Marked changes of arginine vasopressin, oxytocin, and corticotropin-releasing hormone in hypophysial portal plasma after pituitary stalk damage in the rat.
Marked changes of arginine vasopressin, oxytocin, and corticotropin-releasing hormone in hypophysial portal plasma after pituitary stalk damage in the rat.
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DOI：
10.1210/endo.136.5.7720631
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发表时间：
1995-05
期刊：
影响因子：
4.8
通讯作者：
G. Makara;S. Sutton;S. Otto;P. Plotsky
中科院分区：
文献类型：
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作者：
G. Makara;S. Sutton;S. Otto;P. Plotsky
在钝的立体定向刀的帮助下机械压迫垂体柄导致垂体后神经失支配（PPD）并在损伤的近端发芽，导致垂体柄形成异位神经垂体。这为那些创伤性损伤切断了通往神经叶的神经纤维，但没有消除垂体-门静脉循环的病例提供了一个实验模型。在PPD后的不同时间，研究了PPD对推定促ACTH分泌物的垂体-门静脉浓度谱以及体外促ACTH基础分泌和刺激分泌的影响。PPD后1周，茎正中隆起提取物中精氨酸抗利尿素（AVP）和催产素（OT）含量显著升高，促肾上腺皮质激素释放激素（CRH）含量未受影响。在假手术或PPD手术后的各组大鼠中，麻醉下从横断茎的近端残端（或异位神经叶）采集的垂体门静脉血液中这三种神经肽的水平每隔一周测量一次。PPD后，垂体-门静脉AVP水平随时间单调升高，从PPD后1周的1.8倍升高到PPD后4周假手术组的最高浓度6倍。门脉血浆OT水平也表现出极度升高。相比之下，ppd后1周门静脉血浆CRH水平下降72%。我们认为垂体柄的机械损伤和随后的发芽将AVP和OT的分泌从神经叶转移到垂体柄。这导致门脉血浆AVP和OT浓度持续升高。由此产生的张力暴露于AVP和/或OT可能下调垂体前受体对这些神经垂体肽的反应，并间接减少CRH释放到门静脉循环中。
Mechanical compression of the pituitary stalk with the help of a blunt stereotaxic knife results in posterior pituitary denervation (PPD) and sprouting proximal to the injury, leading to formation of an ectopic neurohypophysis in the stalk. This provides an experimental model for those cases in which traumatic damage severs the nerve fibers to the neural lobe but does not obliterate the hypophysial-portal circulation. The effect of PPD on the hypophysial-portal concentration profile of putative ACTH secretagogues as well as basal and stimulated ACTH secretion in vitro were investigated at varying times after PPD. The contents of arginine vasopressin (AVP) and oxytocin (OT) in extracts of the stalk median eminence 1 week after PPD were markedly elevated, whereas corticotropin-releasing hormone (CRH) content was unaffected. Levels of these three neuropeptides in hypophysial-portal blood collected under anesthesia from the proximal stump of the transected stalk (or the ectopic neural lobe) were measured at weekly intervals in groups of rats after sham or PPD surgery. Hypophysial-portal AVP levels showed a monotonic increase with time after PPD from a 1.8-fold elevation at 1 week post-PPD to a maximum concentration 6-fold greater than that in sham groups at 4 weeks post-PPD. Portal plasma OT levels also exhibited extreme elevation. In contrast, portal plasma CRH levels showed an initial 72% decline 1 week post-PPD. We suggest that mechanical damage to the pituitary stalk and the subsequent sprouting redirected secretion of AVP and OT from the neural lobe to the pituitary stalk. This caused sustained elevations of portal plasma concentrations of AVP and OT. The resulting tonic exposure to AVP and/or OT may down-regulate anterior pituitary receptors to these neurohypophyseal peptides and indirectly decrease CRH release into the portal circulation.