[Preventive effect of TJ-48 on recovery from radiation injury].

Effects of Juzen-taiho-toh (TJ-48) on the recovery of haemopoietic systems from radiation injury are analyzed. Female C57BL/6 mice (6 to 8 week-old) were irradiated at doses of 0, 1, 2, 3, 5 or 7 Gy from a 60Co source. During the 7 days after irradiation, the mice were given TJ-48 solution (1.25g in 100ml distilled water). Seven days after irradiation, the mice were sacrificed, and cell counts of bone marrow (both femurs), thymus, spleen, and peripheral blood were made. The bone marrow cells were used for CFU-f, CFU-GM, BFU-E, and CFU-E assays. No difference were observed between the experimental and control groups. However, the CFU-S. d14 and CFU-S.d9 counts in the TJ-48-treated groups were greater than the respective values in the control groups, especially in the low-dose range of irradiation (1, 2, 3 Gy). In the assay for CFU-S.d14, the mice injected with TJ-48-treated bone marrow cells showed better general condition, heavier spleens with larger and more numerous colonies than the control mice. There was no difference in the number of CFU-f between TJ-48-treated and control groups. Since the CFU-S.d14 assay is thought to reflect the most primitive progenitor cells in the haemopoietic system, these results strongly suggest that TJ-48 acts on stem cells in the G0 phase to manifest recovery-enhancing effects from radiation injury.