Abstract: OBJECTIVE: To investigate the influence of electronic beams on protein expression of the insulin growth factor system and to provide evidence for radiation-induced early damage in livers of mice. METHODS: Mice were irradiated with electron beam at of 0,1,2 and 4 Gy. At 12,48 and 72 h after irradiation,their livers were removed and used for analyses. Western blot was used to detect changes of protein expressions in insulin growth factor 1 receptor (IGF-1R),insulin growth factor binding protein 1 (IGFBP1),insulin growth factor binding protein 4 (IGFBP4),and insulin growth factor 1 (IGF-1). RESULTS: When the irradiation dose was 1 Gy,IGF-1 protein was highly expressed at 48 h after irradiation,and that for IGFBP1,IGFBP4 and IGF1R protein were at 12,48 and 72 h. When the irradiation dose was 2 Gy,IGF-1 and IGFBP4 proteins were up regulated at 48 h after irradiation,and they were down regulated for the rest of the time. IGFBP1 protein was up regulated at 12 h after irradiation,and it was down regulated at 48 h and 72 h. IGF1R protein was down regulated at three time points after irradiation. When the irradiation dose was 4 Gy,the expressions of IGF-1,IGFBP1,and IGFBP4 proteins was down regulated. IGF1R protein was up regulated at 12 h after irradiation,and it was down regulated at 48 and 72 h. CONCLUSION: Our results show that electron beam irradiation caused down-regulation on protein expression of the insulin growth factor-1 system in the liver of mice. Our results are consistent with those performed using PCR. Based on the study,expression of the insulin growth factor-1 system may be useful as a biomarker for radiation-induced liver injury.

Key words: electron beam, insulin-like growth factors, inbred BALB/c mice, Western blot