The Studies On The Damage Mechanism Of Selenium Deficiency On Chicken's Pancreas

Selenium deficiency can cause disease to many kinds of animals, and human beings as well, which happened in many countries in the world and caused serious damages. The selenium-deficient poultry often displyed exudative diathesis, pancreatic atrophy, trophicity pathological change of muscle and so on. The pancreas is the first affected and the most sensitive target organ when selenium deficiency happened in chicken, and this could cause denaturation, necrosis, atrophy and even fibrosis. The effect of selenium deficiency on pancreas was early reported, but the reports were fragmented and mainly focused on the aspect of pathohistology. Moreover, it had not been fully cleared that the damage mechanism of selenium on the pancreas.In the study, selenium deficiency disease model was copyed in chicken by feeding selenium content of 0.032 mg/kg of diet. The blood and pancreas of chicken were obtained in 30, 45, 60 and 75 days old, respectively. Clinical symptoms, autopsy, microstructure and ultrastructure were observed and antioxidant function, free radical content in pancreas and serum, endocrine secretion function of pancreas, apoptosis, fibrosis-related index of pancreas, the expression of PHGPx, TR1 and relative gene of apoptosis Caspase-3, Caspase-8, Fas, FasL mRNA in pancreas were detected. The damage mechanism of selenium deficiency on pancreas was discussed through studying the effects of selenium deficiency on pancreas in different times, which not only enrich the data of selenium-penia in chicken, but also provide a theoretical foundation of knowledge for the damage mechanism of pancreas.The results showed as follows:1. By the observation of clinical symptoms, autopsy, microstructure and ultrastructure of pancreas, it proved that selenium deficiency could cause the pancreatic damage, and display on apoptosis, necrosis, atrophy, but no fibrosis;2. By the detection of the content of insulin and C-peptide in pancreas and serum, it indicated that selenium deficiency not only induced the function of pancreatic exocrine to decline, but also damaged the function of endocrine cell of pancreatic islet;3. By the detection of antioxidative function and free radical content in pancreas and serum, it showed that selenium deficiency could decrease the activity of glutathion peroxidase (GSH-Px), superoxide dismutase (SOD), catalase (CAT), the content of reduced glutathione (GSH) and the inhibiting of OH·ability, reduce the expression level of PHGPx, and TR1 mRNA in pancreas, increase the contents of malonaldehyde (MDA), hydrogen dioxide (H2O2) and nitrogen monoxidum (NO). It proved that selenium deficiency could destroy the antioxidative defence system of organism and the function of scavenging free radical from molecular level and induce the oxidative stress in pancreas,. It was one of mechanisms of selemium deficiency on pancreatic damage;4. By the observation of microstructure and ultrastructure of pancreas, and the detection of the contents of hydroxyproline (Hyp), hyaluronic acid (HA), laminin (LN), it proved that the selenium-deficient chicken in this experiment didn't cause pancreatic fibrous degeneration. It may be related to the degree of low-selenium in diet by feeding;5. By the detection of the pancreatic cells apoptosis and expression level of Caspase-3, Caspase-8, Fas and FasL mRNA in pancreas, it discovered that selemium deficiency could induce the pancreatic cells apoptosis, increase the expression level of these genes. It indicated that apoptosis probably played an important role in the development of pancreatic damage induced by selenium deficiency, which was induced by the cascade reactions of Fas/FasL-mediated Caspase family. It was one of mechanisms of pancreatic atrophy induced by selemium deficiency in chicken.In a word, selenium deficiency could injure pancreatic tissue of chicken, then decline the exocrine and endocrine function of pancreas, affect the ability of antioxygen and the metabolism of free radical, induce the pancreatic cells apoptosis, alter mRNA expression of PHGPx, TR1, Caspase-3, Caspase-8, Fas and FasL in pancreas. All above showed that selenium deficiency through oxidative stress and apoptosis exert its effect on pancreatic injury, which maybe cause main mechanism of pancreatic damage induced by selemium deficiency. Whether or not other mechanisms exist in, it requires further study.