| Selenium, an essential trace element, plays a very important role in health protection and diseases survival. But it is not well-distributed in earth. More than 70% areas of all worlds are lack of selenium. It is almost impossible to increase selenium intake by eating certain types of food because most common foods have very low selenium content. So exploiting the selenium-enriched foods is very important. In addition, amounts of trials have verified that selenium has curative effects on many diseases especially on cancer prevention.Reviewed the progress in basic research of selenium and cancer prevention during the past decade, we found some traits as follows: l)Selenium has a dose-dependent response, functions as an essential micronutrient at low level in the animal diet. But it becomes a toxicant at levels of 70 g(Se)/kg(body weight), selenium deficiency can cause many diseases; 2) Chemical forms of selenium are closely connected with its physiologies. But the biochemistry mechanism of selenium is not clear in present, suggest it might be connected with the following: ant oxidation , gene mutation prevention , toxinicidation inhibition of cell growth , immunological defense and inhibition of excess expression of thioredoxin reductase in cancer cell of human body. According to the earlier achievements and our practice, we designed this project to study the physiologies and anticarcinogenic activities of soybean selenoprotein.In this trial, the low selenium-containing fodder (bought from keshan county of Hei Longjiang, Se<0.01mg/kg) was used as control diet, Kunming mice (average weight 18-20g,half was male) were divided into 5 groups. The pharmacological tests on soybean selenoprotein were conducted in Kunming mice by feeding control diet that was supplemented with selenium-enriched soybean selenoprotein to provide selenium at level of <0. 01 g/kg> 22.5 g/kg, 67.5 g/kg, 202.5 g/kg, 607.5 g/kg respectively. Body weights of mice were measured in all period. After 3 weeks, 5 mice in every groups were sacrificed and various tissues of mice (blood and liver )were collected to determine the activities of Se-Containing enzymes(GPx), the activities of SOD and the content of LPO. We also measured the immunological defense of mice by detecting the weight of thymus and spleenand the amount of seucocyte. Others were inoculated with tumour Si go- continually feeding for 2 weeks. Then 5 mice in every groups were killed and several of tissue were collected to determine the tumour weight, other data were determined as former. The remainder was fed continually to detect the mortality.15 mice were inoculated with tumour S180 after feeding control diet for 20d, and then soybean selenoprotein at level of 202.5 g/kg was supplemented to determine the curative effects of soybean selenoprotein.General results can be concluded as follows: 1) The activities of GPx in serum, Gpx in liver were increased and the content of LPO were decreased by feeding soybean selenoprotein for 3 weeks. The immunological defense power also was enhanced with the increasing of soybean selenoprotein supplement under the level of 202.5Mg/kg. But the activities of GPx in serum were decreased and the contents of LPO in liver were increased when selenoprotein has been supplemented at level of 607.5 g/kg. These changes might be used as early biochemical parameters for chronic selenium intoxication; 2) A dose-dependent cancer protective effect was expressed in rang of 22.5-202.5 g/kg Se of soybean selemoprotein in the diet. Soybean selenoprotein could postpone the death of carcinoma mice. Total tumour yield was consistently reduced by 78% with 202.5 g/kg supplementation; 3) An increased power of antioxidation and immunological defense might represent a mechanism of tumour suppression by soybean selenoprotein; 4) The effects of soybean protein on mice growth was expressed before 3 weeks, The highest dosage (607.5 g/kg) inhibited the growth of mice. But after 5 weeks, this appearance wasn't found. 5) No any abnormal response was noticed during all...
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