Demonstration and characterization of the specific binding of growth hormone-releasing peptide to rat anterior pituitary and hypothalamic membranes.
Demonstration and characterization of the specific binding of growth hormone-releasing peptide to rat anterior pituitary and hypothalamic membranes.
复制标题
生长激素释放肽与大鼠垂体前叶和下丘脑膜特异性结合的证明和表征。
DOI：
10.1016/0006-291x(91)91775-8
复制
发表时间：
1991
影响因子：
3.1
通讯作者：
Bowers,CY
中科院分区：
文献类型：
--
作者：
Sethumadhavan,K;Veeraragavan,K;Bowers,CY
由于生长激素释放肽（GHRP）His-d-Trp-Ala-Trp-d-Phe-Lys-NH2被发现可以通过对垂体和下丘脑的互补但尚未明确定义的作用来特异性释放生长激素，因此进行了体外研究来证明和表征大鼠垂体前叶和下丘脑外周膜上的GHRP结合位点。使用[125I]Tyr-Ala-GHRP 作为放射性配体建立了最佳结合测定条件。膜结合位点是特异性的、可逆的、可饱和的并且依赖于时间、温度、pH 和浓度。竞争实验的计算机分析表明垂体和下丘脑膜中存在两类结合位点。在两种组织中，在 pH 5.0 时观察到最大特异性结合，而不是在生理 pH 值下。用胰蛋白酶预处理膜可防止特异性结合。 Bmax 的增加具有统计学意义，垂体和下丘脑分别增加了 2.0 至 8.9 倍和 5.8 至 11.2 倍，而亲和常数 (Kds) 不显着。在影响生长激素释放 GH 的合成和天然神经肽中，只有 (d-Lys3)GHRP、P 物质拮抗剂和生长激素释放因子类似物是两种组织中 GHRP 结合的有效抑制剂。
Since the growth hormone-releasing peptide (GHRP), His-d-Trp-Ala-Trp-d-Phe-Lys-NH2, was found to specifically release growth hormone by a complementary but yet not clearly defined action on the pituitary as well as the hypothalamus,in vitrostudies have been performed to demonstrate and characterize GHRP binding sites on peripheral membranes of both the rat anterior pituitary and hypothalamus. Optimum binding assay conditions were established using [125I]Tyr-Ala-GHRP as the radioligand. The membrane binding sites were specific, reversible, saturable and time, temperature, pH and concentration dependent. Computerized analyses of competition experiments suggested two classes of binding sites in both pituitary and hypothalamic membranes. The maximum specific binding was observed at pH 5.0 than the physiological pH in both tissues. Pretreatment of the membranes with trypsin prevented specific binding. The increase in Bmaxwas statistically significant and showed a 2.0- to 8.9-fold and 5.8- to 11.2-fold in pituitary and hypothalamus, respectively, whereas the affinity constants (Kds) were not significant. Of the synthetic and natural neuropeptides that influence the release of GH from somatotrophs, only (d-Lys3)GHRP, substance P antagonists and growth hormone-releasing factor analog were potent inhibitors of GHRP binding in both tissues.