饲养方式对苏尼特羊肌内脂肪沉积途径AMPK-ACC-CPT1通路和肉品品质的影响

以放牧和舍饲两种饲养条件下12月龄苏尼特羊股二头肌为实验材料,利用酶联免疫吸附测定法和实时荧光定量聚合酶链式反应法对肌内脂肪沉积动态平衡中脂肪酸β氧化一磷酸腺苷激活蛋白激酶(AMP-activated proteinkinase,AMPK)-乙酰辅酶A羧化酶(acetyl-CoAcarboxylase,ACC)-肉毒碱脂酰转移酶1(carnitine palmitoyltransferase,CPT1)通路所涉及的相关酶活力和质量浓度、相关基因mRNA表达量及肉品品质等指标进行测定,研究不同饲养方式对AMPK-ACC-CPT1信号通路相关指标、肌内脂肪含量及肉品品质产生的影响。结果表明:放牧饲养组羊股二头肌AMPK质量浓度、AMPK活力、CPT1质量浓度、AMPK mRNA表达量、亮度、黄度和剪切力显著大于舍饲饲养组(P0.05);放牧饲养组羊股二头肌ACC活力、ACC mRNA表达量、肌内脂肪含量显著低于舍饲饲养组(P0.05)。由此可见,放牧饲养可以一定程度上激活AMPK-ACC-CPT1通路,从而减少肌内脂肪沉积,增加羊肉亮度和黄度,降低嫩度,进而影响肉品品质。

Effects of Different Feeding Systems on Intramuscular Fat Deposition Pathway AMPK-ACC-CPT1 and Meat Quality in Sunit Lamb

In the present study, we assessed the effects of two different feeding systems on the activities and mRNA expression levels of enzymes involved in the AMP-activated protein kinase-acetyl-CoA carboxylase-carnitine palmitoyltransferase (AMPK-ACC-CPT1) pathway, fat content and meat quality in the Biceps femoris muscle of 12-month-old Sunit lambs. The enzyme activities were determined by enzyme-linked immunosorbent assay and gene expression was measured by real-time fluorescence quantitative polymerase chain reaction (PCR). The results showed that AMPK concentration and activity, AMPK mRNA expression, CPT1 concentration, brightness (L* value), yellowness (b* value) and shear force in the biceps femoris muscle of grazed lambs were significantly higher than those in stall-fed lambs (P < 0.05), while the opposite was observed for ACC activity, ACC mRNA expression and intramuscular fat content (P < 0.05). Accordingly we concluded that grazing can activate the AMPK-ACC-CPT1 pathway to reduce intramuscular fat deposition, increase L* and b* values and decrease tenderness, consequently affecting lamb meat quality.