THE SOMATOTROPIC AXIS IN YOUNG STEERS - INFLUENCE OF NUTRITIONAL-STATUS ON PULSATILE RELEASE OF GROWTH-HORMONE AND CIRCULATING CONCENTRATIONS OF INSULIN-LIKE GROWTH FACTOR-I
THE SOMATOTROPIC AXIS IN YOUNG STEERS - INFLUENCE OF NUTRITIONAL-STATUS ON PULSATILE RELEASE OF GROWTH-HORMONE AND CIRCULATING CONCENTRATIONS OF INSULIN-LIKE GROWTH FACTOR-I
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DOI：
10.1677/joe.0.1110209
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发表时间：
1986-11-01
影响因子：
4
通讯作者：
GLUCKMAN, PD
中科院分区：
文献类型：
--
作者：
BREIER, BH;BASS, JJ;GLUCKMAN, PD
在 15 头年轻安格斯公牛中研究了三种不同营养水平下血浆 GH 分布与胰岛素样生长因子 I (IGF-1) 循环浓度之间的关系，这三种营养水平分别代表高、中和低营养水平（每天活重的 3%、1.8% 和 1% 干物质）。所有阉牛都维持 3% 干物质 5 周，然后在三种营养平面之一上维持 4 周，然后全部恢复 3% 干物质 3 周。在研究的每个阶段结束时，每隔 15 分钟通过颈静脉导管采集血液样本，持续 25 小时，并且每周 2 天采集额外样本。仅在高营养摄入量的阉牛中，GH 的脉冲式释放会间歇性地发生，并且在夜间和早晨时段增加。中平面和低平面的饲喂量的减少消除了昼夜节律，并显着增加了平均血浆 GH 浓度、GH 脉冲的幅度和 GH 曲线下的面积。 GH 基线浓度和脉搏频率不会因营养控制而改变。重新喂食后，先前营养不良的两个组的血浆 GH 浓度均下降，而那些喂食 1% 干物质的组在重新喂食 10 天后其水平仍然升高。血浆 IGF-1 浓度没有表现出周期性。营养缺乏时，仅在负能量平衡（1% 组）时观察到 IGF-1 浓度下降。在该组中，血浆IGF-1浓度在重新调整后1周内逐渐恢复。每个营养层面的 GH 和 IGF-1 释放之间的不同关系表明，在中等和低水平的采食量下，组织对 GH 的不敏感性可能存在于外周，也可能存在于中枢。有人认为，营养状况可能通过调节 GH 的组织敏感性，成为决定出生后反刍动物生长和生长轴调节的主要因素。
The relationship between plasma GH profiles and circulating concentrations of insulin-like growth factor I (IGF-1) at three different planes of nutrition, chosen to represent a high, medium and low level of nutrition (3%, 1.8% and 1% dry matter of liveweight per day) was studied in 15 young Angus steers. All steers were maintained on 3% dry matter for 5 weeks, then on one of three nutritional planes for 4 weeks and then all were returned to 3% dry matter for 3 weeks. Blood was sampled through jugular catheters at 15-min intervals for 25 h at the end of each phase of the study and additional samples were taken on 2 days each week. Pulsatile release of GH occurred episodically with a diurnal increase during night and morning hours only in steers on high nutritional intakes. Reduced feeding at both the medium and the low plane abolished the diurnal rhythm and significantly increased mean plasma GH concentrations, the amplitude of GH pulses and the area under the GH profiles. Baseline concentrations of GH and pulse frequency did not change through nutritional manipulation. Upon realimentation, plasma GH concentrations decreased in both previously undernourished groups, with those fed 1% dry matter still having increased levels 10 days after refeeding. Plasma IGF-1 concentrations showed no periodicity. With nutritional deprivation, a decrease in IGF-1 concentration was observed only at negative energy balance (1% group). In this group plasma IGF-1 concentrations were progressively restored within 1 week of realimentation. The different relationship between GH and IGF-1 release at each plane of nutrition suggests that at both medium and low levels of feed intake, tissue insensitivity to GH may exist peripherally and perhaps centrally. It is suggested that nutritional status may, through modulation of tissue sensitivity of GH, be a primary factor in determining growth and the regulation of the somatotrophic axis in the postnatal ruminant.