speculate that H-induced modification of lipid composition depresses energy production and endosomal transport concomitant with enhancement of oxidative stress, which transiently stimulates stress response pathways to protect cells.