Abstract: Objective: To investigate the influence of Ginkgo biloba L. extract(GBE) in the expressions of oxidative damage-related proteins in the spleen tissue of the mice with radiation damage, and to clarify its mechanism.Methods: Sixty ICR mice were randomly divided into normal control (NC) group, irradiation control (IC) group(4.0 Gyγ-ray radiation), low dose of GBE (IC+GBEL) group(4.0 Gyγ-ray+5.0mg·kg^-1 GBE), medium dose of GBE (IC+GBEM) group(4.0 Gyγ-ray+10.0mg·kg^-1 GBE) and high dose of GBE (IC+GBEH) group(4.0 Gyγ-ray+20.0mg·kg^-1 GBE)(n=12). After continuous administration of GBE for 14 d, all mice received the whole body radiation of γ-ray with the total dose of 4.0 Gy on the 15th day except for the mice in NC group. The levels of malonaldehyde (MDA), the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-px) in the spleen tissue of the mice in various groups were measured by biochemical method 24 h after radiation. The expression levels of 8-hydroxy-2 deoxyguanosine (8-OHdG) in the spleen tissue of the mice in various groups were examined by immunohistochemistry. The activities of protein kinase C(PKC) in the spleen tissue of the mice in various groups were detected by ELISA.Results: Compared with NC group, the levels of MDA and 8-OHdG in the spleen tissue of the mice in IC and different doses of GBE groups were significantly increased(P<0.05), and the activities of SOD, CAT, GSH-px and PKC were significantly decreased(P<0.05). Compared with IC group, the levels of MDA and 8-OHdG in the spleen tissue of the mice in different doses of GBE groups were significantly decreased(P<0.05), and the activities of SOD, CAT, GSH-px and PKC were significantly increased(P<0.05).Conclusion: GBE can inhibit the oxidative stress and regulate the PKC activity in the spleen tissue of the mice with irradiation damage to play a protective role against the radiation damage.

Key words: Ginkgo biloba L. extract, ionizing radiation, oxidative stress, protein kinase C