Grillon Christian, Baas Johanna M P, Pine Daniel S, Lissek Shmuel, Lawley Megan, Ellis Valerie, Levine Jessica
Mood and Anxiety Disorder Program, National Institutes of Mental Health, Bethesda, Maryland 20892-2670, USA.
Biol Psychiatry. 2006 Oct 1;60(7):760-6. doi: 10.1016/j.biopsych.2005.11.027. Epub 2006 Apr 21.
The startle reflex is potentiated by aversive states. It has been proposed that phasic startle potentiation to a threat cue and sustained startle potentiation to contextual stimuli reflect distinct processes mediated by different brain structures. The present study tested the hypothesis that alprazolam would reduce the sustained startle potentiation to contextual threats but not the startle potentiation to a threat cue.
Sixteen healthy subjects received each of four treatments: placebo, .5 mg of alprazolam, 1 mg of alprazolam, and 50 mg of diphenhydramine (Benadryl) in a crossover design. Participants were exposed to three conditions, including one in which predictable aversive shocks were signaled by a cue, a second in which shocks were administered unpredictably, and a third condition in which no shocks were anticipated. Acoustic startle were delivered regularly across conditions.
Phasic startle potentiation to the threat cue in the predictable condition was not affected by alprazolam. In contrast, the sustained increase in startle in the predictable and unpredictable conditions was reduced significantly by the high dose of alprazolam.
Startle responses to an explicit threat cue and to an aversive context are psychopharmacologically distinct, suggesting that they may represent functionally dissociable aversive states.
惊吓反射会因厌恶状态而增强。有人提出，对威胁线索的阶段性惊吓增强和对情境刺激的持续性惊吓增强反映了由不同脑结构介导的不同过程。本研究检验了以下假设：阿普唑仑会降低对情境威胁的持续性惊吓增强，但不会降低对威胁线索的惊吓增强。
16名健康受试者采用交叉设计接受四种治疗，分别为安慰剂、0.5毫克阿普唑仑、1毫克阿普唑仑和50毫克苯海拉明（苯那君）。参与者暴露于三种情境中，一种是线索预示可预测的厌恶电击，第二种是电击不可预测地施加，第三种是不预期有电击。在不同情境下定期给予听觉惊吓刺激。
在可预测情境中，对威胁线索的阶段性惊吓增强不受阿普唑仑影响。相比之下，高剂量阿普唑仑显著降低了可预测和不可预测情境中惊吓的持续增加。
对明确威胁线索和厌恶情境的惊吓反应在心理药理学上是不同的，这表明它们可能代表功能上可分离的厌恶状态。
