Objective    To study the effect of genistein on the hematopoiesis in irradiated mice.     Methods    Adult male BALB/c mice were administered orally with genistein (160 mg/kg) 24 h before whole body exposure to gamma irradiation at a sublethal dose of 6.0 Gy. On day 1

3

7

14

21 and 30 after irradiation injury

the hematopoiesis-stimulating and hematopoiesis-suppressing activities of the serum were determined by CFU-E and CFU-GM culture in vitro

respectively.     Results    The hematopoiesis-stimulating activities of serum enhanced distinctly in all irradiated groups. With genistein administration 24 h before irradiation

the hematopoiesis-stimulating activities of serum became enhanced

resulting in the increase of numbers of CFU-GM and CFU-E

as compared to those in only irradiated mice

and stimulating activities on CFU-GM were more enhanced than that on CFU-E. The hematopoiesis-suppressing activities of serum were decreased in genistein pre-treated mice

but showed no significant difference between CFU-GM and CFU-E.     Conclusion    Enhancing hematopoiesis-stimulating activity of serum in the irradiated mice may be one of the important mechanisms of genistein against irradiation-induced hematopoietic syndrome and accelerating restoration of hematopoiesis.