Spokes R A, Lee Y C, Yiangou Y, Domin J, Bloom S R
Department of Medicine, Royal Postgraduate Medical School, Hammersmith Hospital, London, U.K.
Eur J Pharmacol. 1990 Jan 3;175(1):43-7. doi: 10.1016/0014-2999(90)90150-5.
Neuromedin-N, a hexapeptide recently isolated and purified from porcine spinal cord, has close sequence homology with the C-terminal region of the tridecapeptide neurotensin. Both peptides have a remarkably similar peripheral distribution. Little is known of the biological activity of neuromedin-N. Neurotensin and peptide histidine methionine are known to stimulate net fluid secretion into rat small intestine. We have therefore tested the effect of neuromedin-N and the hexapeptide neurotensin-(8-13), the smallest fully active analogue of neurotensin in this system, compared with that of neurotensin and peptide histidine methionine. All four peptides reduced net absorption in low doses and caused net secretion in larger doses. However, whereas peptide histidine methionine was active in all areas of the small intestine, neurotensin, neurotensin-(8-13) and neuromedin-N were inactive in the duodenum. In the post-duodenal areas neurotensin was approximately 7 times more active than peptide histidine methionine, 21 times more potent than neuromedin-N and 33 times more potent than neurotensin-(8-13).
神经介素 - N是最近从猪脊髓中分离纯化出的一种六肽，它与十三肽神经降压素的C末端区域具有紧密的序列同源性。这两种肽的外周分布非常相似。人们对神经介素 - N的生物活性知之甚少。已知神经降压素和肽组氨酸蛋氨酸可刺激大鼠小肠的净液体分泌。因此，我们测试了神经介素 - N以及六肽神经降压素 -（8 - 13）（该系统中神经降压素最小的完全活性类似物）与神经降压素和肽组氨酸蛋氨酸相比的作用。所有四种肽在低剂量时都会减少净吸收，在高剂量时会导致净分泌。然而，肽组氨酸蛋氨酸在小肠的所有区域都有活性，而神经降压素、神经降压素 -（8 - 13）和神经介素 - N在十二指肠中无活性。在十二指肠后的区域，神经降压素的活性约为肽组氨酸蛋氨酸的7倍，比神经介素 - N强21倍，比神经降压素 -（8 - 13）强33倍。
