Faylon M P, Koltes D E, Spurlock D M
Department of Animal Science, Iowa State University, Ames 50011.
Department of Animal Science, Iowa State University, Ames 50011.
J Dairy Sci. 2014 May;97(5):2847-55. doi: 10.3168/jds.2013-7565. Epub 2014 Mar 13.
Lipid metabolism plays a crucial role in the adaptation of dairy cows to periods of energy insufficiency. The objective of the current study was to determine if lipolytic proteins are consistently regulated when energy mobilization is stimulated by different factors. We evaluated 2 models of altered energy balance in mid-lactation Holstein cows, including feed restriction (FR) and administration of bovine growth hormone (GH), by quantifying the abundance and (or) phosphorylation of hormone-sensitive lipase (HSL), perilipin (PLIN), and adipose triglyceride lipase (ATGL). For GH administration, adipose tissue and blood samples were collected 4d before and 3 and 7d after administration of GH (n=20 cows). Similarly, adipose and blood samples were obtained 6d before and 1 and 4d after initiation of FR (n=18 cows). Estimated net energy balance decreased and nonesterified fatty acid concentration increased in both experimental models. Decreased ATGL and PLIN protein abundance was observed with GH administration and FR. Additionally, the abundance of phosphorylated HSLSer565 decreased in both models. Decreased abundance of phosphorylated PLIN was observed with GH administration, but not FR. Decreased ATGL protein abundance appears to be a consistent response to energy insufficiency in lactating cows, as this response was also described with negative energy balance at the onset of lactation. In contrast, the abundance of PLIN protein and phosphorylation of HSL using antibodies targeting serine residue 565 of HSL (HSLSer565) were altered in the current research, but not at the onset of lactation. Our findings demonstrate that lipolysis is altered through the regulation of multiple proteins, and that this regulation differs according to physiological state in lactating cows.
脂质代谢在奶牛适应能量不足期的过程中起着至关重要的作用。本研究的目的是确定当能量动员受到不同因素刺激时，脂解蛋白是否受到持续调控。我们通过量化激素敏感性脂肪酶（HSL）、围脂滴蛋白（PLIN）和脂肪甘油三酯脂肪酶（ATGL）的丰度和（或）磷酸化水平，评估了两种中泌乳期荷斯坦奶牛能量平衡改变的模型，包括限饲（FR）和注射牛生长激素（GH）。对于注射GH的情况，在注射GH前4天以及注射后3天和7天采集脂肪组织和血液样本（n = 20头奶牛）。同样地，在开始限饲前6天以及限饲后1天和4天采集脂肪和血液样本（n = 18头奶牛）。在两个实验模型中，估计净能量平衡均下降，非酯化脂肪酸浓度均升高。注射GH和限饲均导致ATGL和PLIN蛋白丰度降低。此外，两个模型中磷酸化HSLSer565的丰度均降低。注射GH后观察到磷酸化PLIN丰度降低，但限饲未出现此情况。ATGL蛋白丰度降低似乎是泌乳奶牛对能量不足的一致反应，因为在泌乳开始时负能量平衡的情况下也描述过这种反应。相比之下，在本研究中，使用靶向HSL丝氨酸残基565（HSLSer565）的抗体检测到PLIN蛋白丰度和HSL磷酸化发生了改变，但在泌乳开始时未出现这种情况。我们的研究结果表明，脂解作用通过多种蛋白质的调控而改变，并且这种调控在泌乳奶牛的不同生理状态下有所不同。
