Département des Sciences de la Vie, Faculté des Sciences, Université de Nice-Sophia Antipolis, 06108 Nice, France.
Psychopharmacology (Berl). 2013 Jan;225(1):209-16. doi: 10.1007/s00213-012-2806-x. Epub 2012 Jul 24.
The post-extinction exposure of rats to a sub-conditioning procedure (SCP; i.e., retraining with a shock intensity that is too weak to induce by itself significant fear conditioning) has been reported to provoke the reemergence of extinguished fear. This phenomenon can be prevented by chronic fluoxetine treatment.
We sought to examine another potential inducer of fear reemergence, acute stress, in rats and determine whether fluoxetine prevents this phenomenon.
Because in previous studies fluoxetine was administered before extinction, we first analyzed its effect on the SCP-associated reemergence of auditory-cued conditioned fear in rats injected after extinction to avoid any interaction between fluoxetine and extinction learning. Next, we used the same protocol but replaced the SCP with acute stress.
We found that the SCP and acute stress, which were carried out 3 weeks after fear extinction, similarly provoked the reemergence of extinguished fear in rats injected with vehicle during the 3-week period. In contrast, the animals treated with fluoxetine during this period behaved similarly to those not exposed to an inducer of fear reemergence.
Our data establish acute stress as an inducer of fear reemergence. The results provide further support for the hypothesis that fluoxetine interfered with mechanisms that reactivated extinguished fear, even when administered after fear extinction.
据报道，在灭绝后，大鼠暴露于亚条件化程序（SCP；即，使用强度太弱而不能单独引起显著恐惧条件化的电击进行再训练）会引发已灭绝的恐惧重新出现。这种现象可以通过慢性氟西汀治疗来预防。
我们试图研究另一种潜在的恐惧重新出现诱导剂，即急性应激，在大鼠中，并确定氟西汀是否可以预防这种现象。
因为在以前的研究中，氟西汀是在灭绝前给予的，所以我们首先分析了它对大鼠听觉线索条件恐惧的 SCP 相关重新出现的影响，这些大鼠在灭绝后注射，以避免氟西汀和灭绝学习之间的任何相互作用。接下来，我们使用相同的方案，但用急性应激代替 SCP。
我们发现，SCP 和急性应激在灭绝后 3 周进行，在这段时间内用载体注射的大鼠同样引起了已灭绝的恐惧重新出现。相比之下，在这段时间内用氟西汀治疗的动物与未暴露于恐惧重新出现诱导剂的动物表现相似。
我们的数据确立了急性应激作为恐惧重新出现的诱导剂。这些结果进一步支持了氟西汀干扰重新激活已灭绝恐惧的机制的假设，即使在恐惧灭绝后给予。
