Treit D, Spetch M L
Physiol Behav. 1986;36(2):311-7. doi: 10.1016/0031-9384(86)90022-3.
These experiments demonstrate that rats can immediately adjust their meal size in response to variations in the caloric density of a novel diet. However, this immediate caloric sensitivity only seems to appear when rats have been adapted to small, calorically insufficient meals. Rats in Experiment 1 were given timed access to unlimited quantities of an oil/water diet during baseline, and they showed no indication of compensating for changes in the caloric density of the oil/water diet during a test meal. Instead, they consumed about the same amount they had consumed during the preceding baseline meal, suggesting that a learned habit of consuming a certain volume of food controlled their meal size. In contrast, rats that were accustomed to receiving only a very small quantity of food for one of their daily meals during baseline immediately responded to the caloric density of an oil/water test diet by consuming a larger meal if the diet was dilute than if it was calorically more concentrated (Experiments 2 and 3). This immediate sensitivity to caloric density occurred whether or not the rats were exposed to the oil/water diet during baseline, suggesting that rats have some way of directly "metering" the caloric density of new foods. Thus, rats' caloric intake during a meal appears to be controlled by two factors: under certain conditions, control is by caloric learning, under other conditions control is by a caloric metering mechanism.
这些实验表明，大鼠能够根据新饮食热量密度的变化立即调整其进食量。然而，这种即时的热量敏感性似乎仅在大鼠适应了少量、热量不足的餐食时才会出现。实验1中的大鼠在基线期被定时给予不限量的油/水饮食，并且在测试餐期间，它们没有表现出补偿油/水饮食热量密度变化的迹象。相反，它们的进食量与前一餐基线期的进食量大致相同，这表明摄取一定量食物的习得习惯控制着它们的进食量。相比之下，在基线期每天一餐只习惯摄取非常少量食物的大鼠，如果测试饮食是稀释的，它们会比热量更高时摄取更多食物，从而立即对油/水测试饮食的热量密度做出反应（实验2和3）。无论大鼠在基线期是否接触过油/水饮食，都会出现这种对热量密度的即时敏感性，这表明大鼠有某种直接“计量”新食物热量密度的方法。因此，大鼠一餐中的热量摄入似乎受两个因素控制：在某些情况下，控制是通过热量学习，在其他情况下，控制是通过热量计量机制。
