湖羊肌肉组织H-FABP和PPARγ基因表达水平与肌内脂肪含量的相关研究

Association of the H-FABP and PPARγ Gene Expression with Intramuscular Fat Content in Hu Sheep Muscles

【目的】研究湖羊不同部位肌肉H-FABP和PPARγ基因mRNA的发育变化规律,结合屠宰试验分析H-FABP和PPARγ基因mRNA表达水平对肌内脂肪沉积的影响。【方法】选取初生、1、2、3、4、5、6月龄湖羊公羔和12月龄的成年公湖羊各5只,屠宰后取背最长肌、腰大肌和股二头肌检测肌内脂肪含量,用荧光实时定量PCR法检测湖羊不同部位肌肉H-FABP和PPARγ基因mRNA表达水平,分析其在不同时期的变化及其与肌内脂肪含量的关系。【结果】(1)随着月龄的增加,肌内脂肪(intramuscular fat,IMF)含量持续上升;同月龄背最长肌和腰大肌IMF含量显著高于股二头肌(P<0.05)。(2)0～6月龄及12月龄,湖羊不同部位肌肉H-FABP基因和PPARγ基因mRNA表达的发育变化模式不同,具有组织特异性。随着月龄的增加,背最长肌和腰大肌H-FABP基因mRNA的表达模式基本相同,2月龄达最高(P<0.01),总体呈现上升-下降-上升的趋势,而股二头肌H-FABP基因mRNA的表达量无显著变化。对于PPARγ基因来说,背最长肌PPARγ基因mRNA的表达量4月龄达最高(P<0.01),然后下降并保持相对稳定水平,而腰大肌和股二头肌PPARγ基因mRNA的表达量随着月龄的增长大体呈上升-下降-上升-下降的趋势。同月龄H-FABP基因和PPARγ基因mRNA的表达量在湖羊不同部位肌肉表现有明显的差异。(3)湖羊不同肌肉部位基因的表达量与IMF含量相关分析表明,不同部位肌肉H-FABP基因mRNA的表达量与IMF含量呈不同程度的正相关;而PPARγ基因mRNA的表达量与IMF含量则呈不同程度的负相关。【结论】湖羊不同部位肌肉肌内脂肪沉积的发育变化基本相同,在生长发育期都是随着月龄的增加其IMF含量上升;不同部位肌肉H-FABP和PPARγ基因表达模式不同,H-FABP基因在湖羊生长早期对肌内脂肪的沉积可能有正调控作用,而PPARγ基因可能对肌内脂肪的沉积产生一定的影响。

[Objective] The objectives of this study were to investigate the developmental changes of the heart fatty acid-binding protein （H-FABP） and peroxisome proliferator-activated receptor γ（PPARγ） mRNA level in different parts of muscles in Hu sheep and its effect on intramuscular fat （IMF） accumulation. [ Method ] Male Hu lamb at 0 to 12 months age were selected to investigate the developmental changes of heart fatty acid-binding protein （H-FABP） and peroxisome proliferator-activated receptor γ （PPARγ） mRNA expression and its effect on intramuscular fat content in three different parts of muscles. Five animals were slaughtered at 0, 1, 2, 3, 4, 5,6, 12 months to collect samples from longissimus dorsi muscle, psoas major muscle, bicepsfemoris muscle, for the purpose of determining the IMF content and extracting total RNA in order to investigate the developmental changes of the H-FABP and PPAR7 mRNA expression by real-time PCR. [Result] With growing, the IMF content increased with the progress of development; longissimus dorsi muscle and psoas major muscle were higher than biceps brachii muscle （P〈 0.05） at the same age. H-FABP and PPARγ mRNA expression level was different in different parts of muscles from 0 to 12 month in Hu sheep and has tissues-dependent. In longissirnus dorsi muscle and psoas major muscle their mRNA expression level was the highest （P〈 0.01） in 2 month old Hu sheep, then declined slowly and increased with growing; In bicepsfemoris muscle, the mRNA expression level was no significant difference from 0 to 12 month in Hu sheep. For PPARγ mRNA expression level, in longissimus dorsi muscle, the mRNA expression level was the highest （P〈0.01） in 4 month old Hu sheep, then continued declining and kept a steady level; In psoas major muscle and biceps femoris muscle, the mRNA expression level presented increasingdecreasing-increasing-decreasing with growing; In the same month H-FABP and PPARγ mRNA expression level has tissues-dependent in muscles of three different parts in Hu sheep. In the early development stage, H-FABP mRNA expression level was positively related to IMF content; PPARγ mRNA expression level was negatively related to IMF content. [Conclusion] There were same models of IMF accumulation in muscles of different parts in Hu sheep, in the development stage the IMF content increased with the age increasing; There were different models in different parts of muscles, H-FABP mRNA expression was positively effect on IMF accumulation in the early development stage, while PPAR）, mRNA expression level was likely to influence on IMF accumulation.