Postweaning changes in the expression of chemerin and its receptors in calves are associated with the modification of glucose metabolism
Postweaning changes in the expression of chemerin and its receptors in calves are associated with the modification of glucose metabolism
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DOI：
10.2527/jas.2016-0677
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发表时间：
2016-11-01
影响因子：
3.3
通讯作者：
Roh, S.
中科院分区：
文献类型：
--
作者：
Suzuki, Y.;Haga, S.;Roh, S.
趋化素最初被认为是一种来源于脂肪组织和肝脏的趋化剂，据报道在糖异生、外周胰岛素敏感性和胰岛素分泌中具有调节功能。本研究旨在评估断奶后该细胞因子表达的变化及其在与断奶相关的糖代谢调节中的生理作用。收集荷斯坦犊牛（90 d龄，n = 4） 18份组织样本，研究趋化素及其受体基因在组织中的分布。趋化素在肝脏中高表达，血浆中有分泌的趋化素蛋白。趋化素受体中，趋化因子样受体1和C-C趋化因子样受体2在肝脏中普遍表达，而G蛋白偶联受体1在肝脏中主要表达。通过比较日本黑牛哺乳犊牛（n = 6）和断奶犊牛（n = 8），研究断奶后糖代谢及这些基因表达的变化。泌乳犊牛血浆葡萄糖水平与断奶犊牛无显著差异（P = 0.22），血浆总酮体水平显著高于断奶犊牛（P < 0.01）。血浆胰岛素和皮质醇水平在哺乳期和断奶期犊牛之间没有差异。参与肝糖异生的一些关键酶的mRNA水平也发生改变；其中，断奶后犊牛丙酮酸羧化酶水平较低（P < 0.05），磷酸烯醇丙酮酸羧化激酶2 （PCK2）水平有升高趋势（P = 0.08）。然而，断奶后PCK1没有改变。血浆肝脏应激指标水平也发生了变化，断奶后犊牛的天冬氨酸转氨酶、丙氨酸转氨酶和乳酸脱氢酶显著升高（P < 0.05）。断奶犊牛肝组织中趋化蛋白含量较低（P < 0.05），但其转录水平没有变化。断奶后血浆趋化素蛋白丰度无变化（P = 0.95）。综上所述，这些数据表明，断奶引起生理应激并改变肝脏代谢，导致肝脏内趋化素蛋白表达下调，表明趋化素通过抑制肝脏糖异生作用而上调肝脏PCK2表达。
Chemerin, originally known as a chemoattractant derived from adipose tissue and the liver, has been reported to have regulatory functions in gluconeogenesis, peripheral insulin sensitivity, and insulin secretion. This study was conducted to assess the postweaning changes in expression of this cytokine and its physiological role in the modification of glucose metabolism associated with weaning. Eighteen tissue samples were collected from Holstein calves (90 d of age; n = 4) to investigate the tissue distributions of chemerin and its receptors genes. Chemerin was highly expressed in the liver, and secreted chemerin protein was found in the plasma. Among the receptors of chemerin, chemokine-like receptor 1 and C-C chemokine receptor-like 2 were ubiquitously expressed whereas G protein-coupled receptor 1 was predominantly expressed in the liver. The changes in glucose metabolism and expression of these genes after weaning were assessed by comparing suckling calves (n = 6) and weaned calves (n = 8) of Japanese Black cattle. No significant difference was observed in plasma glucose levels between suckling and weaned calves (P = 0.22), whereas the plasma level of total ketone bodies was significantly higher in weaned calves (P < 0.01). Plasma levels of insulin and cortisol did not differ between suckling and weaned calves. The mRNA levels of certain key enzymes involved in hepatic gluconeogenesis were also altered; for instance, pyruvate carboxylase level was lower in postweaning calves (P < 0.05) and phosphoenolpyruvate carboxykinase 2 (PCK2) level tended to be higher after weaning (P = 0.08). However, PCK1 was not altered after weaning. The plasma levels of hepatic stress indicators were also changed, with aspartate transaminase, alanine transaminase, and lactate dehydrogenase being significantly elevated in postweaning calves (P < 0.05). Chemerin protein in liver tissue was less abundant in weaned calves (P < 0.05), although there were no changes in its transcript levels. The abundance of plasma chemerin protein did not change after weaning (P = 0.95). In summary, these data indicate that as a consequence of weaning, which causes physiological stress and alters hepatic metabolism, chemerin protein expression within the liver is downregulated, indicating that chemerin plays a role in the upregulation of hepatic PCK2 expression via its inhibitory effect on hepatic gluconeogenesis.