Baker R A, Wilson T G, Padbury R T, Toouli J, Saccone G T
Department of Surgery, Flinders Medical Centre, Australia.
Peptides. 1996;17(6):933-41. doi: 10.1016/0196-9781(96)00147-7.
The neuropeptide galantin (GAL) is found in neurons in the biliary tract of several species. We mapped the distribution of GAL-like immunoreactive nerve (GAL-LI) fibers in the sphincter of Oddi of the Australian brush-tailed possum by immunohistochemistry. The pharmacological effects of GAL in vitro and in vivo were studied by measuring sphincter of Oddi muscle strip contractility and transsphincteric flow, respectively. Muscle layers, and ganglionated and perivascular plexuses, contained GAL-LI nerve fibers. Exogenous GAL caused a concentration-dependent (10(9)-10(-6)M) increase in the spontaneous longitudinal but not circular muscle contractions. At 10(-6) M GAL, contractile activity was elevated two- to fourfold. This response was tetrodotoxin insensitive but competitively inhibited by galantide (10(-8)-10(-7) M). In vivo, intra-arterial bolus injections of GAL (1001000 ng/kg), decreased transsphincteric flow, with a maximum reduction to 80.2 +/- 6.8% of control. In conclusion, GAL appears to selectively stimulate longitudinally oriented sphincter of Oddi smooth muscle via a direct mechanism, which results in a modest reduction in transsphincteric flow.
神经肽甘丙肽（GAL）在多个物种的胆道神经元中均有发现。我们通过免疫组织化学方法绘制了澳大利亚刷尾负鼠奥迪括约肌中甘丙肽样免疫反应性神经（GAL-LI）纤维的分布。分别通过测量奥迪括约肌肌条收缩性和跨括约肌流量，研究了GAL在体外和体内的药理作用。肌层以及神经节化和血管周围丛中均含有GAL-LI神经纤维。外源性GAL导致自发性纵向肌收缩呈浓度依赖性（10⁹ - 10⁻⁶M）增加，但对环形肌收缩无影响。在10⁻⁶M GAL时，收缩活性提高了两到四倍。这种反应对河豚毒素不敏感，但被丙谷酰胺（10⁻⁸ - 10⁻⁷M）竞争性抑制。在体内，动脉内推注GAL（100 - 1000 ng/kg）可降低跨括约肌流量，最大降幅可达对照的80.2±6.8%。总之，GAL似乎通过直接机制选择性刺激奥迪括约肌纵向平滑肌，导致跨括约肌流量适度降低。
