Preventive Effects Of Soybean Isoflavones On Radiation Damage And The Mechanism Involved

As a non-special stimulator, radiation can damage the organs and systems of body, and the immune and hematogenic systems are the two most radiation-sensitive systems. Radiation can produce large quantity of free radicals in these tissues and damage their structures and functions.Soybean isoflavones is a sort of polyphenol compound with various biological functions, including clear away the free radicals, inhibit the lipid peroxidation and enhance the activities of antioxidase, so it can protect celluar components from oxidative damage. Based on the biological functions of the soybean isoflavones we hypothesis it has some anti-radiation effects, though there is no any experiment report on it.The object of this paper is to study the preventive effects of the soybean isoflavones on radiation damage and its possible mechanism. 137Cs was used as a radiation source and the mice were exposed to 137Cs rays (4Gy or 8Gy) with the whole body to establish the animal model of radiation damage. The soybean isoflavones was added to the feedstuffs of mice, and its influence on the 30th day survival rate and the antioxidant, immune and hematogenic systems in mice were investigated .The main results of the study are as follows:(1) Soybean isoflavones supplementation could raise the 30th days survival rate of mice exposed to radiation, and minimize the increasing degree of MDA and the decreasing degree of the activities of SOD and GSH-Px in serum and tissues.(2) The influence of radiation on the thymus index and spleen index could be alleviated by soybean isoflavones supplementation,and the apoptosis rate of thymocytes and splenocytes induced by radiation also could be decreased significantly. The soybean isoflavones supplementation could ameliorate the effects of radiation on cell cycles of thymocytes and splenocytes by decreased the G1 phase arrest and increased thepercentages of G2 and S phase cells, and obviously promote the proliferation of immune cells. The effects of soybean isoflavones on cell apoptosis and cell cycles were coincident.(3) Soybean isoflavones supplementation could raise the expression of CD3+, CD4+, CD4+/CD8+ of peripheral blood cell and CD3+, CD4+/CDg+ of splenocyte and thymocytes, and promote the T cell signal transduction and maturity of thymocytes, enhance immune function.(4) Soybean isoflavones supplementation could decrease the influence of radiation on the apoptosis rate and cell cycle of bone marrow cells, decrease the G1 phase arrest and elevate the percentages of G2 and S phase cells, obviously promote the proliferation of bone marrow cells. Soybean isoflavones supplementation also could increase the quantity of marrow nucleate cells and recover the peripheral hemogram.The aforesaid experiment results suggest that soybean isoflavones can raise survival rate of mice suffered by radiation, enhance the antioxidant ability of body, obviously strengthen the anti-radiation ability of the immune system, and alleviate the radiation damage effects on hematogenic system. So we can conclude that the soybean isoflavones has some preventive effects on mice exposed to radiation and may be a good anti-radiation food functional factor.