| BackgroundRadiotherapy is an important method for cancer patient, and 70% cancer patients receive radiotherapy. However, the strong side effects such as nausea, vomiting and anorexia made many patients have to give up therapy. In addition, there are some people, for example, computer operator, usually exposed to low-dose radiation. Radiation has become the fourth pollution besides the pollution of water, air, and sound. Therefore, to strengthen the prevention of radiation or reduce the occurrence of radiation lesion is one of the most important topics.According to the free radicals theory of radiobiology, when radiation interacts with target atoms, energy is deposited, resulting in ionization or excitation, and then formation of free radical. Since the predominant molecule in biological systems is water, it is usually the intermediary of the radical formation and propagation. The production of reactive free radicals results in the damage of key molecule including antioxidant enzyme, and the balance between oxidant and antioxidant is destroyed which leading to oxidative stress. As the formation of free radicals is main reason of radiation lesion, its prevention and elimination is always an important problem.The previous study shows that soybean isoflavone (SI) has much biological function in anticancer, prevention of cardio-vascular disease and osteoporoses etc., these functions are all correlated with the antioxidant activity of SI in some degree. Its antioxidant activity could end chain reaction through the elimination of free radicals and induce activity of antioxidant enzyme. Wei H et al. found that genistein had protective effect against UV light. Considering both the energy and penetrability of X ray of yray are stronger than UV light, if SI can alleviate side-effect by enhancing the antioxidant and immune ability worth to be deep into studied.In present studies, we first observed the protective effects of SI in vivo, on the base of the radiation injury model; In order to investigate the mechanism of protectiveeffects of SI, secondly, we screened the differentially expressed genes by cDNA microarray and some of important genes were verified by RT-PCR. Finally, some unknown sequences were analyzed and identified by bioinformatics methods.Part I The radiation-protective effects of soybean isoflavone on miceAim To investigate the radiation-protective effect of soybean isoflavone. Methods 80 normal female KunMing mice were randomized into 5 groups equally based on body weight: low, medium, and high dose SI intervention groups, positive group(radiation group), and control group. The control group and positive groups were given 0.5%CMC-Na, and the three intervention groups were given different doses of soybean isoflavone (50, 100, 400mg/kg) respectively for 14 d continuously. The whole body of positive group and intervention groups were given 5.0 Gy 60Co- radiation one time at the 7th d, and then the mice were put to death at the 2nd d and the 7th d after radiation. The protective effect were observed from several aspects as follows: (1) antioxidant system: the activity and mRNA expression levels of antioxidant enzyme as well as the content of MDA were analyzed of liver tissue, the pathology change of liver were observed with HE staining; (2) the change of peripheral blood cells number after radiation were also obeserved; (3) immune system: spleen IOS of different group the 7th day after radiation were compared.Results (1) different doses of soybean isoflavone especially medium one could significantly induce CAT and GSH-Px activities at both early and later stage after radiation, while reduce MDA content of liver tissue significantly at later stage compared with positive group, this antioxidant effect were not dependent on dose. The CAT and GSH-Px mRNA expression levels of medium dose SI group were higher than that of positive group. The histological observation shows that the liver tissue lesion degree of soybean isoflavone groups were less than positive one, but the low and high dose group w... |
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