Mechanism Of Maternal T10,c12-CLA On Lipid Metabolism In Offspring Chickens

Excessive fat deposition in broilers not only reduces feed conversion efficiency,but also increases the risk of ascites and sudden death in broilers,which seriously affects broiler production.How to effectively reduce fat deposition in broilers has become a pressing problem in broiler production.Studies have shown that conjugated linoleic acid has a physiological role in reducing body fat deposition,and the maternal effect of maternal conjugated linoleic acids in reducing offspring fat deposition has become a new research hotspot in recent years,which provides a new idea to solve the problem of excessive abdominal fat deposition in broiler chickens in production.In this study,we investigated the regulatory effects and potential mechanisms of maternal t10,c12-CLA on offspring lipid metabolism through in vivo and ex vivo experiments.（1）Effect of embryonic egg administration of t10,c12-CLA on the lipid metabolism of chicken embryos.A total of 360 specific pathogen free eggs were selected and randomly divided into 6 groups.0,1.5,3.0,4.5,6.0 and 7.5 mg t10,c12-CLA were injected into embryonic eggs on day 11（E11）of hatching.The results showed that embryonic egg administration of t10,c12-CLA significantly reduced subcutaneous adipose tissue mass and relative subcutaneous adipose tissue weight in chicks（P < 0.05）.In the liver,total triglyceride cholesterol levels in the liver were significantly reduced with increasing doses of t10,c12-CLA（P < 0.05）.And the t10,c12-CLA-treated group significantly increased carnitine palmitoyl transterase enzyme-1a content and polyunsaturated fatty acid ratio（P < 0.05）,while malondialdehyde levels decreased and glutathione peroxidase and total antioxidant capacity increased（P < 0.05）.In addition,embryonic egg administration at t10,c12-CLA significantly reduced the m RNA expression of FAS,ACC1,ATGL and SCD1 in the liver（P < 0.05）and promoted the m RNA expression of CPT1 a and AMPKα（P < 0.05）.In subcutaneous adipose tissue,the m RNA expression of PPARγ and SREBP-1c decreased significantly（P < 0.05）and the expression of PPARα and CPT1 a genes increased significantly（P < 0.05）with increasing doses of t10,c12-CLA.The results suggest that embryonic egg administration of t10,c12-CLA reduces lipid accumulation in chicks by inhibiting fatty acid synthesis and stimulating lipolysis in the liver as well as inhibiting adipocyte differentiation in subcutaneous adipose tissue.（2）Effect of t10,c12-CLA on lipid metabolism in hepatocytes.specific pathogen free chick embryos of 17 embryonic age were selected and primary hepatocytes were cultured in vitro.When the cells reached 90% fusion,the hepatocytes were treated with 0,100,200 and300 μM t10,c12-CLA for 6 h,12 h and 24 h to observe the changes of lipid metabolism.The results showed that t10,c12-CLA treatment significantly reduced hepatocyte triglyceride content and up-regulated the transcript levels of LPL,PPARα,ATGL,CPT1,HMGCR and SREBP2（P < 0.05）,down-regulated the transcript levels with ACC1 and SREBP-1c（P <0.05）,and increased the total protein expression of AMPK and phosphorylation levels（P <0.05）and increased protein phosphorylation levels of ERK（P < 0.05）.After treatment of hepatocytes with ERK phosphorylation inhibitor（U0126）,the results showed that along with a significant decrease in ERK protein phosphorylation level（P < 0.05）,AMPK protein phosphorylation level increased significantly（P < 0.05）and the m RNA expression of SREBP2,LPL and CPT1 changed significantly（P < 0.05）.The results indicated that t10,c12-CLA promoted hepatic lipid oxidative catabolism and inhibited lipid deposition through activation of ERK pathway.（3）Effect of t10,c12-CLA on lipid metabolism in preadipocytes.specific pathogen free chick embryos of 17 embryonic age were selected and preadipose was cultured in vitro and treated with 0,10 and 20 μM t10,c12-CLA for 6 h,12 h and 24 h to observe the effects of conjugated linoleic acid on lipid metabolism in preadipocytes.t10,c12-CLA treatment significantly reduced triglyceride levels in preadipocytes（P < 0.05）and inhibited the production of ATGL,LPL and PLIN1（P < 0.05）,which are key regulators of lipogenic differentiation,promoted CPT1 m RNA expression（P < 0.05）,inhibited PPARγ,C/EBPαtranscript levels（P < 0.05）,and promoted SREBP-1c expression（P < 0.05）.Phosphorylation levels of AMPK and ERK were significantly inhibited（P < 0.05）.After PLC inhibitor（U73122）treatment,the protein expression level of PLC was reduced,the phosphorylated protein level of AMPK was significantly increased,the m RNA expression of ATGL and C/EBPα was significantly increased（P < 0.05）and the m RNA expression of CPT1 and SREBP-1c was significantly reduced（P < 0.05）.The results indicated that t10,c12-CLA reduced preadipocyte triglyceride content,promoted lipid oxidative catabolism and inhibited adipose differentiation via the PLC-AMPK pathway.In conclusion,maternal t10,c12-CLA could regulate lipid metabolism in offspring chickens,reduce lipid accumulation in chicks,promote hepatic oxidative catabolism and inhibit hepatic lipid deposition by activating the hepatic ERK pathway,and in adipocytes,t10,c12-CLA reduced preadipocyte triglyceride content,promoted lipid oxidative catabolism and inhibited lipid differentiation.