Decreased insulin response in dairy cows following a four-day fast to induce hepatic lipidosis
Decreased insulin response in dairy cows following a four-day fast to induce hepatic lipidosis
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DOI：
10.3168/jds.s0022-0302(06)72572-3
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发表时间：
2006-08-01
影响因子：
3.5
通讯作者：
Oetzel, G. R.
中科院分区：
文献类型：
--
作者：
Oikawa, S.;Oetzel, G. R.
负能量平衡与奶牛脂肪肝、胰岛素抵抗和健康受损有关。此前有报道称，4 天禁食模型可使肝脏甘油三酯增加 2.5 倍以上。本研究的目的是评估该禁食模型中的胰岛素反应。将非泌乳、非妊娠荷斯坦奶牛禁食 4 天（6 头奶牛）或作为对照奶牛（4 头奶牛）连续饲喂。禁食前 5 天、禁食期间、禁食 4 天后立即、禁食后 8 天和禁食后 16 天收集样本。与对照奶牛相比，禁食期结束时，禁食奶牛的肝脏甘油三酯含量更高（湿重基础上分别为 49.4 毫克/克和 16.2 毫克/克）。禁食期结束时，禁食奶牛的血浆非酯化脂肪酸 (NEFA) 浓度也增加（1.24 vs. 0.21 mmol/L），血浆 β-羟基丁酸 (BHBA) 浓度也增加。实验结束时，禁食奶牛的肝脏甘油三酯、血浆 NEFA 和血浆 BHBA 恢复到禁食前浓度。血浆葡萄糖浓度不受禁食的影响。与禁食结束时的对照奶牛相比，禁食奶牛的血浆胰岛素浓度降低（6.3 vs. 14.1 mu U/mL），胰岛素刺激的血糖降低也减少（24.9 vs. 48.6%），表明胰岛素反应减弱。胰岛素反应与血浆NEFA和肝脏甘油三酯呈负相关。胰岛素反应降低可能是能量负平衡和肝脂质沉积的重要并发症。
Negative energy balance has been implicated in the development of fatty liver, insulin resistance, and impaired health in dairy cows. A 4-d fasting model previously was reported to increase liver triglycerides more than 2.5-fold. The purpose of the present study was to evaluate insulin response in this fasting model. Nonlactating, nonpregnant Holstein cows were fasted for 4 d ( 6 cows) or fed continuously as control cows ( 4 cows). Samples were collected 5 d before fasting, during fasting, and immediately after the 4-d fast, 8 d after the fast, and 16 d after the fast. Fasted cows had greater liver triglyceride content ( 49.4 vs. 16.2 mg/g, wet-weight basis) at the end of the fasting period compared with control cows. Fasted cows also had increased plasma nonesterified fatty acid ( NEFA) concentrations ( 1.24 vs. 0.21 mmol/L) and increased plasma beta-hydroxybutyrate ( BHBA) concentrations at the end of the fasting period. Liver triglyceride, plasma NEFA, and plasma BHBA in fasted cows returned to prefasting concentrations by the end of the experiment. Plasma glucose concentrations were not affected by fasting. Plasma insulin concentrations were decreased ( 6.3 vs. 14.1 mu U/mL) and insulin-stimulated blood glucose reduction was decreased ( 24.9 vs. 48.6%) in the fasted cows compared with control cows at the end of the fast, indicating reduced insulin response. Insulin response was negatively correlated with plasma NEFA and liver triglycerides. Decreased insulin response may be an important complication of negative energy balance and hepatic lipidosis.