Christensen R A, Malinowski K, Massenzio A M, Hafs H D, Scanes C G
Department of Animal Science, Rutgers-The State University of New Jersey, New Brunswick 08903, USA.
J Anim Sci. 1997 May;75(5):1351-8. doi: 10.2527/1997.7551351x.
Two studies were performed with Standardbred geldings 7 to 21 yr of age to determine the sequence of changes in blood plasma concentrations of some hormones and metabolites during feed deprivation for 48 h and for 12 h after refeeding. Plasma hormone and metabolite concentrations were determined with methods validated for horse plasma. Insulin-like growth factor binding proteins (IGFBP) were determined with radioligand analysis following SDS-PAGE electrophoresis. In both experiments, plasma concentrations of triiodothyronine and thyroxine decreased (P < .01) during feed deprivation and increased (P < .01) during refeeding. Plasma glucose and IGF-I either decreased or were not altered during feed deprivation. In contrast, plasma concentrations of NEFA and urea nitrogen increased (P < .01) during feed deprivation and decreased (P < .01) during the refeeding period. Plasma somatotropin (ST) increased (P < .01) approximately 80% at 24 to 36 h of feed deprivation, declined (P < .01) to control values at 48 h of feed deprivation, increased (P < .01) nearly three fold at 3 h after refeeding, and returned to control values by 6 h after refeeding. We identified five IGFBP, and their plasma concentrations were not significantly altered during feed deprivation or following refeeding. We conclude that metabolite availability during feed deprivation and following refeeding alters the secretion of thyroid hormones, ST, and possibly IGF-I, thereby maintaining homeostasis in horses.
对7至21岁的标准赛马 geldings 进行了两项研究，以确定在禁食48小时及重新喂食后12小时期间，某些激素和代谢物的血浆浓度变化顺序。采用经过马血浆验证的方法测定血浆激素和代谢物浓度。在SDS - PAGE电泳后，通过放射性配体分析测定胰岛素样生长因子结合蛋白（IGFBP）。在两项实验中，禁食期间三碘甲状腺原氨酸和甲状腺素的血浆浓度降低（P < 0.01），重新喂食期间升高（P < 0.01）。禁食期间血浆葡萄糖和IGF - I要么降低，要么未改变。相比之下，禁食期间非酯化脂肪酸（NEFA）和尿素氮的血浆浓度升高（P < 0.01），重新喂食期间降低（P < 0.01）。禁食24至36小时时，血浆生长激素（ST）升高（P < 0.01）约80%，禁食48小时时降至对照值（P < 0.01），重新喂食后3小时升高（P < 0.01）近三倍，并在重新喂食后6小时恢复到对照值。我们鉴定出五种IGFBP，其血浆浓度在禁食期间或重新喂食后未发生显著变化。我们得出结论，禁食期间和重新喂食后的代谢物可用性改变了甲状腺激素、ST以及可能的IGF - I的分泌，从而维持马的体内平衡。
