An increasing body of evidence suggests that the state of hyperalgesia could be socially transferred from one individual to another through a brief empathetic social contact. However, how the social transfer of pain develops during social contact is not well-known. Utilizing a well-established mouse model, the present study aims to study the functional role of visual and olfactory cues in the development of socially-transferred mechanical hypersensitivity. Behavioral tests demonstrated that one hour of brief social contact with a conspecific mouse injected with complete Freund's adjuvant (CFA) was both sufficient and necessary for developing socially-transferred mechanical hypersensitivity. One hour of social contact with visual deprivation could not prevent the development of socially-transferred mechanical hypersensitivity, and screen observation of a CFA cagemate was not sufficient to develop socially-transferred mechanical hypersensitivity in bystanders. Methimazole-induced olfactory deprivation, a compound with reversible toxicity on the nasal olfactory epithelium, was sufficient to prevent the development of socially-transferred mechanical hypersensitivity. Intriguingly, repeated but not acute olfactory exposure to the CFA mouse bedding induced a robust decrease in 50 % paw withdrawal thresholds (50 %PWTs) to mechanical stimuli, an effect returned to the baseline level after two days of washout with clean bedding. The findings strongly indicate that the normal olfactory function is crucial for the induction of mechanical hypersensitivity through brief empathetic contact, offering valuable insights for animal housing in future pain research.

中文翻译：

---

视觉和嗅觉方式在雄性 C57BL/6J 小鼠社会转移机械超敏反应发展中的功能作用

越来越多的证据表明，痛觉过敏的状态可以通过短暂的同理心社交接触从一个人转移到另一个人。然而，在社会接触过程中疼痛的社会转移是如何发展的尚不清楚。本研究利用成熟的小鼠模型，旨在研究视觉和嗅觉线索在社会传递的机械超敏反应发展中的功能作用。行为测试表明，与注射了完全弗氏佐剂（CFA）的同种小鼠进行一小时的短暂社交接触对于发展社交转移的机械超敏反应是充分且必要的。一小时的视觉剥夺社交接触并不能阻止社会转移性机械过敏的发生，而对 CFA 笼友的屏幕观察也不足以使旁观者发生社会转移性机械过敏。甲硫咪唑引起的嗅觉剥夺是一种对鼻嗅上皮具有可逆毒性的化合物，足以防止社会转移的机械超敏反应的发生。有趣的是，重复而非急性嗅觉暴露于 CFA 小鼠垫料会导致机械刺激下的 50% 缩爪阈值 (50%PWT) 大幅下降，在使用干净垫料清洗两天后，效果恢复到基线水平。研究结果强烈表明，正常的嗅觉功能对于通过短暂的共情接触诱导机械过敏至关重要，这为未来疼痛研究中的动物饲养提供了宝贵的见解。