Differential effects of pituitary stalk-section on posterior pituitary and hypothalamic contents of prolactin-releasing factor, oxytocin, dopamine and beta-endorphin.
Differential effects of pituitary stalk-section on posterior pituitary and hypothalamic contents of prolactin-releasing factor, oxytocin, dopamine and beta-endorphin.
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垂体柄切断对垂体后叶和下丘脑催乳素释放因子、催产素、多巴胺和β-内啡肽含量的不同影响。
DOI：
10.1159/000125028
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发表时间：
1988
影响因子：
4.1
通讯作者：
Ben-Jonathan,N
中科院分区：
文献类型：
--
作者：
Hyde,JF;Murai,I;Ben-Jonathan,N
我们最近发现，垂体后叶(神经中间叶)含有一种强有力的催乳素(PRL)释放因子(PRF)，这与已知的PRL促分泌剂不同。垂体后叶PRF似乎是一种小肽，其细胞来源不明。本研究的目的是：(1)确定促性腺激素释放因子是从下丘脑运输来的，还是在脑垂体腺内合成的；(2)比较促性腺激素释放因子活性的变化与垂体后叶β-内啡肽(β-End)、催产素(Oxy)和多巴胺(DA)含量的变化。在垂体SS或假手术(Sham)后1周或2周，分析垂体后叶和下丘脑内侧基底核(MBH)的酸性提取物的激素含量。测定垂体前叶细胞分泌催乳素的活性，高效液相色谱法测定DA，放射免疫分析法测定Oxy和β-End水平。在SS后1周和2周，垂体后叶中的Oxy和DA浓度均下降了95%以上。SS后1周和2周，垂体后叶PRF活性分别下降75%和90%。相反，与假手术组相比，在这两个时间点，垂体后叶的β-END水平分别增加了20%和60%。与垂体后叶不同的是，在SS后1周，MBH中的Oxy水平增加了123%，在2周时增加了1260%。这些增加可能反映了切断神经中含氧分泌囊泡的积聚。MBH中DA浓度呈双相分布。DA水平最初下降了70%，然后又上升，但仍比假手术水平低30%。DA水平发生这些变化的原因尚不清楚。结果表明：(1)与OXY和DA相似，但与β-END不同，PRF可能从下丘脑运输到垂体后叶；(2)MBH中PRF活性低，提示PRF可能是作为一种生物非活性前体合成的，其含量太低而无法检测到，或者是PRL分泌的抑制剂掩盖了PRF的活性。
We have recently shown that the posterior pituitary (neurointermediate lobe) contains a potent prolactin (PRL)-releasing factor (PRF) which is distinct from known PRL secretagogues. Posterior pituitary PRF appears to be a small peptide of an unknown cellular origin. Using pituitary stalk-sectioned (SS) male rats, the objectives of this study were: (1) to determine if PRF is transported from the hypothalamus or is synthesized within the pituitary gland, and (2) to compare changes in PRF activity with alterations in the posterior pituitary content of β-endorphin (β-END), oxytocin (OXY), and dopamine (DA). One or two weeks following pituitary SS or sham surgery (SHAM), acid extracts of the posterior pituitary and medial basal hypothalamus (MBH) were analyzed for their hormone content. PRF activity was assessed by determining the stimulation of PRL secretion from perifused anterior pituitary cells, DA was measured by HPLC, and OXY and β-END levels were determined by RIAs. OXY and DA concentrations in the posterior pituitary were reduced more than 95% at both 1 and 2 weeks after SS. PRF activity in the posterior pituitary was significantly reduced by 75 and 90%, 1 and 2 weeks after SS, respectively. In contrast, β-END levels in the posterior pituitary at these times increased 20 and 60%, as compared to SHAM rats. Unlike the posterior pituitary, OXY levels in the MBH increased 123% 1 week following SS, and 1,260% at 2 weeks. These increases may reflect the accumulation of OXY-containing secretory vesicles in the severed nerves. DA concentrations in the MBH showed a biphasic pattern. DA levels were initially decreased by 70%, and then increased, but remained 30% below SHAM levels. The reason for these alterations in DA levels is not clear. It is concluded that: (1) similar to OXY and DA, but unlike β-END, PRF is likely transported from the hypothalamus to the posterior pituitary, and (2) the low levels of PRF activity in the MBH suggest that PRF may be synthesized as a biologically inactive precursor, the amount of PRF in the MBH is too low to detect, or inhibitors of PRL secretion mask the PRF activity.