Dietary selenium influences pancreatic tissue levels of selenoprotein W in chickens.

Selenium (Se) influences the levels of selenoprotein W (SelW) in mammals. However, little is known about the pattern of SelW expression in the pancreatic tissue of birds. To investigate the effects of dietary Se levels on the expression of SelW mRNA in the pancreatic tissue of birds, one-day-old chickens were randomly allocated to three groups. The L group was fed a basal diet deficient in Se (containing 0.033mg/kg Se); the M and H groups were fed Se-supplemented diets with either 0.15 or 1.5mg/kg Se, respectively (as sodium selenite) for 55days. The pancreatic tissue was collected and examined for Se content and mRNA levels of SelW at 15, 25, 35, 45 and 55days old. In the H group, a significant increase (P<0.05) in mRNA levels of SelW was observed. When the chickens were fed a Se-deficient basal diet, the abundance of SelW mRNA significantly decreased (P<0.05) during the sampling period. In this study, two enzymes were also examined, namely, selenocysteine-tRNA([Ser]Sec) synthase (SecS) and selenophosphate synthetase 1 (SPS1). The mRNA levels of two factors were slightly enhanced in the Se-supplemented groups, and a Se-deficient diet down regulated the mRNA expression of SecS. These data indicate that SelW is expressed in the pancreatic tissue of birds and that the transcription of the SelW gene is very sensitive to dietary Se. Se also has an effect on the mRNA levels of SecS, but has a little effect on SPS1 in this study.