School of Experimental Psychology, University of Bristol, 12a Priory Road, Bristol, BS8 1TU, UK.
Physiol Behav. 2012 Mar 20;105(5):1202-7. doi: 10.1016/j.physbeh.2011.12.022. Epub 2011 Dec 30.
It has been suggested that obese individuals over-eat in order to compensate for deficits in the dopaminergic reward system. The current study used acute tyrosine/phenylalanine depletion (ATPD) to investigate the effect of reduced dopamine function on appetite and the reward value of food in healthy volunteers. The compensatory-eating hypothesis would predict an increase in the reward value and consumption of food following depletion by this method. In a double-blind, counterbalanced, crossover study, 17 male participants (mean age=29.2 (SEM=2.7) years; mean body mass index=24.4 (SEM=0.6) kg/m(2)) were administered with a tyrosine/phenylalanine-free mixture (TYR/PHE-free; depletion condition) and a balanced amino acid mixture (BAL; control). Plasma amino acid levels were measured at baseline and peak depletion (300 min). Appetite, willingness to pay for food, liking, desired portion size and ad libitum food intake were also assessed. The TYR/PHE-free mixture was associated with significant decreases in tyrosine, phenylalanine, and the ratio of tyrosine+phenylalanine to the other large neutral amino acids (all p<.001). There were no effects on our measures of willingness to pay for food or liking. However, in the TYR/PHE-free condition, participants reported significantly lower levels of hunger following a fixed-test meal relative to the BAL condition. In conclusion, we found no evidence for compensatory eating following ATPD. Our results also provide support for the role of dopamine in motivational components of eating.
有人认为，肥胖者会过度进食以弥补多巴胺能奖励系统的缺陷。本研究使用急性酪氨酸/苯丙氨酸耗竭（ATPD）来研究减少多巴胺功能对健康志愿者的食欲和食物奖励价值的影响。补偿性进食假说预测，通过这种方法进行耗竭后，食物的奖励价值和摄入量会增加。在一项双盲、对照、交叉研究中，17 名男性参与者（平均年龄=29.2（SEM=2.7）岁；平均体重指数=24.4（SEM=0.6）kg/m2）接受了酪氨酸/苯丙氨酸缺乏混合物（TYR/PHE-free；耗竭条件）和平衡氨基酸混合物（BAL；对照）的处理。在基线和峰值耗竭（300 分钟）时测量血浆氨基酸水平。还评估了食欲、购买食物的意愿、喜好、期望的份量和随意食物摄入量。TYR/PHE-free 混合物与酪氨酸、苯丙氨酸和酪氨酸+苯丙氨酸与其他大中性氨基酸的比例显著降低有关（均 p<.001）。对我们购买食物的意愿或喜好的测量没有影响。然而，在 TYR/PHE-free 条件下，与 BAL 条件相比，参与者在固定测试餐后报告饥饿感明显降低。总之，我们没有发现 ATPD 后补偿性进食的证据。我们的结果还支持多巴胺在进食动机成分中的作用。
