McCann J P, Bergman E N, Beermann D H
Department of Physiology, New York State College of Veterinary Medicine, Ithaca.
J Nutr. 1992 Mar;122(3):496-505. doi: 10.1093/jn/122.3.496.
The chronology of changes in body weights, food intakes and plasma concentrations of selected metabolic hormones and metabolites were determined in sheep during the induction (dynamic) and static phases of diet-induced obesity. Lean adult Dorset ewes weighing 47 kg were fed a pelleted hay-grain diet at maintenance (lean; n = 7) or were fed the same diet ad libitum to a maximum intake of 3 kg.sheep-1.d-1 (obese; n = 8) for 78 wk. Body weight of obese sheep doubled (97 vs. 47 kg) by wk 42 of ad libitum intake. Average daily intakes of dry matter (12.8 g/kg) and digestible energy (165 kJ/kg) were comparable in maintenance-fed lean sheep and ad libitum-fed obese sheep consuming maintenance after wk 50, which began the static phase of obesity. Fasting plasma concentrations of insulin in the obese sheep increased steadily from 50 +/- 6 pmol/L at wk 0 to a sustained plateau of 249 +/- 21 pmol/L after wk 30. Plasma levels of glucose, immunoreactive glucagon and thyroid hormones were consistently greater (P less than 0.05) in obese sheep than in lean sheep after wk 2, 3 and 25, respectively, of the experiment. Concentration of lipid (49 vs. 25%) in the carcass stripped of internal fat was greater (P less than 0.01) in obese sheep than in lean sheep, but concentration of protein (10.4 vs. 15.3%) was less in the heavier carcass (58 vs. 24 kg) of the obese sheep. We conclude that hyperinsulinemia and abnormal fuel metabolism are early events during dynamic obesity and these defects persist throughout the static phase of obesity. Maintenance energy requirements relative to unit body weight (W1.0) seem similar in lean and dietary obese sheep.
在饮食诱导肥胖的诱导（动态）和静态阶段，测定了绵羊体重、食物摄入量以及选定代谢激素和代谢物的血浆浓度变化的时间顺序。体重47千克的成年瘦型多塞特母羊，维持期饲喂颗粒状干草谷物日粮（瘦型；n = 7），或随意采食相同日粮，最大摄入量为3千克·绵羊⁻¹·天⁻¹（肥胖型；n = 8），持续78周。随意采食至第42周时，肥胖绵羊的体重翻倍（97千克对47千克）。维持期饲喂的瘦羊和第50周后随意采食并消耗维持量的肥胖羊，干物质平均日摄入量（12.8克/千克）和可消化能量平均日摄入量（165千焦/千克）相当，第50周开始进入肥胖的静态阶段。肥胖绵羊空腹血浆胰岛素浓度从第0周的50±6皮摩尔/升稳步增加，第30周后持续稳定在249±21皮摩尔/升。实验分别在第2周、第3周和第25周后，肥胖绵羊的血浆葡萄糖、免疫反应性胰高血糖素和甲状腺激素水平始终高于瘦羊（P < 0.05）。去除内脏脂肪的胴体中，肥胖绵羊的脂肪浓度（49%对25%）高于瘦羊（P < 0.01），但肥胖羊较重的胴体（58千克对24千克）中蛋白质浓度（10.4%对15.3%）较低。我们得出结论，高胰岛素血症和异常燃料代谢是动态肥胖早期出现的情况，这些缺陷在肥胖的静态阶段持续存在。相对于单位体重（W¹.⁰）的维持能量需求，瘦羊和饮食诱导肥胖的绵羊似乎相似。
