Veldhuis J D, Iranmanesh A, Johnson M L, Lizarralde G
Division of Endocrinology and Metabolism, University of Virginia Health Sciences Center, Charlottesville 22908.
J Clin Endocrinol Metab. 1990 Dec;71(6):1616-23. doi: 10.1210/jcem-71-6-1616.
To evaluate the nature of anterior pituitary secretory events in vivo, we have applied a novel waveform-independent deconvolution technique that dissects the underlying secretory behavior of endocrine glands quantitatively from available serial plasma hormone concentration measurements assuming one- or two-compartment elimination kinetics. We used this new tool to ask the following physiological questions. 1) Does the pituitary gland secrete exclusively in randomly dispersed bursts, and/or does a tonic (constitutive) mode of interburst hormone secretion exist? 2) What secretory mechanisms generate the nyctohemeral rhythms in plasma hormone concentrations? Analysis of 24-h plasma concentration profiles of GH, LH, FSH, PRL, TSH, ACTH, and beta-endorphin (n = 6-8 men/group) revealed that 1) pituitary secretion in vivo occurs in an exclusively burst-like mode for all hormones except TSH and PRL (for the latter two, a mixed burst and constitutive mode pertained); 2) significant nyctohemeral regulation of secretory burst frequency alone was not demonstrated for any hormone; 3) prominent 24-h variations in secretory burst amplitude alone were delineated for ACTH and LH; 4) TSH, GH, and beta-endorphin were both frequency and amplitude controlled; 5) no significant diurnal variations in FSH secretory parameters occurred; and 6) a fixed hormone half-life yielded fits of the 24-h data series with a normalized residual variance of less than 8%. We conclude that the normal human anterior pituitary gland releases its multiple (glyco)protein hormones via punctuated secretory episodes unassociated with tonic basal (constitutive) hormone secretion, except in the case of TSH and PRL. Hormone-specific amplitude and/or frequency control of secretory burst activity over 24 h provides the mechanistic basis for the classically recognized 24-h rhythms in plasma concentrations of adenohypophyseal hormones in men.
为了评估体内垂体前叶分泌活动的性质，我们应用了一种新型的与波形无关的去卷积技术，该技术可根据可用的系列血浆激素浓度测量值，在假设单室或双室消除动力学的情况下，定量剖析内分泌腺的潜在分泌行为。我们使用这个新工具来探讨以下生理问题。1）垂体是否仅以随机分散的脉冲形式分泌，和/或是否存在脉冲间期激素分泌的持续性（组成性）模式？2）哪些分泌机制产生血浆激素浓度的昼夜节律？对生长激素（GH）、促黄体生成素（LH）、促卵泡激素（FSH）、催乳素（PRL）、促甲状腺激素（TSH）、促肾上腺皮质激素（ACTH）和β-内啡肽（每组n = 6 - 8名男性）的24小时血浆浓度曲线分析表明：1）除TSH和PRL外（后两者为混合脉冲和组成性模式），所有激素在体内的垂体分泌均仅以脉冲样模式发生；2）未证明任何激素仅存在显著的昼夜调节分泌脉冲频率；3）仅确定ACTH和LH的分泌脉冲幅度有显著的24小时变化；4）TSH、GH和β-内啡肽的分泌受频率和幅度控制；5）FSH分泌参数无显著昼夜变化；6）固定的激素半衰期对24小时数据系列的拟合产生的标准化残余方差小于8%。我们得出结论，正常人类垂体前叶通过间断性分泌事件释放其多种（糖）蛋白激素，除TSH和PRL外，这些分泌事件与持续性基础（组成性）激素分泌无关。激素特异性的分泌脉冲活动幅度和/或频率控制为男性腺垂体激素血浆浓度经典公认的24小时节律提供了机制基础。
