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Molecular hydrogen (H2) has been previously reported playing an important role in ameliorating damage caused by acute radiation. In this study, we investigated the effects ofH2on the alterations induced by low-dose long-term radiation (LDLTR). All the mice in hydrogen-treated or radiation-only groups received 0.1 Gy, 0.5 Gy, 1.0 Gy, and 2.0 Gy whole-body gamma radiation, respectively. After the last time of radiation exposure, all the mice were employed for the determination of the body mass (BM) observation, forced swim test (FST), the open field test (OFT), the chromosome aberration (CA), the peripheral blood cells parameters analysis, the sperm abnormality (SA), the lymphocyte transformation test (LTT), and the histopathological studies. And significant differences between the treatment group and the radiation-only groups were observed, showing thatH2could diminish the detriment induced by LDLTR and suggesting the protective efficacy ofH2in multiple systems in mice against LDLTR.

Background/Aims: As a major complication after thoracic radiotherapy, radiation-induced lung injury (RILI) has great impact on long term quality of life and could result in fatal respiratory insufficiency The present study was aimed to evaluate the effects of Myrtol standardized on RILI, and to investigate the underlying mechanism. Methods: A mouse model of radiation-induced lung injury was generated by using thoracic irradiation with a single dose of 16Gy. Mice were orally administrated with Myrtol (25 mg/kg/day) for 4 weeks after irradiation, while prednisone (5 mg/kg/day) was used as a positive control. After then, the body weight and lung coefficient were calculated. The severity of fibrosis was evaluated by observing pulmonary sections after radiation and collagen content in lung tissues was calculated following the hydroxyproline (HYP) assay. Pathological changes were observed in all the groups by using HE staining and Masson staining. The serum levels of TGF-β1, TNF-α, IL-1β, IL-6, and PGE2 were also measured with an ELISA assay. Western blot assay was used to measure the impact of Myrtol on AKT and its downstream signaling pathway, including MMP-2 and MMP-9. The levels of Vimentin and α-SMA were evaluated with an immunofluorescence assay. Results: Treatment with Myrtol standardized, but not prednisone, reduced lung coefficient and collagen deposition in lung tissues, while attenuated histological damages induced by irradiation. Myrtol standardized also reduced the production of MDA, while increased the level of SOD. It was also observed that Myrtol standardized inhibited TGF-β1 and a series of pro-inflammatory cytokines including TNF-α, IL-1β, IL-6, PGE2. While in prednisone group, even though the early pneumonitis was ameliorated, the collagen disposition remained unchanged in latter times. Immunofluorescence analysis also revealed elevation of vimentin and α-SMA in the alveoli after a single dose of 16Gy. Conclusion: The present results suggest Myrtol standardized as an effective agent for attenuating the lung injury induced by irradiation.