Temporal dynamics of pituitary prolactin depletion and release in three strains of rats.
Temporal dynamics of pituitary prolactin depletion and release in three strains of rats.
复制标题
三种大鼠品系垂体催乳素消耗和释放的时间动态。
DOI：
10.1016/0024-3205(91)90638-r
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发表时间：
1991
期刊：
影响因子：
6.1
通讯作者：
Lawson,DM
中科院分区：
文献类型：
--
作者：
Phelps,SJ;Moy,JA;Lawson,DM
以前的报道表明，在从催乳素释放之前，脑下垂体催乳素会迅速转化为一种较难溶的形式，但更容易释放。这种转变的一个表现是，无论是在体内还是体外，垂体催乳素的消耗都明显大于同步释放。本研究的目的是在体外比较三种不同品系的去卵巢雌激素处理大鼠的脑垂体耗竭和释放的大小和时间动态，以评估不同品系对转化过程的影响。成年Wistar-Furth(WF)、SD(SD)和Long-Evans(Long-Evans，Long-Evans)大鼠每组7天后断头处死。注射聚雌二醇磷酸盐100μg。在没有多巴胺或其他催乳素分泌剂的情况下，迅速取出垂体并将其切成四个季度，孵育长达4小时。来自每个菌株的代表性片段没有孵化，但被快速冷冻以测量预孵化含量。在30、60、120、180和240min从每个菌株中取出片段，用于催乳素含量的测定。每隔30分钟收集一次培养液，换成新鲜的培养液。这些实验重复了两次。以NIAMDD-RP-1为标准，用放射免疫法测定培养液和垂体匀浆中催乳素的含量。在所有三种菌株中，催乳素的释放量约为4小时内从脑垂体排出的催乳素的30-50%。菌株在这种差异的大小和发生的时间过程中各不相同。当数据以μg催乳素/mg垂体表示时，WF和SD大鼠比LE大鼠表现出更大的催乳素消耗和释放。当数据表示为可释放的催乳素百分比时，品系之间的耗竭差异消失，LE大鼠释放的可释放催乳素的百分比明显高于其他两个品系。我们认为，垂体催乳素在释放前经历了一个转化过程，使其从垂体中消失，但不出现在培养基中。我们进一步得出结论，这一过程的大小和时间动力学在所有品系的大鼠中并不相同。
Previous reports have shown that pituitary prolactin is rapidly transformed to a less soluble, but much more releasable, form prior to release from the lactotroph. One manifestation of this transformation is that pituitary prolactin depletion is significantly greater than concurrent release both in vivo and in vitro. The objective of this study was to compare the magnitude and temporal dynamics of depletion and release from pituitaries of ovariectomized estrogen-treated rats of three different strains in vitro to assess the effect of strain on the transformation process. Mature ovariectomized Wistar-Furth (WF), Sprague-Dawley (SD) and Long-Evans (LE) rats (7–10/group) were killed by decapitation 7 days after a single s.c. injection of 100 μg of polystradiol phosphate. The anterior pituitaries were quickly removed and cut into quarters which were incubated for up to 4 hrs in the absence of dopamine or other prolactin secretagogues. Representative fragments from each strain were not incubated but were snap frozen to measure pre-incubation content. Fragments from each strain were removed from incubation at 30, 60, 120, 180 and 240 min for prolactin content measurement. Medium was collected at 30 min intervals and replaced with fresh medium. The experiments were repeated twice. Prolactin in medium and pituitary homogenates was measured by radioimmunoassays using NIAMDD-RP-1 as standard. In all three stains release of prolactin was approximately 30–50% of the prolactin depleted from the pituitary in 4 hrs. Strains varied in the magnitude of this difference and the time course over which it occurred. WF and SD rats showed significantly greater depletion and release of prolactin than did LE rats when the data were expressed as μg prolactin/mg pituitary. When the data were expressed as a percentage of prolactin available for release, the differences in depletion between strains disappeared and the LE rats released a significantly greater percentage of the prolactin available for release than did the other two strains. We conclude that pituitary prolactin undergoes a process of transformation prior to release which causes it to disappear from the pituitary but not appear in culture medium. We further conclude that the magnitude and temporal dynamics of this process are not equivalent across all strains of rats.