Effect Of Taurine On Cholesterol Metabolism In FLHS Laying Hens

FLHS is a metabolic disease involving multiple systems,which is mainly manifested by decreased egg production,decreased production performance,and increased mortality in laying hens.It will cause serious economic losses and seriously affect the development of layer breeding industry.Taurine is a free amino acid present in the body and has a wide range of biological effects.The previous research of the research group showed that taurine can effectively improve the liver lipid metabolism in rats with NAFLD,and has the effect of protecting the liver.In this experiment,the FLHS model of laying hens was constructed and taurine was added to the diet to explore the effect of taurine on cholesterol metabolism in FLHS laying hens and its regulation of lipid metabolism,and clarify the mechanism of taurine regulating cholesterol metabolism,in order to provide a theoretical basis for the application of taurine to prevent FLHS.Method: 180 highland brown laying hens with the age of 300 days were selected,and were randomly divided into 5 groups: Normal control group(C),Taurine control group(T),FLHS model group(M),Taurine Ⅰ preventive group(MT1)and Taurine Ⅱ preventive group(MT2).Laying hens in groups C and T were fed soy-corn-type basal diets,while laying hens in groups M,MT1 and MT2 were fed high-fat and low-protein diets.The MT1 group’s diet was supplemented with 0.02% taurine,and the T and MT2 group’s diets were supplemented with 0.05% taurine.After 24 weeks of testing,blood,liver,terminal ileum,intestinal contents and feces were collected.Prepare paraffin sections and frozen sections,observe histopathological changes with HE staining and Oil Red O staining;detect the activity of ALT and AST in serum;TG,TC,HDL-C and LDL-C content in serum and liver tissue;extract total RNA from liver tissue and ileum tissue,and use RT-PCR to detect the key factors of cholesterol synthesis(HMGCR)and key factors of cholesterol transport(ABCA1,ACAT2,LDLR),bile acid synthesis key factors(CYP7A1,CYP7B1),bile acid transport key factors(BSEP,MRP2,NTCP),bile acid receptor pathway key factors(FXR,SHP,FGFR4,β-klotho and PXR),the m RNA expression of key factors of the ileal bile acid transport receptor(ASBT,OSTα,OSTβ,OATP1 and IBABP).Results:(1)Taurine can significantly improve the structural damage of liver tissue caused by FLHS,reduce the accumulation of lipid droplets in liver cells,and significantly reduce liver index(p<0.01)and blood ALT and AST levels(p<0.05);(2)Taurine can reduce the content of TC,TG,LDL-C in liver tissue and serum(p<0.01),and increase the content of HDL-C(p<0.01);(3)Taurine can also up-regulate the m RNA expression of liver of ABCA1(p<0.01),and down-regulate the m RNA expression of HMGCR,ACAT2 and LDLR(p<0.01);(4)Taurine can up-regulate the m RNA expression levels of CYP7A1,BSEP,MRP2,FGFR4,β-Klotho,FXR,SHP in liver tissue and the m RNA expression levels of FXR,PXR and FXR in the ileum tissues,it also decreased the m RNA expression of CYP7B1 and NTCP in the liver tissues,and the m RNA expression levels of OSTα,OSTβ,ASBT,IBABPand OATP1 in the ileum tissues(P < 0.05).The results of this experiment show that taurine can Inhibit cholesterol deposition in the body in FLHS laying hens.The mechanism may be through inhibiting liver cholesterol synthesis,promoting its transport and conversion,and then regulating the metabolism of cholesterol in the liver.