[摘要]：Our recent studies suggest that H-2 (hydrogen) has a potential as a novel radioprotector without known toxic side effects. The present study was designed to examine the underlying radioprotective mechanism of H-2 and its protective role on irradiated germ cells. Produced by the Fenton reaction and radiolysis of H2O, hydroxyl radicals ((OH)-O-center dot) were identified as the free radical species that were reduced by H-2. We used a H-2 microelectrode to dynamically detect H-2 concentration in vivo, and found H-2 significantly reduced in situ fluorescence intensity of hydroxyphenyl fluorescein; however, as we treated the mice with H-2 after irradiation, the decrease is not significant. We found that pre-treatment of H-2 to IR (ionizing radiation) significantly suppressed the reaction of (OH)-O-center dot and the cellular macromolecules which caused lipid peroxidation, protein carbonyl and oxidatively damaged DNA. The radioprotective effect of H-2 on male germ cells was supported by ameliorated apoptotic findings examined by morphological changes and TUNEL (terminal deoxynucleotidyltransferase-mediated dUTP nick-end labelling) in testicular tissue, and by preserved viability of stem spermatogonia examined for testicular histological parameters, daily sperm production and sperm quality; we used WR-2721 [S-2-(3-aminopropylamino)ethyl phosphorothioic acid] as a reference compound. Our results represent the first in vivo evidence in support of a radioprotective role of H-2 by neutralizing (OH)-O-center dot in irradiated tissue with no side effects.
