热应激对陆川猪脂肪沉积和脂肪代谢的影响及EGCG调控机制

Heat stress leads to a significant reduction in the quality of pork has become an important issue in swine industry of the south China. Intramuscular fat is an important factor in the quality of pork meat and key regulation. AMPK plays an important role in the regulation of animal fat deposition. Heat stress can induce high expression of HSP70 in pig adipocytes. EGCG is a polyphenol compounds isolated from tea. Recent studies found that EGCG can inhibit the expression of HSP70 and found that EGCG can increase the expression of AMPK. We study the heat stress of Luchuan pig, and explore the effect of heat stress on performance, heat stress indexs, carcass traits, meat quality, fat deposition, lipid metabolism of Luchuan pig. We use Luchuan pig intramuscular preadipocytes to establish heat stress model, and study the effect of anti-heat stress effect and fat deposition by regulating HSP70, AMPK signaling pathway. At last study on the effect of EGCG on fat deposition and lipid metabolism of Luchuan pig in heat stress. we explore the appropriate add rato feeding the Luchuan pigs in heat stress at the stage of the growing-finishing. The study provides important scientific theory of developing EGCG as a important feed additive for improving meat quality by regulating fat deposition and lipid metabolism in Luchuan pigs in heat stress.

热应激导致猪肉质降低已成为我国南方养猪业面临的重要问题。猪肌内脂肪是决定猪肉质的一个重要因素和调控肉质的关键。腺苷酸活化蛋白激酶（AMPK）在调控动物脂肪沉积和代谢发挥重要作用。热应激诱导猪脂肪细胞高表达HSP70。表没食子儿茶素没食子酸酯（EGCG）是多酚化合物，近年来研究发现它能抑制HSP70的表达，上调AMPK的表达。本项目先开展陆川猪热应激试验，弄清热应激对陆川猪生长性能、热应激指标、胴体性状、肉质指标、脂肪沉积和脂肪代谢的影响；后期建立陆川猪肌内前体脂肪细胞热应激模型，研究EGCG通过调控HSP70，AMPK信号通路对热应激下陆川猪肌内前体脂肪细胞脂肪沉积和脂肪代谢的影响，通过饲养试验研究EGCG通过调控热应激陆川猪脂肪沉积和脂肪代谢，探讨其应用于热应激陆川猪生长肥育饲养中适宜的添加比例。本项目为开发EGCG作为缓解陆川猪热应激并调控脂肪代谢进而改善肉质的饲料添加剂提供科学依据。

热应激导致猪肉质降低已成为我国南方养猪业面临的重要问题。猪肌内脂肪是决定猪肉质的一个重要因素和调控肉质的关键。本项目先开展陆川猪热应激实验，研究发现，热应激显著降低陆川猪的生长性能，升高热应激指标，降低胴体性状，降低背最长肌的肉色、系水力和肌内脂肪含量，提高脂肪分解关键酶活。分子机制研究表明热应激增加了陆川猪背最长肌中HSP70的表达，激活AMPK-SIRT1-PGC-1α信号通路，促进脂肪分解关键基因的表达，抑制脂肪合成基因的表达，从而抑制肌内脂肪沉积。在细胞水平上，利用41.5℃高温刺激建立猪肌内前体脂肪细胞热应激模型并诱导分化，结果显示，热应激能够促进猪肌内前体脂肪细胞HSP70的表达，通过激活AMPK-SIRT1-PGC-1α信号通路下调猪脂肪合成基因表达，上调脂肪分解基因的表达，从而抑制脂肪的沉积。研究发现EGCG显著降低热应激猪肌内前体脂肪细HSP70的表达，缓解了热应激，EGCG通过抑制AMPK-SIRT1-PGC-1α信号通路，上调脂肪合成关键基因的表达，下调脂肪分解关键基因表达，进而促进猪肌内前体脂肪细胞的脂质积累。后期开展了饲粮中添加不同比例EGCG饲喂热应激陆川猪试验，研究发现，EGCG能有效缓解陆川猪热应激反应，改善生长性能和胴体性状，提高背最长肌的肉色、系水力和肌内脂肪含量，其中0.05%添加量能达到改善肉质的最佳效果；研究还发现EGCG通过抑制AMPK-SIRT1-PGC-1α信号通路，上调脂肪合成关键基因表达，下调脂肪分解关键基因表达，进而促进热应激陆川猪肌内脂肪的沉积。总之，本项目弄清了热应激对陆川猪生长性能、热应激指标、胴体性状、肉质指标、脂肪沉积、脂肪代谢的影响，找到了EGCG应用于热应激陆川猪生长肥育饲养中最适宜的添加比例，为开发EGCG作为一种能通过调控热应激陆川猪脂肪沉积和脂肪代谢进而改善猪肉品质的绿色饲料添加剂提供科学理论依据。