Structural correlates of stimulated and inhibited secretion: electron microscopic observations of somatotrophs in perifused rat pituitary.
Structural correlates of stimulated and inhibited secretion: electron microscopic observations of somatotrophs in perifused rat pituitary.
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刺激和抑制分泌的结构相关性：灌注大鼠垂体中生长激素的电子显微镜观察。
DOI：
10.1159/000124476
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发表时间：
1986
影响因子：
4.1
通讯作者：
Tyler,JM
中科院分区：
文献类型：
--
作者：
Stachura,ME;Costoff,A;Tyler,JM
细胞内储存的大鼠生长激素（rGH）在体外释放对几种分泌剂的反应表明，rGH储存至少分为两个“室”或“池”。第一种是立即释放的隔室，其响应是简短的。第二个是一个隔间，用来满足更长时间的分泌需求。这些观察结果要么与单一的、同质的生长营养物质群体一致，每个生长营养物质群体都表现出功能分区的储存，要么与异质的生长营养物质群体一致，每个家庭都提供一种观察到的反应。我们使用浸润/形态测量系统寻找这种功能区隔化的解剖学相关性，该系统允许检查第一种模型，同时不排除第二种模型。我们选择了一种已建立的扩散方案进行研究，该方案的行为是一致的，其先前的结果表明了立即释放池的填充和排空阶段。进行了5次平行垂体碎片灌注。第五次灌注用于监测rGH释放，并确认实验符合标准方式。在基础灌注期间拆除第一个垂体腔以获得用于显微镜的组织，在暴露于25 nMSRIF时拆除第二个垂体腔，在暴露于25 nMSRIF和1 mM(Bu)2cAMP时拆除第三个垂体腔，在SRIF退出后快速释放后不久拆除第四个垂体腔。SRIF存在时，生长滋长性肉芽减少54%，添加（Bu）2cAMP后，生长滋长性肉芽增加45%。颗粒的细胞内分布也随刺激性和抑制性分泌因子的变化而波动。此外，在srif诱导的rGH释放抑制过程中，次级溶酶体增加了549%。25 nMSRIF的存在使细胞体积减少37%；添加（Bu）2cAMP并没有逆转这种SRIF效应。我们得出的结论是，我们称之为“立即释放池”的体外释放现象在近膜颗粒中具有解剖学相关性，rGH释放的抑制伴随着次级溶酶体活性的显着增加，尽管可能存在异质生长因子群体，但个体细胞具有一系列与功能区隔化一致的反应。rGH的释放不仅涉及解剖上可证明的隔室之间的颗粒运动，而且还涉及躯体营养体积的重大和快速变化。
The in vitro release of stored intracellular rat growth hormone (rGH) in response to several secretagogues suggests the functional division of rGH storage into at least two ‘compartments’ or ‘pools’. The first is an immediately releasable compartment whose response is brief. The second is a compartment which responds to more prolonged secretory demands. These observations are consistent with either a single, homogeneous population of somatotrophs, each of which exhibits functional compartmentalization of storage, or with heterogeneous populations of somatotrophs, each family of which provides one of the observed responses. We sought anatomical correlates of this functional compartmentalization using a perifusion/morphometric system which permitted examination of the first model while not excluding the second model. We selected for study an established perifusion protocol whose behavior was consistent and whose previous results suggested phases of both filling and emptying of the immediate release pool. Five parallel perifusions of pituitary fragments were run. The fifth perifusion was used to monitor rGH release and to confirm that the experiment had behaved in standard fashion. The first pituitary chamber was dismantled during basal perifusion to obtain tissue for microscopy, the next during exposure to 25 nMSRIF, the third during exposure to both 25 nMSRIF and 1 mM(Bu)2cAMP, and the fourth shortly after the rapid release which followed SRIF withdrawal. Somatotroph granulation was decreased by 54% in the presence of SRIF, and then increased by 45% with the addition of (Bu)2cAMP. The intracellular distribution of granules also fluctuated in relation to the stimulatory and inhibitory secretagogues. In addition, secondary lysosomes increased by 549% during SRIF-induced inhibition of rGH release. Cell volume was decreased by 37% in the presence of 25 nMSRIF; the addition of (Bu)2cAMP did not reverse this SRIF effect. We conclude that the in vitro release phenomenon we have termed the ‘immediate release pool’ has an anatomic correlate in juxtamembrane granules, that inhibition of rGH release is accompanied by a significant increase in secondary lysosome activity, that while heterogeneous populations of somatotrophs probably exist, individual cells possess a range of responses consistent with functional compartmentalization, and that rGH release involves not only granule movement between anatomically demonstrable compartments, but in addition, major and rapid changes in somatotroph volume.