Effect And Mechanism Of Lactobacillus Acidophilus On Liver Cholesterol Metabolism In Broilers

Lactobacillus acidophilus can regulate cholesterol levels,but the regulation mechanism is unclear.Most studies still use a single or a limited number of metabolic enzymes,proteins or genes to test,and most of them are based on in vitro tests and mouse tests.In this study,white feather broilers were used as a model,and the actual production of large-scale feeding mode was adopted to systematically study the cholesterol metabolism signaling pathway related genes and their regulatory networks to observe the effect of Lactobacillus acidophilus on the liver cholesterol metabolism of growing broiler chickens and the mechanism.The content and results of this research are as follows:60,000 1-day-old white-feather broilers were randomly divided into 3 groups,each with 8 repetitions,and 2500 per repetition.The control group was fed with a basic diet,and the experimental group was fed with a basic diet supplemented with 1‰(low dose group)),1.5‰(high-dose group)of Lactobacillus acidophilus.1 broiler chicken is randomly selected from each repeat of each group at the age of 20 and 40 days,that is,8 broilers are taken from each group.The body weight and liver weight of the broilers were measured,serum and liver samples were collected,and the serum and liver triglycerides were tested.Lipid and cholesterol content;Real-time PCR to detect the expression of liver cholesterol metabolism-related genes;Western blotting to detect the protein content of liver cholesterol metabolism regulatory factors and enzymes;use histone H3 acetylation(H3ac)antibody,histone H3K4 trimethylation(H3K4me3)antibody,histone Protein H3K9 monomethylated(H3K9me)antibody and histone H3K27 trimethylated(H3K27me3)antibody were used for chromatin immunoprecipitation to detect the acetylation and methylation modification of histone H3 in the promoter region of HMGCR gene.The results showed: 1.Compared with the control group,the 40-day-old high-and low-dose broiler chicken liver weight and liver index increased significantly(P < 0.01),but there was no difference in body weight;20-day-old high-dose group and 40-day-old low The serum triglyceride concentration in the dose group was significantly increased(P < 0.05),the serum triglyceride concentration in the 40-day-old high-dose group was extremely significantly increased(P < 0.01),and the 40-day-old high-and low-dose group had low serum density The lipoprotein cholesterol concentration was significantly reduced(P <0.01),and the liver cholesterol content in the 20-day-old low-dose group and 40-day-old high-dose group was significantly reduced(P < 0.05).2.In terms of related gene and protein expression,compared with the control group,the key enzyme of the alternative pathway of cholesterol degradation in the liver of broilers in the high and low dose groups-Cholesterol 27 Alpha Hydroxylase(CYP27A1)m RNA expression was significantly increased(P < 0.05),while the key enzymes of the classical pathway of liver cholesterol degradation-Cholesterol 7 Alpha Hydroxylase(CYP7A1)and insulin-induced gene(INSIG)m RNA expression did not difference;at 40 days of age,the m RNA expression of CYP7α1,a key enzyme in the classical pathway of liver cholesterol degradation in high and low dose broilers,was significantly increased(P < 0.05),and INSIG m RNA expression was significantly reduced(P < 0.05),while liver cholesterol degradation replaced There was no difference in the m RNA expression of the key enzyme of the pathway-CYP27α1.In addition,compared with the control group,the 40-day-old high-and low-dose group of broilers liver cholesterol esterification key enzyme acyl-Coenzyme A: cholesterol acyltransferase 2(ACAT2)m RNA expression levels were significantly reduced(P < 0.05),high and low dose broiler liver cholesterol regulatory element binding protein 2(SREBP2),cleavage activation protein(sterol regulatory element binding protein cleavage activating protein,SCAP)and 3-hydroxy-3-methylglutaryl Co A reductase(HMGCR)m RNA expression increased significantly(P < 0.01),but the protein content of SREBP2 in the liver of the low-dose group of 40-day-old broilers was significant decrease(P < 0.05)and there was no difference in the protein content of HMGCR in 40-day-old broilers.3.In terms of histone acetylation and methylation modification in the promoter region of HMGCR gene,compared with the control group,at 40 days of age,the acetylation level of histone H3 in high and low dose groups increased significantly(P < 0.01),the low-dose group near the 5’untranslated region histone H3K4 trimethylation level extremely significantly increased(P < 0.01),the low-dose group near the 5’untranslated region histone H3K27 trimethylation level extremely significantly increased(P < 0.005),the level of histone H3K27 trimethylation in the low-dose group far from the 5’untranslated region was significantly increased(P < 0.05),but the level of histone H3K9 monomethylation was not significantly different.The above results indicate that feeding white-feather broilers with standard diets supplemented with Lactobacillus acidophilus significantly reduces the serum and liver cholesterol content of broilers,and is accompanied by changes in liver cholesterol conversion,synthesis and esterification-related gene expression patterns,suggesting broiler feeding The standard diet supplemented with Lactobacillus acidophilus can increase the degree of histone H3 acetylation in the promoter region of the HMGCR gene,increase the epigenetic markers of H3K4 trimethylation and H3K27 trimethylation,thereby regulating the expression of HMGCR gene,probably mainly by increasing the degradation of cholesterol and affecting the liver of broilers Cholesterol metabolism.