Koopmans Sietse J, van der Meulen Jan, Dekker Ruud, Corbijn Henk, Mroz Zdzislaw
Division of Nutrition and Food, Edelhertweg 15, P.O. Box 65, 8200 AB Lelystad, The Netherlands.
Physiol Behav. 2005 Mar 16;84(3):497-503. doi: 10.1016/j.physbeh.2005.01.017.
Diurnal rhythms in plasma cortisol, insulin, glucose, lactate and urea concentrations were investigated in eight catheterized pigs of approximately 35 kg BW. Pigs were fed isoenergetic/isoproteinic diets at a restricted level (2.5 x maintenance requirement for energy) in two daily rations (06:00 and 18:00 hours) in order to obtain equal intervals between feed intake. Preprandial plasma cortisol concentration was 22+/-3 ng/mL in the morning and 14+/-2 ng/mL in the evening (p<0.025), whereas the concentrations of insulin, glucose, lactate, and urea were similar. In the postprandial period in the morning (06:00-09:00 hours) plasma cortisol, insulin and lactate concentrations (expressed as the total area under the curve) were greater (p<0.001) compared to the evening (18:00-21:00 hours) by 100%, 42%, and 24%, respectively, while postprandial plasma glucose and urea concentrations were not affected by time of the meal. When postprandial plasma concentrations were expressed as a response over preprandial concentrations (decremental or incremental area under the curve), the diurnal rhythm was not observed for cortisol and glucose, persisted for insulin and lactate, and appeared for urea with a smaller postprandial urea response (p<0.05) in the morning compared to the evening. We conclude that the diurnal rhythm in plasma cortisol is independent of feeding whereas the diurnal rhythms in plasma insulin, lactate and urea are unveiled by the morning/evening meals in pigs. At equal 12-h intervals between meals, the postprandial responses of lactate and urea show diurnal variations, each in a specific manner, which suggest decreased postprandial efficiency of carbohydrate metabolism and increased postprandial efficiency of protein metabolism in the morning compared to the evening.
在8头体重约35千克、已插入导管的猪身上，研究了血浆皮质醇、胰岛素、葡萄糖、乳酸和尿素浓度的昼夜节律。为了使进食间隔相等，给猪饲喂能量/蛋白质等能/等蛋白日粮，限制水平为（能量维持需要量的2.5倍），分两次每日定量投喂（06:00和18:00）。餐前血浆皮质醇浓度上午为22±3纳克/毫升，晚上为14±2纳克/毫升（p<0.025），而胰岛素、葡萄糖, 乳酸和尿素的浓度相似。在上午的餐后阶段（06:00 - 09:00），血浆皮质醇、胰岛素和乳酸浓度（以曲线下总面积表示）比晚上（18:00 - 21:00）分别高100%、42%和24%（p<0.001），而餐后血浆葡萄糖和尿素浓度不受进餐时间影响。当将餐后血浆浓度表示为相对于餐前浓度的反应（曲线下减量或增量面积）时，未观察到皮质醇和葡萄糖的昼夜节律，胰岛素和乳酸的昼夜节律持续存在，尿素出现昼夜节律，与晚上相比，早上餐后尿素反应较小（p<0.05）。我们得出结论，血浆皮质醇的昼夜节律与进食无关，而血浆胰岛素、乳酸和尿素的昼夜节律在猪中由早晚餐揭示。在餐间间隔相等的12小时内，乳酸和尿素的餐后反应呈现昼夜变化，各有特定方式，这表明与晚上相比，早上碳水化合物代谢的餐后效率降低，蛋白质代谢的餐后效率增加。
