断尾对兰州大尾羊脂肪细胞结构和脂肪代谢相关基因表达的影响OA北大核心CSTPCD

The objective of this study was to observe the effect of tail docking on the number and structure of adipocytes,and gene expression related to lipid metabolism in Lanzhou fat tailed sheep. The results help in clarifying the molecular regulation mechanism leading to redistribution of fat after tail docking in fat-tailed sheep. Eighteen Lanzhou fat-tailed lambs (5 d old and weighing 3.79±0.12 kg) from eighteen ewes were randomly divided into a control (C) group and a test (T) group,with nine lambs in each group. Tails of lambs in the T group were ligated with rubber bands. The two groups were fed with same formula diet after weaning at 2 months;the trial period was 240 days. At the end of the experiment,samples were collected for analysis. It was found that:1) With respect to the longissimus dorsi and visceral fat,tail-docking had an observable effect on gene expression related to formation of tail fat and subcutaneous fat. For T sheep,SCD,LEP,PLIN1 expression levels were higher,and LPL,FAS,PEPCK expression levels were lower in the tail,SCD was higher and LEP,ADPN,FABP4,PLIN1 were lower in subcutaneous fat,LPL,ADPN,PEPCK,UCP1 were lower in kidney fat and PEPCK was lower in omental fat (P<0.05) than for C sheep. In addition,SCD expression was higher,PEPCK and PLIN1 expression levels were significantly lower in longissimus dorsi of T than of C sheep (P<0.05). 2) Intramuscular fat was significantly higher in the T than in the C group (6.96％ and 6.05％,respectively). Similarly,lipid droplets in the longissimus dorsi were significantly increased in T group sheep compared to C (4.28％ and 3.04％,respectively;P<0.05),while the area ratio of lipid droplets increased by about 1％,the area ratio of lipid droplets in tail fat decreased by 10％ (87.58％ and 97.58％ for T and C groups,respectively),and the diameter of adipocytes was significantly decreased (P<0.05) in tail fat from sheep in the T group. 3) Transmission electron microscopy observation showed that the fat cells in the tail were filled with large fat droplets,the nucleus and cytoplasm were squeezed to the edge of the cell by these large fat droplets,and the cytoplasm at the edge of the cell contained organelles such as mitochondria,endoplasmic reticula,golgi apparatus,autophagosomes and small lipid droplets in Lanzhou fat-tailed sheep. Compared to the C group,the single lipid droplets were smaller,and the glycogen granules were more numerous in the cytoplasm in fat cells in tail-docked sheep. To summarize,the results showed that tail-docking early in the life of Lanzhou fat-tail sheep increased the area ratio of fat droplets in the longissimus dorsi and decreased the area ratio of fat droplets in tail fat. Moreover,tail-docking changed the expression of genes related to fat metabolism. The distribution of fat deposits is indicated to be regulated by the genes related to fat metabolism:SCD,PLIN1,LPL,FAS,PEPCK and others.