| Cold stress is the most common stress factor to the animals in the cold region. Studies have demonstrated that cold stress could affect the health and welfare of animals. Low temperature can increase the free fatty acids and trioxypurine levels in serum, decrease the level of blood glucose and enhance the lipid metabolism in poultry. Immune response and metabolic regulation have highly unity and functional interdependence. During cold stress large amounts of body energy is used for anabolic, however the energy to protect the supply of immune and inflammatory activation reduced, which is related to metabolic inflammation. In this study, coding sequences of PPARa and AMPKa were cloned by the methods of molecular biology. As the experimental animals, chickens were treated with acute and chronic cold stress (12±1℃) to investigate the effect of cold stress on lipid metabolism and inflammatory factors in chicken liver. Biochemical indicator in serum, the expression and content of adiponectin, PPARα, AMPKα and lipid metabolism-related genes in liver, and the expression of inflammation-related and HSP genes in liver were detected. The results showed as follows:1. Fusion proteins of PPARα and AMPKα were expressed in prokaryotic system. The polyclonal antibodies were prepared by using expressed fusion proteins.2. Acute and chronic cold stress could influence the content of FFA, TG, GHO, LDL, HDL and the activity of ALT in serum. It indicated that cold stress could accelerate fat dissolution to provide the energy for the body. It also indicated that cold stress could cause liver damage.3. Acute and chronic cold stress could increase the adiponectin and its receptors’ mRNA expression and concentration in liver. It indicated that cold stress might change the liver lipid metabolism through adiponectin pathway in chickens.4. Acute and chronic cold stress could increase the expression of PPARα, AMPKα protein in liver, increase the concentration of AMPKα1, AMPKα2, CPT1, ACAO and decrease the concentration of ACC, malonyl CoA in liver, increase the expression of PPARα, LXRα, AMPKα1, AMPKα2, CPT1mRNA and decrease the expression of ACC mRNA in liver. It indicated that cold stress might change the liver lipid metabolism through adiponectin-PPARα-AMPKα pathway in chickens.5. Acute and chronic cold stress could increase the expression of PGE synthase, Cox-2, NF-κB protein and the expression of PGE synthase, Cox-2, NF-κB, TNFα, iNOS, HO-1mRNA in liver. It indicated that these genes might be involved in the process of liver inflammation of chicken caused by cold stress.6. Acute and chronic cold stress could increase the HSP70and GRP78’ mRNA and protein expression and we first verified that acute and chronic cold stress could increase the HSP60and HSP90’ mRNA expression. It indicated that organism could resistance to the damage in chicken’s liver through HSP pathway caused by cold stress.In present study, it indicated that cold stress could change the liver lipid metabolism through adiponectin-PPARα-AMPKα pathway and increase the activity of ALT in chickens. It also clarified that cold stress could increase the expression of PGE synthase, Cox-2, NF-kB, TNFα, iNOS, HO-1gene and HSP gene and the expression of HSP70, GRP78, HSP60, HSP90. It indicated that cold stress could cause lipid metabolism disorders, liver damage and accompanied with increasing in inflammation-related genes and heat shock protein gene. This study provides theoretical basis and experimental evidence for exploring the mechanisms of chicken metabolic inflammation caused by cold stress. |
