Grill H J, Kaplan J M
Department of Psychology, University of Pennsylvania, Philadelphia 19104.
Am J Physiol. 1992 Jun;262(6 Pt 2):R1070-4. doi: 10.1152/ajpregu.1992.262.6.R1070.
In the traditional sham-feeding paradigm, the amount of sugar solution consumed by the rat is influenced by its concentration and the open or closed condition of the gastric fistula. The present experiments examine: 1) whether sham intake effects obtained under the "intraoral intake" paradigm, developed to explore controls of ingestion in otherwise aphagic preparations such as the decerebrate, are similar to those of previous studies in which intact rats obtained the fluid stimulus by spout licking; and 2) whether chronic decerebrate and intact rats show a similar elevation of their sucrose intake when ingesting with an open (sham intake) vs. closed gastric fistula. Experiment 1 showed that sham intraoral intake exceeded intake in the closed condition only for sucrose concentrations greater than 0.1 M. After it was established that the results obtained with the intraoral paradigm were consistent with those reported in the literature, the new paradigm was applied to the chronic decerebrate rat in experiment 2 to determine whether forebrain structures are necessary for sham-feeding effects. The effect of sucrose concentration and fistula condition on the behavior of chronic decerebrates was similar to that of intact rats. Like intact rats, decerebrate rats consumed more sucrose in the open condition but only for concentrations exceeding 0.1 M. This concentration-dependent sham sucrose intake of chronic decerebrate rats provides compelling evidence that the integration of sucrose's taste and postingestive effects that modulates ingestive behavior can be accomplished by the caudal brain stem.
在传统的假饲范式中，大鼠消耗的糖溶液量受其浓度以及胃瘘开放或闭合状态的影响。本实验旨在研究：1）在“口腔内摄入”范式下获得的假摄入效应，该范式是为探索诸如去大脑等其他失食准备中的摄食控制而开发的，是否与先前完整大鼠通过舔舐喷嘴获得液体刺激的研究中的效应相似；2）慢性去大脑大鼠和完整大鼠在开放（假摄入）与闭合胃瘘情况下摄食时，其蔗糖摄入量是否会有相似的升高。实验1表明，仅当蔗糖浓度大于0.1M时，假口腔内摄入量才超过闭合状态下的摄入量。在确定口腔内范式获得的结果与文献报道一致后，在实验2中将新范式应用于慢性去大脑大鼠，以确定前脑结构对于假饲效应是否必要。蔗糖浓度和瘘管状态对慢性去大脑大鼠行为的影响与完整大鼠相似。与完整大鼠一样，去大脑大鼠在开放状态下消耗更多蔗糖，但仅在浓度超过0.1M时如此。慢性去大脑大鼠这种依赖浓度的假蔗糖摄入量提供了令人信服的证据，表明调节摄食行为的蔗糖味觉和摄食后效应的整合可由延髓完成。
