延髓最后区对犬消化间期移行性复合运动的调节作用

摘要

Objective To determine the effect of the area postrema (AP) of the medulla oblongata on gastrointestinal interdigestive migrating motor complex (MMC) and the plasma motilin level. Methods Interdigestive MMC activities of the antrum and duodenum were recorded by strain gauge implanted on the serosa of 8 conscious dogs. A cannula was intubated in femoral vein for motilin injection. The plasma motilin concentration was measured by RIA. We observed: (1) normal interdigestive MMC activity and fluctuations in plasma motilin concentration; (2) the effects of electrically damaging the AP on MMC activity and plasma motilin level; (3) whether intravenous injection of motilin could induce phase Ⅲ contractions after the AP was destroyed. Results (1) Typical interdigestive MMC with phase Ⅰ, Ⅱ, Ⅲ, and Ⅳ was recorded in normal dogs. Phase Ⅲ was concurrent with the peak of plasma motilin level. (2) In damaged AP dogs, antroduodenal interdigestive MMC contractions were suppressed; cyclic, phasic and migratory pattern of MMC was disrupted. Plasma motilin concentration was decreased. Intravenous injection of motilin could not induce phase Ⅲ contractions. Conclusions The area postrema might play an important role, which is mediated by motilin, on the regulation of interdigestive MMC.%目的　探讨延髓最后区对胃肠消化间期移行性复合运动（MMC）及血浆胃动素水平的影响.方法　在8只犬的胃窦和十二指肠浆膜埋植应力传感器记录胃窦和十二指肠消化间期复合运动.在一侧股静脉内置慢性静脉插管供注射外源性胃动素.用RIA法测定血浆胃动素含量.观察：（1）消化间期正常MMC活动和血浆胃动素浓度变化；（2）电损毁延髓最后区对MMC活动和血浆胃动素水平的影响；（3）电损毁延髓最后区对外源性胃动素启动MMC Ⅲ相收缩作用的影响.结果　（1）正常犬消化间期出现典型的Ⅰ、Ⅱ、Ⅲ、Ⅳ相MMC.MMC Ⅲ相与血浆胃动素释放高峰同步发生.（2）电损毁延髓最后区后, 胃窦和十二指肠MMC的收缩运动明显抑制,MMC Ⅰ相延长,Ⅱ、Ⅲ相明显缩短,失去了损毁前MMC周期性﹑时相性和移行性的特点,血浆胃动素浓度明显降低,外源性静脉注射胃动素不能启动MMC Ⅲ相收缩.结论　延髓最后区对消化间期 MMC的周期发生和移行有重要的调控作用,其作用途径与胃动素介导有关.