H(2)-induced transient upregulation of phospholipids with suppression of energy metabolism

Molecular hydrogen (H(2)) 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(2) is more soluble in lipids than in water. A recent study demonstrated that H(2) 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(2) 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(2) for 1 hour revealed transient increases in glycerophospholipids including phosphatidylethanolamine, phosphatidylinositol, and cardiolipin. Metabolomic analysis also showed that H(2) 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(2)-exposed cells. We speculate that H(2)-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.