AMP激活蛋白激酶在肉鸡PSE肉形成过程中作用机制研究

With the increase in the overall production of broiler meat and its proportion in the whole meat consumption all over the world, the research on broiler meat quality gets much more attention; moreover, the incidence of broiler pale,soft,exudative (PSE) meat produce affects the improvement of broiler meat quality significantly.Recently, it has confirmed that AMP-activated protein kinase (AMPK) play a key role in the energy metabolism in living cells, which is involved in the regulation of glycolysis in muscle and play a important role in regulating the development of PSE meat of animal after slaughtering. Thus,the study on the mechanism of action of AMPK on development of broiler PSE meat will have an intense theoretical significance and an extensive applicanation prospect. In this project, the change of activity of AMPK and key glycolytic enzymes (glycogen phosphorylase, pyruvate kinase, lactate dehydrogenase) and the correspondence between them will be investigated during the processing of develpoment of PSE meat. Change of meat quality, as well as changes in two-dimensional electrophoretic patterns of proteins, will also be studied in this study. Therefore, according to these results the pathways of AMPK in the development of PSE meat will be analysed. Furthermore, through establishing a model of inhibition pathway of AMPK activity in broiler muscle both in vitro and in vivo and comparing with the control group, the study of the effect of AMPK activity change on the quality of meat will be analyzed in order to investigate the possible way to decrease the incidence of PSE meat. The purpose of this project is to enrich the underlying mechanisms of the conversion of muscle into meat, which may have a certain guiding significance in the regulation of broiler meat quality.

随着肉鸡总体产量的提升及在世界肉类消费中比重的增加，其品质的研究日益受到重视，而肉鸡PSE肉产生是影响鸡肉品质提升的重要因素。目前已证实AMP激活蛋白激酶（AMPK）在生物体细胞能量代谢中发挥关键调控作用，参与调控宰后动物肌肉中糖酵解并对PSE肉的形成起到关键调控作用，因此研究AMPK在肉鸡PSE肉形成过程中的作用机制具有较强的理论意义和广泛的应用前景。本课题拟通过研究PSE肉形成过程中AMPK与糖酵解关键酶（糖原磷酸化酶，丙酮酸激酶，乳酸脱氢酶）的活性变化及对应关系，并结合其对肌肉品质的变化以及蛋白质组成二维电泳图谱变化的影响，分析AMPK在PSE肉形成过程中的作用途径。进一步根据体外和体内两种抑制途径来建立抑制肌肉中AMPK活性的模型，分析AMPK活性变化对肌肉品质的影响，从而研究降低肉鸡PSE肉发生率的可行性方法。本课题旨在完善现有肉品品质的形成机理，指导肉鸡品质调控具有重要意义。

目前已证实AMP 激活蛋白激酶（AMPK）在生物体细胞能量代谢中发挥关键调控作用，参与调控宰后动物肌肉中糖酵解影响肉质，研究AMPK 在肉鸡PSE 肉形成过程中的作用机制具有广泛的应用前景。.通过分析AMPK和糖酵解关键酶活性的变化过程，可以看出，宰后高温条件下可以激活AMPK，而后可能通过激酶级联系统磷酸化下游的磷酸果糖激酶，从而打开糖酵解通道，导致pH下降速度增快，最终影响到鸡肉肉质。.禁食处理是肉鸡屠宰加工常用的手段，通过分析禁食处对AMPK的调控，从而研究禁食对宰后糖酵解及品质的影响，来进一步分析调控AMPK的方式。通过研究发现禁食处理导致肉鸡鸡肉糖酵解显著受到影响，表现为初始糖原含量的明显降低，乳酸含量升高从而引起极限pH值的提高。同时禁食处理会导致宰后初期AMPK酶显著激活，AMPK酶可能参与了禽肉糖酵解的调控，加快了糖酵解速度，对肌肉保水性影响显著，后续有必要进一步研究蛋白特性的变化与保水性的关系。.AMPK影响鸡肉品质模型中保水性指标极为重要，但保水性影响因素及与蛋白特性关系相对复杂需要进一步从水分状态层面进行研究。通过设置反复冻融模型来研究鸡肉保水性的变化，研究发现反复冻融后鸡肉解冻汁液损失逐步降低，同时伴随着肌肉中自由水的比例的下降。需要指出的是，该过程中反复冻融对肌肉pH值影响不大，但由于肌肉中冰晶反复产生对肌丝微观结构，尤其可能对肌原纤维蛋白分子空间构象变化有影响，最终一定程度上影响肌肉保水性，该研究进一步验证了蛋白特性与保水性的关系。.最后对典型的猪肉PSE肉产生模型进行类比研究。结果发现宰后早期不同温度对猪肉中糖原酵解的速度有着显著的影响，高温下肌肉中的糖原酵解速度较快，从而造成了高速下降的pH和高温相结合的环境。宰后40°C高温伴随着较快速的糖原酵解能引起猪肌肉颜色发白以及较低的保水性等PSE特征，肌肉的加工性能也显著下降。部分的肌浆蛋白变性，以上过程首先降低了蛋白质的盐溶性，甚至影响了肌肉内微环境的保水性，进而造成宏观上肌肉颜色发白和保水性下降等现象。