Schubert M L, Jong M J, Makhlouf G M
Department of Medicine, Medical College of Virginia, Richmond 23249.
Am J Physiol. 1991 Nov;261(5 Pt 1):G885-9. doi: 10.1152/ajpgi.1991.261.5.G885.
The mechanism of action of bombesin, also known as gastrin-releasing peptide (GRP), on somatostatin secretion was examined separately in superfused segments of rat antral and fundic mucosa. Bombesin/GRP (1 nM) stimulated somatostatin secretion from both regions. In fundic segments, the somatostatin response was strongly inhibited (86%; P less than 0.01) by tetrodotoxin (5 microM) but augmented by atropine (1 microM) (P less than 0.01). In antral segments, both tetrodotoxin and atropine augmented the somatostatin response to bombesin/GRP by 42-45% (P less than 0.01), whereas the gastrin antagonist L 365260 (1 microM) abolished it. The gastrin antagonist augmented the gastrin response to bombesin/GRP by 103% (P less than 0.01). The results indicate that bombesin/GRP stimulates somatostatin secretion by distinct mechanisms in the fundus and antrum. In the fundus, bombesin/GRP acts indirectly on somatostatin cells by activating stimulatory noncholinergic neurons and, to a lesser extent, inhibitory cholinergic neurons. In the antrum, bombesin/GRP acts indirectly on somatostatin cells by stimulating release of gastrin and, to a lesser extent, by activating inhibitory cholinergic neurons. A dual paracrine pathway links gastrin and somatostatin secretion in the antrum.
蛙皮素（也称为胃泌素释放肽，GRP）对生长抑素分泌的作用机制，在大鼠胃窦和胃底黏膜的灌流片段中分别进行了研究。蛙皮素/GRP（1 nM）刺激了这两个区域的生长抑素分泌。在胃底片段中，河豚毒素（5 microM）强烈抑制了生长抑素反应（86%；P<0.01），但阿托品（1 microM）增强了该反应（P<0.01）。在胃窦片段中，河豚毒素和阿托品均使生长抑素对蛙皮素/GRP的反应增强了42-45%（P<0.01），而胃泌素拮抗剂L 365260（1 microM）则消除了该反应。胃泌素拮抗剂使胃泌素对蛙皮素/GRP的反应增强了103%（P<0.01）。结果表明，蛙皮素/GRP通过不同机制刺激胃底和胃窦中的生长抑素分泌。在胃底，蛙皮素/GRP通过激活刺激性非胆碱能神经元并在较小程度上激活抑制性胆碱能神经元，间接作用于生长抑素细胞。在胃窦，蛙皮素/GRP通过刺激胃泌素释放并在较小程度上通过激活抑制性胆碱能神经元，间接作用于生长抑素细胞。一条双重旁分泌途径将胃窦中的胃泌素和生长抑素分泌联系起来。
