Fractional reduction of somatostatin concentration interacted with rat growth hormone releasing hormone to titrate the magnitude of pulsatile growth hormone and prolactin release in perifusion.
Fractional reduction of somatostatin concentration interacted with rat growth hormone releasing hormone to titrate the magnitude of pulsatile growth hormone and prolactin release in perifusion.
复制标题
生长抑素浓度的分数降低与大鼠生长激素释放激素相互作用，以滴定灌注中脉动生长激素和催乳素释放的幅度。
DOI：
10.1159/000125056
复制
发表时间：
1988
影响因子：
4.1
通讯作者：
Farmer,PK
中科院分区：
文献类型：
--
作者：
Stachura,ME;Tyler,JM;Farmer,PK
体内生长激素（GH）脉冲与下丘脑门脉生长激素释放激素（GH- rh）浓度升高有关，可通过GH- rh抗血清加以预防。生长激素脉冲也与门静脉生长抑素（SRIF）浓度的降低有关，尽管SRIF抗血清并不能消除生长激素脉冲。在体外，GH- rh脉冲和SRIF停药后是GH释放脉冲；GH- rh的存在增强了srif后GH的释放。我们提出了四个问题：(1)在体外GHRH-SRIF联合暴露期间，是否必须完全停用SRIF才能产生生长激素释放脉冲，或者SRIF是否存在阈值降低从而允许其释放？(2)当搏动性GH释放确实发生时，这是一种全有或无的现象，还是可以通过SRIF的分数还原来滴定？(3)在给药SRIF的同时改变GH- rh浓度是否会系统性地改变GH释放以响应SRIF的部分减少？(4)鉴于GH-RH对该系统中储存催乳素（PRL）释放的影响虽小但明显，那么SRIF的部分还原是否会平行改变PRL的释放？用氚预先标记激素储存的大鼠垂体组织在25 nMSRIF和3或10 nMrat GH-RH （rGH-RH）中联合灌注120分钟。然后，在保持rGH-RH浓度的同时，SRIF浓度保持不变（对照组）或降低到20、15、10、5或0 nm，持续60分钟。通过免疫沉淀法评估储存的rGH和rPRL的释放。rGH和rPRL脉冲的振幅通过SRIF分数还原来滴定。随着SRIF的算术减少，激素释放呈对数增长。改变rGH-RH浓度会改变响应曲线。结论：已知下丘脑门静脉GH-RH和SRIF浓度的变化可调节搏动释放的大小。
Growth hormone (GH) pulses in vivo are associated with increased hypothalamic portal growth hormone releasing hormone (GH-RH) concentration and can be prevented by GH-RH antisera. GH pulses are also associated with prior reduction of portal somatostatin (SRIF) concentrations, although SRIF antisera do not abolish GH pulses. In vitro, pulses of GH-RH as well as SRIF withdrawal are followed by pulses of GH release; the presence of GH-RH enhances post-SRIF GH release. We asked four questions: (1) During combined GHRH-SRIF exposure in vitro, must SRIF withdrawal be complete to produce a pulse of GH release, or is there a threshold diminution of SRIF which permits it? (2) When pulsatile GH release does occur, is it an all-or-none phenomenon, or is it titratable by fractional reduction of SRIF? (3) Does varying the GH-RH concentration while administering SRIF systematically alter GH release in response to fractional SRIF reduction? (4) Given a small but distinct effect of GH-RH on release of stored prolactin (PRL) in this system, does fractional SRIF reduction alter PRL release in parallel? Rat pituitary tissue whose hormone stores had been prelabeled with tritium was perifused for 120 min in combined 25 nMSRIF and 3 or 10 nMrat GH-RH (rGH-RH). Then, while maintaining rGH-RH concentrations, the SRIF concentration was left unchanged (control) or was reduced to 20, 15, 10, 5, or 0 nMfor 60 min. Release of stored rGH and rPRL was assessed by immunoprecipitation. The amplitude of rGH and rPRL pulses was titrated by fractional SRIF reduction. The hormone release increased logarithmically as SRIF was reduced arithmetically. Altering the rGH-RH concentration shifted the response curve. Conclusion: known changes of hypothalamic portal GH-RH and SRIF concentrations can regulate the magnitude of pulsatile release.