Chronic Environmental Enrichment (EE) has been shown to prevent the relapse to addictive behaviours, such as drug-taking and -seeking. Recently, acute EE was shown to reduce cue-induced sucrose-seeking, but its effects on contextual (Cx)-induced sucrose-seeking is still unknown. Here we report the effects of brief EE exposure on Cx-induced sucrose-seeking with and without prior Cx-memory reactivation.

Adult male Sprague-Dawley rats were trained to sucrose self-administration associated to a specific conditioning Cx (CxA), followed by a 7-day extinction in a different Cx (CxB). Afterwards, rats were exposed for 22 h to EE, and 1 h later to either i) Cx-induced sucrose-seeking (1 h, renewal without Cx-memory reactivation), ii) or two different Cx-memory reactivations: short (2-min) and long (15-min) CxA-retrieval session (Cx-Ret). In Cx-Ret experiments, CxA-induced sucrose-seeking test (1 h) was done after a subsequent 3-day extinction phase. The assessment of molecular markers of memory reactivation/reconsolidation, Zif-268 and rpS6P, was performed 2 h after Cx-Ret.

Brief EE exposure enhanced Cx-induced sucrose-seeking without and with short but not long Cx-retrieval. Moreover, EE impaired discriminative responding at test prior to long, whereas improved it with or without short Cx-retrieval. Different changes in Zif-268 and rpS6P expression induced by short vs. long Cx-Ret were correlated to behavioural data, suggesting the occurrence of different memory processes affected by EE.

Our data show that brief EE exposure may differently affect subsequent appetitive relapse depending on the modality of re-exposure to conditioned context. This finding suggests caution and further studies to understand the proper conditions for the use of EE against appetitive and addiction disorders.

慢性环境丰富（EE）已被证明可以防止上瘾行为的复发，例如吸毒和寻求。最近，急性 EE 被证明可以减少线索诱导的蔗糖寻找，但它对上下文 (Cx) 诱导的蔗糖寻找的影响仍然未知。在这里，我们报告了短暂的 EE 暴露对 Cx 诱导的蔗糖寻找的影响，无论是否有先前的 Cx 记忆重新激活。

成年雄性 Sprague-Dawley 大鼠接受与特定调节 Cx (CxA) 相关的蔗糖自我给药训练，然后在不同的 Cx (CxB) 中消退 7 天。之后，大鼠暴露于 EE 22 小时，1 小时后暴露于 i）Cx 诱导的蔗糖寻找（1 小时，没有 Cx 记忆重新激活的更新），ii）或两种不同的 Cx 记忆重新激活：短（2 -min) 和长 (15 分钟) CxA 检索会话 (Cx-Ret)。在 Cx-Ret 实验中，在随后的 3 天消退阶段后进行 CxA 诱导的蔗糖寻找测试（1 小时）。在 Cx-Ret 后 2 小时进行记忆重新激活/重新巩固的分子标记 Zif-268 和 rpS6P 的评估。

短暂的 EE 暴露增强了 Cx 诱导的蔗糖寻找，没有和有短但不长的 Cx 检索。此外，EE 在长期测试中损害了判别响应，而在有或没有短 Cx 检索的情况下改善了它。由短与长 Cx-Ret 诱导的 Zif-268 和 rpS6P 表达的不同变化与行为数据相关，表明受 EE 影响的不同记忆过程的发生。

我们的数据表明，短暂的 EE 暴露可能会不同地影响随后的食欲复发，具体取决于重新暴露于条件环境的方式。这一发现建议谨慎和进一步研究，以了解使用 EE 对抗食欲和成瘾障碍的适当条件。