Otsuki M, Fujii M, Nakamura T, Tani S, Oka T, Yajima H, Baba S
Am J Physiol. 1987 Apr;252(4 Pt 1):G491-8. doi: 10.1152/ajpgi.1987.252.4.G491.
Neuromedin B and neuromedin C are novel decapeptides that have recently been isolated from porcine spinal cord and canine intestinal mucosa and show striking sequence homology with bombesin and gastrin-releasing peptide (GRP-27) at the carboxyl-terminal region. The effects of synthetic neuromedin B and C on exocrine pancreatic function and insulin release have been compared with bombesin and GRP-27 in isolated pancreatic acini and isolated perfused pancreas in rat. Neuromedin B and C as well as bombesin and GRP-27 were able to cause stimulation of amylase release. The relative efficacy of neuromedin B, C, bombesin, and GRP-27 was the same as that of cholecystokinin octapeptide (CCK-8). Bombesin and GRP-27 were equipotent, and both were approximately 15-fold less potent than CCK-8. Neuromedin C was approximately 2-fold more potent, whereas neuromedin B as approximately 10-fold less potent than bombesin and GRP-27. All of these peptides stimulated insulin release that was limited to the first 3 min of a 20-min perfusion. However, GRP-27 and its related peptides were weak stimulants of insulin release compared with their abilities to stimulate exocrine pancreatic secretion. Bombesin and neuromedin B id not stimulate insulin release at doses stimulating pancreatic exocrine secretion. Neuromedin B was also approximately 10-fold less potent than neuromedin C, bombesin, and GRP-27 in eliciting insulin secretion. Because bombesin-like immunoreactivity is found to be present in nerves in the pancreas, neuromedin B and C may be neurotransmitters or neuromodulators and exert a direct local neurocrine action on enzyme secretion by acinar cells and insulin secretion by the islets.
神经介素B和神经介素C是最近从猪脊髓和犬小肠黏膜中分离出的新型十肽，在羧基末端区域与蛙皮素和胃泌素释放肽（GRP - 27）具有显著的序列同源性。在大鼠分离的胰腺腺泡和分离的灌注胰腺中，已将合成的神经介素B和C对胰腺外分泌功能和胰岛素释放的作用与蛙皮素和GRP - 27进行了比较。神经介素B和C以及蛙皮素和GRP - 27均能刺激淀粉酶释放。神经介素B、C、蛙皮素和GRP - 27的相对效力与八肽胆囊收缩素（CCK - 8）相同。蛙皮素和GRP - 27效力相当，且两者效力均比CCK - 8低约15倍。神经介素C的效力约高2倍，而神经介素B的效力比蛙皮素和GRP - 27低约10倍。所有这些肽均刺激胰岛素释放，且胰岛素释放仅限于20分钟灌注的前3分钟。然而，与刺激胰腺外分泌的能力相比，GRP - 27及其相关肽对胰岛素释放的刺激作用较弱。在刺激胰腺外分泌的剂量下，蛙皮素和神经介素B不刺激胰岛素释放。在引发胰岛素分泌方面，神经介素B的效力也比神经介素C、蛙皮素和GRP - 27低约10倍。由于在胰腺神经中发现存在蛙皮素样免疫反应性，神经介素B和C可能是神经递质或神经调节剂，并对腺泡细胞的酶分泌和胰岛的胰岛素分泌发挥直接的局部神经分泌作用。
