Marshall Andrew T, Liu Angela T, Murphy Niall P, Maidment Nigel T, Ostlund Sean B
Department of Anesthesiology and Perioperative Care, Center for Addiction Neuroscience, University of California, Irvine, Irvine, California, United States of America.
Hatos Center, Department of Psychiatry and Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, Los Angeles, California, United States of America.
PLoS One. 2017 Jul 14;12(7):e0180907. doi: 10.1371/journal.pone.0180907. eCollection 2017.
It has been hypothesized that brain development during adolescence perturbs reward processing in a way that may ultimately contribute to the risky decision making associated with this stage of life, particularly in young males. To investigate potential reward dysfunction during adolescence, Experiment 1 examined palatable fluid intake in rats as a function of age and sex. During a series of twice-weekly test sessions, non-food-deprived rats were given the opportunity to voluntarily consume a highly palatable sweetened condensed milk (SCM) solution. We found that adolescent male, but not female, rats exhibited a pronounced, transient increase in SCM intake (normalized by body weight) that was centered around puberty. Additionally, adult females consumed more SCM than adult males and adolescent females. Using a well-established analytical framework to parse the influences of reward palatability and satiety on the temporal structure of feeding behavior, we found that palatability-driven intake at the outset of the meal was significantly elevated in adolescent males, relative to the other groups. Furthermore, although we found that there were some group differences in the onset of satiety, they were unlikely to contribute to differences in intake. Experiment 2 confirmed that adolescent male rats exhibit elevated palatable fluid consumption, relative to adult males, even when a non-caloric saccharin solution was used as the taste stimulus, demonstrating that these results were unlikely to be related to age-related differences in metabolic need. These findings suggest that elevated palatable food intake during adolescence is sex specific and driven by a fundamental change in reward processing. As adolescent risk taking has been hypothesized as a potential result of hypersensitivity to and overvaluation of appetitive stimuli, individual differences in reward palatability may factor into individual differences in adolescent risky decision making.
有假设认为，青春期的大脑发育会扰乱奖励处理机制，这种方式最终可能导致与这个生命阶段相关的冒险决策，尤其是在年轻男性中。为了研究青春期潜在的奖励功能障碍，实验1研究了大鼠可口液体摄入量与年龄和性别的关系。在一系列每周两次的测试阶段，未处于食物剥夺状态的大鼠有机会自愿饮用一种非常可口的甜炼乳（SCM）溶液。我们发现，青春期雄性大鼠而非雌性大鼠的SCM摄入量（按体重标准化）出现了明显的、短暂的增加，且集中在青春期前后。此外，成年雌性大鼠比成年雄性大鼠和青春期雌性大鼠消耗更多的SCM。使用一个成熟的分析框架来剖析奖励适口性和饱腹感对进食行为时间结构的影响，我们发现，相对于其他组，青春期雄性大鼠在进食开始时由适口性驱动的摄入量显著增加。此外，尽管我们发现饱腹感开始出现时存在一些组间差异，但这些差异不太可能导致摄入量的差异。实验2证实，即使使用无热量的糖精溶液作为味觉刺激，青春期雄性大鼠相对于成年雄性大鼠仍表现出更高的可口液体消耗量，这表明这些结果不太可能与代谢需求的年龄相关差异有关。这些发现表明，青春期可口食物摄入量的增加具有性别特异性，并且是由奖励处理的根本变化驱动的。由于青春期冒险行为被假设为对食欲刺激过敏和过度重视的潜在结果，奖励适口性的个体差异可能是青春期冒险决策个体差异的一个因素。
