Reverchon Maxime, Ramé Christelle, Cognié Juliette, Briant Eric, Elis Sébastien, Guillaume Daniel, Dupont Joëlle
INRA, UMR 7247 Physiologie de la Reproduction et des Comportements, Nouzilly, France; CNRS, UMR6175 Physiologie de la Reproduction et des Comportements, Nouzilly, France; Université François Rabelais de Tours, Tours, France; Institut Français du Cheval, Nouzilly, France.
PLoS One. 2014 Mar 27;9(3):e93198. doi: 10.1371/journal.pone.0093198. eCollection 2014.
Resistin is an adipokine that has been implicated in energy metabolism regulation in rodents but has been little studied in dairy cows. We determined plasma resistin concentrations in early lactation in dairy cows and investigated the levels of resistin mRNA and protein in adipose tissue and the phosphorylation of several components of insulin signaling pathways one week post partum (1 WPP) and at five months of gestation (5 MG). We detected resistin in mature bovine adipocytes and investigated the effect of recombinant bovine resistin on lipolysis in bovine adipose tissue explants. ELISA showed that plasma resistin concentration was low before calving, subsequently increasing and reaching a peak at 1 WPP, decreasing steadily thereafter to reach pre-calving levels at 6 WPP. Plasma resistin concentration was significantly positively correlated with plasma non esterified fatty acid (NEFA) levels and negatively with milk yield, dry matter intake and energy balance between WPP1 to WPP22. We showed, by quantitative RT-PCR and western blotting, that resistin mRNA and protein levels in adipose tissue were higher at WPP1 than at 5 MG. The level of phosphorylation of several early and downstream insulin signaling components (IRβ, IRS-1, IRS-2, Akt, MAPK ERK1/2, P70S6K and S6) in adipose tissue was also lower at 1 WPP than at 5 MG. Finally, we showed that recombinant bovine resistin increased the release of glycerol and mRNA levels for ATGL (adipose triglyceride lipase) and HSL (hormone-sensitive lipase) in adipose tissue explants. Overall, resistin levels were high in the plasma and adipose tissue and were positively correlated with NEFA levels after calving. Resistin is expressed in bovine mature adipocytes and promotes lipid mobilization in adipose explants in vitro.
抵抗素是一种脂肪因子，在啮齿动物的能量代谢调节中发挥作用，但在奶牛中研究较少。我们测定了奶牛泌乳早期的血浆抵抗素浓度，并研究了产后一周（1 WPP）和妊娠五个月（5 MG）时脂肪组织中抵抗素mRNA和蛋白水平以及胰岛素信号通路几个组分的磷酸化情况。我们在成熟牛脂肪细胞中检测到了抵抗素，并研究了重组牛抵抗素对牛脂肪组织外植体脂解作用的影响。酶联免疫吸附测定（ELISA）显示，产犊前血浆抵抗素浓度较低，随后升高并在1 WPP时达到峰值，此后稳步下降，在6 WPP时降至产犊前水平。血浆抵抗素浓度与血浆非酯化脂肪酸（NEFA）水平显著正相关，与WPP1至WPP22期间的产奶量、干物质摄入量和能量平衡呈负相关。通过定量逆转录聚合酶链反应（RT-PCR）和蛋白质印迹法，我们发现WPP1时脂肪组织中抵抗素mRNA和蛋白水平高于5 MG时。1 WPP时脂肪组织中几个早期和下游胰岛素信号组分（IRβ、IRS-1、IRS-2、Akt、丝裂原活化蛋白激酶ERK1/2、P70S6K和S6）的磷酸化水平也低于5 MG时。最后，我们发现重组牛抵抗素增加了脂肪组织外植体中甘油的释放以及脂肪甘油三酯脂肪酶（ATGL）和激素敏感性脂肪酶（HSL）的mRNA水平。总体而言，产犊后血浆和脂肪组织中抵抗素水平较高，且与NEFA水平正相关。抵抗素在牛成熟脂肪细胞中表达，并在体外促进脂肪组织外植体中的脂质动员。
