Table_7_Sex separation unveils the functional plasticity of the vomeronasal organ in rabbits.xlsx

Chemosensory cues are vital for social and sexual behaviours and are primarily detected and processed by the vomeronasal system (VNS), whose plastic capacity has been investigated in mice. However, studying chemosensory plasticity outside of laboratory conditions may give a more realistic picture of how the VNS adapts to a changing environment. Rabbits are a well-described model of chemocommunication since the discovery of the rabbit mammary pheromone and their vomeronasal organ (VNO) transcriptome was recently characterised, a first step to further study plasticity-mediated transcriptional changes. In this study, we assessed the plastic capacity of the rabbit male and female VNO under sex-separation vs. sex-combined scenarios, including adults and juveniles, to determine whether the rabbit VNO is plastic and, if so, whether such plasticity is already established at early stages of life. First, we characterised the number of differentially expressed genes (DEGs) between the VNO of rabbit male and female under sex-separation and compared it to sex-combined individuals, both in adults and juveniles, finding that differences between male and female were larger in a sex-separated scenario. Secondly, we analysed the number of DEGs between sex-separated and sex-combined scenarios, both in males and females. In adults, both sexes showed a high number of DEGs while in juveniles only females showed differences. Additionally, the vomeronasal receptor genes were strikingly downregulated in sex-separated adult females, whereas in juveniles upregulation was shown for the same condition, suggesting a role of VRs in puberty onset. Finally, we described the environment-modulated plastic capacity of genes involved in reproduction, immunity and VNO functional activity, including G-protein coupled receptors. Our results show that sex-separation induces sex- and stage-specific gene expression differences in the VNO of male and female rabbit, both in adults and juveniles. These results bring out for the first time the plastic capacity of the rabbit VNO, supporting its functional adaptation to specifically respond to a continuous changing environment. Finally, species-specific differences and individual variability should always be considered in VNO studies and overall chemocommunication research.

化学感应信号（chemosensory cues）对于社交与性行为至关重要，其主要由犁鼻系统（vomeronasal system, VNS）检测并处理，该系统的可塑性已在小鼠中得到研究。然而，在实验室环境之外开展化学感应可塑性研究，能够更真实地展现犁鼻系统如何适应不断变化的环境。自兔乳腺信息素被发现以来，家兔已成为化学通讯研究的经典模型；近期其犁鼻器（vomeronasal organ, VNO）转录组已得到表征，这为进一步研究可塑性介导的转录变化奠定了基础。本研究中，我们针对成年与幼年家兔，分别在单性饲养与混合性别饲养两种条件下，评估其雌雄个体犁鼻器的可塑性，以明确家兔犁鼻系统是否具有可塑性，若存在可塑性，该特性是否在生命早期阶段就已形成。首先，我们分别在成年与幼年群体中，表征了单性饲养条件下家兔雌雄个体犁鼻器的差异表达基因（differentially expressed genes, DEGs）数量，并与混合性别饲养个体进行对比，结果发现单性饲养条件下雌雄个体间的基因表达差异更为显著。其次，我们分别针对雌雄个体，分析了单性饲养与混合性别饲养两种条件下的差异表达基因数量。成年个体中，雌雄两性均存在大量差异表达基因；而幼年个体中仅雌性出现显著差异。此外，单性饲养的成年雌性家兔的犁鼻受体基因（vomeronasal receptor genes, VRs）呈现显著下调，而同一饲养条件下的幼年雌性则表现为基因上调，这提示犁鼻受体基因在青春期启动过程中发挥作用。最后，我们分析了参与生殖、免疫及犁鼻系统功能活动的基因（包括G蛋白偶联受体（G-protein coupled receptors））受环境调控的可塑性。本研究结果表明，单性饲养可诱导成年与幼年家兔雌雄个体犁鼻系统出现性别与发育阶段特异性的基因表达差异。本研究首次证实了家兔犁鼻系统的可塑性，支持其通过功能性适应以响应持续变化的环境。最后，在犁鼻系统研究及整体化学通讯研究中，均需始终考虑物种特异性差异与个体间的变异性。