Department of Animal Science, Iowa State University, Ames, IA 50011, USA.
Domest Anim Endocrinol. 2012 Nov;43(4):307-16. doi: 10.1016/j.domaniend.2012.05.004. Epub 2012 May 27.
Negative energy balance at the onset of lactation is unfavorably associated with fitness traits in high-producing dairy cows. Angiopoietin-like protein 4 (ANGPTL4) is an adipokine that has been associated with the regulation of lipid metabolism through the inhibition of lipoprotein lipase activity and regulation of lipolysis. Expression of ANGPTL4 messenger RNA (mRNA) increases during early lactation, but its regulation with changing energy status is currently unknown. Accordingly, the objective of this study was to determine whether ANGPTL4 mRNA abundance is responsive to declining energy balance induced by the transition from pregnancy to lactation, feed restriction, and GH administration in lactating dairy cows. The mRNA abundance of leptin, adiponectin, and adiponectin receptor 2 were also measured to compare adipokine mRNA profiles during changes in energy metabolism. Repeated adipose tissue biopsies were taken from different cows during transition from late pregnancy to lactation (n = 26), feed restriction (n = 19), and GH administration (n = 20). As expected, milk yield increased with the onset of lactation and GH administration (P < 0.01) but declined during feed restriction. Energy balance declined in each experiment, resulting in negative energy balance at the onset of lactation and after feed restriction. Abundance of ANGPTL4 mRNA expression increased 2- to 6-fold with declining energy balance in each experiment. Leptin mRNA declined with feed restriction, and adiponectin mRNA decreased with the onset of lactation. The consistency and magnitude of the increase in ANGPTL4 mRNA across multiple models of altered energy balance identifies it as an adipokine that is uniquely responsive to changes in energy balance in the lactating dairy cow.
哺乳期开始时的负能量平衡与高产奶牛的健康特征呈负相关。血管生成素样蛋白 4 (ANGPTL4) 是一种脂肪因子，通过抑制脂蛋白脂肪酶活性和调节脂肪分解来调节脂质代谢。ANGPTL4 信使 RNA (mRNA) 的表达在泌乳早期增加，但目前尚不清楚其随能量状态变化的调节方式。因此，本研究的目的是确定 ANGPTL4 mRNA 丰度是否对从妊娠到泌乳、饲料限制和生长激素 (GH) 给药过渡引起的能量平衡下降有反应，泌乳奶牛。还测量了瘦素、脂联素和脂联素受体 2 的 mRNA 丰度，以比较能量代谢变化期间脂肪因子 mRNA 谱。在从妊娠晚期到泌乳期（n = 26）、饲料限制（n = 19）和 GH 给药（n = 20）期间，从不同奶牛身上重复采集脂肪组织活检。如预期的那样，产奶量随着泌乳和 GH 给药的开始而增加（P < 0.01），但在饲料限制期间下降。每个实验中的能量平衡都下降了，导致泌乳开始和饲料限制后出现负能量平衡。在每个实验中，随着能量平衡的下降，ANGPTL4 mRNA 的丰度增加了 2-6 倍。在饲料限制时瘦素 mRNA 下降，在泌乳开始时脂联素 mRNA 下降。在改变能量平衡的多种模型中，ANGPTL4 mRNA 增加的一致性和幅度将其确定为一种脂肪因子，它对泌乳奶牛能量平衡的变化有独特的反应。
