脑室注入多巴胺或乙酰胆碱对小肠电活动的影响

Effects of Intracerebroventricular Administration of Dopamine or Acetyicholine on intestinal electrical Activity

14只狗沿小肠浆膜面埋植4对Ag—Agcl双极电极,记录小肠的电活动;并于侧脑室插入不锈钢套管作为中枢给药的途径。结果发现(1)侧脑室给予多巴胺10ug/kg后,小肠各部几乎同时发生强烈的峰电活动,持续1～5分钟,并在74.8％的实验中出现呕吐。消化间期综合肌电(IDMEC)周期和Ⅱ相时程明显延长。(2)阻断外周交感神经的α和β受体后,不影响多巴胺的中枢效应。切除迷走神经后,多巴胺引起的强烈峰电活动和呕吐消失,但对IDMEC的影响不变。(3)侧脑室给予乙酰胆碱12ug/kg后,IDMEC周期、Ⅱ相和Ⅰ相时程均明显缩短;阻断交感神经受体和切除迷走神经后,乙酰胆碱的上述效应仍然存在。以上结果提示,中枢神经系统内的多巴胺机制和乙酰胆碱能机制的互相拮抗协调,使小肠的肌电活动保持着正常的生理状态。

The central effects of dopamine and acetylcholine on the interdigestive myoelectric complex (IDMEC) of the small intestine was investigated in 14 concious, fasted dogs. Intracerebroventricular (ICV) administration of dopamine (10μg/kg) significantly increased spike bursts of the intestine and generated vomiting immediatelyurations of IDMEC cycle and phase H were significantly prolonged. But the effects of spike bursts and vomiting were abolished after vagotomy. When acetylcholine was centrally administrated(12μgKg) , durations of IDMEC, phase II and phase I were all significantly shortened. It is concluded that in the CNS of the dog, there exisis a central dopaminergic mechanism and an acetylcholinergic mechanism, acting in coordination to modify the frequency of IDMEC and the durations of phases II and I, and belonging to the same physiological control mechanism of intestinal motility.