脑室注射五肽胃泌素对胃肠道电活动的影响

Effect of Intracerebro-ventricular Injection of Pentagastrin on the Interdigestive Myoelectric Complex of Dog

沿狗胃窦和小肠浆膜面埋植6对Ag-Agcl双极记录电极,侧脑室埋植不锈钢套管。观察侧脑室注射微量五肽胃泌素(G_5)对胃肠道电活动的影响。结果提示:侧脑室注射G_5可使中枢神经内对胃泌素敏感的神经元功能改变,通过植物神经系统影响胃肠道消化间期综合肌电的活动,尤以胃肠道近端的改变较为明显。静脉注射G_5还可以引起胃窦和十二指肠及空肠上部的慢波电频率增加,但振幅降低。

Gastrin was considered as a brain-gut pepdite. Up to now, nothing has been obtained about the effect of gastin in the brain on interdigestive myoelectric complex (IDMEC) of gastrointestinal tract. Therefore, we performed chronic experiments on healthy, conscious, and fasted dog on which six bipolar silver-silverchloride electrodes were implanted on the serosal surface of the antrum and small intestine and a stainless steel tube into the lateral ventricle of brain, pentagastrin (G5) was used in our experiment. Electric activity of gastrointestinal tract was recorded with electroencephalogram recorder at all points of dogs fasted 18-24 hr. The aim of our study is to investigate the effect of intracerebroventricular injection of G5 on IDMEC of gastrointestinal tract and determine the action of vegetative nerve system in this process.The results were as follows:The timing between two phases Ⅲ at duodenal electrode were taken as 100% of IDMEC period. During 30-40%, G5(6μg/30μl,10μg/50μl,20μg/ 100μl or 40μg/200μ1) was injected into the lateralcerebroventricle, respectively,We observed phase Ⅲ of IDMEC was inhibited and the period of IDMEC was significantly prolonged(P<0.05-0.01). These effects were doe-dependent. When administered via the intracerberoventricular route at dose of 20μg/ 100 or 40 μg/200μl, G5 markedly inereased spiking activity in proximal gastrointestinal tract, The duration of phase I was shorted 15% and that of phase Ⅱ longer 15% than normal condition(P<0.01). These effects were significantly enhanced by administering intravenously Regitine(0.5mg/kg) and Propranolol(0.5mg/kg), and abolished by bilateral thoracic vagotomy(P<0.01). No effect were observed in duration of phase Ⅰ,Ⅱ and period of IDMEC after intracerebroventricular injection of saline 200ul and introvenous injection of G5 40μg / ml (P>0.5).Administered intravenously of a dose of 40μg/ml. G5 significantly increased the frequency of slow wave and spiking activity in proximal gastrointestinal tract for short time (below five minutes).These results suggest that gastrin in brain can act on the some region of central nerve system which are sensitive to G5 and modify the IDMEC in fasted dog, These effects are mediated by the vegetative nerve system, especially vagus, G5 can increase frequency of slow wave in proximal gastrointestinal tract.