Rimonabant's reductive effects on high densities of food reinforcement, but not palatability, in lean and obese Zucker rats
Rimonabant's reductive effects on high densities of food reinforcement, but not palatability, in lean and obese Zucker rats
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DOI：
10.1007/s00213-013-3366-4
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发表时间：
2014-05-01
影响因子：
3.4
通讯作者：
Rasmussen, Erin B.
中科院分区：
文献类型：
--
作者：
Buckley, Jessica L.;Rasmussen, Erin B.
据称，与不那么可口的食物相比，大麻素拮抗剂在减少高度可口食物的摄入量方面具有更大的效果。然而，这一断言是基于自由喂养研究，在这些研究中，在基线条件下吃的可口食物的数量经常与其他变量混淆，例如获得食物选择的机会不平等以及食物质量特征的差异。我们试图通过使用一个选择模型来减少这些混淆，该模型对蔗糖和胡萝卜味颗粒的传递速度进行了编程。在阶段1中，将10只瘦(Fa/Fa或Fa/fa)和10只肥胖(Fa/fa)Zucker大鼠置于三种条件下，其中两个杠杆上的食物颗粒编程比例为5：1、1：1和1：5。在第一阶段，对两个杠杆的反应产生一种颗粒(蔗糖或胡萝卜)；在第二阶段，一个杠杆上的反应产生蔗糖颗粒，另一个杠杆上的反应产生胡萝卜颗粒。在每种食物比例下的反应稳定后，在实验前给予急性剂量的利莫那班(0、3和10 mg/kg)。比较在每个比例和每个水平下每一次会议获得的增强剂和反应的数量。利莫那班在第一阶段减少了1：5和5：1食物比例的增强剂，在第二阶段所有比例中减少了增强剂。利莫那班同样减少了蔗糖和胡萝卜味颗粒的摄入量；利莫那班没有影响对蔗糖的偏爱，但增加了对数量差异的敏感性。这表明，食物的相对数量，而不是适口性，可能是利莫那班作用的一个重要的行为机制。
Cannabinoid antagonists purportedly have greater effects in reducing the intake of highly palatable food compared to less palatable food. However, this assertion is based on free-feeding studies in which the amount of palatable food eaten under baseline conditions is often confounded with other variables, such as unequal access to both food options and differences in qualitative features of the foods.We attempted to reduce these confounds by using a model of choice that programmed the delivery rates of sucrose and carrot-flavored pellets.Lever pressing of ten lean (Fa/Fa or Fa/fa) and ten obese (fa/fa) Zucker rats was placed under three conditions in which programmed ratios for food pellets on two levers were 5:1, 1:1, and 1:5. In phase 1, responses on the two levers produced one type of pellet (sucrose or carrot); in phase 2, responses on one lever produced sucrose pellets and on the other lever produced carrot pellets. After responses stabilized under each food ratio, acute doses of rimonabant (0, 3, and 10 mg/kg) were administered before experimental sessions. The number of reinforcers and responses earned per session under each ratio and from each lever was compared.Rimonabant reduced reinforcers in 1:5 and 5:1 food ratios in phase 1, and across all ratios in phase 2. Rimonabant reduced sucrose and carrot-flavored pellet consumption similarly; rimonabant did not affect bias toward sucrose, but increased sensitivity to amount differences in lean rats. This suggests that relative amount of food, not palatability, may be an important behavioral mechanism in the effects of rimonabant.