Erecius L F, Dixon K D, Jiang J C, Gietzen D W
Food Intake Laboratory and Department of Anatomy, Physiology, and Cell Biology, School of Veterinary Medicine, University of California, Davis, Davis, CA 95616, USA.
J Nutr. 1996 Jun;126(6):1722-31. doi: 10.1093/jn/126.6.1722.
Rats offered an amino acid-imbalanced diet (IMB) respond to the ensuing amino acid deficiency rapidly with a decrease in food intake of at least 50%. Pretreatment with tropisetron (TROP), an antagonist at serotonin3 (5-HT3) and 5-HT4 receptors, increases intake of IMB to approximately 85% of control. Vagotomy has two effects: it increases intake of an IMB to about 65%, and also blocks the increased response to tropisetron. This indicates that the greater IMB intake after tropisetron, approximately 20% more than in vagotomized rats, is dependent on an intact vagus. Rats were either 1) vagotomized or sham-operated, or 2) given tropisetron or saline injections. We then examined free-feeding meal patterns in rats fed an IMB to determine whether the microstructure of the feeding behavior differed, either between treatments, or by comparison with the meal patterns in rats fed the control diet. Vagotomy did not alter meal patterns in rats consuming the basal control diet. During the first 6 h after introduction of the IMB, the control rats showed significantly longer intermeal intervals (over twice the length of intervals recorded in those fed the basal diet), with corresponding effects on meal numbers, which were restored to basal values in tropisetron and vagotomized rats. Meal size was increased after vagotomy also. After 6 h, in intact tropisetron-treated rats only, a fourfold faster rate of eating throughout the late dark period accounted for the significantly greater intake of the IMB than in controls. The results demonstrated differential effects of the two treatments on the anorectic responses to amino acid deficiency.
给大鼠提供氨基酸失衡饮食（IMB）时，它们会迅速对随之而来的氨基酸缺乏做出反应，食物摄入量至少减少50%。用托烷司琼（TROP）进行预处理，托烷司琼是5-羟色胺3（5-HT3）和5-HT4受体的拮抗剂，可使IMB的摄入量增加到对照组的约85%。迷走神经切断术有两个作用：它使IMB的摄入量增加到约65%，并且还会阻断对托烷司琼的反应增强。这表明托烷司琼处理后IMB摄入量增加得更多，比迷走神经切断术的大鼠多约20%，这依赖于完整的迷走神经。大鼠被分为两组：1）进行迷走神经切断术或假手术，或2）给予托烷司琼或生理盐水注射。然后我们检查了喂食IMB的大鼠的自由进食餐模式，以确定喂食行为的微观结构在不同处理之间是否存在差异，或者与喂食对照饮食的大鼠的餐模式相比是否存在差异。迷走神经切断术并未改变食用基础对照饮食的大鼠的餐模式。在引入IMB后的最初6小时内，对照大鼠的餐间间隔明显更长（是喂食基础饮食的大鼠记录间隔长度的两倍多），对餐数有相应影响，而在托烷司琼处理的大鼠和迷走神经切断术的大鼠中，餐数恢复到基础值。迷走神经切断术后餐量也增加了。6小时后，仅在完整的托烷司琼处理的大鼠中，在整个黑暗后期进食速度快四倍，这导致其IMB摄入量比对照组显著增加。结果表明两种处理对氨基酸缺乏的厌食反应有不同影响。
