| Selenium has long been shown playing an important role in reducing oxidative stress. But there are very limited data on effects of different levels of dietary selenium concentrations on DM, especially on GDM. This feeding study was conducted to evaluate effects of different levels of dietary selenium concentrations on gestational insulin resistance. This was achieved by feeding rats three levels of dietary selenium, based on the se-deficient basal diet(BD), that were from High level (3mg/kg yeast selenium+BD, High), Medium level (0.3mg/kg yeast selenium+BD, Medium), to se-deficient level (BD, Low).7 selenoprotein genes'transcription level in pancreas was examined in order to identify the particular type(s) of selenoprotein that assocaiated with this process, based on the changes of their expression levels.Forty five 67d old female Wistar rats were divided into three test groups with 15 rats in each group. Each group was feed with the specified selenium diet as listed above. After 4 w on the diets, subgroups within each group were mated. During premating period (each group, n=15), mid trimester of pregnancy (High rats, n=9; Medium rats, n=10; Low rats, n=9), late pregnancy (High rats, n=9; Medium rats, n=10; Low rats, n=9) and two weeks after delivery (each group, n=7), the insulin level was monitored and insulin sensitivity index was obtained. At the end of experiment, rats were sacrificed in order to harvest the pancreas to measure mRNA abundance for 7 selenoprotein in pancreas using Real-time PCR.The group of rats fed with high level of dietary selenium have higher plasma insulin concentration compared with the group fed with medium level or selenium-deficient dietary (P<0.01), and they also displayed high insulin resistance (P<0.01) during late pregnancy. For the ipGTT analysis during late pregnancy, the high selenium feed rat group had much higher blood glucose concentration compared with the other two groups at 15 min,30 min and 60min after glucose injection (P<0.01), indicating that this group of rats developed glucose intolerance. By means of ITT, identifying this type of glucose intolerance was caused by insulin resistance, and this insulin resistance symptom didn't relieve two weeks after delivery when the monitering ended.For the 7 selenprotein genes tested, the mRNA abundance for 3 selenoprotein in pancrea s were different between three groups of rats, that were Gpxl, Gpx4 and Sepp. However, only Gpxl mRNA abundance varied in accordance with the levels of the dietary selenium (P<0.01). The Gpxl mRNA abundance in the high level selenium feed rats was 1.6 times compared with the normal level fed rats while the in turn, whose Gpxl mRNA abundance was about 6.4 times of selenium deficient feed rats.High level of selenium intake in rats will facilitate insulin resistance during gestation, and GDM was achieved in this study by feeding rats ten times of the normal does of selenium. mRNA abundance of Gpxl varys according to selenium intake during late pregancy, indicating that Gpxl may play a role in gestation insulin resistance.
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