Buck Cara L, Malavar Jordan C, George Olivier, Koob George F, Vendruscolo Leandro F
Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, United States; Department of Psychology, University of California, San Diego, La Jolla, CA, United States.
Department of Psychology, University of California, San Diego, La Jolla, CA, United States.
Behav Brain Res. 2014 Sep 1;271:171-6. doi: 10.1016/j.bbr.2014.06.003. Epub 2014 Jun 7.
Rats emit 50kHz ultrasonic vocalizations (USVs) in situations of increased motivation, such as during the anticipation of palatable food or drugs of abuse. Whether the same holds true for the anticipation of alcohol intake remains unknown. Alcohol drinking in a nondependent state is thought to be mediated by its rewarding effects (positive reinforcement), whereas drinking in the dependent state is motivated by alcohol's stress-relieving effects (negative reinforcement). Here, we measured context-elicited 50kHz USVs in alcohol-dependent (alcohol vapor-exposed) and nondependent rats immediately before operant alcohol self-administration sessions. Dependent rats showed escalated levels of alcohol intake compared with nondependent rats. Overall, dependent and nondependent rats showed similar levels of anticipatory 50kHz USVs. However, the number of anticipatory USVs was positively correlated with alcohol intake in dependent rats but not nondependent rats. Additionally, dependent rats with higher alcohol intake displayed increased anticipatory 50kHz USVs compared with rats that had lower alcohol intake, whereas no difference was observed between rats with high and low alcohol intake in the nondependent group. Increased 50kHz USVs were specific for the anticipation of alcohol self-administration and did not generalize to a novel environment. These findings suggest that anticipatory 50kHz USVs may be an indicator of context-elicited negative reinforcement learning.
大鼠在动机增强的情况下会发出50千赫兹的超声发声（USV），例如在期待美味食物或滥用药物期间。对于期待酒精摄入的情况是否同样如此仍不清楚。非依赖状态下的饮酒行为被认为是由其奖赏效应（正强化）介导的，而依赖状态下的饮酒则是由酒精的缓解压力效应（负强化）驱动的。在此，我们在操作性酒精自我给药实验前，测量了酒精依赖（酒精蒸汽暴露）和非依赖大鼠在特定环境下引发的50千赫兹USV。与非依赖大鼠相比，依赖大鼠的酒精摄入量有所增加。总体而言，依赖和非依赖大鼠表现出相似水平的预期50千赫兹USV。然而，预期USV的数量在依赖大鼠中与酒精摄入量呈正相关，而在非依赖大鼠中则不然。此外，与酒精摄入量较低的大鼠相比，酒精摄入量较高的依赖大鼠表现出更多的预期50千赫兹USV，而非依赖组中酒精摄入量高和低的大鼠之间未观察到差异。50千赫兹USV的增加是酒精自我给药预期所特有的，不会推广到新环境。这些发现表明，预期50千赫兹USV可能是环境引发的负强化学习的一个指标。
