Glucocorticoid hormones are crucially involved in modulating mnemonic processing of stressful or emotionally arousing experiences. They are known to enhance the consolidation of new memories, including those that extinguish older memories. In this study, we investigated whether glucocorticoids facilitate the extinction of a striatum-dependent, and behaviorally more rigid, stimulus-response memory. For this, male rats were initially trained for six days on a stimulus-response task in a T-maze to obtain a reward after making an egocentric right-turn body response, regardless of the starting position in this maze. This training phase was followed by three extinction sessions in which right-turn body responses were not reinforced. Corticosterone administration into the dorsolateral region of the striatum after the first extinction session dose-dependently enhanced the consolidation of extinction memory: Rats administered the higher dose of corticosterone (30 ng), but not lower doses (5 or 10 ng), exhibited significantly fewer right-turn body responses and had longer latencies compared to vehicle-treated animals on the second and third extinction sessions. Co-administration of the glucocorticoid receptor antagonist RU 486 (10 ng) prevented the corticosterone effect, indicating that glucocorticoids enhance the extinction of stimulus-response memory via activation of the glucocorticoid receptor. Corticosterone administration into the dorsomedial striatum did not affect extinction memory. These findings indicate that stress-response mechanisms involving corticosterone actions in the dorsolateral striatum facilitate the extinction of stimulus-response memory that might allow for the development of an opportune behavioral strategy.

糖皮质激素在调节压力或情绪激动经历的记忆过程中起着至关重要的作用。众所周知，它们可以增强新记忆的巩固，包括那些消除旧记忆的记忆。在这项研究中，我们调查了糖皮质激素是否有助于消除依赖纹状体的、行为上更僵硬的刺激反应记忆。为此，雄性大鼠最初在 T 形迷宫中接受刺激反应任务训练六天，以在做出以自我为中心的右转身体反应后获得奖励，无论在这个迷宫中的起始位置如何。这个训练阶段之后是三个灭绝课程，其中右转身体反应没有得到加强。在第一次消退期后向纹状体背外侧区域施用皮质酮剂量依赖性地增强消退记忆的巩固：大鼠给予较高剂量的皮质酮（30 ng），但不是较低剂量（5 或 10 ng），表现出显着减少在第二次和第三次灭绝过程中，与车辆处理的动物相比，右转身体反应和潜伏期更长。糖皮质激素受体拮抗剂 RU 486 (10 ng) 的共同给药阻止了皮质酮的作用，表明糖皮质激素通过激活糖皮质激素受体增强了刺激-反应记忆的消退。皮质酮给药到背内侧纹状体不影响消退记忆。