The lateral habenula (LHb) integrates critical information regarding aversive stimuli that shapes decision making and behavioral responses. The three major LHb outputs innervate dorsal raphe nucleus (DRN), ventral tegmental area (VTA), and the rostromedial tegmental nucleus (RMTg). LHb neurons that project to these targets are segregated and nonoverlapping, and this led us to consider whether they have distinct molecular phenotypes and adaptations to stress exposure. In order to capture a time-locked profile of gene expression after repeated forced swim stress, we used intersectional expression of RiboTag in rat LHb neurons and next-gen RNA sequencing to interrogate the RNAs actively undergoing translation from each of these pathways. The “translatome” in the neurons comprising these pathways was similar at baseline, but diverged after stress, especially in the neurons projecting to the RMTg. Using weighted gene co-expression network analysis, we found one module, which had an overrepresentation of genes associated with phosphoinositide 3 kinase (PI3K) signaling, comprising genes downregulated after stress in the RMTg-projecting LHb neurons. Reduced PI3K signaling in RMTg-projecting LHb neurons may be a compensatory adaptation that alters the functional balance of LHb outputs to GABAergic vs. monoaminergic neurons following repeated stress exposure.

外侧缰核 (LHb) 整合了关于塑造决策和行为反应的厌恶刺激的关键信息。三个主要的 LHb 输出支配中缝背核 (DRN)、腹侧被盖区 (VTA) 和喙内侧被盖核 (RMTg)。投射到这些目标的 LHb 神经元是分离的且不重叠的，这使我们考虑它们是否具有不同的分子表型和对压力暴露的适应。为了在反复强迫游泳压力后捕获基因表达的时间锁定图谱，我们使用 RiboTag 在大鼠 LHb 神经元中的交叉表达和下一代 RNA 测序来询问从这些途径中的每一个积极进行翻译的 RNA。包含这些通路的神经元中的“翻译组”在基线时是相似的，但在压力后会发散，特别是在投射到 RMTg 的神经元中。使用加权基因共表达网络分析，我们发现了一个模块，其中与磷酸肌醇 3 激酶 (PI3K) 信号传导相关的基因过多，包括在 RMTg 投射 LHb 神经元中应激后下调的基因。RMTg 投射的 LHb 神经元中 PI3K 信号的减少可能是一种补偿性适应，在反复的压力暴露后改变 LHb 输出到 GABAergic 与单胺能神经元的功能平衡。