Objective      To identify the radioprotective effect of an isoflavonids (T1)

three hydroxyl isoflavone (or genistein) on the hemopoietic system of male SD rats.     Methods      Sixty rats were weighed and randomly divided into 4 groups

control (5%DMSO was intraperitoneally injected at a dose of 10 mg/kg

once per day for 3 d)

radiation group (5% DMSO was intraperitoneally injected at a dose of 10 mg/kg

once per day for 3 d

and then 4.5 Gy

60

Co γ-ray irradiatio

n was given in 4 h after last injection)

T1 prevention group (intraperitoneal injection of T1 at a dose of 10 mg/kg was given once per day for 3 d

and then the irradiation was given as irradiation group)

and T1 treatment group (First intraperitoneal injection of T1 at a dose of 10 mg/kg was given in 4 h after irradiation

and then for another 2 d). The dynamic weight before and after irradiation and blood WBC count were measured for 4 consecutive weeks after irradiation. Then pathological changes in the bone marrow were observed in the first week and the fourth week after radiation. Antioxidase activity in the liver were measured by colorimetry in a week after radiation.     Results       Compared with control group

no significant weight loss was observed in the other 3 groups after radiation (P0.05). In 1

4 and 5 d after radiation

the blood WBC count in T1 preventive group and T1 treatment group were significantly higher than those in radiation group (P0.05)

and there was no significant difference between T1 preventive group and T1 treatment group. The blood WBC count in each group (except the control group) had no difference in 6 d after radiation (P0.05) among these groups. Bone marrow hematopoietic cells were decreased significantly with adipose tissue hyperplasia in radiation group in a week after radiation

while relatively minor damages were seen in T1 preventive group and T1 treatment group. Over 7 d after irradiation

MDA content of T1 prevention group were much lower than those in radiation group (4.06±0.19 vs 5.61±0.46

P0.05)

meanwhile

CAT and GSH-Px activities were much higher (P0.05)

respectively.     Conclusion       T1 can significantly slow down the descent speed of WBC after irradiation and bring forward the recovery time. In addition

T1 plays an important role in radiation protection against the hemopoietic damage

and its mechanism might be related to eliminating the excessive free radicals.