Abstract
Fibroblast growth factors (FGFs) have such important roles in numerous biological events such as angiogenesis, wound repair and so on, that they may also be able to protect intestine against radiation injuries. FGF receptor 2 IIIb (FGFR2b; KGFR) is a high-affinity receptor for FGF1, FGF7 and FGF10, which can be expressed only by epithelial cells. In this study, we demonstrated that total body irradiation of γ-ray induced the expression of KGFR transcripts in jejunum of Balb/c mice, although these transcripts were not detected until 16 hours after irradiation. In contrast, other FGFRs, which could react with FGF1, but not FGF7 and FGF10, were expressed in spite of irradiation. Intraperitoneal administration of FGF1, FGF7 or FGF10 at 24 hours before irradiation increased the crypt number at 3.5 days after irradiation. Especially, FGF1 induced the more crypt survival than FGF7 or FGF10. The number of apoptotic cells in crypts of jejunum was also lower in FGF1-treated mice than that in other FGF-treated mice at 16 hr after irradiation. In addition, FGF1 increased the LD50/6 of C3H mice. Moreover, the administration of each FGF at 24 hr after irradiation also increased the crypt number; however it did not show any significant difference in the level of increase among the FGF-treated mice. These findings suggest that FGF1 protects jejunum against the radiation-induced injuries more effectively than FGF7 and FGF10, because FGF1 could react with all other FGFRs except KGFR at an early phase of radiation exposure.
