Studies On Regulation Of Selenium Deficiency On SELW MRNA Expression And Mechanism Of Pancreatic Fibrosis In Chickens

Selenium (Se) is an important, biologically necessary trace element, which plays important biological roles in many kinds of animals, and human beings as well. In previous studies, Se exerts its biological effects mainly through its incorporation into selenoprotein. Selenoprotein W (SelW) is an important member of selenoprotein family. In avian, the pancreas is the most sensitive target organ when selenium deficiency happened, and this could cause denaturation, necrosis, atrophy and even fibrosis. The effect of selenium deficiency on chicken pancreas was early reported, but the reports were mainly focused on the aspect of pathohistology. Moreover, it had not been fully cleared that the pancreatic fibrosis mechanism of selenium deficiency-induced on the pancreas.In the study, selenium deficiency model was copyed. One-day-old chickens were randomly allocated to three groups. The L group was fed a basal diet deficient in Se (containing 0.033 mg/kg Se); the M and H groups were fed Se-supplemented diets with either 0.15 or 1.5 mg/kg Se, respectively (as sodium selenite) for 55 days. The pancreatic tissue was collected at 15, 25, 35, 45 and 55 days old respectively. Clinical symptoms, autopsy, microstructure and fibrosis-related index of pancreas-Hyp, fibrosis-related gene TβRⅠ, TβRⅡ, Smad3, MMP2, TIMP2 mRNA expression were detected. The fibrosis mechanism of selenium deficiency on pancreas was discussed. In this study, SelW and two enzymes were also examined by quantitative RT-PCR, namely, SecS and SPS-1.Elaborated the relationship between SelW and fibrosis, the results was displayed as follows:1. By the observation of clinical symptoms, autopsy, microstructure and the detection of Hyp contents, it proved that selenium deficiency could cause the pancreatic damage, and display on apoptosis, necrosis, atrophy, and fibrosis.2. By the detection of SelW, SecS and SPS1 mRNA levels, it showed that Se supplement and Se dificiency affected Se content and SelW, SecS, SPS1 mRNA expression of chicken pancreas within different day of age.In the H group, a increase in mRNA levels of SelW and Se contents were observed. When the chickens were fed a Se-deficient basal diet, the abundance of SelW mRNA significantly decreased during the sampling period. Se could affect SecS and SPS1 mRNA expression level, however, the regulation mechanism of the latter two gene on SelW expression need further research.3. By the detection expression level of TβRⅠ, TβRⅡ, Smad3 mRNA in pancreas, it discovered that selenium deficiency-induced pancreatic fibrosis could increase the expression levels of these genes. It indicated that TGF-β/Smad signaling pathways played an important role in the development of pancreatic fibrosis induced by selenium deficiency, It was one of mechanisms of pancreatic fibrosis induced by selemium deficiency in chicken.4. Selenium deficiency could affect the expression levels of MMP2, TIMP2. The mRNA levels of TIMP2 and MMP2 were slightly enhanced in the Selenium deficiency groups. It indicated that selenium deficiency could induce pancreatic fibrosis by increase TIMPs levels.5. By the Pearson correlation analyze between Whole blood Hyp, tissuse Hyp and the SelW mRNA expression level. Results show that a certain negative correlation between them.