Gregersen S, Lindskog S, Land T, Langel U, Bartfai T, Ahrén B
Department of Medicine, University of Lund, Malmö, Sweden.
Eur J Pharmacol. 1993 Feb 23;232(1):35-9. doi: 10.1016/0014-2999(93)90725-w.
The neuropeptide galanin occurs in pancreatic adrenergic nerves and has been suggested to be the adrenergic mediator of the stress-induced inhibition of insulin release. To study its physiological function, we recently synthesized a galanin-like galanin receptor antagonist, galantide. However, this antagonist contains a methionine moiety, and is therefore easily oxidized. We have now synthesized another galanin antagonist which does not contain methionine. This peptide, M35, is a chimeric 21 amino acid peptide in which galanin-(1-13) is coupled to bradykinin-(2-9). M35 (10 microM to 1 pM) had no effect by itself on glucose (11.1 mM)-stimulated insulin secretion in isolated mouse islets, but potently counteracted the inhibitory action of galanin (100 nM). The lowest effective dose of M35 was 10 nM. M35 did not counteract the inhibitory action of clonidine (1 microM) or somatostatin (1 microM) on insulin secretion. Furthermore, M35 displaced 125I-monoiodo-[Tyr26]galanin from membranes of insulin producing RINm5F cells. The displacement curve fitted to a two-site model in which 60% of label bound with a K1 of 0.1 +/- 0.01 nM and 40% with a K2 of 3 +/- 0.5 nM. In conclusion, M35 is a specific, non-methionine-containing galanin receptor antagonist on insulin-producing cells.
神经肽甘丙肽存在于胰腺肾上腺素能神经中，有人提出它是应激诱导的胰岛素释放抑制作用的肾上腺素能介质。为了研究其生理功能，我们最近合成了一种甘丙肽样甘丙肽受体拮抗剂，即丙谷酰胺。然而，这种拮抗剂含有一个甲硫氨酸部分，因此容易被氧化。我们现在已经合成了另一种不含甲硫氨酸的甘丙肽拮抗剂。这种肽，即M35，是一种嵌合的21个氨基酸的肽，其中甘丙肽-（1-13）与缓激肽-（2-9）偶联。M35（10微摩尔至1皮摩尔）本身对分离的小鼠胰岛中葡萄糖（11.1毫摩尔）刺激的胰岛素分泌没有影响，但能有效对抗甘丙肽（100纳摩尔）的抑制作用。M35的最低有效剂量为10纳摩尔。M35不能对抗可乐定（1微摩尔）或生长抑素（1微摩尔）对胰岛素分泌的抑制作用。此外，M35能从产生胰岛素的RINm5F细胞的膜上置换出125I-单碘-[酪氨酸26]甘丙肽。置换曲线符合双位点模型，其中60%的标记物以0.1±0.01纳摩尔的K1结合，40%以3±0.5纳摩尔的K2结合。总之,M35是一种作用于产生胰岛素细胞的特异性、不含甲硫氨酸的甘丙肽受体拮抗剂。
